Bilateral carotid aneurysms unmasked by severehypopituitarism
Alain Michils, Daniele Baleriauxl and Jean Mockel
Departments ofEndocrinology and 'Radiology, Erasme Hospital, Universite Libre de Bruxelles, B-1070Brussels, Belgium
Summary: We describe a patient who initially presented with severe hyponatraemia and grand malseizures, without any focal neurological symptoms. The final diagnosis was that of giant bilateral carotidaneurysms extending into the sella turcica with anterior hypopituitarism. To the best of our knowledge,this is the first case report of symmetrical carotid aneurysms manifested exclusively by an acute endocrineemergency with none of the concomitant usual focal signs such as headache, failing vision, oculomotorpalsy or subarachnoid hemorrhage.
Introduction
Carotid aneurysms mimicking pituitary tumoursare responsible for parasellar syndromes withneurological and mass effect symptoms dominatingthe clinical presentation.`-5 The patient reported isexceptional in two ways. Firstly giant bilateralintracavernous carotid aneurysms were presentand secondly the grand mal seizures leading todiagnosis resulted from severe hyponatraemiarelated to an anterior hypopituitarism, with noneof the usual symptoms of parasellar syndromes.
Case report
A 73 year old woman was transferred to ourhospital because of grand mal seizures and persis-tent hyponatraemia. Nine months earlier, she hadbeen admitted to another hospital for transientdiplopia resulting from sudden palsy of the rightexternal oculomotor muscle. The only neurologicalinvestigation performed was a normal electro-encephalogram. The diplopia disappeared within afew days, with a diagnosis of transient cerebralischaemia. Five months prior to admission, thepatient noted progressive weight loss, increasingfatigue and severe orthostatic dizziness with falls.During this period, she was hospitalized three timesin another hospital, where hyponatraemia(115- 125 mmol/l) was repeatedly documented butremained without valid explanation. When increas-ing confusion and grand mal seizures occurred, thepatient was finally transferred to our hospital.
On arrival, the patient was alert. Physicalexamination disclosed no abnormality, exceptweak but equal tendon reflexes. There was nodiplopia. Serum sodium was 125 mmol/l with inap-propriate renal sodium losses (113 mmol/day in the24 h urine collection), potassium was 3.2 mmol/l(28 mmol/day in urine), plasma osmolality was lowat 262 mOsm/kg with diluted urines (386 mOsm/kgin the 24 h collection). The urea nitrogen was3.2 mol/l, creatinine 106 fmol/l and uric acid0.17 mmol/l. There was a slight normochromicnormocytic anaemia with a haemoglobin at 104 g/l.An X-ray film of the chest was normal, while thestandard skull X-ray showed an enlarged sellaturcica due to bony destruction of the floor of thesella and of the anterior and posterior clinoids.The provisional symptomatic treatment in-
cluded restriction of fluid intake, administration ofintravenous hypertonic saline and frusemide, andof oral urea. Thyroid function tests showed:thyroxine 55.0 nmol/l (normal 80.6-154), tri-iodothyronine 0.51 nmol/l (normal 1.3-3), TSH0.14mU/l (normal 0.2-5.5), an 08.00h plasmacortisol was 143.5 nmol/l (normal 248-690) and afree 24h urinary cortisol 65 nmol (normal55-276); LH was <0.4 mg/l (normal postmenopausal > 5,5) and FSH 0.5 mg/l (normal postmenopausal > 11); GH was < 0.75 mg/l (normal<5.5) and somatomedin C 0.2 U/ml (normal0.4-1.5), prolactin was 1400 mU/I (normal< 240). Because of the critical clinical situation ofthe patient no further dynamic tests were per-formed, except a diagnostic and therapeutic intra-muscular injection of corticotrophin (Synacthendep6tR 2 mg). Plasma cortisol peaked to highvalues within 2 days, while serum sodium nor-malized and 24 h natriuria fell to low values.
Correspondence: J. Mockel, M.D., Ph.D.Accepted: 20 September 1990
The neuroradiological images are shown inFigure 1. Computed tomography scan demon-strated an intra- and parasellar non-homogeneousspace occupying lesion. The tumour enhancedhomogeneously and vividly after intravenous con-trast injection. A digital angiography demon-strated that the mass resulted from bilateral intra-cavernous giant carotid aneurysms extending intothe sellar cavity. In a magnetic resonance imaging(MRI) study, a series of sagittal T. weighted imagesas well as two series of coronal T2 weighted imagescentred on the sellar region were obtained: bilateralaneurysms of the carotid siphons could specificallybe diagnosed due to the characteristic blackappearance of the lesions on all images (flow voidphenomenon). Fundoscopic examination, visualacuity and visual field testing were normal.
