Intracranial dissecting aneurysms of the posterior circulation. Report of six cases and review of the literature

Endovascular treatment of symptomatic intradural vertebral dissecting aneurysms

BACKGROUND AND PURPOSE

The purpose of this study was to report our experience with endovascular treatment of 14 patients with symptomatic intradural vertebral dissecting aneurysms.

MATERIALS AND METHODS

Between January 2000 and January 2006, 14 patients with symptomatic intradural dissecting vertebral aneurysms were treated. A total of 756 (568 ruptured, 188 unruptured) endovascular treated aneurysms (incidence, 1.9%) were treated during this period. There were 7 female and 7 male patients with a mean age of 48 years (age range, 10-64 years). Thirteen patients (93%) presented with subarachnoid hemorrhage (SAH) and 1 (7%) presented with acute symptoms of mass effect on the brain stem.

RESULTS

Treatment consisted of coil occlusion of the dissected arterial segment including the aneurysm (internal coil trapping) in 13 of 14 patients and stent placement over the aneurysm as the only therapy in 1 patient. All aneurysms and occluded arterial segments remained occluded on follow-up imaging at 6 to 13 months, and none of the patients had infarctions in the medulla or territory of the posterior inferior cerebellar artery. Clinical outcome was excellent in 11 patients; 3 had cognitive impairment after SAH but were independent in daily activities. There were no episodes of recurrent hemorrhage.

CONCLUSION

Intradural vertebral dissecting aneurysms presenting with SAH should be treated promptly because of the high risk of recurrent hemorrhage. In our experience, trapping of the dissected segment with coils was straightforward, could be done in most patients, and was effective in preventing rebleeding. In our opinion, only in exceptional circumstances are more sophisticated techniques aimed at preservation of the parent artery necessary.

Dissecting aneurysms limited to the basilar artery: report of two cases and review of the literature

Spontaneous dissecting aneurysms limited to the basilar artery are rare. We describe two patients who presented to our institution with different clinical problems, one with brain stem infarction and the other with subarachnoid hemorrhage. We describe the clinical and imaging features in these patients, their treatment, and outcome. We also reviewed the literature concerning this entity, and we have identified 32 patients (including our two patients) with angiographically confirmed dissecting aneurysms limited to the basilar artery. Of these, 40.6% presented with brain stem infarction, 50.0% presented with subarachnoid hemorrhage, and 9.4% presented with both infarction and subarachnoid hemorrhage. Patients who presented with basilar artery dissecting aneurysms and brain stem infarction tended to be younger (mean age, 38 +/- 7 years) than those who presented with subarachnoid hemorrhage (48 +/- 12 years) and were more likely to be male. We discuss the natural history of this entity and suggest an approach to clinical management for these patients.

Spontaneous dissecting aneurysm of the intracranial vertebral artery: management strategies

PURPOSE

Pathogenesis and treatment of spontaneous dissecting aneurysm of the intracranial vertebral artery (VA) remain controversial. This study was designed to provide management strategies and to improve management outcome in patients with these aneurysms.

MATERIALS AND METHODS

Among a total of 1,990 patients treated for intracranial aneurysms from February 1992 to June 2005, 28 patients (1.4%) were treated either by surgery (8 patients) or neurointervention (20 patients) for spontaneous dissecting aneurysms of the intracranial VA. Twenty-two patients had ruptured aneurysms. We analyzed indications of surgery or neurointervention for each case, and assessed the management outcome at a 6-month follow-up.

RESULTS

For selection of therapeutic options, patients were initially evaluated as possible candidates for neurointervention using the following criteria: 1) poor clinical grade; 2) advanced age; 3) medical illness; 4) unruptured aneurysm; 5) equal or larger opposite VA; 6) anticipated surgical difficulty due to a deep location of the VA-posterior inferior cerebellar artery (PICA) junction. Surgery was considered for patients with: 1) high-risk aneurysms (large or irregular shaped); 2) smaller opposite VA; 3) failed neurointervention; or 4) dissection involving the PICA. Management outcomes were favorable in 25 patients (89.3%). Causes of unfavorable outcome in the remaining 3 patients were the initial insult in 2 patients, and medical complications in one patient.

CONCLUSION

Ruptured aneurysms must be treated to prevent rebleeding. For unruptured aneurysms, follow-up angiography would be necessary to detect growth of the aneurysm. Treatment modality should be selected according to the clinical characteristics of each patient and close collaboration between neurosurgeons and neurointerventionists is essential.

Dissection of the posteroinferior cerebellar artery: clinical characteristics and long-term follow-up in five cases

BACKGROUND AND PURPOSE

Spontaneous isolated posteroinferior cerebellar artery (PICA) dissection is very rare. The aim of the study was to investigate the clinical manifestations, the neuroradiological aspects and the treatment of 5 cases collected in 5 years.

METHODS AND RESULTS

From 1999 to 2003, five patients (40-71 years old) were hospitalized for PICA dissection. Two patients presented symptoms after cervical manipulation. No predisposing factor or traumatic cause was described in the other cases. The diagnosis was carried out by cerebral angiography in all the cases: in 4, angiography showed focal stenosis with saccular or fusiform dilatation of the artery at the site of the dissection; in 1 a double lumen aspect was described. One patient presented ischemic manifestations; he was treated with heparin. The others presented subarachnoid hemorrhage (SAH) and were treated by embolization (endovascular sacrifice of the PICA). No ischemic complication and no rebleeding were observed after sacrifice of the PICA. Three patients presented acute hydrocephalus and were treated with surgical derivation. The angiographic and clinical follow-up lasted more than 3 years. We assessed the long-term results with the Glasgow Outcome Score and the modified Rankin Score. A good recovery was achieved for 4 patients (modified Rankin Score 0); one patient who presented SAH and who was in bad clinical state on admission had a Glasgow Outcome Score of 3 and a modified Rankin Score of 4 three years later.

CONCLUSION

Clinical course and prognosis are variable in PICA dissections. The treatment depends on the existence of a hemorrhagic event. In the group of patients presenting SAH, endovascular treatment was safe and effective. The long-term clinical results depend mainly on the clinical status on admission.

Postpartum dissecting aneurysm of the posterior cerebral artery

Intracranial dissecting aneurysm may cause subarachnoid hemorrhage (SAH) or infarction, and postpartum dissecting aneurysm is rare. A 30-year-old 6 days postpartum woman presented with posterior cerebral artery (PCA) dissection evolving dramatically over a short period. She had been well until 6 days after delivery when she suffered sudden onset of headache, vomiting, and unconsciousness. CT scan demonstrated SAH and digital subtraction angiography (DSA) revealed a fusiform dilatation of the left PCA (P3/P4 segment). The initial diagnosis was ruptured dissecting aneurysm, and conservative management was recommended in the acute period. DSA showed smoothening of the vascular wall 6 days after onset, and obliteration of the left P3/P4 segment was observed 13 days after onset. She was discharged without neurological deficits 26 days after onset. Postpartum SAH due to dissecting aneurysm of the PCA is rare, but should be considered in the differential diagnosis of postpartum headache.

