6ournal of Neurology, Neurosurgery, and Psychiatry 1995;58:116-124

Proceedings of the 125th Meeting of the Society of BritishNeurological Surgeons, University of Dundee,7-9 September 1994

FAMILIAL FRONTONASAL DERMOID CYSTSJT H CALLOSAL AGENESIS

I Jacobson, MA Jeeves, W Mcnab. RoyalInfiriaary, Dundee and the University of StAndre*s, UK

Objective-To report a unique family inwhich three generations have presentedwith frontonasal dermoids, epilepsy, andsignificant psychometric and interhemis-phere transfer abnormalities.Design-Over a 30 year period eight

members of a family have been clinicallyand radiologically studied with extensivepsychometric and neurophysiological con-

firmation. Five have been operated on.

Results-The syndrome described has a

poor long term outcome particularly inrespect of seizure control and the develop-ment of progressive dementia. Althoughfamilial nasal dermoid cysts and also famil-ial syndromes of callosal agenesis have beendocumented to date,' 2 no similar family hasever been recorded. Also, this syndromeseems to be progressive with increasing longterm disability. This is also different fromother callosal syndromes. A combinedsingle stage frontonasal approach is recom-

mended for surgical management ofdermoid cysts.

1 Baarsma EA. The median nasal sinus and der-moid cyst. Archiv Otorhinolaryng 1980;226:107-13.

2 Aderman E. Agenesis of the corpus callosum.In: Vinken PJ, Bruyn GW, eds. Handbookfor clinical neurology. Amsterdam: NorthHolland 1981;1:6-9.

AVOIDABLE RISK FACTORS ANDPOSTOPERATIVE HAEMATOMA

JD Palmer, OC Sparrow, F Iannotti.Wessex Neurological Centre, Southampton,UK

This study has examined the surgical prac-tice at the Wessex Neurological Centre over

a five year period from 1989 to 1993 todetermine the incidence of postoperativehaematoma (POH) and identify risk factorsfor a perioperative bleeding disorder. Thestudy included only those POHs (at anysite) that followed, and were related to, a

neurosurgical operation and were surgicallyevacuated. The study was prospective forthe year 1993 and retrospective for the pre-ceding years.

Over the five years 6668 operations were

performed and 71 POHs were surgicallyevacuated giving an overall rate of 1-06% ofoperations. The records were available on 69cases. The most frequent diagnosis leading toPOHs was meningioma surgery with a rateof 6-16% of cases (13/211), followed by cranio-tomy for trauma 3-65% (7/192), aneurysmsurgery 2-57% (11/428), and intrinsicsupratentorial tumours 2-22% (10/451).POHs were intracerebral (ICH) in 43%,

subdural in 5%, extradural (EDH) in 33%,

mixed in 8%, and wound in 11% of cases.The mortality from POH was 32% (37%for ICH, 12% for EDH). Risk factors for aperioperative bleeding disorder were presentin 2/3 of the patients. Administration ofantiplatelet agents (aspirin, NSAIDs) wasthe most common risk factor, identified in30 of the 69 patients. At least 75% of iden-tified risk factors could have been avoidedor corrected before surgery.

A RANDOMISED DOUBLE BLIND STUDY OFSODIUM VALPROATE FOR THE PREVENTIONOF SEIZURES IN NEUROSURGICAL PATIENTSJP Holland, SR Stapleton, AJ Moore, HTMarsh, D Uttley, BA Bell. AtkinsonMorley's Hospital, London, UK

Objective-Anticonvulsant drugs are com-monly prescribed to prevent seizuresthat may follow head trauma or craniotomydespite no evidence from prospective stud-ies of a truly prophylactic benefit. A ran-domised double blind study of sodiumvalproate has been performed to assess itsefficacy in the prevention of postoperativeseizures.Design-A total of 301 patients were ran-

domly assigned to treatment with sodiumvalproate (n = 152) or placebo (n = 149)for one year in a double-blind trial. Anintravenous loading dose was given in theanaesthetic room before craniotomy orwithin 24 hours of head injury. Patientswere stratified prospectively into high orlow risk categories in the head injury andcraniotomy groups. Serum concentrationsof valproate were maintained in the thera-peutic range 40-80 jug/l for one year andfollow up was continued for two years fromrandomisation.

Results-The overall incidence of seizureswas similar in both arms of the study, 21%for placebo and 18% for active treatment,but there was a significant reduction inthe incidence of seizures in the low riskcraniotomy group (non-space occupyinglesions): 11% v 24% (p < 0-01 at sixmonths, p < 0 05 at two years).

Conclusions-Sodium valproate given for12 months exerts a prophylactic anticonvul-sant effect in those patients undergoing acraniotomy for a non-space occupyinglesion by significantly reducing the inci-dence of seizures up to two years fromrandomisation.

USE OF GUIDELINES FOR HEAD INJURYMANAGEMENT IN SCOTLANDDL Oluoch-Olunya, AD Braes, GMTeasdale. Institute of NeurologicalSciences, Glasgow and Scottish HealthManagement Efficiency Group, UK

Objectives-To discover current approachesto management of head injuries in Scotland,how this relates to published guidelines, andhow well these are known.

Design-Questionnaires were sent on pre-hospital and hospital management to hospi-tals with accident and emergencydepartments in Scotland.

Subjects-Fifty one hospitals (teachingn = 10, district general n = 16, rural/remoten = 25) in all the 13 Scottish boards weresurveyed between April 1993 and February1994.Outcome measures-Facilities available

and type of guidelines used.Results-Ninety seven per cent of the hos-

pitals had a local 24 hour skull x ray servicebut only 24% had a local CT service.Teaching and district general hospitals usedguidelines, but in only 39% were thesederived from the Harrogate Seminar' andthe guidelines of 1984.2 Thirty six per centof the remote/rural hospitals did not use anytype of guidelines.

Conclusion-The guidelines published adecade ago need to be revised to takeaccount of changes in CT availability andclinical practices. There is a need to targetthe remote/rural hospitals to use head injurymanagement guidelines.

1 Lewis AF, ed. The management of acutehead injury. Harrogate Seminar Report 8.London: DHSS, 1983.

2 Guidelines for the initial management afterhead injury in adults. BMJ 1984;288:983-5.

MONITORING OF INTRACRANIAL OXY ANDDEOXYHAEMOGLOBIN LEVELS IN HEADINJURED PATIENTS USING NEAR INFRAREDSPECTROSCOPY: ARE CALCULATIONS OFCEREBRAL HAEMOGLOBIN SATURATIONVALID?PJ Kirkpatrick, P Smielewski, M Czosnyka,JD Pickard. Addenbrookes Hospital,Cambridge, UK

Near infrared spectroscopy (NIRS-Hamamatsu 1000) and jugular venousoximetry aJVO-Oximetrix 3) have beenemployed in six ventilated, severely headinjured patients to monitor potentialchanges in cerebral oxygenation. In allpatients, NIRS demonstrated transientreductions in oxygenated haemoglobin(Hbo,) levels during waves of raisedintracranial pressure (ICP) that were closelycorrelated with transcranial Doppler middlecerebral artery flow velocities (FV) and cor-tical perfusion (laser Doppler flowmetry-LDF). Although about 15% of these eventswere correlated with JVO changes, mostepisodes of potential desaturation duringraised ICP were not registered by JVO.

During stable states of ICP, FV, LDF,JVO, and NIRS, spontaneous variations inthe Hb and Hbo, signals were found. Oncalculating the ratio [AHbo2]/[A(Hbo2 +Hb)] derived during 10 minute epochs, atheoretical value for cerebral haemoglobinsaturation (HbSat) can be calculated.Comparison with static JVO measurements

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calibrated with co-oximetry indicated a rea-sonable correlation (r2 = 0 68). The NIRSderived HbSat, however, assumes a con-stant saturation during the sampling epochwhich is affected by changes in cerebralblood volume. These conditions may not besatisfied during dynamic changes in ICPand cerebral blood flow. Indeed, NIRSderived calculations of HbSat during ICPwaves showed poor correlation with JVO,and occasionally gave results which werenot sensible (for example, HbSat > 100%).

It is concluded that whereas NIRSderived Hbo2 signal changes are sensitive tocerebral haemodynamic changes that pre-dict focal ischaemia, algorithms that calcu-late continuous and dynamic changes inHbSat from rapid variations in HbO2 andHb signals should not be regarded as reli-able.

EFFECT OF EXTRACEREBRAL TISSUE ON NON-INVASIVE MEASUREMENT OF CEREBRALBLOOD FLOW BY NEAR INFRAREDSPECTROSCOPYH Owen-Reece, CE Elwell, M Smith, DTDelpy, JS Wyatt, WFJ Harkness. NationalHospital for Neurology and Neurosurgeryand University College, London, UK

Near infrared spectroscopy (NIRS) is atechnique with potential for quantifyingcerebral blood flow (CBF) non-invasively.The theoretical and practical aspects' havepreviously been described and CBF hasbeen measured in conscious and anaes-thetised subjects.2 Median CBF duringanaesthesia was 25 ml.100g-'.min-', whichis lower than typically obtained by altema-tive methods. It was predicted that thiseffect was due to extracerebral tissue andwould not be seen in measurements madeon the dura. The purpose of this study wasto obtain measurements of CBF by posi-tioning the optical fibres on the dura inpatients undergoing craniotomy.

