J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.48.2.111 on 1 February 1985. Downloaded from

Journal of Neurology, , and Psychiatry 1985;48: 111-121

Fatal intracranial arterial : clinical pathological correlation

MICHAEL A FARRELL,* JOSEPH J GILBERT,t JOHN CE KAUFMANN* From the Department ofPathology (Neuropathology), University of Western Ontario and the Departments of , University Hospital, Victoria* and St Joseph'st Hospital, London, Ontario, Canada

SUMMARY The clinical pathological features of fatal arterial dissection confined to the intracranial vessels are described. Three patients with anterior circulation dissections presented with focal ischaemic neurological deficits and pathological examination of involved vessels revealed a dis- section plane between internal elastic lamina and media accompanied by intravascular throm- bosis. Three of four patients with posterior circulation dissections had clinical pathological fea- tures of subarachnoid haemorrhage and at necropsy had transmural dissections. In contrast to previous reports, primary vasculopathies either degenerative or inflammatory were not identified in affected vessels. The pathogenesis of intracranial arterial dissection is discussed and the clinical features are correlated with the pathological abnormalities. Protected by copyright.

Spontaneous dissection of the intracranial vessels Detailed pathological study of seven consecutive leading to or occlusion of the vessel cases of fatal arterial dissection confined to the has been recognised with increasing frequency as an intracranial circulation was performed to establish important cause of focal ischaemic neurological dis- whether or not there was an associated primary vas- ease.'-5 In contrast, until recently little attention has culopathy and to determine pathological correlates been focused on spontaneous intracranial arterial of and subarachnoid haemorrhage, the two dissection as a cause of subarachnoid haem- principal clinical manifestations of intracranial ar- orrhage.6-9 terial dissection. Though the clinical' 37 and radiological2 3 6 features of intracranial arterial dissection have been Patients and methods described in detail, pathological reports are infre- quent, lack detailed description6 10- '3 and have Seven consecutive cases (1972-1983) of intracranial ar- perhaps over-emphasised the importance of unusual terial dissection were retrieved from the neuropathology necropsy files at the University of Western Ontario teach- vasculopathies.24'6 The association of an uncom- ing hospitals. At necropsy the cervical carotid and/or ver- mon arterial disease with an uncommon vascular tebral were removed, had been fixed in 20% event may in many instances be the actual reason for formaldehyde for a minimum seven days. The circle of http://jnnp.bmj.com/ reporting the case, a pathologist or clinician being Willis and its major branches were dissected off the less likely to report cases of dissection where a rec- after fixation. Following paraffin impregnation but before ognisable pathological cause is not identified.'' blocking individual arterial branches were sectioned at 3 Furthermore, as a consequence of major anatomical mm intervals and embedded on end. Affected vessels were differences'78 between the intracranial and extra- sectioned through the involved area at 100 ! intervals. All cranial vasculature, certain vasculopathies which sections were stained with haemotoxylin and eosin, PAS, Masson Trichome, Reticulin, Movats, Elastic-Van Gieson have a predilection for large diameter vessels are and some with Alcian Blue. The clinical and pathological unlikely to involve the medium and small diameter findings are summarised in the table. on October 2, 2021 by guest. intracranial vessels. Case I Address for reprint requests: Dr JCE Kaufmann, Department of Pathology (Neuropathology), University Hospital, PO Box 5339, Clinical data A 63-year-old previously hypertensive male Postal Station A, London, Ontario, N6A 5A5, Canada. developed sudden severe posterior neck pain walking up a steep incline. The pain initially decreased in intensity and a Received 18 May 1984. neurological examination one hour later was normal with Accepted 14 July 1984 no nuchal rigidity. Two hours later while walking down- 111 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.48.2.111 on 1 February 1985. Downloaded from