Treatment of vertebral artery aneurysms with transposition of the posterior inferior cerebellar artery to the vertebral artery combined with parent artery occlusion. Technical note

The authors describe transposition of the posterior inferior cerebellar artery (PICA) to the vertebral artery (VA) combined with parent artery occlusion for the treatment of VA aneurysms in cases in which a clip could not be applied because of the origin of the ipsilateral PICA. The aneurysm is trapped through a lower lateral suboccipital craniectomy. The PICA is then cut just distal to the aneurysm, and the PICA and VA proximal to the aneurysm are anastomosed in an end-to-end or end-to-side fashion. The surgical procedure was successfully performed in two patients, each of whom had hypoplastic occipital arteries (OAs). The PICA contralateral to the lesion was hypoplastic in one patient and distant to the ipsilateral PICA in the other patient. Mild transient dysphagia developed postoperatively in one patient due to glossopharyngeal and vagus nerve palsy, and the other patient had an uneventful postoperative course. In both patients, postoperative cerebral angiography demonstrated good patency of the transposed PICA. These results show that transposition of the PICA to the VA is a useful procedure for the reconstruction of the PICA when parent artery occlusion is necessary to exclude a VA aneurysm involving the origin of the PICA and when OA-PICA anastomosis or PICA-PICA anastomosis cannot be performed.

Trunkal intracranial aneurysms: dissecting and fusiform aneurysms

Aneurysms arising along the arterial trunk are uncommon and not well-characterized lesions in contrast to saccular aneurysms. According to pathological studies, most of spontaneous trunkal aneurysms are related to dissecting phenomena. On the basis of clinical presentation, dissecting aneurysms can be separated into acute or chronic lesions. Understanding of the underlying pathological mechanisms associated with these aneurysms is useful for planning appropriate treatment. This article reviews the etiopathogenesis, the angiographic aspects, and the endovascular treatment of dissecting aneurysms. Fusiform aneurysms and aneurysms in atherosclerotic disease also are discussed briefly.

Endovascular treatment of ruptured posterior circulation dissecting aneurysms

BACKGROUND

and aim: Dissecting aneurysms of the posterior circulation constitute a relatively uncommon subgroup of aneurysms. They account for 3-7% of cases of nontraumatic subarachnoid hemorrhage. Because of high risk, in most cases the patients require surgical or endovascular therapy. In this study we discuss the clinical efficacy of endovascular treatment with long-term follow-up in ruptured dissecting aneurysms of the posterior circulation.

MATERIALS AND METHODS

This retrospective study was conducted at our institution between January 1995 and June 2005. Eight patients (4 male; 4 females) ranging in age from 24 to 65 years (mean, 46.75 years), were included. All presented with SAH. Endovascular treatment was based on the configuration of the dissecting aneurysm. Attempt was made to occlude the dissecting aneurysm.

RESULT

A total of 8 ruptured dissecting aneurysms in the posterior circulation were treated. Out of them 5 were in the intradural vertebral artery, 2 in the basilar trunk and one in the proximal PCA. All the cases were technically successful. We have seen only two complications. The pre and post procedure (at the time of discharge) mean modified Rankin scores in the patients were 4.6 (SD 0.51) and 1.7 (SD 1.98). This improvement in Rankin score after endovascular treatment was statistically significant (Wilcoxon signed rank test, P=.017).

CONCLUSION

Endovascular management of these lesions is safe and effective mode of treatment and gives adequate protection from rebleed.

Prediction of rebleeding from angiographic features in vertebral artery dissecting aneurysms

To identify patient characteristics and angiographic features that predict high risk for rebleeding in vertebral artery (VA) dissecting aneurysms. We analyzed 62 patients treated for subarachnoid hemorrhage (SAH) from VA dissecting aneurysms (male: female, 46:16; mean age, 51.7 +/- 8 years). Univariate and multivariate stepwise logistic regression analyses were performed to assess relationships between rebleeding rate and age, gender, history of hypertension, sidedness of the aneurysm, angiographic configuration, and location relative to the origin of the posterior inferior cerebellar artery (PICA). Rebleeding occurred in 22 patients (37%), mostly within 24 h. Patients without rebleeding had favorable outcomes, while patients with rebleeding showed higher mortality. Angiographic patterns with high rebleeding rates included "stenosis and dilation" (50%), and "lateral protrusion" (43%), contrasting with "dilation and stenosis" (20%) and other types. Rebleeding also was likely in aneurysms proximal to or at the PICA origin (rate, 47% or 46%) than distal to the PICA origin (21%). Multivariate logistic regression analysis found two factors independently associated with rebleeding: angiographic pattern of the aneurysm (odds ratio 1.88:1, P=0.0366), and location relative to the PICA origin (odds ratio 4.93:1, P=0.028). High risk of rebleeding in VA dissecting aneurysms can be predicted by angiographic configurations such as "stenosis and dilation" and "lateral protrusion" and by location at or proximal to the PICA origin.

Intracranial Aneurysms: an Overview

The outcome of intracranial aneurysms remains disastrous despite progress in diagnosis, management, care, and follow-up. This article discusses the pathology, the etiologies, the epidemiology and the classifications of intracranial aneurysms.

Paediatric dissecting posterior cerebral aneurysms: report of two cases and review of the literature

INTRODUCTION

Intracranial aneurysms in the paediatric population are uncommon, accounting for 2% to 6% of all aneurysms, and spontaneous arterial dissection is rarely reported as the cause of aneurysms in children, especially in the posterior cerebral artery.

METHODS

Two cases of paediatric spontaneous posterior cerebral artery dissecting aneurysms are reported, one in a 33-month-old male child presenting with aneurysmal rupture and subarachnoid haemorrhage and the other in a 9-year-old boy with an unruptured aneurysm.

RESULTS

The first child was successfully treated by endovascular parent vessel occlusion without neurological deficit and in the second a spontaneous thrombosis of the aneurysm and its parent artery occurred associated with hydrocephalus and a favourable outcome.

CONCLUSION

Dissecting aneurysms are dynamic lesions with variable and unpredictable evolution and close follow-up and/or early treatment is warranted. Spontaneous arterial dissection is a rare, probably still under-recognized, cause of intracranial aneurysms that may be responsible for a significant number of aneurysms and spontaneous aneurysmal thromboses in children.

Clinical analysis of vertebrobasilar dissection

BACKGROUND

The natural history of vertebrobasilar artery dissection (VAD) is not fully known. The purpose of this study was to review the clinical outcome of the patients with VAD, then to propose an appropriate management strategy for VAD.