Six patients undergoing excision of atemporal lobe epileptic focus were anaes-thetised with a standard technique. Beforesurgery CBF was measured as described,'after craniotomy, CBF measurements wererepeated on the dural surface. In eachpatient arterial pCO2 and blood pressurewere standardised for the two measure-ments.Mean CBF measured on the scalp was

21 (8) and on the dura 67 (23)ml.100g'.min-'. The difference was highlysignificant (p < 0-001). The most likelyexplanation is light scattering by extracere-bral tissue. These data support the theoreti-cal validity of CBF measurement by NIRS.

1 Elwell CE, et al. Measurement of cerebralblood flow in adult humans using nearinfrared spectroscopy-methodology and pos-sible errors. Adv Exp Med Biol 1992;317:235-45.

2 Owen-Reece H, et al. Use of near infraredspectroscopy to measure cerebral blood flowin conscious and anaesthetised subjects. BrJAnaesth 1994 (in press).

EFFECT OF CLOWARD'S ANTERIOR CERVICALFUSION ON INTERVERTEBRAL FORAMINALSIZERD Strachan, CGH West. Hope Hospital,Salford, UK

Objective-The presumed effect ofCloward's cervical fusion on intervertebralforaminal topography is largely anecdotal.

Many surgeons believe that restoration ofdisc height and intervertebral foraminaldimensions are important for a successfulsurgical outcome. Few efforts have beenmade, however, to quantify what happensto the configuration of the intervertebralforamen after insertion of a cylindrical graft.This prospective study considers this ques-tion.Design-Using standardised preoperative

and postoperative oblique cervical spineradiographs, image magnification, cross sec-tional planimetry, and computer assistedanalysis, the effects of Cloward's anteriorcervical fusion on intervertebral foraminaldimensions have been quantified.

Results-A study of the first 12 patientsconfirmed that after fusion, mean cross sec-tional area increased from 0-66 (0 03) cm2to 0 75 (0 05) cm,2 or by an average 13-5%.This increase in area was significant whencompared with control non-operative values(p < 0 05). The maximum transverseforaminal dimension also significantlyincreased from 12-6 (0-31) mm to 13-6(0 38) mm after surgery (p < 0 05). Thischange was highly significant when com-pared with the control non-operative values(p < 0 005).

Conclusion-Cloward's discectomy andfusion does increase the intervertebralforaminal dimensions.

DOES THE USE OF BOP OCTA PROVIDE ASUITABLE ALTERNATIVE TO ILIAC CRESTAUTOLOGOUS BONE GRAFT IN ANTERIORCERVICAL DISCECTOMY AND FUSIONT Sattar, A Penrose-Stevens, JRS Leggate.North Manchester General Hospital,Crumpsall, UK

In anterior cervical discectomy and fusion,whether by the technique of Cloward or ofSmith-Robinson, the major cause of mor-bidity and prolonged stay in hospital isrelated to the bone graft donor site.Substitutes for autologous bone have beentried but have failed due to mechanical col-lapse, non-union, or graft rejection. In aseries of 36 patients (61% women, 39%men) the bone graft was replaced by anacrylic polymer implant, BOP (octa). Themean age of the group was 46-5 years and29 (81%) underwent a single level fusionand seven (19%) a two level fusion. Thecommonest level involved was C5/6 (56%)and then C6/7 and C4/5. Preoperative MRIwas obtained in 25 (70%) and postoperativeMRI or CT were performed in nine patients(27%). The median inpatient stay was 5-5days, and mean follow up was 13 months(range 6-24). Anterior prominence hasbeen noted on MRI in one patient, but todate no graft rejection, infection, or collapsehas been found. It seems that BOP (octa)may be a suitable altemative to iliac crestbone. This pilot data is the basis for aprospective trial of BOP (octa) in anteriorcervical spinal surgery.

LATERAL BRANCH OF THE POSTERIORPRIMARY RAMUS-KEY FOR THEPOSTEROLATERAL APPROACH TO EXTREMELATERAL LUMBAR DISC HERNIATIONSM O'Brien, D Peterson, HA Crockard. TheNational Hospital for Neurology andNeurosurgery, London, UK

Introduction-Extreme lateral lumbar discherniations (EL-TLH) are reliably detectedon MRI and CT. Access remains problem-atic with conventional posterior approaches.

Objective-To identify constant anatomi-cal landmarks which will facilitate access tothese disc hemiations via an approach thatdoes not require bone resection.

Design-(a) Anatomical dissections:Bilateral lumbar spine dissections were per-formed on 10 cadavers. The lateral branchof the posterior primary ramus (LBPPR)was identified and its relation to adjacentvertebral structures was analysed. (b)Operative procedures: A longitudinal skinincision 8-10 cm from the midline was fol-lowed by an oblique posterolateral musclesplitting approach. Microsurgical tech-niques were used for nerve root decompres-sion.

Patients-Nine men and one woman wereexplored for 10 ELLDJHs identified at L1-2in one patient, L2-3 in one patient, L3-4 inthree patients, L4-5 in three patients, andat L5-S 1 in two patients.

Outcome measures-Postoperative relief ofnerve root compression symptoms.

Results-(a) Anatomical dissections:Accompanied by the terminal branch of thesegmental artery, the LBPPR was consis-tently found medially between the longis-simus and the intertransverse muscleoverlying the transverse process of the adja-cent caudal vertebra. Laterally it entered theiliocostalis. (b) Operative Procedures: Bluntdissection with the index finger consistentlyidentified the LBPPR as a taut band inthe iliocostalis. This was followedto the intervertebral foramen. Decom-pression was achieved without bone resec-tion. Operative time ranged from 45-95minutes. All patients obtained relief of clini-cal symptoms.

Conclusions-Identification of the LBPPRduring the posterolateral approach facili-tates rapid localisation and safe removal ofE I Hs without bone resection.

THE PATHOGENESIS OF PERIDURALFIBROSIS-A MACROSCOPIC, MICROSCOPIC,AND IN SITU HYBRIDISATION STUDYKM Morris, AJ Freemont, JA Hoyland,MIV Jayson. Department of Neurosurgeryand Rheumatology, Hope Hospital,Manchester and Department of Pathology,University of Manchester, UK

Objective-To determine the time courseand pathological processes leading to theformation of peridural fibrosis after discalsurgery in a rabbit- model and to re-evaluatethe proposed role of peridural haematoma.'Design-Macroscopic and microscopic

observational study of the formation ofperidural scar including evaluation of tem-poral and spatial changes in mRNA expres-sion for types I, II, and Ill collagen andfibroblast collagenase by in situ hybridisa-tion.

Subjects-Twenty rabbits with 40 macro-scopically and 40 microscopically studiedsurgical sites were examined at two and fourdays and 1, 2, 3, 6, 9, 12, 15, and 18 weeksafter trans-spinal discal surgery.

Outcome measures-Four point gradedmacroscopic dissection and observation ofmatrix formation during peridural repair.2Microscopic observation of the formation ofperidural fibrosis and correlation withchanges in matrix protein mRNA expres-sion.

Results-Formation of clinically signifi-cant scarring was delayed until three weekspostsurgery. Blood clot was cleared fromthe peridural space by one week andreplaced by an "inflammatory exudative"

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provisional matrix which together with bio-mechanical factors maintained contactbetween injured dural and canal surfaces.

Fibroblast proliferation occurred from allinjured surfaces except the dura. Type IIIcollagen mRNA was expressed at the duracanal interface for three weeks, and type ImRNA for six weeks after surgery.Collagenase mRNA was expressed for sixweeks after surgery. Type H collagenmRNA was not expressed at the dural inter-face.

Prolonged matrix protein mRNA expres-sion occurred in deep structures in associa-tion with remodelling or secondarydegeneration.

Conclusions-Peridural wound healingwas similar to repair in other tissues.Mechanical apposition, formation of anexudative matrix, and prolonged productionof matrix proteins are likely to be at least asimportant as peridural haematoma in theformation of peridural fibrosis. The poten-tial for matrix deposition persists for at leastsix weeks after surgery.

1 LaRocca H, Macnab I. The laminectomymembrane. Study of its evolution, charac-teristics, effects and prophylaxis in dogs.JEBone joint Surg Br 1974;56B:545-50.

2 Songer ML, Ghosh L, Spencer DL. Effects ofsodium hyaluronidate on peridural fibrosisafter lumbar discectomy. Spine 1990;15:550-4.

DOES SURGERY ON THE RHEUMATOIDCERVICAL SPINE BENEFIT THE BED BOUND,NON-AMBULATORY (RANAWAT 3B)MYELOPATH? 3B OR NOT 3B ?ATH Casey, HA Crockard. The NationalHospital, London, UK

Objectives-To determine the efficacy ofcervical spine surgery on Ranawat class 3bpatients, and to identify by statistical analy-sis the prognostic factors determining surgi-cal success.Design-A prospective study of rheuma-

toid patients undergoing surgery formyelopathy secondary to atlantoaxial sub-luxation during a 10 year period 1983-93.

Patients-There were 256 patients treatedfor cervical spine involvement by therheumatoid process of which 55 fromRanawat class 3b underwent surgery.

