Isolated Dissecting Aneurysm of the Left Posterior Inferior Cerebellar Artery: Endovascular Treatment with a Guglielmi Detachable Coil Tapani Tikkakoski, Sami Leinonen, Topi Siniluoto, and John Koivukangas Summary: An isolated progressive dissecting aneurysm of the Via the transfemoral route, a Fastracker-10 microcath- left posterior inferior cerebellar artery (PICA) associated with a eter (Target Therapeutics, Fremont, Calif) was advanced persistent trigeminal artery was successfully treated by endo- coaxially through a 6F guiding catheter to the proximal vascular occlusion of the proximal PICA with a Guglielmi detach- part of the left PICA. A GDC-10 (2 3 80 mm) was inserted able coil. into the proximal left PICA. The control angiogram ob- tained just after the insertion showed some flow distal to Index terms: Aneurysm, dissecting; Aneurysm, embolization; the coil. After 30 minutes, a second control angiogram Arteries, cerebellar, posterior inferior; Interventional materials, showed no flow in the PICA distal to the coil and the patient coils had no immediate neurologic deficits. The coil was then detached (1.4 to 6.7 mV, 1 mA, 3.3 seconds). A third Dissecting aneurysms of the intracranial pos- control angiogram confirmed occlusion of the proximal terior circulation are unusual lesions that affect PICA. A day after the embolization, the patient had only otherwise healthy young adults (1). We suc- mild trigeminal pain, which disappeared 2 days later. She cessfully treated a 34-year-old woman with a had no permanent or late ischemic brain stem symptoms and she was discharged 1 week after the procedure. Her dissecting aneurysm of the left posterior inferior recovery was uneventful, and occlusion of the PICA was cerebellar artery (PICA) by endovascular occlu- seen on a left vertebral angiogram obtained 6 months later sion of the PICA with a Guglielmi detachable (Fig 1D). coil (GDC). Case Report Discussion A 34-year-old woman had mild asthma but was other- Dissecting aneurysms of the intracranial pos- wise healthy, until May 1995, when she presented with terior circulation are rare (2, 3). Berger and sudden severe headache, momentarily losing conscious- ness. On admission, Hunt and Hess grade II subarachnoid Wilson (1) reported six of their own cases and hemorrhage was diagnosed. Computed tomography (CT) found 36 additional cases in the literature. Only showed blood in the fourth ventricle, suggesting an aneu- three of these dissecting aneurysms were lo- rysm in the PICA. Four-vessel cerebral digital subtraction cated in the PICA, and these patients died 5 to angiography showed a 15 3 7 3 5-mm fusiform aneurysm 14 days after their initial symptoms. The re- of the left PICA (Fig 1A). In addition, a trigeminal artery ported symptoms in those three patients in- from the right internal carotid artery supplied the superior cluded suspected aneurysmal rupture and cerebellar arteries and the left posterior cerebral artery via coma in one and abrupt coma in two (1). In a the basilar artery (Fig 1B). The fusiform nature of the recent study by Hosoya et al (4), seven of 16 aneurysm was confirmed by three-dimensional helical CT. patients with Wallenberg syndrome had a defin- Initially, the patient was treated conservatively; but a itive vertebral artery dissection and only one control angiogram obtained 6 weeks later showed that the fusiform aneurysm had enlarged considerably, mainly lon- patient with a suspected vertebral artery dissec- gitudinally, consistent with a dissecting aneurysm (Fig tion had pathologic involvement of the PICA at 1C). The flow distal to the aneurysm was slow. Numerous angiography (4). Our patient had an isolated collaterals were seen from the anterior inferior cerebellar dissecting PICA aneurysm with no visible con- artery to the brain stem. nection to the vertebral artery. Received March 28, 1996; accepted after revision August 1. From the Departments of Diagnostic Radiology (T.T., S.L., T.S.) and Neurosurgery (J.K.), Oulu (Finland) University Hospital. Address reprint requests to Tapani Tikkakoski, MD, Department of Diagnostic Radiology, Oulu University Hospital, Kajaanintie 50, FIN-90220, Oulu, Finland. AJNR 18:936–938, May 1997 0195-6108/97/1805–0936 © American Society of Neuroradiology 936 AJNR: 18, May 1997 DISSECTING ANEURYSM 937 Fig 1. A 34-year-old woman with iso- lated dissecting aneurysm of the PICA. A, Lateral projection of the original left vertebral angiogram shows a 15 3 7 3 5-mm fusiform PICA aneurysm (arrow- head). Some contrast material fills the persistent trigeminal artery (arrow). B, Right carotid angiogram shows fill- ing of the right posterior cerebral artery and the trigeminal artery supplying the su- perior cerebellar arteries and the left pos- terior cerebral artery via the