METHOD

From 1992 to 2004, 35 VAD patients admitted to our institutes were retrospectively reviewed. There were 28 men and 7 women, whose age ranged from 4 to 67 years with a mean age of 44 years. Angiography was assessed to document the shape, and location of the dissecting aneurysm with respect to the posterior inferior cerebellar artery (PICA). A modified Rankin score was assigned for functional outcome. The functional outcome scores were analyzed according to the patient's age, gender, hypertension history, the pattern of initial manifestation, angiographic shape of VAD, angiographic location of VAD, treatment modality.

FINDINGS

There was no statistically significant difference between the functional outcome with age, gender, trauma history and past medical history of hypertension. Of 35 patients, 22 presented with SAH, 11 with ischemic symptoms and 2 were incidentally detected. The patients without SAH had a better functional outcome than those with SAH (p = 0.029). There was statistical significance between Hunt-Hess (H-H) grade and clinical outcome (p = 0.032). The shape and location of VAD was not significantly related to the functional outcome (p = 0.294, 0.840). But all the cases of rebleeding and mortality (except one case with initially poor H-H grade) developed exclusively in patients with aneurysms. There was no statistically significant correlation between the treatment modality and the outcome (p = 0.691).

CONCLUSION

The VAD patients with SAH would be recommended to be managed by either surgical or endovascular treatment, but those without SAH, could be managed conservatively with antiplatelet therapy and/or anticoagulation.

De Novo Vertebral Artery Dissecting Aneurysm After Contralateral Vertebral Artery Occlusion-Two Case Reports-

Two patients developed de novo vertebral artery dissecting aneurysm after contralateral vertebral artery occlusion. A 36-year-old man presented with brainstem ischemia and was treated non-surgically. Subsequent angiography showed spontaneous vertebral artery occlusion at the site of dissection. A 45-year-old man developed subarachnoid hemorrhage due to vertebral artery dissecting aneurysm. He underwent endovascular occlusion of the vertebral artery proximal to the dissecting aneurysm. These patients developed de novo dissecting aneurysm on the contralateral vertebral artery at 13 months and 11 days after unilateral vertebral artery occlusion, respectively. These cases strongly suggest that changes in hemodynamic stress due to unilateral vertebral artery occlusion are related to de novo dissecting aneurysm on the contralateral side. The risk of de novo dissecting aneurysm may be increased by proximal occlusion or trapping of dissecting aneurysm of the contralateral vertebral artery.

A hyperdense artery sign and middle cerebral artery dissection

We describe a rare case of spontaneous middle cerebral artery (MCA) dissection that caused cerebral infarction and subarachnoid hemorrhage (SAH), which also presented with a hyperdense artery sign. A hyperdense artery sign of the MCA in acute cerebral infarction strongly indicates thromboembolic MCA occlusion, which is often treated with thrombolytic therapy. However, thrombolytic therapy for intracranial artery dissections has both risks and benefits, due to the association of artery dissections with SAH. Therefore, it is important to keep in mind that an MCA dissection can also cause cerebral infarction with a hyperdense artery sign, particularly in young patients presenting with headache.

Acute basilar artery dissection treated by emergency stenting in a 13-year-old boy

We report a 13-year-old boy who presented with acute basilar artery occlusion due to traumatic arterial dissection. Because a grave prognosis was expected if left untreated, and the chance of neurological recovery was believed to be unlikely but not zero, given that emergency stenting for the dissection was performed within 6 h of ictus. Recanalization of the basilar artery with stent placement did not change the poor prognosis in this patient because there was extension of dissection into the posterior cerebral arteries.

Staged bilateral vertebral artery occlusion for ruptured dissecting aneurysms of the basilar artery: a report of 2 cases

BACKGROUND

Dissecting aneurysm of the basillary artery BA is rare. Although mortality rate is high, management remains controversial. We report 2 cases of dissecting aneurysm of the BA presenting with subarachnoid hemorrhage (SAH), both of which were successfully treated using staged occlusion of bilateral vertebral arteries (VAs).

CASE DESCRIPTION

A 64-year-old man and a 34-year-old woman presented with SAH associated with ruptured dissecting aneurysm of the BA. After endovascular occlusion of a single VA, blood flow in the dissected lumen was reduced. However, one aneurysm rebled and the bleb of the other did not change. Vertebral arteries were also occluded using endovascular techniques at 4 and 2 weeks after initial treatment, respectively. On the second intervention, stump pressure ratios of VAs intended for occlusion were 62.5% and 50.6%, respectively. The patients tolerated temporary occlusion of bilateral VAs well. Subsequent permanent occlusion of bilateral VAs resulted in no neurological complication. Complete obliteration of the aneurysmal lumen was demonstrated on magnetic resonance angiography performed 72 and 5 months later, respectively.

CONCLUSION

Staged bilateral VA occlusion might be the last recourse to prevent further hemorrhage from BA dissecting aneurysm. The technique can be safely applied when the stump pressure ratio is 50.6% or greater and when the patient tolerates temporary occlusion, which suggests the existence of sufficient collateral flow from the anterior circulation.

Clinical presentation and surgical management of dissecting posterior inferior cerebellar artery aneurysms: 2 case reports

Intracranial dissection presenting with subarachnoid hemorrhage (SAH) most commonly involves the vertebral artery. The natural history of this lesion suggests frequent early rehemorrhage and need for urgent treatment. Isolated dissection of the posterior inferior cerebellar artery (PICA) is very rare. We present 2 cases of isolated PICA dissections presenting with SAH. Both patients were middle-aged men who presented with transient loss of consciousness, severe headache, and cranial neuropathies. Initial angiography showed dilatation and narrowing of PICA consistent with dissection and aneurysm formation. The vertebral arteries were normal and there was no other cause for the SAH. Repeat angiography 2 weeks after admission revealed significant enlargement of the aneurysmal dilation of the dissected segment of PICA in both patients. Both patients were treated operatively. One patient had clip reconstruction of the PICA with preservation of flow through the PICA. Follow-up angiography one year later showed no recurrence. The other patient underwent direct surgical trapping and resection of the dissected segment of PICA after passing balloon occlusion testing at the vertebral-PICA junction. Both patients have more than 2 years of clinical follow-up and remain well. Isolated PICA dissection seems to have a less ominous natural history compared to vertebral artery dissection. These lesions need to be followed carefully for evidence of aneurysmal enlargement. Direct surgical reconstruction of the dissected segment may be possible. Balloon occlusion testing may be very helpful in determining if the involved PICA segment can be sacrificed.

Endovascular management of dissecting vertebrobasilar artery aneurysms in patients presenting with acute subarachnoid hemorrhage

Object. The authors report on a series of 29 patients presenting with acute subarachnoid hemorrhage (SAH) related to the rupture of a vertebrobasilar dissecting aneurysm. Special attention was focused on embolization techniques and immediate and midterm anatomical and clinical outcomes.

