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

Traumatic vascular injuries and their management

Traumatic vascular injury to the intracranial and extracranial circulation can be sequelae of blunt, penetrating, or iatrogenic insults to the head, face, or neck. Treatment options include conservative medical management, or more invasive surgical or endovascular therapy. The appropriate treatment depends on the risk-benefit ratio of each option considering the natural history of each. Injuries include mild intimal irregularities, intimal flaps, pseudoaneurysms, fistulas, and occlusions. Need for treatment is partly determined by the collateral circulation to the brain, and the degree to which the lesion is thrombogenic. Advances in endovascular devices and techniques provide us with less invasive alternatives to surgery intervention or allow the interventionalist to treat lesions not treatable by any other modality.

Vertebral artery-posterior inferior cerebellar artery bypass with a superficial temporal artery graft to treat aneurysms involving the posterior inferior cerebellar artery

OBJECT

In patients with aneurysms that require occlusion of the posterior inferior cerebellar artery (PICA), revascularization of this artery should be performed. A novel surgical method for revascularization of the PICA is presented.

METHODS

After a segment of the superficial temporal artery (STA) was harvested, the aneurysm was treated by trapping, followed by placement of a vertebral artery (VA)-PICA bypass in which the STA segment was used as a graft. When the length of the proximal PICA was inadequate, the distal end of the STA was anastomosed to the proximal PICA in an end-to-side fashion. When the length of the proximal PICA was adequate, the STA was anastomosed to the proximal PICA in an end-to-end fashion. In either case, the proximal end of the STA was anastomosed to the VA in an end-to-side fashion. This procedure was used in nine patients whose aneurysms involved the PICA. Although partial lateral medullary syndrome developed in one of them, follow-up evaluation revealed graft patency in all patients. There were no instances of recurrent hemorrhage or ischemia.

CONCLUSIONS

Although this procedure requires harvesting of an STA graft and two anastomoses, it facilitates anterograde flow to the PICA territory. It also involves minimal mobilization of brainstem perforating vessels and the proximal PICA.

Dissecting aneurysms of intracranial carotid circulation

BACKGROUND AND PURPOSE

Clinical features of nontraumatic dissecting aneurysms of intracranial carotid circulation remain unclear because investigation of this disease has been limited to case reports. The aim of this study was to investigate the clinical features of this disease through the use of cooperatively collected cases.

METHODS

The cases diagnosed as dissecting aneurysms of intracranial carotid circulation on the basis of clinical signs and neuroradiological findings in 46 stroke centers from 1995 through 1999 were collected, and their clinical features were analyzed.

RESULTS

Forty-nine cases of dissecting aneurysms of intracranial carotid circulation were collected. Thirty-two patients presented with subarachnoid hemorrhage (SAH), and 17 presented with cerebral ischemia. The ratio of this disease to all intracranial dissecting aneurysms treated in the same institutes for the same period was 19.1%, and the ratio of SAH resulting from this disease to SAH of unverified origin treated in the same institutes for the same period was 6.2%. The predominant site of lesion was the internal carotid artery in 18 of 32 patients (56%) with SAH and the anterior cerebral artery in 13 of 17 patients (76%) with cerebral ischemia. The predominant angiographic findings were that stenosis with dilatation occurred in 20 of 32 patients (63%) with SAH and stenosis without dilatation was seen in 11 of 17 patients (65%) with cerebral ischemia. Poor prognosis was seen in 21 of 32 patients (66%) with SAH, which was due largely to rebleeding seen preoperatively, during operation, and even postoperatively when clipping or wrapping of the aneurysmal bulge was performed.

CONCLUSIONS

Nontraumatic dissecting aneurysm of intracranial carotid circulation is not as rare as expected. It seems to be one of the important causes of SAH of unverified origin.

Vertebrobasilar dissection: a possible role of whiplash injury in its pathogenesis

We reviewed 29 patients with vertebrobasilar dissections (VBD) to investigate the correlation between minor trauma and VBD and the clinical features of this trauma-related condition. Mean age was 43 years, with a male predominance (male/female ratio was 25/4). Seventeen patients presented with subarachnoid hemorrhage (SAH), and 12 with ischemic symptoms. Two patients presenting with ischemia had extracranial VBD (V3 segment). Angiographically, aneurysmal dilatation was observed in most SAH patients (13 patients) in contrast to narrowing or occlusion in most ischemic patients (10 patients). Among the 12 SAH patients treated with coil embolization or conservatively, five died, whereas all ischemic patients recovered well with anticoagulation and/or antiplatelet therapy. Seven patients had received minor or trivial head/cervical trauma, due to whiplash injury, minor fall, or during exercise, which were identified to precede with the lapse of some time (a few minutes or days) the onset of symptoms. All of these patients presented with ischemic symptoms, and they were younger than the other ischemic or SAH patients. The site of vertebral artery dissection was intracranial in four cases, extracranial in one case, and combined in two cases at the level of the V3 segment and the origin of the posterior inferior cerebellar artery. However, no SAH occurred. These clinicopathological findings, i.e. ischemia and angiographic narrowing/occlusion, suggest that dissections were subintimal. Therefore, it is believed that this minor or trivial trauma may primarily cause subintimal dissection with luminal compromise, leading to ischemic symptoms, rather than subadventitial or transmural dissection with aneurysmal dilatation, leading to SAH. This lesion may also occur in younger patients with a favorable outcome. Careful note should be made of patient for the early recognition of this disorder.