Outcome measures-Neurological outcomewas assessed using the Ranawat classifica-tion (1-3b), and functional outcome usingthe Health Activity Questionnaire (HAQ)disability index. Statistical analysis was per-formed by univariate analysis, multiplelogistic regression, and survival analysis,with significance accepted at the 5% level.

Results-There were 55 class 3b patients(mean age 65; 44 women, 11 men) whounderwent surgery either by a combinedanterior transoral and posterior approach(37) or a posterior approach alone (18).The mean duration of hospital stay was 26days of which 5-3 days were spent in ITU.Postoperative morbidity was recorded in 27patients (49%) and the 30 day mortalitywas 12-7%. During follow up a further 24patients have died (47%) with a mean timeto death of only 14-4 months. Significantneurological or functional improvement wasseen in 14 patients (24-5%). Adverse prog-nostic factors included increasing age, levelof pre-operative disability, spinal canaldiameter, and spinal cord area.

Conclusions-Surgery on Ranawat class3b carries a high morbidity and mortalitywith only modest improvement in neurolog-

ical or functional outcome. Surgical referralpatterns need to be improved and it ishoped that prompt surgery before the devel-opment of irreversible cord damage andatrophy may yield more favourable results.

COMPLEX DISORDERS OF THE PAEDIATRICCRANIOCERVICAL JUNCTIONHA Crockard, ATH Casey, WFJ Harkness,RD Hayward. The National Hospital andthe Hospital for Sick Children, London,UK

Osseous anomalies affecting the paediatriccraniocervical junction malformation arerare making it difficult for any one surgeonto accrue significant experience in this area.To redress this deficiency a paediatric cran-iocervical clinic has been created whichcombines the experiences of the depart-ments of surgical neurology at the NationalHospital and those at Great Ormond Street.The purpose of this presentation is to pre-sent the first year's experience.

Material and methods-Eleven patients(four male; seven female) mean age 5-6years, have been treated to date. Their pre-operative diagnoses included spondyloephy-seal dysplasia (four), cervical dysplasia(one), otopalatal digital syndrome (one),achondroplasia (one), Morquio's syndrome(one), two cases of atlantoaxial rotarydislocation, and congenital atlantoaxialsubluxation (one). Abnormalities encoun-tered in the congenital group included osodontoideum, atlantoaxial subluxation,anterior and posterior spina bifida, and seg-mentation defects. Preoperative evaluationby other paediatric specialists hasbeen particularly informative. Under-standing of the pathomechanics of thesecomplex problems and surgical planning isassisted by CT (both two and three dimen-sional reconstructions), MRI, and angiogra-phy in selected cases.

Surgical technique-The surgical approachwas tailored to the individual case withthree approaches being used (transoral, farlateral, and posterior). A halo device wasapplied preoperatively when instability wasanticipated. For stabilisation and fusion wehave employed a technique that uses auto-logous calvarium harvested from theparietoccipital region. It is secured by thetitanium sof' wires(rM), which facilitatespostoperative imaging. The resultant bonydefect is repaired by using split thicknesscalvarium.The management of these complex cases

and their complications shows the advan-tages of a combined speciality clinic in unitswith a full array of paediatric services.

DOES THREE DIMENSIONAL MAGNETICRESONANCE ANGIOGRAPHY SUBSTITUTE FORCONVENTIONAL ANGIOGRAPHY IN SURGICALMANAGEMENT OF RUPTURED CEREBRALANEURYSM?DA Jellinek, D Wilcock, JL Firth, T Jaspan,I Holland, B Worthington. Departments ofNeurosurgery and Radiology, UniversityHospital, Nottingham, UK

Objective-To determine -if magnetic reso-nance angiography (MRA) is an acceptablesubstitute for conventional angiography insurgical management of subarachnoidhaemorrhage (SAH).Design-Comparison of the sensitivity

and specificity of MRA with conventionalangiography in the detection and surgicalcharacterisation of cerebral aneurysm in

patients with a proved diagnosis of recentSAH.Patients-Twenty patients with proved

diagnosis of SAH had both MRA and con-ventional angiography.Method-A three dimensional "time of

flight" MR angiogram sequence was per-formed before surgery to image the circle ofWillis, the cavernous carotid arteries, theMl segments, and the posterior circulationto the origin of the PICAs. The examiningradiologist (blind to the results of conven-tional angiography) recorded whether ornot he thought an aneurysm was present.When an aneurysm was found on MRAthe images were reviewed neurosurgically toestablish if sufficient information was avail-able for surgery; MRA images were alsoreviewed in the light of operative findingsand compared with the conventionalangiogram.Results-MRA was a sensitive and speci-

fic test for the diagnosis of cerebralaneurysm. The MRA also provided infor-mation not available from the conventionalangiogram about the distal (clotted)aneurysm sac. In the presence of a largeperianeurysmal haematoma, however, surgi-cal characterisation of the aneurysm wasstill difficult.Conclusion-MRA has a valid role in the

management of aneurysmal subarachnoidhaemorrhage.

MAGNETIC RESONANCE ANGIOGRAPHY INTHE MANAGEMENT OF ANEURYSMALSUBARACHNOID HAEMORRHAGE: A STUDYOF 51 CASESS Sankhla, WJ Gunawardena, CMACoutinho, AJ Keogh. Royal PrestonHospital, Preston, UK

Objective-To assess the usefulness of mag-netic resonance angiography (MRA) in themanagement of subarachnoid haemorrhage(SAH) from a suspected berry aneurysm'with the object of early surgical obliterationof any aneurysms found.Method-Review of 51 patients who had

sustained a SAH and were investigated byMRA. Fifty aneurysms at a variety of siteswere identified in 43 patients, with normalresults in eight. MRA was performed(Siemens 1-5 T Magnetom) using a threedimensional time of flight sequence2 as wellas standard MRI. Intra-arterial digital sub-traction angiography (IA DSA) was alsoperformed at some stage.

Results-(a) Group 1: 38 patients (75%)were classified as having satisfactory andaccurate MRA results (findings (32 withaneurysms and six without) were confirmedat surgery and/or on IA DSA). On the basisof the MRA results alone 20 patients (23aneurysms) underwent surgery before IADSA. (b) Group 2: Thirteen patients (25%)were classified as having unsatisfactoryMRA results, nine had movement artefacts;three false negatives (6%), and one falsepositive (2%).

Conclusion-The safe and non-invasiveinvestigation of MRA gives satisfactoryinformation in a high percentage of patientssustaining an SAH, 38/51 (74 5%), allow-ing early surgery without recourse to IADSA in most 20/32 (62-5%).

1 Gouliamos A, Gotsis E, Vlahos L, et al.Magnetic resonance angiography comparedto intra-arterial digital subtraction angiogra-phy in patients with subarachnoid haemor-rhage. Neuroradiology 1992;35:46-9.

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2 Ross JS, Mararyk TJ, Modic MT, et al.Intracrnial aneurysms: evaluation by MRangiography. Am Neuroradiol 1990;11:449-56.

A PROSPECTIVE RANDOMISED TRIAL OFEFFICACY OF TIRILAZAD MESYLATE IN

PATIENTS WITH SUBARACHNOIDHAEMORRHAGEAD Mendelow. European/AustralianTirilazad SAH Study Group

Tirilazad mesylate (U-74, 006F) is a syn-thetic non-glucocorticoid steroid thatinhibits iron catalysed lipid peroxidation. Aprospective randomised placebo controlledclinical trial of three doses (0-6, 2-0, and 6-0mg/kglday) given at six-hourly intervals forup to 10 days was conducted in patientswith CT or LP confirmed subarachnoidhaemorrhage and angiographically con-

firmed aneurysms. A total of 1015 patientsfrom 41 centres was randomised andreceived at least one dose of treatmnent. Allpatients received nimodipine. End pointsincluded the functional outcome on theGlasgow outcome scale (GOS) at threemonths, incidence and severity of angio-graphic and symptomatic vasospasm, andCT infarction at 14 days and three months.

There was no significant difference in theprimary end point of favourable outcome(good recovery/moderate disability) com-

pared with unfavourable outcome (severedisability/vegetative/dead) between placeboand the three doses given, although at thehighest dose favourable outcomes occurredin 72% of treated patients compared with67% of controls. There was a significantreduction in mortality at the highest dose(6-0 mg/kg/day) compared with placebo(12% v 21%) and a significant increase inthe number of patients who made a goodrecovery (64% v 53%). There were also nosignificant differences in the proportion oftreated and untreated patients with CTinfarction (nor in the volume of infarction)at three months.