Methods. Between March 1994 and January 2003, 29 patients presented with acute SAH caused by the rupture of a vertebrobasilar dissecting aneurysm. Eleven patients (37.9%) had Hunt and Hess Grade I SAH, four (13.8%) Grade II, six (20.7%) Grade III, five (17.2%) Grade IV, and three (10.3%) Grade V. Aneurysms were classified into five groups based on lesion location, and treatment courses were decided. All patients except two were treated by endovascular trapping of the aneurysm with concomitant occlusion of the involved vertebral artery (VA). No technical or clinical complication was observed in 28 patients (97%). Aneurysm perforation occurred during the procedure in one patient (3%). There was evidence of aneurysm recanalization in one patient. One patient with Hunt and Hess Grade IV SAH and two patients with Grade V SAH died. One patient died of respiratory infection 1 year after aneurysm trapping. One patient presented with a recurrent hemorrhage 1 month after treatment and died. Overall morbidity and mortality rates were 13.8 and 17.2%, respectively.

Conclusions. Twenty-nine patients with acute SAH due to rupturing of vertebrobasilar dissecting aneurysms were treated using endovascular techniques. In most cases, endovascular trapping of the aneurysm and concomitant occlusion of the VA was technically and clinically successful.

Aneurisma dissecante de artéria vertebral intracraniana fenestrada submetido ao tratamento endovascular: relato de caso

Aneurismas dissecantes da artéria vertebral em seu segmento intracraniano são lesões pouco comuns, principalmente quando associadas a hemorragia subaracnóidea, sendo também raras as fenestrações da artéria vertebral. Apresentam elevada morbidade e mortalidade, com elevado índice de ressangramento e dificuldade de abordagem cirúrgica. Apresentamos o caso de um homem de 19 anos, o qual foi vitima de agressão física em região occipto-cervical, apresentando hemorragia subaracnóidea e aneurisma dissecante na artéria vertebral direita, a qual era fenestrada, sendo submetido ao tratamento endovascular. Realizamos revisão da literatura sobre o assunto, sendo colocado o tratamento endovascular como uma opção terapêutica para estes casos.

Late morphological progression of a dissecting basilar artery aneurysm after staged bilateral vertebral artery occlusion: case report

BACKGROUND

The authors present a patient who experienced late (5-year follow-up) morphological progression of a dissecting aneurysm of the distal basilar artery after treatment with a combined microsurgical and neuroendovascular Hunterian strategy. In addition to postulating about the possible reasons underlying the evolution of this lesion, the role of stenting is discussed.

CASE DESCRIPTION

The patient was 37 years old when she suffered a subarachnoid hemorrhage from spontaneous basilar artery dissection. At the time of the hemorrhage, minimal aneurysmal enlargement was noted angiographically, and she was therefore treated nonoperatively. On reimaging 5 months later, massive enlargement of the aneurysm was noted. The patient was treated with staged bilateral vertebral artery sacrifice using a combination of microsurgical and neuroendovascular techniques. The dominant vertebral artery was clip-ligated distal to the posteroinferior cerebellar artery, whereas the contralateral vertebral artery was coil-occluded cervically 1 week later.

CONCLUSIONS

Despite the patient remaining asymptomatic, follow-up angiography 5 years after the initial hemorrhage revealed further enlargement of the aneurysm as well as a newly discovered inferiorly projecting daughter sac measuring 5 mm in diameter. Clearly, certain aneurysms exist for which indirect approaches involving hemodynamic attenuation fail to prevent progression. With greater refinements in stent technology, such lesions may be more effectively treated.

Basilar artery dissection

Object. Little is understood about the clinical manifestations of basilar artery (BA) dissections, which can present with subarachnoid hemorrhage (SAH), brainstem compression, or ischemia. In any instance, the prognosis seems poorer than that for vertebral artery (VA) dissection. The authors analyzed clinical presentations and radiological features of BA dissection with and without rupture.

Methods. Between 1998 and 2003, the authors treated 10 patients (eight men and two women, ranging in age from 32–78 years; mean age 54 years) with BA dissection. Diagnosis was based on clinical and radiological findings, including those from magnetic resonance imaging and cerebral angiography studies.

Of the 10 patients, five had impaired consciousness at disease onset. Among four patients presenting with SAH, two were treated conservatively and had fair outcomes without recurrent hemorrhage. The other two patients with SAH were treated using unilateral endovascular VA occlusion, but one of them subsequently suffered fatal rebleeding. A fifth patient presented with progressive signs of a mass involving the brainstem, whereas the remaining five patients showed brainstem ischemia; all were treated conservatively. Four patients could not return to their previous daily activities.

Conclusions. Basilar artery dissections are rare lesions associated with significant morbidity and death. The natural course of and the treatment options for BA dissection differ considerably from those for VA dissections. Management of these lesions is controversial and difficult, and requires particular care.

Vertebrobasilar dissection with subarachnoid hemorrhage: a retrospective study of 29 patients

We have reviewed initial diagnostic features, treatment, and outcome in 29 patients with acute subarachnoid hemorrhage due to non-traumatic vertebrobasilar artery dissection diagnosed in our hospital between 1993 and 2003. The dissections occurred in the vertebral artery in 19 patients, the posterior inferior cerebellar artery (PICA) in two patients, the basilar artery in four patients, and in the vertebral artery extending into the PICA in four patients. A pseudoaneurysm was found in 20 patients. Clinical manifestations typically included sudden onset of moderate to severe headache, nuchal rigidity, and drowsiness. Fourteen patients were treated conservatively. Fifteen patients underwent endovascular treatment with either parent artery occlusion (13 patients) or aneurysmal coil occlusion with preservation of the parent artery (2 patients). Re-bleeding occurred within 12 days and before treatment in nine patients. Eight of these had a pseudoaneurysm. No patient bled after endovascular treatment. Poor grade and early re-bleeding were associated with less favorable outcome. Outcome at 6 months did not differ significantly between endovascular and conservative treatment. Altogether, good recovery was achieved for 16 patients, moderate disability was seen in one, severe disability in four, and eight patients (27%) died. The absence of bleeding subsequent to endovascular treatment in this study suggests that endovascular treatment may be a rational approach in these patients at high risk of re-bleeding, especially those with a pseudoaneurysm.

Emergent endovascular treatment of ruptured vertebral artery dissecting aneurysms

The goal of this study was to evaluate the results of endovascular and surgical treatments for ruptured vertebral artery dissecting aneurysms (VADAs) to determine which treatment is preferable. We evaluated the cases of 25 consecutive patients with ruptured VADAs treated in our institution. From 1992 to 1997, five patients were treated surgically. Since 1998, 20 patients with VADAs have been treated with endovascular therapy. The goal of the treatment was to exclude the aneurysm from the circulation. Among the five patients undergoing surgery, three aneurysms were treated with proximal clipping, one with trapping, and one with dome clipping. None of the patients were treated during the acute stage of rupture. Transient complications occurred in two patients. Of the 20 patients treated through the endovascular approach, 15 were treated within 24 h of rupture, but 12 had rebleeding before treatment. Eighteen aneurysms were occluded, along with the affected vertebral artery (VA), by using detachable coils (internal trapping), and one was occluded with the VA preserved. A stent-assisted occlusion of one aneurysm was done in a patient who had a contralateral hypoplastic VA. In both groups, the outcome of each patient depended greatly on the patient's condition before treatment and whether there was rebleeding. No posttreatment bleeding occurred. All procedures were effective, but endovascular treatment was less invasive and easier to use during the acute stage of subarachnoid hemorrhage. Although this report does not describe a controlled study, we found that endovascular treatment is preferable for treating ruptured VADAs in the acute stage.

