British Journal of Neurosurgey (1994) 8, 97-99 SHORT REPORT Br J Neurosurg Downloaded from informahealthcare.com by Nyu Medical Center on 10/26/14 For personal use only. A traumatic giant posterior cerebral artery aneurysm mimicking a tentorial edge meningioma A. T. H. CASEY & A. J. MOORE! Department of Neurosurgey , Atkinson Morley s' Hospital, Wimbledon, London, UK Abstract Traumatic intracranial aneurysms due to non-penetrating trauma are rare. Commonly they are associated with an overlying fracture or secondary to trauma against the falcine edge in the case of the distal anterior cerebral artery. T o date, only one case of traumatic posterior cerebral artery aneurysm has been reported associated with a comminuted depressed occipital fracture and lacerated transverse sinus. We report a case of a giant traumatic aneurysm of the posterior cerebral artery P2 branch directly associated with the tentorial edge. Its mechanism of formation is analogous to the falcine distal anterior cerebral artery aneurysms. Key words: Traumatic aneurysm, posterior cerebral artery, subarachnoid haemorrhage. Introduction The first traumatic intracranial aneurysm reported in 1829 was subsequent to a left temple fracture causing an aneurysm of the middle meningeal artery.' Birley and Trotter are credited with pioneering the surgical treatment of these lesions.' They remain comparatively rare comprising less than 1% of intracranial aneurysms in most large s e r i e ~ . Posterior ~.~ circulation aneurysms are seldom d e ~ c r i b e d . ~ - ' ~ Burton described a case of a 14-year-old boy with a right comminuted depressed parieto-occipital fracture following an automobile accident.s The patient suffered a subarachnoid haemorrhage 6 days later from a traumatic aneurysm of the right distal posterior cerebral artery (PCA) which was coagulated. The patient made an excellent recovery. We describe a patient with a giant traumatic PCA aneurysm presenting with epilepsy two years after the initial head injury. It is speculated that the 97 injury arose following a rapid deceleration head injury with sudden brain and artery movement causing vessel wall injury against the stationary edge of the tentorium. Case history A 24-year-old police officer accidentally tripped whilst walking on patrol, sustaining a head injury against a low wall. He was unconscious for fifteen minutes. On arrival at hospital he experienced a grand ma1 seizure. He required 48 h hospital admission for observation, analgesia and antiemetics. No skull fracture was demonstrated. H e remained well for 6 months, but then developed absence attacks lasting approximately 30 s. These increased in frequency and became refractory to anticonvulsants. One year following his head injury he sustained two grand ma1 seizures with a tonic clonic phase, tongue biting and incontinence. It was at this stage that he was finally referred Br J Neurosurg Downloaded from informahealthcare.com by Nyu Medical Center on 10/26/14 For personal use only. 98 A. T. H. Casey Cj A . J. Moore FIG.1. CT Scan with contrast enhancement shows a well defined mass deep to the left temporal lobe. to a neurologist who investigated him by C T (see Fig. 1). Neurological examination was normal. The C T scan was erroneously interpreted as representing a tentorial edge meningioma. Craniotomy via a left subtemporal approach was performed. At surgery the findings were of a fusiform aneurysm, and no neck was identifiable. A clip was placed proximally to occlude the feeding posterior cerebral artery branch. The aneurysm was located adjacent to the tentorial edge. Post-operatively, the patient made a full recovery with no visual field deficit. Post-operative angiography demonstrated occlusion of the aneurysm and its feeding vessel. The patient remains on carbamazepine with no epileptic seizures since surgery. Discussion Traumatic aneurysms can be due to penetrating or non-penetrating trauma with the latter being more common. They may be subdivided into skull base or peripheral lesions. The peripheral traumatic aneurysms are either distal cortical aneurysms associated with an overlv- ing fracture or aneurysms of the distal anterior cerebral artery (ACA) secondary to trauma against the falcine edge. l 7 Approximately 40% of traumatic aneurysms occur in the absence of a fracture shown radiographically.' Other less common causes include various iatrogenic causes, craniotomy 5%, pituitary surgery 3%, cranial tongs l%"," and ventriculostorny." It is convenient to divide traumatic aneurysms into either true or false, mixed and dissecting." The traditional criteria for true traumatic aneurysms is arterial wall disruption with the adventitial layer remaining intact8~'8'20 in contrast to a berry aneurysm which contains both intima and adventitia in its wall. A false aneurysm results from a full thickness laceration which is sealed by haematoma which subsequently excavates to leave a saccular defect with none of the normal arterial wall structures present. Mixed aneurysms arise from a post-traumatic rupture of the true aneurysm which produces a secondary false aneurysm.8J20A dissecting aneurysm results from the formation of a false lumen between the intima and elastica." Parkinson has suggested the following diagnostic criteria to distinguish traumatic aneurysms from congenital aneurysms: (1) history of trauma, (2) site of aneurysm, (3) age of patient and (4) histological findings." Historically, the diagnosis has been dependent on angiography. However, with the advent of C T superceding this mode of investigation, it is likely that the diagnosis will be missed" or misdiagnosed' as in our case. Most authors would agree that surgical treatment is indicated. The natural history of traumatic aneurysm is variable. The overall Aneumortality ranges from 20 to 32%.'2,21,22 rysm rupture is associated with a high mortality (4 1 4 3 % ).