CHANGES IN MICROVASCULAR PERMEABILITYIN A RODENT MODEL OF FOCAL CORTICALINJURY USING 14C AIB AUTORADIOGRAPHY:THE EFFECT OF TIRILZAD MESYLATE

P Mathew, DI Graham, R Bullock, JMcCulloch, GM Teasdale. Institute ofNeurological Sciences, Glasgow, UK

O0jective-To determine the changes inmicrovascular permeability with time in a

new rodent model of focal cortical injury,and to assess the effects of Tirilazad.Design-Forty adult Sprague-Dawley rats

were studied. Focal cortical contusions were

produced by applying a localised suctionimpact.1 Animals were randomly allocatedto sham operated (n = 5), lesion (n = 5),and Tirilazad tested (n = 5) groups for eachsurvival time of 30 minutes, four hours, and24 hours. Animals receiving Tirilazad were

given 10 mg/kg intravenously, five minutesafter injury.End points-Measurement of cerebral

microvascular permeability by 14C AIBquantitative autoradiography,2 and volumetrcassessment of the autoradiographic lesion.Results-Compared with sham operated

animals there was a significant increase in

perilesional microvascular permeability atall time points studied; this increase was

most pronounced at four hours (mean k

(SEM) = 21-9 (0-6/1000) min), and coin-cided with the greatest volume of the lesion

(mean volume (SE) = 15-48 (0-7) mm3). Intirilazad treated animals at four hours therewas a significant reduction in microvascularpermeability (k = 3-1 (0-5), p < 0 001) andlesion volume (4-86 (0 7) mm3, p < 0.01).

Conclusions-In this model a delayedincrease in microvascular permeabilityoccurs which is significantly minimised bypostinjury treatment with IV tirilazad.

1 Mathew P, Graham DI, Bullock R, et al. Focalbrain injury: histological evidence of adelayed inflammatory response in a newrodent model of focal contusion injury. ActaNeurochir (Wein) 1994;60(suppl 1):428-30.

2 Blasberg RG, Padak CS, Jehle JW, et al. Anautoradiographic technique to measure thepermeability of normal and abnormal braincapillaries. Neurology 1978;28:363.

INTRATHECAL CALCITONIN GENE-REIATEDPEPTIDE REDUCES ISCHAEMIC BRAIN DAMAGEJP Holland, BA Bell. Atkinson Morley'sHospital, London, UK

Objective-Calcitonin gene-related peptide(CGRP) is an endogenous vasodilating neu-ropeptide which has a selective action onthe cerebral arteries causing an increase incerebral blood flow.' High doses of intra-venous CGRP are known to cause systemicvasodilatation resulting in an unwanteddrop in blood pressure,2 and this study setout to test the efficacy of the peptide givenintrathecally.Design-A series of dose response experi-

ments have defined an intrathecal bolusdose of CGRP of 225 ng/kg whichincreased cerebral blood flow by 28% in theanaesthetised rat but had no effects on sys-temic blood pressure. Using this dose theeffects of pretreatment with intrathecalCGRP (n = 10) compared with normalsaline (n = 10) were studied in a model offocal cerebral ischaemia.

Results-The treatment group maintaineda higher cerebral blood flow (31 ml/100g/min compared with 15 ml/100 g/min, p <0-01) and the concomitant volume ofischaemic brain injury was reduced by 57%(94 (18) compared with 204 (21) mm,2 p <0-001). There was no systemic hypotension.

Conclusions-These findings show thepotential benefits of intrathecal CGRP infocal cerebral ischaemia.

1 Edvinnson L, et al. Calcitonin gene-relatedpeptide and cerebral blood vessels; distribu-tion and vasomotor effects. J Cereb BloodFlow Metab 1986;7:720-8.

2 European CGRP in subarachnoid haemor-rhage study group. Effect of CGRP inpatients with delayed post-operative cerebralischaemia after aneurysmal subarachnoidhaemorrhage. Lancet 1992;339:831-4.

POSSIBLE THERAPELUTC ROLE FORENDOTHELIN ANTAGONISTSS Galbraith, T Patel, M McAuley,J McCulloch. Wellcome Surgical Instituteand the Department of Neurosurgery,University of Glasgow, UK

Endothelins are implicated as a cause ofneural damage after cerebral ischaemia.Their role in focql cerebral ischaemia andthe therapeutic possibilities of their modifi-cation by the endothelin antagonist bosen-tan has been examined.

Materials and methods-In anaesthetisedadult cats a craniectomy was made over theparietal cortex and the dura reflected. Themiddle cerebral artery was permanentlyoccluded via a transorbital approach.

Arteriolar calibre was measured with animage splitter. Artificial CSF or drugs dis-solved in CSF were injected into theperivascular subarachnoid space.

Results-Occlusion of the middle cerebralartery produced a mixture of vasoconstric-tion and vasodilatation. The perivascularmicroapplication of bosentan (30 #M)resulted in an increase in arteriolar diameterof 20% (p < 0 001 v CSF). The numericalincrease was greater in vessels which wereconstricted after induction of ischaemia.

Conclusions-Endogenous endothelinsconstrict or impair the dilatation of corticalvessels in the territory of focal ischaemiaand this can be attenuated by the endothe-lin antagonist bosentan. Endothelin antago-nists may therefore have a therapeutic rolefollowing cerebral ischaemia.

RESECTION OF THE PATHOLOGICALSUBSTRATE IN THE TEMPORAL NEOCORTEXJP Phillips, 0 Hardiman, M Farrell, HStaunton. Beaumont Hospital, Dublin,Ireland

Fifty patients underwent superficial tempo-ral lobectomy for intractable temporal lobeepilepsy. Total cure rate was 52% and sig-nificant improvement was achieved in 88%.Cytoarchitectural changes in grey and whitetissue were analysed under lightmicroscopy. Neuronal dysgenesis was corre-lated with the duration of seizure disorder,age on onset, and other aetiological factors,and with clinical outcome. Temporal lobesfrom 33 neurologically normal necropsybrains which were age and sex matchedwith patients were examined as controls.Severe neuronal ectopia (> 8 neurons/2mm2 white matter) was present in 42% ofpatients with epilepsy and in none of thecontrols. There was neuronal clustering in28% of those with epilepsy and Chaslin's(subpial) gliosis in 38%. Controls did nothave these changes. The presence of severeneuronal ectopia and clustering was predic-tive of a favourable clinical outcome aftersurgery (p < 0-05). No correlation wasfound between microdysgenesis and otherfactors. These findings suggest that thepresence of neuronal dysgenesis may be ofsignificance in the clinical outcome aftersurgery, and that the abnormal tissue maybe important as a morphological substratefor seizures in some patients. It is proposedthat micro dysgenesis is one spectrum ofcortical dysplasia and that resection of thispathological substrate is in effect a lesion-ectomy procedure.

ICTAL SPECT AS A LOCALISINGINVESTIGATION IN EXTRATEMPORALEPLEPSIESR Duncan, J Patterson, K Lindsay, RRoberts, D Hadley. Institute ofNeurological Sciences, Glasgow, UK

Ictal HMPAO SPECT has proved reliableas a localising investigation in mesial tem-poral lobe epilepsies, but focal epilepsiesoriginating elsewhere in the brain have beenlittle studied.

Ictal HMPAO SPECT images in 10patients with focal epilepsies are presented,where other localising data (seizure semiol-ogy, interictal and ictal EEG, MRI) haveshown extratemporal origin, in eightpatients in different areas of the frontallobe, and in two patients at the temporo-occipital junction.

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All 10 patients showed hyperperfusion atthe site of the focus. Among the eightfrontal lesions, two patients also showedactivation of parts of the contralateralfrontal lobe. Activation of the basal ganglia,thalamus, and/or cerebellum were seen infive patients, as well as hypoperfusion of thehemisphere contralateral to the focus inthree patients, and ipsilateral in one. In thetwo temporo-occipital lesions, activation ofthe ipsilateral lateral temporal lobe wasseen, involving the mesial temporal struc-tures and basal ganglia to a lesser degree.Ictal hypoperfusion in these two patientswas ipsilateral to the focus.

Ictal rCBF patterns may be complex inextratemporal seizures, but do seem to dis-tinguish them from mesial temporal seizuresand to provide useful localising information.

CORRELATION BETWEEN PRE-OPERATIVE MRIDIAGNOSIS AND HISTOLOGICAL FINDINGS INPATIENTS UNDERGOING SURGERY FORINTRACTABLE EPILEPSYJ Allibone, N Alsanjari, DR Fish, J Duncan,H Cross, B Neville, WFJ Harkness. TheNational Hospital for Neurology andNeurosurgery and the Hospital for SickChildren, London, UK

Objective-To demonstrate the value ofMRI, as part of a predominantly non-inva-sive protocol, in the preoperative assess-ment of patients undergoing surgery formedically intractable epilepsy.Design-Comparison of the preoperative

anatomical MRI diagnosis with the histo-logical findings after surgery for medicallyintractable seizures.

Patients-The first 100 patients who wereoperated on by the senior surgical author astreatment for epilepsy.

Results-Seventy-four patients presentedwith partial seizures due to an underlyingtemporal lobe abnormality. MRI sequencesused included Ti and T2 imaging, T2mapping,' IR, FLAIR, MPRAGE, and vol-umetric analysis of- hippocampal volume.2Preoperative MRI indicated hippocampalsclerosis (HS) in 45 cases and mass lesionsin 29. All patients in this group underwenttemporal lobectomy. HS was confirmed in47 cases and mass lesions of variable histol-ogy in all 29 cases. Seventeen patients, all ofwhom showed gross anatomical abnormali-ty on MRI, underwent hemispherectomy.Eight patients underwent craniotomy forextratemporal lesions (six stereotactically)and one had a stereotactic biopsy. Foreigntissue was detected in all pathological speci-mens.