Two cases of dissecting aneurysm of the distal posterior inferior cerebellar artery: possible involvement of segmental mediolytic arteriopathy in the pathogenesis

BACKGROUND

Dissecting aneurysm of the posterior inferior cerebellar artery (PICA) uninvolved with the vertebral artery is rare. The exact pathohistological diagnosis might result in 'unknown' because the underlying pathoanatomical features are, for a variety of reasons, not always identified.

CASE DESCRIPTION

We report herein two cases of dissecting aneurysm harbored in different segments of the distal posterior inferior cerebellar artery. In our cases, after trapping the PICA at both just proximal and distal to the aneurysm, the abnormal portion was successfully resected with/without an end-to-end anastomosis. The first patient made a good recovery, while the other died 2 days after the surgery. Although its pathogenetic etiology was unidentified in the second case, the formation of dissecting aneurysm had resulted from a segmental mediolytic arteriopathy in the first case.

CONCLUSION

This is the first report of a segmental mediolytic arteriopathy possibly being identified as causing an isolated dissecting aneurysm at this site.

Multiple Spontaneous Dissecting Aneurysms of the Anterior Cerebral and Vertebral Arteries-Case Report-

A 50-year-old woman presented with rare multiple dissecting aneurysms that appeared first in the anterior cerebral artery (ACA) and shortly afterwards in the vertebral artery (VA). She initially suffered sudden motor weakness in the left lower limb due to acute brain infarction. Angiography revealed diffuse string sign in the right ACA. Conservative treatment resulted in resolution of the deficits. Follow-up angiography performed 1 year later revealed recovery of the ACA stenosis. Fourteen days later, she complained of sudden headache and became comatose. Computed tomography showed diffuse subarachnoid hemorrhage. Angiography revealed a new right VA dissecting aneurysm involving the posterior inferior cerebellar artery (PICA). The orifice of the dissection was not apparent in the operative field and the dissection extended to the median. The patient underwent extracranial right VA ligation, clipping of the proximal PICA, and revascularization between the right occipital artery and distal PICA. Her postoperative course was uneventful and she was discharged without neurological deficits. VA dissecting aneurysms involving the PICA without evident orifice or extending over the median can be treated by extracranial ligation with clipping of the PICA, followed by revascularization.

Antegrade recanalization of a completely embolized vertebral artery after endovascular treatment of a ruptured intracranial dissecting aneurysm

✓ Occlusion of the parent artery is a traditional method of treatment of unclippable cerebral aneurysms. Surgical or endovascular occlusion of the parent artery proximal to the aneurysm has been recommended for the treatment of dissecting aneurysms located in the vertebrobasilar circulation. Nevertheless, occlusion of the parent artery may not result in permanent exclusion of the aneurysm from the systemic circulation because, occasionally, postoperative rebleeding occurs after proximal occlusion. Alternatively, endovascular occlusion of the affected site, including the aneurysmal dilation, and parent artery, is a safe and reliable treatment for dissecting aneurysms.

The authors present two rare cases of ruptured vertebral artery (VA) dissecting aneurysms that were treated by endovascular occlusion of the affected site including the aneurysm and parent artery by using Guglielmi detachable coils. In both cases the VA recanalized in an antegrade fashion during the follow-up period. Based on these unique cases, the authors suggest that a careful angiographic follow up of dissecting aneurysms is required, even in patients successfully treated with endovascular occlusion of the affected artery and aneurysm.

Successful treatment of a ruptured dissecting basilar artery aneurysm

✓ Dissecting basilar artery (BA) aneurysms in patients presenting with subarachnoid hemorrhage are life threatening, especially in those who experience subsequent bleeding or progressive dissection, and immediate surgical or endovascular intervention may be necessary. The authors report on a 52-year-old woman whose dissecting BA aneurysm was treated successfully with proximal occlusion and flow reversal. Clipping of the proximal BA above the level of the anterior inferior cerebellar arteries facilitated retrograde flow from a radial artery graft placed between the left vertebral artery and the left posterior cerebral artery, thereby providing continuous perfusion of the BA and its branches. Postoperative angiograms obtained 1 year later revealed good retrograde flow through the BA and dilation of the radial arterial graft. There were no episodes of recurrent hemorrhage.

Treatment of vertebral artery aneurysms with posterior inferior cerebellar artery-posterior inferior cerebellar artery anastomosis combined with parent artery occlusion

BACKGROUND

In patients with aneurysms that involve the origin of the posterior inferior cerebellar artery (PICA) and require occlusion of the vertebral artery (VA), revascularization of the PICA is commonly performed. We present six patients with dissecting VA aneurysms who underwent PICA-PICA anastomosis combined with parent artery occlusion.

METHODS

After a lower lateral suboccipital craniectomy and partial resection of the jugular tubercle, anastomoses were performed in a side-to-side fashion at the posterior medullary segment of the PICA. The VA was subsequently occluded by clipping proximal and distal to the aneurysm, and the PICA was occluded by clipping distal to the aneurysm.

RESULTS

Postoperative cerebral angiography demonstrated patency of the anastomosis and regression of the aneurysm in five of six patients. The remaining patient experienced hemorrhage from contralateral VA dissection and subsequently died. One patient experienced myopathy of the lower extremities secondary to intraoperative fixed board compression and developed permanent lower extremity muscular weakness. The remaining four cases experienced no new neurologic deficits.

CONCLUSION

PICA-PICA anastomosis is a useful procedure for reconstruction of the PICA when parent vessel occlusion or trapping is necessary to exclude a VA aneurysm involving the origin of the PICA.

Histological Study of the Normal Vertebral Artery-Etiology of Dissecting Aneurysms-

Histological evaluation of dissecting aneurysms of the cerebral arteries has suggested that defects in the internal elastic lamina (IEL) induce dissection of the arterial wall. Dissecting aneurysms occur most frequently in the vertebral artery (VA). The present study examined sections of the normal VA to elucidate the mechanisms of arterial dissection. Bilateral VAs (20 vessels) were obtained from 10 patients who died of causes other than intracranial lesions. The VAs were detached from the VA union to the site 10 mm proximal from the point penetrating the dura mater. The VAs were cut at 5-mm intervals, and each segment was observed using modified Masson's trichrome staining for elastic fibers. The thickness of the media and adventitia significantly thinned after the origin of the posterior inferior cerebellar artery (PICA). IEL defects were observed at 35 sites in 11 vessels from six subjects. There was a high incidence of IEL defects in the extradural portion and near the origin of the PICA, areas frequently involved in arterial dissection. There was a high incidence of intimal thinning at areas of IEL defects (19 of 35), and thinning was particularly marked distal to the origin of the PICA. In the absence of intimal thickening, the vascular strength at the site of IEL defects may be reduced, which would promote the occurrence and progression of arterial dissection.