Neurologic complications of sit-ups associated with the Valsalva maneuver: 2 case reports

We present 2 cases of potentially catastrophic neurologic consequences occurring in healthy individuals engaged in sit-up exercises. Two young healthy men were engaged in sit-ups when one developed a stroke and the other developed a spinal epidural hematoma. The Valsalva maneuver involved in the sit-up exercise can produce supraphysiologic increases in blood pressure, which can lead to vascular injury and serious neurologic consequences. Proper breathing should be encouraged and patients with known predisposing factors should avoid such exercises. Prompt recognition of neurologic signs and symptoms during exercise can be life saving. This is the first report of the neurologic complications of sit-ups.

Treatment of dissecting vertebral aneurysm

SUMMARY

We report 17 patients with dissecting aneurysm of the vertebral artery (VA) who were treated by direct surgery (n=8) or interventional surgery (n=9). Eight patients presented with subarachnoid hemorrhage (SAH) and nine with ischemia. Ten patients were treated by trapping of the aneurysm that was occlusion of the VA on both sides of aneurysm (direct surgery, n=2; interventional surgery, n=8). The other seven patients were treated by ligation of the VA proximal to the aneurysm (direct surgery, n=6; interventional surgery, n=l). Two patients underwent transposition of the posterior inferior cerebellar artery (PICA). In 15 patients, there were no major complications. Two patients who had been treated by proximal occlusion of the VA developed rebleeding and ischemia due to persistent retrograde filling of the dissecting site. We suggest that angiographic evidence of retrograde filling of the dissecting site should have been considered as an indication for trapping. Trapping of VA dissecting aneurysms is easier and safer by interventional surgery than by direct surgery.

Unpredictability of cerebrovascular ischemia associated with cervical spine manipulation therapy: a review of sixty-four cases after cervical spine manipulation

STUDY DESIGN

A retrospective review of 64 medicolegal records describing cerebrovascular ischemia after cervical spine manipulation was conducted.

OBJECTIVES

To describe 64 cases of cerebrovascular accidents temporally associated with cervical spine manipulation therapy in terms of patient characteristics, potential risk factors, nature of complication, and neurologic sequelae.

SUMMARY OF BACKGROUND DATA

Approximately 117 cases of postmanipulation cerebrovascular ischemia have been reported in the English language literature. Proposed risk factors include age, gender, migraine headaches, hypertension, diabetes, birth control pills, cervical spondylosis, and smoking. It is often assumed that these complications may be avoided by clinically screening patients and by premanipulation positioning of the head and neck to evaluate the patency of the vertebral arteries.

METHODS

Three researchers using a uniform data abstraction instrument performed an independent review of 64 previously unpublished medicolegal records describing cerebrovascular ischemia after cervical spine manipulation. These cases were referred to a single physician for review over a 16-year period from across the United States and Canada. Descriptive statistics were calculated for characteristics of the patients and the complications. Means and standard deviations were computed for continuous variables. Frequencies and proportions were calculated for categorical variables.

RESULTS

This study was unable to identify factors from the clinical history and physical examination of the patient that would assist a physician attempting to isolate the patient at risk of cerebral ischemia after cervical manipulation.

CONCLUSION

Cerebrovascular accidents after manipulation appear to be unpredictable and should be considered an inherent, idiosyncratic, and rare complication of this treatment approach.

[Subarachnoid hemorrhage secondary to dissecting aneurysms of the vertebral artery. Description of 2 cases and review of the literature]

OBJECTIVES AND INTRODUCTION: The pathogenesis and natural history of intracranial vertebral artery dissection remain uncertain up to now due in part to its relative rarity. In this article we review the state of the art of this process and remark the good outcome obtained with embolization using Guglielmi detachable coiling (GDC).

METHODS

Two cases with subarachnoid hemorrhage secondary to rupture of a vertebral dissection aneurysms are described. The first patient initially suffered brain stem infarction, followed by a subarachnoid hemorrhage a year later. The second patient who had a severe subarachnoid hemorrhage with two early rebleedings was successfully treated with embolization using GDC.

CONCLUSIONS

Subarachnoid hemorrhage due to rupture of vertebral dissecting aneurysm is a relatively unknown disease with some important aspects that should be known. The high incidence of early rebleeding (up to 60%), makes early diagnosis and treatment important goals. Classically the preferred treatment has been proximal vertebral artery occlusion. However, the recent introduction of embolization with GDC has made possible the occlusion of the dissection with very good final outcome.