Conclusion-MRI provides an accurate,reliable, and non-invasive method of localis-ing structural abnormality and determiningthe underlying pathology in patients withmedically intractable epilepsy. AdvancedMRI techniques, however- are oftenrequired.

1 Jackson GD, et al. Neurology 1993;43:1793-9.2 Cook MJ. Brain 1992;115:1001-15.

FRAMELESS STEREOTACTIC SURGERY FORNEOCORTICAL LESIONAL EPILEPSYPK Doshi, DGT Thomas, DR Fish, SDShorvon. The National Hospital forNeurology and Neurosurgery, London, UK

The outcome of any lesional epilepsydepends on its complete surgical excision.Frameless stereotactic techniques not onlyhelp in delineating the lesion but, by

their interactive information, also assist incomplete excision. Eight patients with med-ically intractable epilepsy underwent frame-less stereotactic guided excision. Therewere four men and four women, agerange 21-36 (median 31) years. All patientswere subjected to minimal craniotomies andcomplete excision of the lesion. The overallaccuracy in locating the lesion was 1 26(SD 0 35) mm. They were evaluated at twomonths after surgery by MRI to confirm theextent of resection, and for change in theirseizure frequency. Seven patients had com-plete excision of their lesions. Six patientshad not experienced any seizures after dis-charge (Engel grade I) and two patients hadmore than significant reduction (Engelgrade II) in their seizures. Thus framelessstereotaxy is a valuable adjunct to opensurgery for accurately localising and resect-ing epileptogenic lesions.

REVIEW OF THALAMOTOMY: THEMANCHESTER EXPERIENCES Chatterjee, PL Richardson. ManchesterRoyal Infirmary, Manchester, UK

A review of 34 thalamotomies between1984 and 1993 is presented. Twenty twoprocedures were performed for multiplesclerosis related abnormal movements, theremainder for other indications.

Preoperative tremor was scored withrespect to each of rest, action, and terminalaccentuation. Preoperative disability wasscored using the method described byFahn, et al.' Similar scores were obtained atsix months follow up and at yearly followups. The period of follow up varied from 10months to 108 months (median 37months). The thalamotomy was performedby the same surgeon using the Leksell frameand ventriculography for localisation.

Patients with multiple sclerosis weregraded into early, established, or advancedcategories. The results for those with earlyor established disease were favourable ini-tially in 11 out of 13 procedures (83%)although there was recurrence of tremorwithin 18 months in 10 of these 11 (91%).The period of improvement varied from fiveto 18 months. In patients without multiplesclerosis, the results were more satisfyingwith improvement initially in 11/12 proce-dures which was sustained at 18 monthsfollow up in 8/11 cases.We are convinced that there is a definite

role for thalamotomy in patients with invol-untary movements even if these are associ-ated with demyelinating disease.

1 Fahn S, Tolosa E, Mann C. Clinical ratingscale for tremor. In: Janovic J, Tolosa F,eds. Parkinson's disease and movement disor-ders. Baltimore: Urban and Schwarzenberg,1988:225-34.

STEREOTACTIC IIMBIC LEUCOTOMY: ACONTINUING TECHNIQUE FOR THETREATMENT OF AFFECTIVE DISORDERSND Kitchen, HT Marsh, AE Richardson.Atkinson Morley's Hospital, London, UK

In 1973 Richardson and colleaguesdescribed the procedure of stereotactic lim-bic leucotomy.' The technique is still in useat Atkinson Morley's Hospital and consistsof the production of 14 lesions bilaterally inthe cingulum bundle and the ventromedialquadrant of the frontal lobes.

After application of the Leksell frame

under general anaesthetic a sitting LP is per-formed and air ventriculography and tele-radiology used to calculate target sites. Athermistor electrode is then used to createelectrocoagulative lesions of about 1 cm indiameter. Electrophysiological corroborationof electrode placement is achieved by moni-toring the effects on breathing of stimulationand lesioning. Postoperative MRI is used toassess the site and size of lesions.

Since 1987 stereotactic limbic leucotomyhas been successfully performed on 23patients with severe refractory affective dis-orders (depression (five), Gilles de laTourette syndrome (two), and obsessive-compulsive disorders (16)). Neurologicalcomplications have been minor - namely,transient incontinence (five), confusion(one), and lethargy (four) and one tempo-rary facial palsy.The current technique of stereotactic him-

bic leucotomy is simple, safe, and accurate.It retains its place in the treatment of thosefew patients with life threatening affectivedisorders refractory to other therapeuticmodalities.

1 Kelly D, Richardson AE, Mitchell-Heggs N.BrJ Psychiatry 1973;123:133-40.

PREOPERATIVE DIAGNOSIS OF NEUROVASCULARCOMPRESSION OF THE TRIGEMINAL NERVEUSING MAGNETIC RESONANCETOMOANGIOGRAPHYLT Dunn, JF Meaney, PR Eldridge, JBMiles, TE Nixon. The Walton Centre forNeurology and Neurosurgery, Liverpool,UK

Microvascular decompression (MVD) isa well recognised treatment for trig-eminal neuralgia (TGN). Hitherto, however,it has been impossible to demonstrate neu-rovascular compression (NVC) preopera-tively.The use of high definition magnetic reso-

nance tomoangiography (MRTA) was inves-tigated in the preoperative assessment of 52patients with TGN (54 symptomatic and 50asymptomatic nerves) and 25 healthy volun-teers (50 nerves).MRTA findings-(a) TGN: 90% (48/54)

had NVC in the axilla, and a further 4%within 5 mm of this region. Only twopatients showed no evidence of NVC (5%).In 18% of cases NVC was thought to bevenous and in 16% compression from morethan one vessel was demonstrated. (b)Controls: NVC was present in the axilla ofthe nerve in only 8% of cases; in 9% therewas vascular contact within 5 mm of thiszone, and in a further 14% contact occurredmore distally on the trigeminal nerve.

Surgical correlation-In all but one casesurgical findings agreed with the preopera-tive MRTA findings. In this case NVC waspredicted to be in the axilla but found some5 mm away. In four early cases veins andnot arteries were found at surgery.Retrospective analysis of the MRTA coulddemonstrate this distinction. Two cases hadpersistent pain after a technically satisfactoryMVD. Postoperative MRTA showed a sec-ond vessel causing NYC. To date one ofthese cases has successfully undergone re-exploration.Conclusion-MRTA is a sensitive and spe-

cific method for demonstrating NVC. It is auseful aid to preoperative decision makingand is of value in avoiding incomplete oper-ative decompression. It is now a standardpreoperative investigation of TGN at theWalton Centre.

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BRAIN STEM AUDITORY EVOKED POTENITIALSDURING CEREBELLOPONTINE ANGLESURGERYTRK Varma, A Forster. Dundee RoyalInfirmary, Dundee, UK

Objective-To review and evaluate the use

of brain stem auditory evoked potentials(BSAEPs) during cerebellopontine anglesurgery.

Design-A retrospective view of 46patients undergoing cerebellopontine anglesurgery where BSAEP was monitored.

Patients-Thirty four patients undergoingmicrovascular decompression (MVD) hadperoperative BSAEP monitoring in an

attempt to reduce the incidence of hearingloss during this procedure.'2 Nine patientswith acoustic neuromas had BSAEP moni-toring to assist in hearing preservation.Three patients underwent vestibularneurectomy for intractable Meniere's dis-ease where BSAEP helped identify and pre-serve the auditory nerve.

Outcome measures-The value of BSAEPmonitoring during cerebellopontine anglesurgery in relation to the incidence of hear-ing loss.

Results-Peroperative changes in BSAEPwere seen often during MVD proceduresand these were readily reversed by reduc-tion in retraction. Long term hearing losswas seen in only one patient where therewere technical problems with the monitor-ing. BSAEP helped identify and preservethe auditory nerve in acoustic neuroma

surgery. Hearing was preserved in six out ofnine patients. BSAEP confirmed the identi-ty and helped preserve function of the audi-tory nerve during vestibular neurectomy.

Conclusions-BSAEP monitoring duringcerebellopontine angle surgery is a usefulmethod of identifying the auditory nerve

and helps prevent damage to the nerve.

1 Fritz W, Schafer J, Klein HJ. Hearing lossafter microvascular decompression fortrigeminal neuralgia. Neurosurgery 1988;69:367-70.

2 Friedman WA, Kaplan BJ, Gravenstein D,Rhoton AL. Intra-operative brain stem audi-tory evoked potentials during posterior fossamicrovascular decompression. Neurosurg1 985;62:552-7.