112 Farrell, Gilbert, Kaufmann Table 1 Fatal Intracranial dissection; summary-clinicopathological features Case Age (yr) Contributory Clinical Subarachnoid No sex factors presentation haemorrhage 1 63/M Vigorous walk Neck pain Vertebral (R) Yes 2 48/F Heparin Occipital Basilar No 3 46/F - Occipital headache Basilar Yes 4 38/F - Collapse Basilar Yes 5 20/M Tug of war Hemiplegia Carotid (L) No 6 31/F Raking leaves Hemiplegia Carotid (R) No 7 18/M Cerebral trauma Hemiplegia Carotid (R) No

cell infiltrate was stairs, severe neck pain recurred and within minutes the calibre (fig 2). A mild acute inflammatory There was no evi- patient was completely unresponsive with absent present along the adventitial surface. oculovestibular, gag and corneal reflexes. dence of a primary medial or internal elastic lamina defect oculocephalic, of the was 230/120 mm Hg. The neck was at the origin of the dissection or in the remainder The vessels. supple and there were bilateral subhyaloid haemorrhages. right or other intracerebral occurred 48 hours after the onset of neck pain. Neuropathology There was bi-hemispheric swelling with Case 2 massive basal subarachnoid haemorrhage. The arachnoid Clinical data A 48-year-old previously well, normoten- severe intractable was incised and following removal of blood a fusiform dila- sive female had a two-week history of tation of the right vertebral artery with intramural haemor- occipital headache, aggravated by coughing. This was most with rhage was noted (fig 1). The remaining cerebral vessels severe in the morning and was associated , weakness and sensory were normal. Microscopy showed a crescent-shaped blurred vision, dysarthria, episodic Protected by copyright. haematoma extending transmurally from the lumen impairment of the right arm and two days before admis- through the adventitia destroying the internal elastic sion, a left facial palsy. Positive findings on examination and V3 lamina and media and causing a 50% reduction in vessel included reduced pain sensation in the VI, V2 distribution on the left, a diminished left corneal reflex, a Patient 1 left central facial palsy, a mild right upper monoparesis and diminished pain sensation in the left extremities. Gait was broad based and ataxic and the patient was unable to sit without support. Computed tomography did not show intracerebral haemorrhage. The patient was heparinised. Twenty hours later she was unconscious with decerebrate posturing and absent oculocephalic and oculovestibular reflexes and she died four hours later. Neuropathology There was extensive recent of the right basis pontis and right superior cerebellar ped- uncle. At the level of the middle cerebellar peduncles, vir- tually all of the basis pontis, an extensive area of the right cerebellar hemisphere and a small area of white matter in the left cerebellar hemisphere were infarcted. Both occipi- tal lobes and the right thalamus showed foci of recent haemorrhagic infarction. There was an area of old (3-4 http://jnnp.bmj.com/ weeks) infarction in the left occipital lobe. The rest of the brain and the spinal cord were normal. The anterior circu- lation vessels were patent, free of and did not show . The basilar artery was mildly dilated and occluded from the origin of the anterior inferior cerebellar nA arteries to the bifurcation. In addition the proximal seg- I) NZ.-/ ments of both posterior and both superior cerebellar arteries were occluded (fig 3). Microscopy demonstrated complete occlusion of the mid-basilar seg- on October 2, 2021 by guest. ment by an organising haematoma. A dissection plane Haemorrhage extended between internal elastic lamina and media and an area of haemorrhage denoted the origin of the dissection Fig 1 Schematic representation ofvascular territory site. Occasional internal elastic lamina gap defects were involved by dissection. Area A is shown in fig 2. noted close to the dissection site but the remaining cerebral (Circle viewed from below) vessels were unremarkable. J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.48.2.111 on 1 February 1985. Downloaded from

Fatal intracranial arterial dissection: clinical pathological correlation 113 Protected by copyright.

Fig 2 Cross section ofright vertebral artery through area ofmaximum compression. Elastic lamina (straight arrow) interrupted by large transmural haematoma (curved arrow). Elastic Van Gieson.

-Qt,eri 2 Case 3 Clinical data A 46-year-old mildly hypertensive (170/90 mm Hg) female developed sudden severe occipital headache associated with a right hemiparesis and dysar- thria six weeks prior to death. The CSF was bloody and demonstrated basilar trunk narrowing with an atypical mid-segment berry . Over the following seven days the hemiparesis gradually improved, there was no recurrence of headache and apart from horizontal dip- lopia and a right central facial nerve palsy, the patient was

well. http://jnnp.bmj.com/ Neurosurgical fndings At operation 39 days later a left ...:. temporal bone flap was reflected and the tentorium divided to expose the basilar artery. A fusiform red-purple swelling extended along the basilar artery from the origin of the t--- 'N anterior inferior cerebellar artery to the superior cerebellar artery and was recognised as a dissection. The affected i basilar artery segment was mobilised and wrapped with cotton gauze. Post-operatively the only deficit was a mild