Surgical treatment was considered unreasonableand discarded since it implied ligation of bothinternal carotid arteries. Medical treatment withcortisone acetate 25 mg and 1-thyroxine 125 fgdaily rapidly resolved the hyponatraemia andabolished all symptoms presented by the patient
Discussion
The present case report illustrates the exceptionalsituation where bilateral intracavernous carotidaneurysms presented as a severe hyponatraemiaresulting from anterior pituitary insufficiency.Symptomatic hyponatraemia, as initial symp-
tom of hypopituitarism is, by itself, unusual,6although classically described.7'8 In our ownexperience, however, hyponatraemia was thesymptom leading to hospitalization and diagnosisin 12 out of 40 patients with complete pituitaryinsufficiency (personal data). The hyponatraemiain such situations is generally attributed to anincreased secretion ofADH and greater sensitivityto its action of the collecting tubules resulting fromglucocorticoids and thyroid hormone depriva-tion,8`10 although hyporeninism has also been heldresponsible for abnormal sodium losses.7
Hypopotuitarism results in the majority of casesfrom hypophyseal tumours and/or Sheehan's syn-drome in older series, amounting to 59% of allcases in a report collecting 1060 pituitaryinsufficiencies.6 The next most frequent aetiologiesare intra- or parasellar tumours such ascraniopharyngiomas, meningiomas and ger-minomas, trauma, irradiation, and previoussurgery in the sellar region.6"'
Carotid artery aneurysms mimicking pituitarytumours are uncommon but well described.'They can account for up to 10% of the lesionscausing a parasellar syndrome,2 while 1.4% to 5%of all intracranial aneurysms referred to
neurosurgeons projected into the sella turcica inother series.4'5
However, pituitary dysfunction is thought to berare in patients with intracavernous aneurysms ofthe internal carotid artery,'2 the absence of endo-crine symptoms even being considered as an impor-tant diagnostic feature to differentiate aneurysmsfrom pituitary adenomas.'3 Aneurysms were notdescribed as cause of hypopituitarism in a reviewby Sheehan and Summers.'4 More recent literaturedid, however, report the coincidental occurrence of
Figure 1 Radiological demonstration of the bilateralintrasellar carotid aneurysms by (a) intravenous contrastenhanced CT scan (axial view of the level of the sellarregion); (b) digital venous angiography; (c) MRI: coronalslice (0.5 Tesla; SE, TR 1500 ms, TE 30 ms).
intrasellar carotid aneurysms and pituitaryinsufficiency. 10,15-20 In contrast to our patient, theclinical symptoms leading to investigation anddiagnosis of all these cases were related to theneurological manifestations of basal intracranialaneurysms: severe headache, oculomotor palsies,visual failure, sudden exophthalmos and subarach-noid haemorrhage, while documentation of partialor complete hypopituitarism was a secondaryby-product of the complete medical workup of thepatients. Our patient had transient diplopia 10months before admission, but this symptom wasnot spontaneously reported.The exceptional clinical presentation of our case
should discard the general rule excluding thediagnosis of an intracranial carotid aneurysm inthe absence of any concomitant focal 'masseffect'.'2 '2 The pathogenesis of pituitary dysfunc-tion induced by intracranial aneurysms remains
uncertain for two main reasons: (1) the necropsyreports do not often describe the pathology of thepituitary and hypothalamus;'6"17 the endocrineevaluation was frequently incomplete and post-operative dynamic pituitary function testing wasrarely performed. Direct destruction of thepituitary by compression and ischaemic necrosishas been suggested by some,'0"8 but the largestcarotid aneurysm in a series was in a young womanwho had borne a child 6 months earlier.'6 Thehypothesis of compression of the hypothalamuscompromising the secretion of releasing factors,and inducing hyperprolactinaemia as in our case,seems more tenable. Indeed, Verbalis et al.'7 havedescribed the complete reversal of a severehypopituitarism with hyperprolactinaemia afterclipping ofa giant carotid aneurysm in a 59 year oldwoman. Although the aneurysms of our patientwere most likely responsible for this hypo-pituitarism, such a clear cut causal relationshipcannot be established. Diagnostic confusion cancertainly arise from the coincidental occurrence ofaneurysms with secreting or non-functionalpituitary adenomas, disclosed by systematicangiography in 6.7% of such tumours.22Another peculiarity of our patient was the
presence ofsymmetrical intracavernous aneurysmsof both internal carotid arteries. Multipleaneurysms represent 20% of all intracranialaneurysms, with a strong tendency to occur sym-metrically, particularly when the internal carotid ormiddle cerebral arteries are affected.23 25 Of alldouble aneurysms, when one arises on an internalcarotid artery, the second one will be on thecontralateral carotid in 49% of the cases with abetter than 3:1 chance of being symmetricallydisposed.