LONG TERM FACIAL NERVE FUNCTION AFTER

ACOUSTIC NEUROMA SURGERYBA Bell, NF Weir, KS O'Neill. AtkinsonMorley's Hospital, London, UK

Objective-Permanent loss of facial nerve

function is a significant cause of morbidityafter successful surgery to remove largeacoustic neuromas, and all of the existingtechniques to improve a postoperative facialpalsy have drawbacks. A glued sural nerve

graft has been used when the facial nerve

was divided in achieving total removal oflarge tumours and compared with the longterm results from non-grafted patients.Design-Ninety acoustic neuromas have

been removed using intraoperative facialnerve monitoring over the past seven years,

and in 69 (77%) the facial nerve was pre-served. In 21 (23%) the facial nerve wasdivided in achieving total tumour removal,and in 16 of these patients a sural nervegraft was placed between the divided ends

of the facial nerve, and fibrin tissue gluewas used to secure the neural anastomosis.In five patients a direct end to end repairwas possible without the need for a graft.Facial function was assessed using thefacial paralysis prognostic index (FPPI),'

and the House and Brackmann grading sys-tem.2Results-Two year follow up was available

for three patients with a direct repair andeight patients with sural grafts. Good facialfunction (FPPI 5 to 8) was achieved inseven patients (64%), satisfactory facialfunction (FPPI 4) in two (18%), and poorfunction where graft failure was consideredto have occurred (FPPI 0 to 3) in twopatients (18%). Of the 51 patients withintact facial nerves with two year follow upavailable, good facial function was achievedin 40 (78%), satisfactory facial function inthree (6%), and poor function in eightpatients (16%).

Conclusion-Fibrin glue facial nervegrafting is simple to perform at the end ofthe operative removal of a large acousticneuroma and restores satisfactory facialfunction at two years to 82% of patients.This is similar to the two year outcome forpatients where the facial nerve was thoughtto be anatomically intact at the end oftumour removal.

1 Kerbavaz RJ, Hilsinger RL, Adour KK. Thefacial paralysis prognostic index. OtolaryngolHead Neck Surg 1983;91:284-9.

2 House JW, Brackmann DE. Facial nerve grad-ing system. Otolaryngol Head Neck Surg1985;93: 146-7.

CHANGES IN PROTON MRS OF PERITUMOURALOEDEMA BEFORE AND AFTERDEXAMETHASONEP Chumas, A Stewart, B Condon, DOluoch-Olunya, D Hadley, G M Teasdale.Institute of Neurological Sciences,Glasgow, UK

Objective-To date the mechanism of actionof dexamethasone in the treatment of braintumours is poorly understood. We haveutilised MRI and MR spectroscopy (MRS)to further elucidate potential modes of action.

Design-Proton MRS using a Siemens1-5 T system pre and then 12 hours postadministration of dexamethasone.

Subjects-Eight patients (three men, fivewomen, mean age 54) with malignantgliomas were examined using MRI andMRS pre dexamethasone administrationand then within 12 hours after administra-tion and comparison made between ipsilat-eral and contralateral white matter.

Results-There was no significant changein the unsuppressed water peak in either ofthe regions following dexamethasone, whichsupports the findings of Bell,' that peritu-moural oedema takes days to alter. Regionsover the oedema had significantly (p <0-05) higher unsuppressed water than thecontralateral regions. In all cases NAA/Choand NAA/Cr decreased after the adminis-tration of dexamethasone. Lactate wasfound in the oedematous region of onepatient predexamethasone and doubledpostadministration. In two other patientsmeasurable lactate peaks appeared postadministration.

Conclusion-Increases in lactate may rep-resent anaerobic glycolysis in oedematousand hypoxic white matter.2 Changes inNAA are difficult to interpret but may rep-resent attempts at white matter repair.

1 Bell BA, Smith MA, Kean DM, et al. Brainwater measured by magnetic resonanceimaging: Correlation with direct estimationand changes following mannitol and dexa-methasone. Lancet 1987;i:66-9.

2 Cruickshank GS, Rampling R. Acta Neurochir1994;60(suppl):375-7.

INCIDENCE OF INTRACRANIAL TUMOURS INLOTHIAN REGIONR Grant, D Collie. Westem GeneralHospital, Edinburgh, UK

Objective-To identify the incidence ofintracranial tumours in the Lothian Region.Design-Audit of all incident cases of CT

identified intracranial tumour in SEScotland. Data were obtained from all CTcranial scans performed in SE Scotland(1989 and 1990), supplemented by neurol-ogy, neurosurgery, neuro-oncology, neu-ropathology, radiation therapy, andendocrine databases in Lothians and SMR6data. Lothian region patients were identi-fied by post code. Lothian region popula-tion was obtained from the April 1991census.

Patients-A total of 578 patients withintracranial tumour of any type wasanalysed by tumour type (primary intra-cerebral, secondary intracerebral, benignintracranial extra-cerebral, others). Identi-fication of pituitary microadenoma wasbased on hyperprolactinaemia with or with-out CT.

Outcome measures-Incidence of specificintracranial tumours in Lothian Region incases/100 000 population/year.

Results-Incidence of all intracranialtumours of any type in the Lothian Regionis 28/100 000/year. Primary intrinsic braintumours had an incidence of nine (gliomas7 3). Incidence of secondary intracerebraltumour was 13-1, meningioma 2-5, pitu-itary tumours 2-3 (macroadenoma 1-0),acoustics 0-6, and others 0-6.

Conclusion-Cancer registration data inScotland, and single institution studies havesignificantly underestimated the incidenceof brain tumours.

THALLIUM AND HMPAO SPECT EVALUATIONOF MALIGNANT BRAIN TUMOURS: EXTENT OFSURGICAL RESECTION, TUMOUR REGROWTH,AND RESPONSE TO TREATMENTGS Cruickshank, J Patterson, D Hadley.Institute of Neurological Sciences,Glasgow, UK

Objectives-Postsurgical, residual viabletumour volume and recurrence during orafter therapy has been followed by SPECTstudies to determine suitability for deter-mining surgical prognosis, tumour recur-rence, radiation necrosis, and malignantchange in tumours.

Design and patients-Thirty patients withbrain tumours had preoperative 20'T1 andHMPAO SPECT scans, again within fivedays of operation, at six weeks, and at 12weeks with further scans as appropriate.Tumour and contralateral brain indiceswere evaluated together with estimates ofvolume of uptake by tumour.

Outcome measures-(a) Total volume(cm3); (b) tumour to brain ratio; (c) coregis-tration CT/MRI/SPECT.

Results-The most useful finding was theability to detect tumour recurrence at amuch earlier stage than either CT or MRI.The most viable portions of tumour couldbe selected for biopsy or removal and thesedid not always coincide with the morpho-logical picture presented by conventionalscanning. The response to therapy could befollowed.

Conclusions-20'T1 is a useful technique forfollowing tumour regrowth and response totreatment. It can assist in selecting the areasto biopsy tumours and can provide a map of

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viable tumour location to use in conjunc-tion with MRI or CT operative planning.This type of planning offers the possibilityof selecting patients for early aggressivetreatment of their tumours that haverelapsed or show malignant change beforeneurological damage has progressed.

ENDOSCOPIC TREATMENT OF COLLOID CYSTSP Barlow. Institute of NeurologicalSciences, Glasgow, UK

Six patients with a colloid cyst of the thirdventricle underwent endoscopic drainage,or attempted drainage, of the cyst. In fivepatients the procedure was successful inthat it produced relief of symptoms with noserious complications. In one patient thecyst, an incidental CT finding, could not befound.The technique is described and the

advantages and disadvantages discussed.The main disadvantage of endoscopicdrainage is that complete excision of thecyst does not seem feasible; therefore,because the risk of recollection is unknown,long term follow up will be required.Open surgical excision is probably still

the procedure of choice in most patients.

EFFICACY OF OPERATION FORMICROPROLACTINOMA: SUSTAINEDREMISSION AT 10 YEARSGM Teasdale, JA Thomson, DA Davies, HMcLaren. Institute of NeurologicalSciences, Glasgow, UK

Objectives-To define the long term (10years) results of operation for a micropro-lactinoma.Design-Case record and postal follow up

of 61 patients previously reported,' 75% ofwhom had a normal prolactin (PRL) afterfive years.

Subjects-Forty five patients who weretraced at 10 years.

Outcome measures-Serum PRL < 360mU/l.

Results-Thirty three patients (74%) hada normal serum PRL. Relief of symptomswas noted in 76% of those with amenor-rheoa, 87% with galactorrhoea, and 83%with infertility.

Conclusions-The results contradict anotorious previous report of recurrence ofhyperprolactinaemia in > 50% of patients.2Selective microadenomectomy is a usefuloption in management of a microprolactin-oma.

1 Thomson JA, Teasdale GM, Gordon D, et al.Treatment of presumed prolactinoma bytransphenoidal operation: early and lateresults. BMJ 1985;291:1500-3.

2 Serri 0, Raslo E, Beauregard H, et al.Recurrence of hyperprolactinaemia afterselective transphenoidal adenomectomy inwomen with prolactinoma. N Engi J Med1983;309:280-2.

CLINICAL OUTCOME AND HAEMODYNAMICTYPE OF CEREBRAL ARTERIOVENOUSMALFORMATIONS TREATED WITH LINACRADIOSURGERYAH Huneidi, DS-Montefiore, D Doughty,PN Plowman, F Afshar, KE Britton. StBartholomew's Hospital, London, UK

Objective-To correlate the clinical outcomewith the haemodynamic type of arteriove-nous malformations (AVM) after LINAC(linear accelerator) stereotactic radiosurgery(SRS).

Design-Comparison of angiographicobliteration rate and incidence of complica-tions between fast and slow flow AVM afterSRS.