Ischemic Basilar Artery Dissecting Aneurysm Treated by Stenting Only-Case Report-

A 45-year-old man presented with enlargement of basilar artery dissecting aneurysm 10 months after suffering brain stem infarction. Combined stenting and placement of Guglielmi detachable coils (GDCs) was planned to obliterate the aneurysm sac. Stent deployment was performed but the procedure was halted to avoid overdosing with contrast material. Cerebral angiography 10 days later showed thrombosis of the aneurysm sac and normalization of the blood flow in the basilar artery. The patient has been followed up for 2 years and showed good clinical and angiographic outcome. Stenting results in obliteration of the aneurysm sac, so a two-stage procedure is recommended.

Multimodal treatment of ruptured dissecting aneurysms of the vertebral artery during the acute stage

Object. The goal of this study was to implement an algorithm for and assess the multimodal (endovascular and microsurgical) treatment of patients with ruptured dissecting aneurysms of the vertebral artery (VA) during the acute stage.

Methods. During a 4-year period, the authors treated 19 ruptured dissecting aneurysms of the VA during the acute stage, within 3 days after the hemorrhage. Factors guiding management decisions were tolerance of the test occlusion and the site of the dissection. The algorithm takes into account these factors to select among treatment options, that is, trapping of the VA with Guglielmi Detachable Coils (GDCs); trapping of the VA and revascularization of the posterior inferior cerebellar artery (PICA); trapping of the VA and VA—posterior cerebral artery (PCA) anastomosis; and trapping of the VA, VA—PCA anastomosis, and revascularization of the PICA. Of the 15 aneurysms without PICA involvement, 14 were treated by trapping of the VA with GDCs and one by trapping of the VA and a VA—PCA bypass. The other four aneurysms with PICA involvement were treated by VA trapping and PICA revascularization. There was no episode of recurrent hemorrhage or ischemia during the posttreatment follow-up period. Although lateral medullary syndrome developed as a permanent complication in one patient, a good recovery was made by the other 18 patients by 6 months after the ictus.

Conclusions. The factors that determine the appropriate treatment for ruptured dissecting aneurysms of the VA are tolerance of a test occlusion and the site of dissection. Favorable patient outcomes can be achieved when this algorithm is used.

Endovascular management of vertebrobasilar dissecting aneurysms

BACKGROUND AND PURPOSE

Several approaches to the treatment of dissecting aneurysms of the vertebrobasilar system have been used. We evaluated our endovascular experience, which includes trapping and proximal occlusion.

METHODS

Thirty-five patients with intradural vertebrobasilar dissecting aneurysms presented to our institution between 1992 and 2002. Twenty-six were treated by endovascular means and two with surgery. In the endovascular group, 14 were in a supra-posterior inferior cerebellar artery (PICA) location, and three of these extended to the vertebrobasilar junction on the initial angiogram. Ten were located in an infra-PICA location, or no antegrade flow was seen in the PICA or anterior spinal artery. Two were located at the PICA with antegrade flow preserved in the branch. Twelve lesions were treated with trapping; another 14 were initially treated with proximal occlusion techniques, two of which eventually required trapping procedures. Follow-up images were obtained within 1 year of initial treatment in 24 patients. Mean follow-up for these patients was 3.5 years.

RESULTS

Initial treatments were technically successful and without complication in all 26 patients. Follow-up examinations showed complete cure in 19 of 24 patients. One patient died of global ischemia after presenting as Hunt and Hess grade 5 with subarachanoid hemorrhage. Two recurrent hemorrhages occurred in patients in the proximal occlusion group; one died, and the other underwent a trapping procedure. One patient developed contralateral vertebral dissection 24 hours after occlusion of a dissecting aneurysm of the dominant vertebral artery and died of a brain stem infarct. Another died of probable vasospasm, and the last died of an unknown cause 1 month after treatment. Two patients had recanalization despite an initial trapping procedure, both underwent further treatment. Mortality rate was 20% in the treated group (including the two patients treated surgically), with four of five deaths occurring during the initial hospital course. Mortality rate was 50% in the six patients in the untreated group who were available for follow-up.

CONCLUSION

Dissecting aneurysms of the vertebrobasilar system remain high-risk lesions because of their natural history. They can be managed by endovascular methods according to aneurysm location, configuration, collateral circulation, and time of presentation. Trapping results in better prevention of rehemorrhage. Proximal occlusion can achieve occlusion without manipulation of the affected segment when more direct endovascular occlusion or stent placement cannot be performed.

Spontaneous fusiform middle cerebral artery aneurysms: characteristics and a proposed mechanism of formation

OBJECT

The goal of this study was to identify the origins of spontaneous fusiform middle cerebral artery (MCA) aneurysms.

METHODS

One hundred two cases of spontaneous fusiform MCA aneurysms were reviewed, including 40 from the authors' institutions and 62 identified from the literature. The mean age at symptom onset was 38 years, and the male/female ratio was 1.4:1. At presentation, the MCA lumen was stenosed or occluded in 12 patients, focally dilated in 57, and appeared "serpentine" in 33. Most lesions originated from the M1 or M2 segments, and most (80%) presented with nonhemorrhagic symptoms or were discovered incidentally. The presenting clinical features correlated with morphological findings in the aneurysms, which could be observed to progress from a small focal dilation or vessel narrowing to a serpentine channel. Hemorrhage was the most common presentation in small lesions; the incidence of bleeding progressively diminished with larger lesions. Patients with stenoses or occluded vessels most often presented with ischemic symptoms, and occasionally with hemorrhage. Giant focal dilations or serpentine aneurysms were rarely associated with acute bleeding; clinical presentation was most often prompted by mass effect or thromboembolic stroke.

CONCLUSIONS

Analysis of results after various treatments indicates that for symptomatic lesions, therapies that reverse intraaneurysmal blood flow and augment distal cerebral perfusion are associated with better outcomes than other strategies, including conservative management. Based on the spectrum of clinical, pathological, neuroimaging, and intraoperative findings, dissection is proposed as the underlying cause of these lesions.