*,I2 Operative mortality averages 24°/~.20As a rule, associated pathological findings such as cerebral contusion or intracerebral haematoma are more important determinants of outcome. The PCA aneurysm in this report was treated by deliberate occlusion. In Drake's series of non-traumatic PCA aneurysms, occlusion has been followed bv occiDita1 Br J Neurosurg Downloaded from informahealthcare.com by Nyu Medical Center on 10/26/14 For personal use only. Traumatic aneurysm 99 infarction in only two of 27 cases illustrating ing sequelae of head trauma. Radio1 Clin N Am, 1974; 12:315-31. the surprisingly good collateral supply of this 8 Burton C, Velasco F, Dorman J. Traumatic aneuartery.’’ Aneurysm formation in our case was rysm of a peripheral cerebral arte-ry.Review and case almost certainly due to the vessel damage report. J Neurosurg 1968; 28:468-74. 9 Cocknll HH, Jimenez JP, Goree JA. Traumatic false against the rigid tentorial edge. The brain is aneurysm of the superior cerebellar artery simulating free to move to some degree within the skull posterior fossa tumour. Case report. J Neurosurg 1977; 46:377-80. and as a result of inertia the brain lags behind the motion of the skull for a brief moment 10 Dial DL, Maurer GB. Intracranial aneurysms; report of 13 cases. Am J Surg 1933; 35:2-21. after acceleration begins. The result is that the 11 Ferry DJ Jr, Kenye LG. False aneurysm secondaq brain moves relative to the skull and d ~ r a . ’ ~ to penetration of the brain through orbitofacial wounds. J Neurosurg 1972; 36:503-6. This traumatic PCA aneurysm was therefore 12 Fleischer AS, Patton JM, Tindall GT. Cerebral formed in an analogous manner to the trauaneurysms of traumatic origins. Surg Neurol 1975; 41233-9. matic distal ACA against the falx. It fulfils JL. Intracranial aneurysms, Vol. 3. New York: Parkinson’s diagnostic criteria to distinguish 13 Fox, Springer-Verlag 1983; 1455-63. traumatic aneurysms from congenital aneu- 14 Meguro K, Rowed D. Traumatic aneurysm of posterior inferior cerebellar artery caused by fracture of rysms.’* Address for correspondence: Miss A. J. Moore, Atkinson Morley’s Hospital, 3 1 Copse Hill, Wimbledon, London SW20 ONE, UK. References 1 Smith S. On the difficulties attending the diagnosis of aneurysm being a contribution to surgical diagnosis and medical jurisprudence. Am J Med Sci 1873; 66:401-9. 2 Birley JL, Trotter W. Traumatic aneurysm of the intracranial portion of the internal carotid artery. Brain, 1928; 5 1:184-208. 3 Laun A. Traumatic aneurysms. In Pia H W ,Longman C, Zierski J, eds. Cerebral Aneurysms: Advances in Diagnosis and Therapy. Berlin Springer-Verlag 1979; 363-374. 4 Benoit BG, Wortzman G. Traumatic cerebral aneurysms. Clinical features and natural history. J Neurol Neurosurg Psychiatry, 1973; 36: 127-38. 5 Acosta C , Williams PE, Clark K. Traumatic Aneurysms of the cerebral vessels. J Neurosurg 1972; 36:5 3 1-6. 6 Bank WO, Nelson PB, Drayer BP. Traumatic aneurysm of the basilar artery. Am J Res 1988; 130:975-7. 7 Berzeron RT. Runbaueh CL. Non-suace-occuuv clivus. Neurosurgery 1985; 16:666-8. 15 Shaw CM, Alvord EC, Jr. Injury of basilar artery associated with closed head trauma. J Neurol Neurosurg Psychiatry 1972; 35:247-7. 16 Thompson, JR, Harwood-Nash DC, Fitz CR. Cerebral aneurysms in children. Am J Res 1973; 118:163-75. 17 Buckingham MJ, Crone KR, Ball WS, Tomsick TA, Berger TS, Tew JM Jr. Traumatic intracranial aneurysms in childhood: two cases and a review of the literature. Neurosurgery 1988; 22:398-408. 18 Parkinson D, West M. Traumatic intracranial aneurysms. J Neurosurg 1980; 5 2 1 1-20, 19 Lassman LP, Ramani PS, Sengupta RP.Aneurysms of the peripheral cerebral artery due to surgical trauma. Vasc Surg 1974; 8:l-5. 20 Parkinson D. Surgical management of traumatic aneurysm. In Schmidek HH, Sweet WH, eds. Operative Neurosurgical Techniques. Orlando: Grune and Stratton, 1988; 87:991-5. 21 Asari S, Nakamara S, Yamada 0. Traumatic aneurysm of peripheral cerebral artery. J Neurosurg 1972; 46:795-803. 22 Yokota H, Taxaki T, Murayama K. Traumatic cerebral aneurysm: 94 cases from the literature and 5 cases observed by the authors. No Shinkei Geka (Tokyo) 1987; 11~521-9. 23 Peerless SJ, Drake CG. Posterior circulation aneurysms. Youmans Neurological Surgery, 3rd edn. Philadelphia: W. B. Saunders Co. 1990; 1764-806. 24 Gennarelli TA. Mechanisms of cerebral concussion, contusion and other effects of head injury. Youmans Neurological Surgery, 3rd edn. 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