Subjects-Eighty two patients (age 38(12) years) with cerebral AVMs were treat-ed with angiographic SRS (LINAC; 5-ArcSystem; 25 Gy to 90% isodose). All wereassessed clinically and with cerebral bloodflow (CBF) studies before SRS and at threeto six month regular intervals thereafter.The mean follow up period was 36 (10)months.Outome measures-Size of treated AVMs,

incidence of complications, rate of angio-graphic obliteration of AVM, and changesin cerebral reserve (RI) and steal (SI)indices.Results-AVM diameter ranged from 8 to

55 mm (< 25 mm (71%), 25-40 mm (24%)and > 40 mm (5%)). Total obliteration ratewas 70% at 24 months and 75% at 36months. By contrast with slow flow AVMsfor similar sizes, the fast flow AVMresponse to SRS was quicker (ARI = 0-24(0-02); ASI = - 020 (0-02) at 18 months;p < 0-05). Three patients rebled at four, 18,and 20 months; one of whom died (50 mmdiameter AVM). Six patients developednew neurological deficits; most were slowflow AVMs.

Conclusions-Fast flow AVMs show aquicker response to radiosurgery with alower complication rate than slow flowAVMs.

GIANT INTRACRANIAL ANEURYSMS:A REVIEW OF 65 CASESVS Mehta. All India Institute of MedicalSciences, New Delhi, India

Giant intracranial aneurysms defined asbeing larger than 2-5 cm in diameter arereportedly uncommon. Among 374 patientswith intracranial aneurysms managedbetween January 1986 and September1993, 65 (17-4%) patients had giantaneurysms. Among them 39 (60%) present-ed with subarachnoid haemorrhage and 26(40%) as a mass lesion. In two patients thepresentation was unusual.

In 58 patients (89%) the aneurysm wasin the anterior circulation (ICA 39, ACOM11, and MCA eight), in seven patients itwas in the posterior circulation (BA fourand VA three) and there were multipleaneurysms in five patients. Nine patientsdeveloped partial or complete thrombosis ofthe aneurysm either spontaneously or iatro-genically (possibly the result of earlier per-cutaneous carotid angiography). In sixpatients surgery was not carried out becauseof a medical contraindication or poor clini-cal grading. Three patients refused surgeryand one died before surgical intervention.

Fifty two surgical procedures were car-ried out on 45 patients. In 23, the aneurysmwas clipped, in 17 a carotid occlusion(immediate or gradual), and in two patientsa trap ligation was performed. Four patientsunderwent a STA-MCA anastomosis beforecarotid ligation. In five patients a variety ofmethods were used and the procedure wasabandoned in three patients.

HOW GOOD IS GOOD ON THE GLASGOWOUTCOME SCALE AFTER SUBARACHNOIDHAEMORRHAGE?TJ Pigott, M Deane. The Walton Centrefor Neurology and Neurosurgery,Liverpool, UK

After subarachnoid haemorrhage (SAH) thepatients in the good outcome group on theGlasgow outcome scale (GOS) do havesome continuing problems. SF-36 is anewly validated patient centred assessmentproforma developed to survey healthstatus.' The form has eight different areascovering physical, psychological, and socialaspects.The results of a pilot study are reported

using the SF-36 assessment in patients whohave been successfully treated for SAH witha good outcome on the GOS. A total of 29patients were assessed using the SF-36.Responses were received from 26 (93%).The age range was from 33-72 years; themale:female ratio was 1:2.

In each aspect of SF-36 there was areduction in score compared with norma-tive data.2 This was most pronounced in theareas of physical and mental function.Although these were worse than the norma-tive data, they indicate less disruption to anormal lifestyle than in some other chronicconditions such as low back pain and men-orrhagia, but not varicose veins.

1 Ware J, Sherbourne C. The MOS 36-itemshort form health survey (SF-36). Med Care1992;30:473-83.

2 Garratt A, Ruta D, Abdalia M, et al. The SF-36 health survey questionnaire. BM_J 1993;306:1440-4.

REVERSED DRAINAGE OF BRAIN INTERSTITIALFLUID THROUGH VENULAR BLOOD-BRAINBARRIERV Kunanandam. Hull Royal Infirmary,Hull, UK

Objective-To assess brain venules as anadditional pathway for brain interstitial fluid(ISF) drainage,1 particularly when there is arise in brain tissue pressure (BTP).

Design-Electron microscope (EM) studyof passage of intraventricular horseradishperoxidase (HRP) through ISF pathwaysduring periods of normal and raisedintracranial pressure (ICP).

Subjects-Ventricular perfusion with HRPwas carried out in eight anaesthetised Wistarrats. The animals were killed by cardiacperfusion of fixative after exposure of thebrain to a period of raised ICP. Eight con-trol animals had no period of raised ICP.

Outcome measures-EM detected the posi-tion of HRP in the brain tissue and venules.Results-HRP entry from the brain into

venules as vesicles and through the tightjunctions was observed in the experimental,but not the control animals.

Conclusions-Brain venules allow ISFdrainage when the BTP rises: thus venulesprobably regulate BTP. The venular ISFdrainage mechanism has important thera-peutic implications in the management offluid balance and ventilation in raised ICPstates.

1 Cserr HF, Patlak CS. Secretion and bulk flowof interstitial fluid. In: Bradbury MWB, ed.Physiology andpharmacology of the blood-brainbarier. Berlin: Springer-Verlag, 1992:245-61.

A STUDY OF PERIOPERATIVE LUMBAR CSFPRESSURE IN PATIENTS UNDERGOINGACOUSTIC NEUROMA SURGERYR Laing, P Smielewski, M Czosnyka, DHardy, J D Pickard, P J Kirkpatrick.Addenbrooke's Hospital, Cambridge, UK

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Objective-To measure changes in CSFpressure after acoustic neuroma surgery andto relate these to changes in cerebral bloodflow velocity.Design-Lumbar catheters were used to

measure CSF pressure and transcranialDoppler (TCD) to measure flow velocity inthe middle cerebral artery (MCA).Although lumbar catheters were sited no

CSF was drained.Subjects-Twenty five patients undergo-

ing translabyrinthine or retromastoid exci-sion of acoustic neuroma. All hadpreoperative MRI and histological confir-mation after uneventftl tumour excision.Measures-ICP, amplitude of CSF pres-

sure pulse wave, arterial blood pressure,and the correlation coefficient betweenamplitude of pulse wave and CSF mean

pressure (RAP), which reflects exhaustionof compensatory reserve, were recordedevery minute by a microcomputer; TCDflow velocity was recorded on a daily basis.

Results-All patients showed a statisticallysignificant rise in CSF pressure and RAP(suggesting decreased cerebrospinal com-

pensatory reserve) after surgery. Theseincreases tailed off over the next four days.Changes in MCA flow velocity were usuallyindependent of changes in ICP although ina few cases a significant positive correlationwas found.

Conclusion-After acoustic neuroma

surgery there is a transient disturbance ofCSF dynamics with raised ICP anddecreased compliance. The change in com-pliance is not consistently the result ofincreased flow velocity and possibly of cere-

bral blood volume. These findings mayaccount for the significant reported inci-dence of postoperative CSF leakage.

NEUROSURGERY AND GERONTOLOGY: FACTSAND FIGURESDP O'Brien, J Nagaria, D Rawluk.Beaumont Hospital, Dublin, Ireland

Objective-Neurosurgical experience ofhealth care management for the geriatricpopulation was reviewed, in particular thetypes of clinical presentations, neuropathol-ogy, management, and final functional out-come on discharge.

Design-Retrospective analysis of alladmissions to the department of patients of65 years and over, for a 12 month period.Patients-One hundred and eighty

patients were studied (80 men, 100 women)which accounted for 9% of all admissionsthat year.

Outcome measures-Clinical presentations,Glasgow coma score, CT findings, clinicalcourse, management, and Glasgow out-come score on discharge.

Results-The age range was 65-91 (mean72-3) years (median 72 years). Interhospitaltransfers (n = 137) accounted for 76% ofadmissions and were deemed "emergency"(118/137 = 86%) or "urgent" (19/137 =14%). The commonest presentations were

headache (29%), confusion (22%), andhemiparesis (14%). According to theGlasgow coma score (GCS), 8%, 16%, and76% had severe, moderate, and minor

impairment of conscious level respectively.Eleven patients (6%) were transferred intu-bated and ventilated. CT was performed in151 patients (84%) in whom tumour(21%), chronic subdural haematoma(15%), subarachnoid haemorrhage (15%),

and acute subdural haematoma (9%) were

diagnosed. Fifty patients (28%) either didnot require operative intervention or were

unfit for surgery. Overall, intracranialtumours, cerebral trauma, intracranialhaemorrhage, and spinal disease accountedfor 28%, 22%, 18%, and 10% of the geri-atric admissions respectively. There were 14deaths (8%). On discharge, 33%, 21%,35%, and 3% were categorised as full recov-

ery, moderate disability, severe disability,and persistent vegetative states respectively.The overall hospital stay ranged from 1-57days (mean = 12-7 days; median = 10days).

Conclusions-Elderly patients constitute a

major proportion of the neurosurgical work-load. This has major medical, rehabilita-tion, and socioeconomic implications.