basilar artery. C, Lateral left vertebral angiogram 6 weeks later shows that the PICA aneurysm was considerably enlarged (36 3 7 3 7 mm). The progressive changes are consis- tent with a dissecting aneurysm. D, Lateral vertebral angiogram 6 months later shows the PICA is occluded. In nearly all intracranial arterial dissections, brain stem ischemia or infarction (5). We have the intramural hematoma forms between the not found previous reports on the possible as- internal elastic lamina and the media layers. sociation of trigeminal artery and dissecting Rarely, as probably in our case, the dissection PICA aneurysm. Probably it is an incidental involves the adventitia and may rupture to the finding. subarachnoid space. The intracranial arteries The optimal treatment of intracranial dissec- lack an external elastic membrane and have a tions and dissecting aneurysms is not yet thinner adventitia, fewer elastic fibers in the me- known (6, 7). Kitanaka et al (6) concluded that dia, and, generally, a thicker internal elastic unruptured intracranial vertebral artery dissec- lamina than do the extracranial arteries (1). An- tions without subarachnoid hemorrhage can be giographic features of intracranial dissecting treated nonsurgically, with careful angiographic aneurysms may include a narrow tapered lu- follow-up monitoring. Recently, Halbach et al men, a double lumen with both true and false (7) described 16 patients with vertebral artery lumen, occlusion, or, as in our case, a change in dissecting aneurysms or pseudoaneurysms the luminal configuration over several weeks (nine with subarachnoid hemorrhage) who were (1). treated with endovascular occlusion of the par- Persistent trigeminal artery is estimated to be ent artery. Surgical occlusion of the parent ves- present in 0.1% to 0.6% of cases in large angio- sel was considered in our patient, but we elected graphic series; its clinicopathologic significance to attempt controlled occlusion of the PICA with has not been clarified. Most cases have been the GDC technique instead. Our patient had no found incidentally by angiographic exploration neurologic symptoms or signs during the 30 of subarachnoid hemorrhage, oculomotor minutes preceding GDC detachment. Tempo- palsy, brain tumors, head injury, or vertebral or rary balloon test occlusion (7) combined with 938 TIKKAKOSKI AJNR: 18, May 1997 nuclear single-photon emission CT was not giography. Because of the high rate of rehem- considered in this context. This case further orrhage, ruptured dissecting aneurysms should stresses the need for adequate radiologist–neu- be treated as soon as possible (7). rosurgeon interaction during interventional studies. Since the report of Guglielmi et al (8), saccu- References lar aneurysms have been successfully treated with GDCs (9, 10). Vertebrobasilar aneurysms 1. Berger MS, Wilson CB. Intracranial dissecting aneurysms of the associated with fenestrations and aneurysms posterior circulation. J Neurosurg 1984;61:882–894 2. Manz HJ, Luessenhop AJ. Dissecting aneurysm of intracranial associated with moyamoya disease have also vertebral artery. J Neurol 1983;230:25–35 been successfully treated with GDCs (11, 12). 3. Mokri B, Houser OW, Sandok BA, Piepgras DG. Spontaneous Other reported indications for GDC treatment dissections of the vertebral arteries. Neurology 1988;38:880–885 include intracavernous internal carotid aneu- 4. Hosoya T, Watanabe N, Yamaguchi K, Kubota H, Onodera Y. rysms, dural and traumatic caroticocavernous Intracranial vertebral artery dissection in Wallenberg syndrome. AJNR Am J Neuroradiol 1994;15:1161–1165 high-flow fistulas, and vertebrovertebral fistulas 5. Okada Y, Nishida M, Yamane K, Kagawa R. Bilateral persistent (10, 13). Since 1991, 27 patients with saccular trigeminal arteries presenting with brain-stem infarction. Neurora- aneurysms have been treated with GDCs at our diology 1992;34:283–286 institution. Advantages of the GDC technique 6. Kitanaka C, Tanaki J-I, Kuwahara M, Teraoka A, Sasaki T, are the predictability and controllability of the Takakura K. Nonsurgical treatment of unruptured intracranial ver- tebral artery dissection with serial follow-up angiography. J Neu- coils before detachment. Coils are now avail- rosurg 1994;80:667–674 able in several sizes. 7. Halbach VV, Higashida RT, Dowd CF, et al. Endovascular treat- Saccular PICA aneurysms have only occa- ment of vertebral artery dissections and pseudoaneurysms. J Neu- sionally been treated with GDCs (9, 14). A re- rosurg 1993:79:183–191 view of the literature suggests that vertebral ar- 8. Guglielmi G, Vinuela F, Sepetka I, Macellari V. Electrothrombosis of saccular aneurysms via endovascular approach, 1: electro- tery dissections and pseudoaneurysms have chemical basis, technique, and experimental