right hemiparesis. However, on the third post-operative on October 2, 2021 by guest. day, the patient became unconscious with fixed dilated pupils and absent brain stem reflexes. She died on the sixth post-operative day. Neuropathology The immediate cause of death was brain Fig 3 Schematic representation ofvascular territory stem compression caused by haemorrhagic venous infarc- involved by dissection with corresponding cross sections. tion of the left temporal lobe, secondary to thrombotic (Circle viewed from below) occlusion of the anastomotic of Labbe with superim- J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.48.2.111 on 1 February 1985. Downloaded from

114 Farrell, Gilbert, Kaufmann posed diffuse ischaemic encephalopathy. An old, (4-5 weeks) 1 cm diameter area of cystic infarction was present in the left basis pontis. The basal meninges showed exten- sive haemosiderin staining. When the surgical gauze was removed, a 5 mm long segment of ecchymosis was noted to. involve the mid-basilar trunk (fig 4). Microscopy showed a transmural dissection plane extending from the lumen through the internal elastic lamina and media to the adven- titia with, in addition, rostral and caudal extension (figs 5, 6). In the caudal segment, the dissection doubled back creating the false impression of two distinct dissection zones. The media showed moderate to severe myofibro- blast proliferation (fig 7) but this change was confined to the immediate vicinity of the dissection plane and was not seen in the unaffected segments of the basilar artery or in any of the remaining cerebral vessels. The cleavage plane was patent and free of thrombus. Occasional foci of intramural haemosiderin deposition were observed. The basilar internal elastic lamina showed occasional small gap defects (fig 8) close to and remote from the point of origin of the dissection. There was no evidence of either atheroma or other primary vasculopathy involving any of the remaining cerebral vessels. Protected by copyright. Fig 5 Schematic representation ofbasilar artery dissection g in ~~~~~~~~longitudinal and cross section. Cross sections A, B and C - are shown in fig 6.

Case 4 Clinical data A 38-year-old previously well normotensive mother of four while standing quietly in her kitchen sud- denly cried out, fell to the ground and was noted to have flexed anus, extended legs, and absence of speech. One hour later in hospital the patient opened her eyes in response to commands but shortly thereafter showed a rapidly deteriorating level of consciousness progressing to complete unresponsiveness. Computed axial tomography demonstrated mid-brain and pontine infarction. There was no improvement and death occurred eleven days following gt_ onset of symptoms. -Xrt_2Neuropathology Extensive subarachnoid blood clot was dissected off the ventral surface of the brain stem to expose http://jnnp.bmj.com/ a fusiformly enlarged and ecchymotic basilar artery. Bilat- eral tonsillar herniation was accompanied by upward trans- JR: tentorial mid-brain herniation. There was extensive t ;haemorrhagic infarction of the left crus cerebri and sub- stantia nigra with more diffuse haemorrhagic infarction of the basis pontis and pontine tegmentum bilaterally. The ,-.49_.j;4__ haemorrhage extended into and completely obliterated the fourth ventricle. - Furthermore, the patency of the cerebral > . ^ ; j t t aqueduct was severely compromised by the oedematous on October 2, 2021 by guest. and infarcted mid-brain. There was moderate dilatation of both lateral ventricles. Microscopy showed obliteration of the basilar lumen (fig 9) by an organising haematoma which extended Fig 4 Basilar artery transmurally through the internal elastic after removal ofgauze (short arrow) lamina and media to the adventitia where it was continuous 5,howing segmental area ofdiscoloration (long arrow) cross with the subarachnoid A s,ections ofwhich haemorrhage. light acute are depicted in fig 5. inflammatory cell infiltrate was present in the adventitia J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.48.2.111 on 1 February 1985. Downloaded from Fatal intracranial arterial dissection: clinical pathological correlation 115

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Jr j .. http://jnnp.bmj.com/ 0\t 3Wt#' 1F;' on October 2, 2021 by guest. Fig 6 Composite photomicrograph showing origin ofdissection (A), extensive myofibroblast proliferation surroundingpatent false lumen (B) and large organised intramural haematoma extending to adventitia (arrow) (C). Elastic Van Gieson (A, C) Haematoxylinleosin (B). J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.48.2.111 on 1 February 1985. Downloaded from

