Vertebrobazilar aneurysms make about 15% ofall intracranial aneurysms, from which one fifthbelongs to aneurysms a.posterior inferior cerebelli(PICA). Majority of PICA aneurysms is located inthe place of separation from a.vertebralis. Aneurysms of distal part of PICA are very rare,according to literature they make 0.5 to 3% of all

aneurysms. 70 years old man came to neurologist be-cause sudden headache, pain in the neck and a feelingof stiffness followed by throwing up in stream. On the occasion of medical check up attack of sponta-neous subarachnoid hemorhage was suspected. Clinical gradus according to H&H III, initial CT ofendocranium showed existence of smaller intracere-bellar hematoma next to lateral wall of IV ventricleand trace of blood in the very ventricle without signsof acute hydrocephalus. The seventh day after the hemorrhage angio CT wasdone and it showed existence of aneurysm on distalpart of PICA, more specially in the televelotonzilarsegment on the right. After the diagnostics supplemented with standarddigital substractional an-giography which confirmednature and localization of the lesion. In the postponed procedure, and in conformity withstrategy of surgical timing of aneurysms in the backcirculation, patient was operated three weeks after theattack of hemorrhage. Disregarding low incidence of existence of aneurysmsof distal circulation (under 1% of all in the back circu-lation) high level of suspicion should be present andangio CT should be done as screening method, if CTshows hemorrhage which according to localization re-sponses to possible aneurysm.

Key words: distal PICA, aneurysms, SAH

INTRODUCTION

The first review of a case of aneurysm in the vertebro-bazilar flow probably dates from 1829. Cruveilhier.

Afterwards in 1937. Dandy and Tonnis treated two pa-tients with fatal bleeding in the back skull hole - the rea-

son was unknown aneurysm of vertebral artery. Rizzoliand Hayes in 1953. described, for the first time, direct op-eration of aneurysms in the back flow. The role of surgi-cal microscope in the treatment of aneurysms of the backbrain circulation ment revolution in the sense of the iden-tification of the problem, meticulous manipulation withbrain stem, with preservation of the supporting artery andprotecting of surrounding nervous structures.

Vertebrobazilar aneurysms make about 15% of all in-tracranial aneurysms, from which one fifth belongs toaneurysms a. posterior inf. cerebelli (PICA). Majority ofPICA aneurysms is located in the place of separating froma. vertebralis. Aneurysms of distal part of artery posteriorinferior cerebelaris are very rare, according to literaturethey make 0, 5 to 3% of all aneurysms.

REVIEW OF CASE

The patient was 70 years ora many came to neurologistbecause of the sudden headache, pain in the neck and afeeling of stiffness followed by throwing up in stream. Onthe occasion of medical check up attack of spontaneoussubarahnoidal hemoragia was suspected. Clinical gradusaccording to H&H III, initial CT of endocranium showedexistence of smaller intracelebellar hematom next to lat-eral wall of IV ventricle and trace of blood in the IV ven-tricle without signs of acute hydrocephalus (fig.1). Hewas treated with medicines according to protocol forhamoragies including stabilization of hypertension andconsultation with cardiologist. The seventh day after thehemoragia angio CT of endocranium was done and it sho-wed existence of aneurysm on the distal part of PICA,more specifically in the telovelotonzilar segment on the

.........................................Distal posterior cerebellar artery aneurysm: case report

V.T. Jovanovi}, M. Lj. Raki}, B. M. Djurovi},G. M. Tasi}, I. M. Nikoli}, I. A. Pi{~evi}, N. R. RepacInstitut for Neurosurgery, CCS, Belgrade

/PRIKAZ SLU^AJA UDK 616.831-005:616.13-007.64/-07-089

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right (fig.2). After that diagnostics supplemented withstandard digital substractional angiography which con-firmed nature and localization of lesion and pointed to in-cidental finding of small A VM on the same side in theparenhym of cerebellar hemisphere which probably withher hemodynamic influence brought formation of aneu-rysm, and herself wasn’t the reason of hemoragia (fig.3).Afterwards for the purpose of topographic localizationand planning of surgical approach MRI of brain was alsodone and it clearly showed relation of aneurysm with ver-mis and IV cerebral ventricle. Practically, MRI visualiza-tion showed that aneurysim is hanging on the right lateralwall of IV cerebral ventricle (fig.4). ln the postponed pro-cedure,and in conformity with strategy of surgical timingof aneurysms in the posterior circulation, patient was op-erated three weeks after the attack of hemoragia. Opera-tion was realized in the sitting position. The approach wasmiddle-lined subokcipital with unilateral extension. Dur-ing the preparation of supporting artery and aneurysm weapproached through fissure between vermis and cerebellarhemisphere. After identification of clearly defined neckand confirmation of absence of perforator, clips wereplaced in the vicinity. During the operation golden stand-ard in operations of aneurysms was achieved, thereforeaneurysm was directly excluded from circulation like pre-vention from rehemoragia including preserved circulationof supporting artery. Postoperative course passed regu-larly, patient was released eight days after the operationwithout signs of system and local infection. In the neuro-logical finding light truncal ataxia was dominating. Con-trol CT excluded development of hydrocephalus (fig.5).Karnofsky index on the occasion of dismissal was 90.