For the radiologist, carotid aneurysm is a wellknown differential diagnosis for an apparent intra-sellar tumour with lateral extension; bilateralaneurysms are, however, exceptional. Angio-graphy is systematically performed in order to ruleout this uncommon aetiology, particularly when atranssphenoidal approach of the lesion is planned.MRI appears to be a very valuable diagnostic toolas it shows vascular elements without any contrastinjection: flow sensitivity is indeed one of the majoradvantages of MRI. Rapid flowing blood appearsusually as areas without any signal intensity whileslow flowing blood appears hyperintense (para-doxical enhancement).26'27 As a consequence, MRIallows easy differentiation between carotid arteriesand cavernous sinus, and an aneurysm is demon-strated by a signal void black area while if throm-bosed, a typical high signal intensity regionidentifies the lesion.
1. Mitchell, S.W. Aneurysm of an anomalous artery causinganteroposterior division of the chiasm of the optic nerves andproducing bitemporal hemianopia. J Nerv Ment Dis 1889, 16:44-62.
2. Thomas, J.E. & Ross, R.E. The parasellar syndrome: prob-lems in determining etiology. Mayo Clin Proc 1970, 45:617-623.
3. Raymond, L.A. & Tew, J. Large suprasellar aneurysmsimitating pituitary tumour. J Neurol Neurosurg Psychiatry1978, 41: 83-87.
5. Rischbieth, R.H. & Bull, J.W. The significance of enlarge-ment of the superior orbital (sphenoidal) fissure. Br J Radiol1958, 31: 125-135.
6. Imura, H. Hypopituitarism. In: Imura, H. (ed) The PituitaryGland. Raven Press, New York, 1985, pp. 501-525.
7. Major, P., Kuchel, O., Boucher, W., Nowaczynski, W. &Genest, J. Selective hypopituitarism with severehyponatremia and secondary hyporeninism. J Clin Endo-crinol Metab 1987, 46: 15-19.
10. Bethune, J.E. & Nelson, D.H. Hyponatremia inhypopituitarism. N Engl J Med 1965, 272: 771-776.
11. Strong, J.A. The pituitary gland. Clin Endocrinol Metab 1980,9 605-614.
12. Meadows, S.P. Intracavernous aneurysms of the internalcarotid artery. Their clinical features and natural history.Arch Ophthalmol 1959, 62: 566-574.
13. Weinberger, L.M., Adler, F.H. & Grant, F.C. Primarypituitary adenoma and the syndrome of the cavernous sinus:a clinical and anatomic study. Arch Ophthalmol 1940, 24:1197-1205.
15. Driesen, W. On two operative findings in space occupyingintrasellar processes. Zbl Neurochir 1959, 19: 28-35.
16. Van 't Hoff, W., Hornabrook, R.W. & Marrs, V.Hypopituitarism associated with intracranial aneurysms. BrMed J 1961, 2: 1190-1194.
17. Verbalis, J.G., Nelson, P.B. & Robinson, A.G. Reversiblepanhypopituitarism caused by a suprasellar aneurysm: thecontribution of mass effect to pituitary dysfunction. JNeurosurg 1982, 10: 604-611.
18. Gallagher, P.G., Dorsey, J.F., Stefanini, M. & Lonney, J.M.Large intracranial aneurysm producing panhypopituitarismand frontal lobe syndrome. Neurology (New York) 1956, 6:829-837.
19. Kahana, L., Lebovicz, H., Lusk, W. et al. Endocrine manifes-tation of intracranial extrasellar lesions. J Clin EndocrinolMetab 1962, 22: 304-324.
20. Shantharam, V.V. & Clift, G.V. Suprasellar aneurysm: anunusual cause of hypopituitarism. JAMA 1974, 229: 1473.
21. Du Boulay, G.H. Some observations on the natural history ofintracranial aneurysms. Br J Radiol 1965, 38: 721-757.
22. Jakubowski, J. & Kendall, B. Coincidental aneurysms withtumours of pituitary origin. J Neurol Neurosurg Psychiatry1978, 41: 972-979.
23. Locksley, H.B. Report on the cooperative study of intrac-ranial aneurysms and subarachnoid hemorrhage. Section V.Part I. Natural history of subarachnoid hemorrhage, intra-cranial aneurysms and arteriovenous malformations. Basedon 6368 cases in the Cooperative study. J Neurosurg 1966, 25:219-239.
25. Garza-Mercado, R., Rangel, R.A. & Garza-Vazquez, J.F.Coexistence of bilateral aneurysms of the internal carotidarteries and an arteriovenous malformation ofthe left frontallobe. Surg Neurol 1984, 21: 267-271.
26. Norman, D. Vascular disease: hemorrhage. In: Brandt-Zawadzki, M. & Norman, D. (eds) Magnetic ResonanceImaging of the Central Nervous System. Raven Press, NewYork, 1988, pp. 209-220.
27. Krishna, C.V.G.R. & Lee, S.H. Cerebrovascular anomalies.In: Stark, D.S. & Bradley, W.G. (eds) Magnetic ResonanceImaging. C.V. Mosby, St Louis, USA, 1988, pp. 473-505.