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-. Fig 9 Schematic representation ofbasilar artery showing a small atheromatous plaque at origin ofdissection. (Circle viewed from below) occurred and resuscitation was unsuccessful. Neuropathology The brain showed marked bihemi- spheric swelling greater on the left side where, in addition, there was uncal herniation. There was an extensive area of infarction in the distribution of the left middle and anterior cerebral arteries involving the frontoparietal region and extending medially to involve the . mid-brain and Secondary Fig 8 Intima (straight arrow) and media pontine haemorrhages were present. The separated by entire right internal both elastic lamina which shows two gap defects (curved arrow). carotid, vertebral and the left Elastic Van Gieson cervical carotid arteries were patent but the left intracra- nial carotid artery was completely occluded from the distal intracavernous segment through the bifurcation, into the Al and Ml segments of the anterior and middle cerebral adjacent to the dissection site. A small atheromatous arteries respectively (fig 10). Microscopic examination of plaque was noted at the origin of the dissection. In the multiple segments of the occluded area showed a dissecting http://jnnp.bmj.com/ distal basilar segment, the dissection plane involved only haematoma between the media and internal elastic lamina the innermost media. The remaining cerebral vessels were which forced the internal elastic lamina into the lumen normal. (fig 11) thereby severely compromising the patency of the supraclinoid segment; a large intimal/internal elastic Case S lamina tear Clinical identified the origin of the dissection. Although data A 20-year-old male collapsed during a the haematoma diminished in size the tug-of-war game distally terminal and was noted to have a right-sided segment of the left and weakness. One hour later he was drowsy but proximal Al responsive and Ml segments were occluded by thrombus. There was with sensory dysphasia and a dense right on October 2, 2021 by guest. hemiplegia. The no evidence of atheroma or other medial or inter- blood pressure was 150/90 mm and the primary Hg 100 per nal elastic lamina disease in these or in matched contralat- minute and regular. Four hours later he became more eral intracerebral vessels. drowsy with dilated and poorly responsive left pupil but improved following mannitol infusion. On the third hospi- Case 6 tal day however he showed a decreased level of conscious- Clinical data A female while ness, a dilated and 31-year-old raking leaves unresponsive left pupil and bilateral suddenly developed severe headache associ- papilloedema. Twenty-four hours later cardiac right-sided arrest ated with left sided weakness and repeated clonic move- J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.48.2.111 on 1 February 1985. Downloaded from

Fatal intracranial arterial dissection: clinical pathological correlation 117 by continuous oral estrogen therapy. Twenty-four hours after admission the patient became more drowsy with an enlarging, poorly responsive right pupil, did not improve following dexanmethasone and mannitol and died 72 hours after the onset of headache...... Neuropathology The immediate cause of death was mas- sive, recent, bland hemispheric infarction in the distribu- tion of the right internal carotid artery with uncal hernia- tion and secondary mid-brain haemorrhages. There was occlusion of the ipsilateral internal carotid artery extending from the supraclinoid segment through the bifurcation to involve the Al and Ml segments (fig 12). The cervical and cavernous segments were normal as were the remaining cerebral vessels. Microscopy showed of varying severity by a partly organised dissecting haematoma which extended between internal elastic lamina and media (fig 13), forcing the internal elastic lamina into the vessel lumen. The origin of the dissection was identified in the distal carotid segment where the haematoma communicated freely with the lumen through a large intimal/elastic tear. There was no evidence of atheroma or other primary vasculopathy in the affected or other intracranial arteries. Case 7 Fig 0 Schematic representation of internal carotid artery Clinical data An 18-year-old previously well male suf- dissection in longitudinal and cross section. Origin of fered severe thoracoabdominal trauma during a motor ve- Protected by copyright. dissection (A) is shown in fig 11. hicle accident but was neurologically intact when examined (Circle viewed firom below) both before and after surgical evacuation of large retroperitoneal and pelvic haematomas. However, twenty