Isolated dissections and dissecting aneurysms of the posterior inferior cerebellar artery: topic and literature review

Isolated dissections of the posterior inferior cerebellar artery (PICA) are rare. Thus, no large series of cases have been reported in the literature. Due to limited knowledge regarding the natural history of these lesions and the lack of high-quality evidence supporting various treatment options, management is controversial and practice parameters are ill defined. In order to offer a comprehensive reference for the diagnosis and management of isolated PICA dissections, the authors reviewed the National Library of Medicine from 1966 to October 2001. Twenty-seven patients averaging 43.6 years of age and including 14 males and 13 females were reported. Subarachnoid hemorrhage occurred in 20 patients, and two died. Dissections were located in the proximal PICA in 22 patients and were three times more common on the left side (left:right=3:1). Six patients were managed conservatively, and four with endovascular techniques. Seventeen had open surgery: five underwent resection, two went through trapping, and two had proximal clipping. Wrapping with muscle was performed in two patients, encasement with Sundt clips in two, and four had occipital artery (OA)-PICA bypass surgery. A meticulous analysis of reported cases with regard to clinical and pathological features, management strategies, and outcomes is presented.

Arterial reconstruction by direct surgical clipping of a basilar artery dissecting aneurysm after failed vertebral artery occlusion: technical case report and literature review

OBJECTIVE AND IMPORTANCE

Dissecting aneurysms of the basilar artery are rare lesions with significant morbidity and mortality. Their management is controversial and often difficult. Although the rebleeding rate is high, clip reconstruction carries prohibitive risk because of the damage to the parent vessel induced by the dissection and the lack of tissue to gather. An enlarging pseudoaneurysm in the chronic phase, however, may have sufficient tissue for clip reconstruction. We present a case in which this strategy was used successfully.

CLINICAL PRESENTATION

A 45-year-old woman presented 3 months after an initial presentation with a subarachnoid hemorrhage from a dissecting aneurysm of the basilar trunk at an outside institution. The aneurysm had grown compared with previous angiograms.

INTERVENTION

The dominant vertebral artery was sacrificed. Despite this, the aneurysm continued to enlarge. Given the progressive enlargement of the aneurysm, the decision was made to proceed with arterial reconstruction by direct surgical clipping of the saccular component of the dissecting aneurysm. The patient made an excellent recovery with a durable result.

CONCLUSION

Although clipping an intracranial pseudoaneurysm in the acute phase may carry a prohibitive risk, clipping such an aneurysm in the chronic phase may occasionally be warranted. To our knowledge, this is the first case reported in the literature in which direct surgical clipping was used as the primary mode of treatment for a basilar artery dissecting aneurysm that enlarged despite occlusion of the dominant vertebral artery. We review the literature on this rare pathological entity and discuss our management strategy.

Dissecting giant vertebro-basilar aneurysms

OBJECT

Vertebro-basilar dissecting aneurysms (VDAs) are very rare in children. Strokes or subarachnoid hemorrhage are characteristic clinical manifestations, but often only non-specific symptoms are found. Radiological diagnosis may be difficult to obtain and therapy hard to perform. We report on a child who presented with an intracranial mass effect due to a giant VDA.

METHODS

The patient was a 8-year-old girl with right hemiparesis, ataxia, dysphagia and dysphonia and worsening of her neurological deficits. Neuroimaging discovered a giant dissecting aneurysm arising from the left vertebral artery and involving the vertebro-basilar junction. Endovascular treatment by coil embolization was performed. The post-operative course initially showed a remarkable improvement in her clinical condition. Afterwards, she developed cerebral hemorrhage and died.

CONCLUSION

VDAs may have an unusual presentation and their therapy still remains a challenge. Endovascular embolization is a valid option but, as it is surgery, it may cause the death of the patient.

Dissecting aneurysms of the middle cerebral artery: neuroradiological and clinical features

There are few reported cases of nontraumatic dissecting aneurysms of the middle cerebral artery (MCA), and their neuroradiological and clinical features have not been analysed. We looked at these aspects in a collaborative study. We reviewed 13 patients diagnosed as having a dissecting aneurysm of the MCA based on clinical signs and neuroradiological findings in 46 stroke centres between 1995 and 1999. There were four patients who presented with cerebral ischaemia, and nine who presented with bleeding. Of the former group, three were aged less than 15 years. Cerebral angiography showed extensive stenosis and a double lumen of the M1 portion in all four patients. High signal on T1-weighted images around the arterial flow void, due to intramural haematoma, was often seen in the second week. MR angiography showed findings corresponding those of intra-arterial angiography in all four cases. We saw an infarct on CT or MRI in territory of the perforating branches of the M1 segment in all four patients. In the patients presenting with bleeding, pure subarachnoid haemorrhage or a sylvian fissure haematoma was seen on initial CT, and the predominant angiographic finding was dilatation with stenosis, but the site of the lesions was not uniform. A double lumen or intimal flap was seen in about half the cases. Rebleeding occurred within 14 days of the onset in five of the nine patients, with a poor prognosis.

Failure of stent-assisted endovascular treatment for ruptured dissecting aneurysms of the basilar artery

We report two instructive cases of ruptured dissecting aneurysm of the basilar artery. Although stent-assisted endovascular treatment was successful, recurrent bleeding occurred 4 h after the procedure in one patient, and the other's basilar artery occluded 6 days after the procedure. These cases suggest that the high porosity of currently available stents may be insufficient to induce intraluminal thrombosis and merely stenting may fail to prevent bleeding, while postoperative anticoagulation alone may be inadequate to prevent occlusion of the stented vessel.

Vertebrobasilar artery dissection presenting with simultaneous subarachnoid hemorrhage and brain stem infarction: case report

BACKGROUND

Intracranial dissecting aneurysms have been associated with subarachnoid hemorrhage (SAH) or cerebral ischemia. We encountered a patient presenting with simultaneous subarachnoid hemorrhage and brainstem infarction caused by a dissecting aneurysm of the vertebrobasilar artery, which was diagnosed by magnetic resonance imaging (MRI) but did not show abnormal findings on cerebral angiography.

CASE DESCRIPTION

A 55-year-old man had sudden onset of headache and left abducens palsy. Computed tomography revealed a subarachnoid hemorrhage localized in the left prepontine cistern and the left cerebellomedullary fissure. Cerebral angiography showed neither a saccular aneurysm nor fusiform dilatation causing the subarachnoid hemorrhage. MRI demonstrated a small infarction in the left dorsal pons, and an intramural hematoma of the left vertebral artery and lower basilar artery.

CONCLUSION

This is a rare case of a vertebrobasilar dissecting aneurysm that simultaneously caused both SAH and brain stem infarction. MRI should be performed in the acute phase of SAH of unknown origin to determine the possible coexistence of a dissecting aneurysm, as occurred in this case.