DISCUSSION

Because of the higher number of patients with hyperten-sion, especially in cases of aged persons, the most oftenform of hemoragia in projection of posterior fossa arebleeding of paravermicular and nc. dentatus because ofamyloidal degeneration. On the other hand subarahnoidalhemoragia of aneurysm etiology is typical in basal cisternin the cases of middle-aged and young persons too, with-out a presence of hypertension and diabetes as often asso-ciated diseases, more often in cases of women [2,3]. Themost oftenlocalization of 17 aneurysm is connection ofvertebral artery and PICA herself. In spite of the fact thattypical vertebral PICA aneurysm is in close relation withhypoglossal nerves and nerves of foramen jugulare, oftendived in medulla, specific signs are rare and the highestnumber of these patients come with picture of spontane-ous subarahnoidal hemoragia. Long term rigidity of neckis characteristic, because of the often presence of blood inthe cistern magna1,6. Focal neurological deficit is alsooften in the cases of giant aneurysms of this locationwhich didn’t present themselves with hemoragia. Majorityof epidemiologic series emphasizes predomination ofwomen in relation 3:1. According to relatively long vas-cular flow of a. PICA she is divided into several seg-ments. These are: anterior medullar, lateral medullar,tonzilomedullar, telovelotonsilar and cortical. Considering

the way of spreading, she vascularizes caudal medulla ob-longata, cerebellar tonziles, lowejr portion of cerebellarhemisphere and vermis and plexus horoideus of IV ventri-cle.4,5,7

Critical surgical points on the occasion of preparation ofaneurysms of this flow are n. IX, n. X and n. XII, whoselittle traction brings to difficult problems of disfagy, disar-try type and potential life endangering aspiration.

Regarding presented anatomical clinical correlations itis logical that the most of real secular aneurysms are onthe initial point of a. PICA from stem of vertebral artery.Going distal way aneurysms are rarer. According to ourexperience and in conformity with published data distalcirculation is more often place for appearance of fuziformand bizarre spreadings which don’t response to real aneu-rysms.

FIGURE 2. CT ANGIOGRAPHY

FIGURE 1. CT OF ENDOCRANIUM AT THE MOMENT OF COMMINGIN THE HOSPITAL

94 V.T. Jovanovi} i sar. ACI Vol. LV

Distal part of a. PICA, as initial point of aneurysm, ismore characteristic in pediatrics population, especially inthe case of existence of smaller AVM in that region whichcauses appearance of high flowing and in that way bringsto creating of aneurysm.

CONCLUSION

Disregarding low incidence of existence of aneurysmsof distal circulation (under 1% of all in the back flow)high level of suspicion should be present and angio CTshould be done as screening method, if CT of endocra-nium shows hemoragia which according to localization

responses to possible aneurysm. If existence of aneurysmis proved then strategy of treatment means operation withcomplete radiology evaluation which was previously doneand preparation of patient. Besides of review of extremelyrare localizations of sacular aneurysm of back flow thiswould be in the same time algorhytm for treatment ofhemoragia in the back skull hole of grown up patients, be-cause the lesion is definitely surgically curable and sur-gery is cure of choice.

SUMMARY

ANEURIZMA NA DISTALNOM SEGMENTU DONJEZADNJE CEREBELARNE ARTERIJE: PRIKAZSLU^AJA

Vertebrobazilarne aneurizme ~ine oko 15% svih intrak-ranijalnih aneurizmi, od ~ega jedna petina pripadaaneurizmama a. posterior inf. cerebelli (a.PICA).Ve}inaaneurizmi PICA-e lokalizovano je na mestu odvajanja oda.vertebralis. Aneurizme distalnog dela arterije posteriorinferior cerebelaris su veoma retke, prema literaturi od 0,5do 3% svih.

Mu{karac star 70 godina javio se neurologu zbog naglonastale glavobolje, bola u vratu i ose}aja uko~enosti,pra}enog povra}anjem u mlazu. Prilikom pregleda sumnjana atak spontane subarahnoidalne hemoragije. Klini~kigradus po H&H III. Inicijani CT endokranijuma pokazaopostojanje manjeg intracerebelarnog hematoma uz later-alni zid IV komore i trag krvi u samoj komori bez znak-ova akutnog hidrocefalusa. Sedmog dana nakon hemor-agije uradjen angio CT endokranijuma koji je ukazao napostojanje aneurizme na distalnom delu a.PICA-e, ta~nijetelovelotonzilarnom segmentu desno. Nakon toga dijag-nostika dopunjena standardnom digitalnom supstrak-cionom angiografijom koja je potvrdila prirodu i lokali-

FIGURE 4. MRI OF ENDOCRANIUM

FIGURE 3. CONVENTIONAL ANGIOGRAPHY

FIGURE 5. CONTROL CT AFTER SURGERY

Br. 2 Distal postertior cerebellar artery aneurysm 95

zaciju lezije. U odlo‘enom postupku a u skladu sastrategijom hirur{kog tajminga aneurizmi u zadnjem slivubolesnik je operisan nakon tri nedelje od ataka hemoragijeBez obzira na nisku incidencu prisustva aneurizmi dis-talne cirkulacije (ispod l % svih u zadnjem slivu) trebaimati visok stepen sumnje i uraditi angio CT kao skriningmetodu ukoliko CT endokranijuma poka‘e hemoragijukoja po lokalizaciji odgovara eventalnoj aneurizmi

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