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hamtm whc C_ on October 2, 2021 by guest. ments of the left leg. One hour later the patient was drowsy (B tapr ditly nd( but orientated to time, place and person. There was decor- ticate posturing of the left extremities, a left central facial palsy and conjugate deviation of the eyes to the right. The blood pressure was 150/80 mm Hg, pulse 72 per minute, Fig 12 Schematic representation ofinternal carotid artery regular and there were no cardiac murmurs or carotid dissection showing origin ofdissection (A) and intramural . One year previously the patient underwent hys- haematoma (B) which tapers distally (C) and (0). terectomy and bilateral salpingo-oophorectomy followed (Circle viewed from below) J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.48.2.111 on 1 February 1985. Downloaded from l l Farrell, Gilbert, Kaufmnann

Fig 13 Intramural dissecting haematoma which has severely compromised vessel lumen. Corresponds to section (B) in fig 12. Elastic Van Gieson. hours after admission he demonstrated a mild left

hemiparesis and an enlarging right pupil, both improving Protected by copyright. following mannitol infusion. Angiography failed to demon- strate filling of the right internal carotid artery beyond the syphon. Fourteen hours later the patient's level of con- sciousness deteriorated, the right pupil was dilated and unresponsive and there was decerebrate posturing of the Fig 14 Schematic representation ofinternal carotid artery left extremities. Death occurred two hours later. dissection depicting origin ofdissection (A) and associated Neuropathology There were bilateral smear-type sub- acute transmural inflammatory cell infiltrate. dural haematomas over both cerebral convexities. The (Circle viewed from below) immediate cause of death was massive recent, bland, hemispheric infarction in distribution of the right middle typical, reflecting a younger at-risk population cerebral artery with associated sub-falcine and uncal her- (mean age of 37-7 years) though the slight excess of niations and secondary brain stem haemorrhages. The cer- females is contrary to the cumulative experience.' vical segment of the right internal carotid artery showed Headache or neck pain was present in four patients adventitial haemorrhage related to direct arterial puncture and showed regional localisation to the area of the during angiography but the lumen was not compromised. involved vessel, a finding similar to that reported by The intima displayed occasional fatty streaks but was others;7 1019 the pain is usually attributed to stretch- otherwise normal. The internal carotid artery was occluded from the syphon distally through the bifurcation into the ing of pain sensitive nerve fibres in the affected proximal A1 and Ml arterial segments (fig 14). Micros- vessel. Of interest, in some patients the pain may copy showed complete occlusion of the aforementioned precede the onset of stroke or haemorrhage by sev- http://jnnp.bmj.com/ vessels by thrombus. The adventitia and media of the sup- eral days suggesting early non-occlusive dissec- raclinoid carotid segment were extensively infiltrated by tion.7 20 The finding of focal intramural haemosiderin polymorphonuclear leucocytes and also showed loss of the (case 3) is suggestive of previous intramural intima and internal elastic lamina over a wide area with the haemorrhage or dissection.' lateral margins of the intact internal elastic lamina rolled The clear separation of patients into two groups back into the lumen. The occluding haematoma was inti- based on the clinical presentation of a focal mately associated with the medial inflammatory exudate at the dissection origin. The remainder of the circle of Willis ischaemic event (cases 5, 6, 7) and subarachnoid was unremarkable and in particular no defects were noted haemorrhage (cases 1, 3, 4) reflects the underlying on October 2, 2021 by guest. in the internal elastic lamina nor was there evidence of vascular pathology. In the first group the dissection atheroma or a primary vasculopathy. plane lay between the internal elastic lamina and media, a dissecting haematoma of variable age Discussion pushed the elastic lamina into the lumen where occlusion was usually completed by superimposed The clinical features of the seven patients are fairly . An intimal/elastic lamina tear was J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.48.2.111 on 1 February 1985. Downloaded from