Dissecting basilar artery aneurysm growing during long-term follow up--case report

A 58-year-old male presented with a dissecting aneurysm of the basilar artery manifesting as dysarthria, left hemiparesis, and numbness of the left side. Angiography revealed a double lumen at the midportion of the basilar artery which was consistent with a diagnosis of dissecting basilar artery aneurysm. The patient was treated conservatively, and remained neurologically stable for a 5-year period following initial presentation, but serial magnetic resonance imaging revealed growth of the aneurysm compressing the brain stem. His condition then worsened. Computed tomography revealed obstructive hydrocephalus. Ventriculoperitoneal shunting was performed and the patient's symptoms improved. However, he died of subarachnoid hemorrhage. Autopsy showed the patient had had a type 3 "dolichoectatic dissecting aneurysm." Surgical treatment should be seriously considered for treating the patients with dissecting basilar artery aneurysm causing brain stem ischemia, especially if the aneurysm is growing. High-flow bypass and proximal occlusion may be the choice in patients with poor collateral circulations.

Management of intracranial vertebral artery dissections initially presenting without subarachnoid hemorrhage

OBJECTIVE

The clinical and angiographic follow-up results for intracranial vertebral artery (VA) dissections that initially presented without subarachnoid hemorrhage (SAH) were retrospectively investigated, to clarify their management.

METHODS

Twenty-one patients with VA dissections that initially presented without SAH were studied. Initial angiography revealed aneurysmal dilation in 11 cases (typical pearl-and-string sign in 8 cases, aneurysmal dilation only in 2, and aneurysmal dilation with double-lumen sign in 1), occlusion in 7, double-lumen sign in 2, and string-like stenosis in 1. Nine patients (six with pearl-and-string sign, one with occlusion with aneurysmal dilations, and two with double-lumen sign), including three patients who experienced subsequent SAH, underwent endovascular proximal parent artery occlusion. The other 12 patients were treated conservatively. All patients were monitored with magnetic resonance angiography or digital subtraction angiography.

RESULTS

Three patients experienced subsequent SAH, 1 day (two patients) or 51 months after onset. Follow-up angiographic assessments of the 20 patients demonstrated complete resolution in five cases, reduction of aneurysmal dilation in one case, and partial recanalization in one case. However, enlargement or formation of an aneurysmal dilation was recognized in four cases and progression of dissection was observed in one case. Eighteen patients experienced good recoveries, and three patients demonstrated moderate disabilities as a result of the initial ischemic insult.

CONCLUSION

The risk of bleeding from unruptured VA dissections is higher than previously considered. Therefore, endovascular treatment should be considered for patients with VA dissections with relatively large or growing aneurysmal dilations.

Subarachnoid hemorrhage caused by a dissecting aneurysm of the internal carotid artery

Object. Subarachnoid hemorrhage (SAH) caused by the rupture of a dissecting aneurysm of the internal carotid artery (ICA) has been considered rare. Based on data from cooperatively collected cases, the clinical features of patients with dissecting aneurysms of the ICA who presented with SAH were examined.

Methods. Data from 18 patients with dissecting aneurysms of the ICA who presented with SAH diagnosed on the basis of clinical signs, neuroradiological findings, and intraoperative findings from 41 institutions were collected during a 5-year period between 1995 and 1999. The authors found that 0.3% of all cases of SAH and 3.1% of cases of SAH of unverified cause were attributable to a dissecting aneurysm of the ICA. Eleven patients (61%) were middle-aged women, and eight patients (44%) had hypertension. Rebleeding before admission was demonstrated in 13 patients (72%), and intraoperative bleeding was exhibited in half of the patients who underwent surgery during the acute stage. Postoperative growth of an aneurysm bulge or recurrent SAH was seen in five of 10 patients who had undergone wrapping or clipping of the aneurysm bulge in the acute phase. Trapping with or without bypass, which resulted in no postoperative recurrence, was performed in three patients in the acute stage and in two patients in the chronic stage. Twelve patients (67%) had a poor prognosis, primarily attributed to intraoperative bleeding and postoperative recurrence.

Conclusions. Generally, dissecting aneurysms of the ICA are not thought of as frequent causes of SAH. Nonetheless, the presence of these aneurysms should be considered when dealing with SAH because they have a susceptibility to bleeding that can lead to a poor prognosis. Careful surgical planning is necessary to decrease intraoperative bleeding and to avoid postoperative recurrence.

Dissecting aneurysms of the vertebral artery: a management strategy

OBJECT

The authors present a retrospective analysis of their experience in the treatment of vertebral artery (VA) dissecting aneurysms and propose a management strategy for such aneurysms, with special emphasis on the most formidable VA dissecting aneurysms, which involve the origin of the posterior inferior cerebellar artery (PICA).

METHODS

Since 1998, 18 patients with VA dissecting aneurysms, 11 of whom presented with subarachnoid hemorrhage (SAH), have been treated by endovascular surgery at the authors' institution. Obliteration of the entire segment of the dissected site with coils (internal trapping) was performed for aneurysms without involvement of the origin of the PICA (12 cases; among these the treatment-related morbidity rate was 16.7%). The treatment strategy applied to PICA-involved VA dissecting aneurysms presenting with SAH (three cases) included proximal occlusion of the parent artery followed by internal trapping of the aneurysm (one case), proximal occlusion of the parent artery followed by occipital artery (OA)-PICA bypass (one case), and two-staged internal trapping of the aneurysm involving double PICAs (one case). For PICA-involved VA dissecting aneurysms that were not associated with SAH at presentation (three cases), OA-PICA bypass was performed and followed by internal trapping of the aneurysm (two cases). In the remaining case in which a fetal-type posterior communicating artery was present, internal trapping was performed following successful balloon test occlusion (BTO). Overall, there was no sign of infarction in the PICA territory, despite complete occlusion of aneurysms involving the PICA. There was no recurrent bleeding or ischemic symptoms during the follow-up periods. The overall treatment-related morbidity rate for the VA dissecting aneurysms involving the PICA was 16.7%.

CONCLUSIONS

Dissecting VA aneurysms that do not involve the PICA can be safely treated by internal trapping. For those lesions that do involve the PICA, a decision-making algorithm is advocated to maximize the efficacy of the treatment as well as to minimize the risks of treatment-related morbidity based on BTO.

Anterior cerebral artery dissections manifesting as cerebral hemorrhage and infarction, and presenting as dynamic angiographical changes--case report

A 65-year-old woman presented with multiple dissecting aneurysms of the anterior cerebral artery (ACA) manifesting as hemiparesis on the right with dominance in the lower extremity. Computed tomography revealed hematoma in the left frontal lobe, corresponding to the area perfused by the callosomarginal artery. Initial angiography showed string sign and occlusion in the distal portion of the left callosomarginal artery and abnormal feeding suggesting double lumen of the A2 portion of the left ACA. The patient was treated conservatively under a diagnosis of multiple spontaneous dissecting aneurysms of the left ACA. Repeat angiography on Day 8 showed improvement of the string sign and occlusion in the left callosomarginal artery, and change of the double lumen of the A2 portion into string sign. Further angiography on Day 36 showed normalization of the left callosomarginal artery and improvement of the string sign in the A2 portion. Multiple spontaneous dissecting aneurysms of the ACA are extremely rare. Serial angiography beginning in the early stage will be important for correct diagnosis.