MR NEUROGRAPHY OF CERVICAL ROOTS ANDBRACHIAL PLEXUSAG Filler, FA Howe, CE Hayes,JR Griffiths, BA Bell, JS Tsuruda.Atkinson Morley's Hospital, London, UK,CRC Magnetic Resonance ResearchGroup, London, UK, and University ofWashington, Seattle, USA

Objectives-Nerve pathology involving thedistal cervical roots and brachial plexus hasbeen difficult to diagnose accurately.Precise placement of electrodiagnostic elec-trodes has been problematic and mostimaging modalities have yielded poorresults. The initial reports of magnetic reso-

nance neurography all focused on simplelinear nerves such as the sciatic nerve in thethigh and the median nerve in the upperarm. The technical problems involved inadapting MR neurography for use in thelower neck and proximal shoulder regionwere the subject of this investigation.

Design-Specialised radiofrequency coilarrays have been developed to provide goodsaturation of the brachial plexus and distalcervical roots. New pulse sequences havebeen implemented for use on a GE Signa1-5T clinical imager that allows the use ofdiffusion weighting as well as previouslyreported aspects of the technique.'

Subjects-There were two normal subjectsand 18 patients with a variety of diseases.

Outcome measures-This approach has ledto very effective images of the brachialplexus and distal cervical roots based on

image conspicuity.Results-Even mild radiculopathy may be

associated with image changes in individualnerve roots which are detectable by thistechnique, whereas more severe injury alsocauses gross enlargement of the roots. Inmany cases these results have aided surgicalplanning.

Conclusions-Brachial plexus neurographyhas now proved technically feasible.

1 Filler AG, Howe FA, Hayes CE, et al.Magnetic resonance neurography. Lancet1993;341:659-61.

MRI SIGNAL CHANGES IN DENERVATED

MUSCLEGA West, M Kliot. Atkinson Morley'sHospital, London, UK and University ofWashington, Seattle, USA

Objectives-To evaluate peripheral nerve

injuries using MRI in comparison with stan-dard electrodiagnostic studies and clinicalexamination.

Design-All patients had sequential neu-rological examinations, EMG, and MRimaging. Tl, T2, and short-tau inversionrecovery (STIR) images were obtained witha 1-5T magnet.

Patients-A total of 32 patients (10females, 22 males, ages 4-72 years) with awide variety of peripheral nerve lesions wereevaluated.

Outcome measures-Serial clinical exami-nations, EMG, and STIR images were usedto assess peripheral nerve function.

Results-A total of 52 MR studies wasperformed on 32 patients. The average timebetween onset of peripheral nerve symp-toms and MRI in 16 patients was 176 (93)days. Increased STIR signal in muscle, asearly as four days after onset of symptoms,was seen in cases of severe axonotmeticinjuries (transection of axons producingsevere denervation) and correlated with thedegree of denervation. In cases of neuro-praxic nerve injuries (conduction blockwithout axonal loss) the STIR signal inmuscle was normal.

Conclusions-Denervation changes inmuscle can be seen using STIR imagingand correlate with EMG changes and clini-cal examination. The STIR images providea panoramic visual representation of dener-vated muscles useful in localising and grad-ing the severity of peripheral nerve injurysecondary to disease or trauma. Thus STIRimaging may play an important part in pre-diction of outcome and formulation oftreatment soon after peripheral nerve injury.

IMAGE DIRECTED SURGERY OF THE SPINE:PRELIMINARY EXPERIENCE WITH THE ISGVIEWING WANDN Patel, I Nelson, B Cumnmins, DSandeman. Frenchay Hospital, Bristol, UK

Interactive image guided surgery is applica-ble to a complete cross section of intracra-nial problems. Stereotactic techniques havenot, however, been applied outside the cra-nium. The versatility of the ISG viewingwand has made it possible to make use ofthe system in the spine. Three spinal opera-tions out of a total of 260 cases are report-ed. Two of these were anterior approachesto odontoid peg and skull base causingmedullary compression. The third was acase of a small sacral osteoblastoma, pro-ducing lumbar back pain. Both cases of cer-vicomedullary compression had complexatlantoaxial disease with a major element ofbasilar invagination. Wand registration wascarried out using the same techniquedescribed for intracranial procedures. Thewand was used to plan the choice ofapproach, transoral or transmaxillary, todetermine precisely the midline, and todetermine the depth and extent of resectionin drilling out the odontoid peg. In bothcases registration accuracy was comparablewith that obtained with intracranial proce-dures.

Registration to the rest of the spine can-not be carried out using the same tech-niques as used intracranially because of thelack of rigid fixation of the wand base to thepatient. A method has been devised forovercoming this difficulty. Subjectiveassessment suggested that the accuracy of

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12r1oceedings of the 125th meeting of the Society ofBritish Neurological Surgeons

the registration was not as good as could beachieved intracranially and was of the orderof ± 5 mm. If the technique of registrationcan be perfected then this has other applica-tions for spinal surgery-for example, thepositioning of interpedicular screws and ori-enting unfamiliar approaches to the cervicalspine. The system also has application inthe surgery of pelvic disorders, such as frac-tures and tumours.

OPERATIVE TREATMENT OF THE TETHEREDCORD SYNDROME: EVALUATION AND EARLYMORBIDITYRW Kirollos, PT van Hille. GeneralInfirmary, Leeds, UK

Objective-As the indications for surgicaltreatment of the tethered cord syndrome are

increasing, it is essential to assess the surgi-cal risks especially if surgery is to be under-taken as a prophylactic procedure.

Patients-Between June 1991 and May1994, 20 patients underwent surgical treat-ment for the tethered cord syndrome. Theirages ranged from five months to 53 years.There were 14 women and six men. Twentyone operations were performed, 14 for pro-gressive neurological deficit, three for pro-

gressive lower limb deformity, and four as a

prophylactic procedure.All patients underwent MRI to confirm

the diagnosis. Cord tethering was due to a

spinal lipoma in 12 cases, diastematomyeliain four, and a tight filum terminale or

intradural adhesions in the remainder. Ninepatients had undergone previous surgery toclose a myelomeningocoele shortly afterbirth. Previous surgery did not affect therate of subsequent successful untethering.

Results-There were four early postopera-tive complications; three CSF leaks, allrequiring re-operation, and one patientshowed an increase in established neurolog-

ical deficit. None had new irreversible neu-

rological deficit as a result of surgery.

Conclusion-This low rate of complica-tions and the success of satisfactory unteth-ering justifies surgery to prevent furtherneurological deficit as a prophylactic measure.

OUTCOME OF POST-TRAUMATICSYRINGOMYELIAS Sgouros, B Williams. Midland Centre forNeurosurgery and Neurology, Smethwick,UK

Traumatic paraplegia is the commonestcause of non-hindbrain related syringo-myelia. Forty three patients with a mean

age of 33-7 years at presentation have beentreated at the Midland Centre between1972 and 1992. A variety oftreatment strategies have been employedover the years, including syringosubarach-noid and syringopleural shunts, cord tran-section, pedicled omental grafttransposition and recently wide decompres-sive laminectomy with formation of a

surgical meningocele.The overall postoperative complication

rate was 10-6%. Problems specific to theoperation type included dislodged andblocked drains (six). Acute gastric dilatationwas seen after pedicled omental graft(one). One drain became infected. At 10years only 60% of the drains insertedremained functioning. A higher thanexpected rate of cervical spondyloticmyelopathy has been noted. Two patientsdeveloped Charcot's joints.Twenty two patients were asked to score

themselves with regard to limb function andperformance of daily living activities and32% reported improvement.

Since the use of MRI became wide-spread, it has become apparent thatdecompressive laminectomy with openingof the subarachnoid spaces is particularly

effective in controlling the syrinx cavity. Incomplete paraplegics, cord transection is aneffective alternative. Pedicled omental graft-ing was associated with poor outcome andincreased complication rate and has beenabandoned.

SYRINGOMYELIA: A REVIEW OF 51 PATIENTSSY Sharif, MS Eljamel, CN Pidgeon.Beaumont Hospital, Dublin, Ireland

Syringomyelia is a chronic progressive dis-ease with current management being contro-versial. We reviewed 51 consecutive patients(24 men and 26 women) who were treatedsurgically. The mean age at presentation was40 7 years. Main presenting symptoms werecervical pain, sensory disturbance, andmotor deficit. Significant tonsillar herniationwas present in 90% of patients, 18% hadhydrocephalus, and 12% had spina bifida.Average duration of observation betweendiagnosis and surgical intervention was oneyear. Adequate documentation of clinicalcourse before surgery was available in 39patients, and of these 82% reported deterio-ration. Half of these patients had repeat MRIand 78% showed progression of their syrinx.Ventricular shunts were inserted in ninepatients, posterior fossa decompression wasperformed in 40 patients, and syrinxdrainage in 10 patients. There were nodeaths, 70% of patients complained of severeheadache, 4% had a wound infection, and2% had a temporary CSF leak. Adequatepostoperative follow up was available in 42patients, of whom 55% improved and 16%progressed. Postoperatively, MRI was per-formed on 15 patients, and eight showed col-lapse of syrinx and six remained unchanged.Thus shunting the hydrocephalus is advocat-ed as the first line of surgical treatment, fora-men magnum decompression forArnold-Chiari malformation, and lastlysyringotomy, if required.

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