Fatal intracranial arterial dissection: clinical pathological correlation 119 always demonstrable but required extensive serial terised by florid myofibroblast proliferation. Such sectioning of the affected vessel. In the second changes were observed in case 3 and the diagnosis of group, when subarachnoid haemorrhage was the was briefly entertained but primary manifestation of intracranial dissection, the the myofibroblast proliferation was confined to the cleavage plane extended transmurally from the immediate area of dissection, was not apparent lumen through intima, elastic lamina and media to remote from the dissection site and was not seen in the adventitia. This finding contrasts with previous other intra- or extracranial vessels. Furthermore, reports which have suggested that the dissection the long interval (39 days) from onset of symptoms plane lies within media or adventitia,72' does not to death clearly points towards healing with attemp- communicate with the lumen'709 20 and that ted resolution as the most likely explanation for the subarachnoid haemorrhage originates from vasa observed change. vasorum or from areas of neovascularisation which In the absence of a primary vasculopathy it has have developed in response to medial necrosis.22 It is been suggested4 that dissection might arise as a generally accepted that intracranial vessels do not result of vessel wall weakening due to congenital gap have '8 and furthermore it is extremely defects in the internal elastic lamina. A careful unlikely that haemorrhage from small low pressure biophysical analysis28 of the size and distribution of adventitial vessels could cause extrinsic compression elastic lamina gap defects in intracranial vessels has and partial obliteration of a high pressure, large shown that over 80% of normal vessels contain diameter intracranial vessel such as the basilar23 or round or ellipsoid defects of which almost 50% may vertebral artery (cases 2, 4). We believe that all be enlarged. Furthermore, enlargement of the intracranial dissecting haematomas originate within fenestrations is accompanied by a reduced ligament the vessel lumen and extend through intima and efficiency whereby the intervening intact elastic tis- elastic lamina into media for a variable distance. The sue has to bear an increased load resulting in subsequent course of the dissection is determined by increased stress per unit area and leading to further Protected by copyright. several factors which may include systolic blood elastic degeneration. Gap defects were noted in pressure, vessel location and presence of underlying patients 2 and 3 and may have contributed to the . It is noteworthy that all anterior progression of dissection but whether isolated gap circulation dissections (cases 5, 6 and 7) presented defects alone are sufficient to initiate dissection with focal ischaemic events whereas three (cases 1, 3 especially given their very high frequency and the and 4) of four posterior circulation dissections had relative rarity of intracranial dissection is unknown. subarachnoid haemorrhage strongly suggesting a It is difficult to ignore the temporal relationship of role for local anatomical factors in determining the dissection to physical exercise35 102529 30 and it is transmural extent of the dissection. Review of tempting to speculate that perhaps a transient rise in reported cases of dissection causing subarachnoid cerebral pressure during severe physical haemorrhage shows similar findings with approxi- stress accompanied by a minor defect in the elastic mately 80% involvement of the posterior circulation lamina could initiate dissection which as already vessels.6 mentioned would then extend for a variable distance Controversy exists concerning the nature and fre- through the vessel wall or perhaps even remain quency of underlying vasculopathies which would undiagnosed and heal spontaneously. Although predispose the intracranial vasculature to dissection. spontaneous resolution of dissection has been A wide variety of diseases including ,9 documented infrequently.2026 and case 5 of Drake fibromuscular dysplasia,'624 cystic medial necrosiS,20 et al,6 it is possible that non-occlusive subclinical dis- http://jnnp.bmj.com/ intimal fibroelastic aberrations2 4 and moyamoya section is more common that hitherto realised. disease" 1425 have clearly been responsible for dis- Trauma, either direct to the cervical carotid artery section in some well documented instances. We or in association with cervical manipulation is a were unable in an unselected consecutive necropsy common cause of extracranial arterial dissection and series to provide conclusive evidence of an associ- though uncommonly associated with intracranial ated vasculopathy. Others have shown a similar arterial dissection is being recognised with increas- absence of underlying vascular disease in spite of ing frequency, particularly in the posterior fossa careful and detailed examination.7192022232627 Our where relatively minor trauma to the skull base or on October 2, 2021 by guest. series though small lacks the bias inherent in iso- neck may produce massive basal subarachnoid lated case reports and compiled case reports pub- haemorrhage.3' However, it is difficult to determine lished as review articles.' Some of the published from the reported cases whether the involved vessels photomicrographs purporting to show fibromuscular have undergone traumatic laceration, traumatic dis- dysplasia24 are unconvincing and more likely rep- section or both. Similarly, traumatic anterior circula- resent partial healing of the involved vessel charac- tion dissection2 14253233 may follow a relatively mild J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.48.2.111 on 1 February 1985. Downloaded from

120 Farrell, Gilbert, Kaufmann 6 head injury2 1425 and frequently there is a delay of Friedman AH, Drake CG. from intracranial dissecting aneurysm. J Neurosurg several hours2 14 before symptoms are manifest. 1 984;60: 325-34. Pathological examination usually reveals subintimal Yonas H, Agamanolis D, Takaoka Y, White RJ. Dissect- dissection involving the supraclinoid carotid seg- ing intracranial . Surg Neurol 1977;8:407- ment and extending for a variable distance into the 15. ,25 3233 the most likely mechan- R Senter HJ, Sarwar M. Nontraumatic dissecting aneurysm ism of dissection involving acceleration induced of the vertebral artery. J Neurosurg 1982;56: 128-30. shear forces between the mobile supraclinoid and 9 Adams HP, Aschenbrener CA, Kassell NF, Ansbacher fixed intracavernous segments. Occasionally the L, Cornell SH. produced by involved vessel may reveal evidence of a vas- spontaneous dissecting . Arch Neurol 1982;39:773-6. culopathy.2 '° Alexander CB, Burger PC, Goree JA. Dissecting aneur- Although anticoagulation is recommended in the ysms of the basilar artery in 2 patients. Stroke management of intracranial dissection' it is notewor- 1979; 10: 294-9. thy that case 2 in our series, case 7 of Drake' s series6 Yuasa H, Tokito S, Izumi K, Hirabayashi K. Cere- and one other other case20 showed clinical deteriora- brovascular associated with an tion following heparinisation. We were unable to intracranial . I Neurosurg define the pathological correlate of our patients's 1982;56: 131-4. deterioration but there was no evidence of sub- 12 Gagne F, Lemay M, Verret S. H6modissection Parietale arachnoid haemorrhage or haemorrhagic infarction. Obliterante des Vaisseaux Intracraniens, une Forme Dissequant. Can J Neurol It is possible that a small area of mural haemorrhage Particuliere d'Anevrysme Sci 1977;4:63-5. noted at the dissection site compromised an already 3 Kunze St, Schiefer W. Angiographic demonstration of a severely stenosed but still patent lumen. Hochberg's dissecting aneurysm of the middle cerebral artery. patient'9 developed a haematoma within a large Neuroradiology 1971; 2:201-6. haemorrhagic infarct whilst Drake's patient refused ' Yamashita M, Tanaka K, Matsuo T, Yokoyama K, Fujii Protected by copyright. further investigation. Surgery is clearly the treat- T, Sakamoto H. Cerebral dissecting aneurysms in ment of choice for posterior fossa dissections6 and in patients with moyamoya disease. Report of two cases. the absence of any evidence implicating anticoagul- J Neurosurg 1983;58:120-5. ants in the progression of the dissection itself, con- ' Wisoff HS, Yonkers NY, Rothballer AB. Cerebral arter- servative management with is still the ial thrombosis in children.Arch Neurol 1961;4:36-45. 16 Pilz P, Hartjes HJ. Fibromuscular dysplasia and multiple recommended treatment.' dissecting aneurysms of intracranial arteries. Stroke 1976; 7: 393-8. We are grateful to Mr G Helps, Mr W Scarrow and '' Motulsky AG. Biased ascertainment and the natural his- the histopathQlogy technologists at St Joseph's Hos- tory of diseases. N Engl J Med 1978;298: 1196-7. pital for their technical help and we thank Miss Col- 18 Stehbens WE. Structure and patholophysiology of cer- leen Schwartzel for the manuscript preparation. In ebral vessels. Pathology ofthe Cerebral Blood Vessels, particular we thank Dr CG Drake for his encour- St Louis: CV Mosby, 1972;60-97. agement and advice. '9 Hochberg FH, Bean C, Fisher M, Roberson GH. Stroke in a 15-year-old girl secondary to terminal carotid dis- section. Neurology (Minneap) 1975;25: 725-9. 20 Nass R, Hays A, Chutorian A. Intracranial dissecting References aneurysms in childhood. Stroke 1982; 13:204-7. 21 Hayman JA, Anderson R McD. Dissecting aneurysm of http://jnnp.bmj.com/ Hart RG, Easton JD. Dissections of cervical and cer- the basilar artery. Med J Aust 1966; 2:360- 1. In: Barnett HJM, ed, Neurologic Clin- 22 Nedwich A, Haft H, Tellem M, Kauffman L. 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