A dissecting aneurysm of the posterior inferior cerebellar artery. A case report

SUMMARY

Dissecting aneurysms occur when blood extrudes into the wall of a vessel. Posterior circulation dissections are recognised as an important cause of cerbral infarction and subarachnoid haemorrhage(SAH), however posterior inferior cerebellar artery (PICA) aneurysmal dissections are rare. A 49-year-old man who presented with SAH was found to have a left PICA dissection on cerebral angiography. The lesion was treated with surgical clipping proximal to the dissection and a distal PICA to PICA anastomosis. The pathology, diagnosis, presentation and treatment of these difficult lesions is discussed.

Cerebrovascular trauma

Cerebrovascular trauma includes a wide variety of injuries, including dissections, traumatic aneurysms, arteriovenous fistulas, and vascular occlusions. These entities, which are often underdiagnosed, can produce devastating neurologic complications. This article reviews the clinical and radiographic presentations of vascular trauma to increase awareness of these injuries and improve our ability to detect and treat them.

Combined endovascular treatment of dissecting vertebral artery aneurysms by using stents and coils

OBJECT

With the recent development and refinement of endovascular stents, the significant potential for these devices in the treatment of wide-necked dissecting and fusiform aneurysms has become apparent. In this article the authors report on the use of stents and coils to treat dissecting and fusiform vertebral artery (VA) aneurysms.

METHODS

Eight consecutive patients harboring eight dissecting aneurysms and one fusiform aneurysm of the VA were succesfully treated using a procedure in which the authors inserted an intravascular stent and secondary endosaccular coils when needed. In all but one patient complete aneurysm occlusion was achieved, and in all cases there was no neurological complication. Follow-up angiography examinations were performed in all patients (mean duration of follow-up angiography review 13.1 months, range 3-42 months). The patients remained stable throughout the clinical follow-up period (mean 14.1 months, range 4-42 months). No rebleeding was recorded.

CONCLUSIONS

At present this combined approach represents a reliable and safe alternative for the treatment of VA dissecting aneurysms, especially in patients who cannot tolerate occlusion tests.

Dissecting aneurysm of the vertebral artery causing subarachnoid hemorrhage after non-hemorrhagic infarction--case report

A 45-year-old male presented with lateral medullary infarction. Cerebral angiography showed dissecting aneurysm as pearl and string sign in the right vertebral artery (VA). Conservative treatment was administered with antiplatelet agent. However, subarachnoid hemorrhage occurred 2 days after admission, inducing coma. Intraaneurysmal embolization and proximal occlusion of the right VA by intravascular surgery resulted in only mild neurological deficits. Conservative treatment including strict control of blood pressure is the first choice of treatment. Antiplatelet therapy and anticoagulant therapy should not be administered. Patients must be followed up by serial angiography and surgery considered if signs of aneurysmal progression are seen.

Dissecting aneurysms of the posterior inferior cerebellar artery: report of four cases and review of the literature

Dissecting aneurysms frequently involve the vertebral arteries and their branches, but those exclusively on the posterior inferior cerebellar artery (PICA) represent only 24 cases in the literature, including the four cases discussed in this article. The clinical diagnosis lacks pathognomonic signs or symptoms, with presentations such as subarachnoid haemorrhage or ischaemia of the brain stem or the cerebellum, and the management is controversial. Wrapping, clipping and embolisation of the aneurysms were tried in this series with different outcomes. Exclusion of the pathological segment should be performed, as shown by rebleeding from our case which was wrapped or by progression of the vascular disease in cases where treatment was delayed. Surgical or endovascular occlusion are well tolerated in our cases and in those reported from the literature, which implies the absence of normal perforating branches to the brain stem arising from the proximal dissected segment of the PICA and a good collateral circulation. A revascularisation procedure using the occipital artery can be performed in order to prevent infarction if an endovascular test occlusion is not tolerated.

Spontaneous occlusion of ruptured vertebral artery dissection at the extradural fenestration associated with extradural origin of the posterior inferior cerebellar artery--case report

A 69-year-old female suffered from sudden onset of severe headache. Computed tomography showed subarachnoid hemorrhage primarily located in the posterior fossa. Initial angiography demonstrated a fenestration of the vertebral artery and an extracranial origin of the posterior inferior cerebellar artery. However, no bleeding points could be clearly detected. The operative findings revealed a massive clot in subarachnoid space, but no bleeding point. Serial angiography demonstrated dissection in one of the limbs of the fenestrated vertebral artery on the 25th day after the onset. On the 100th day, the lesion was spontaneously occluded. The patient is presently doing well at 8 years after surgery.

Coil Embolization for Ruptured Dissection on the Vertebral Artery Distal to the Origin of Posterior Inferior Cerebellar Artery

Although many surgical or endovascular treatments for ruptured vertebral dissection have been reported, the best treatment remains controversial. Recently endovascular vertebral occlusion using coils has been reported, the appropriate occlusion site has not yet been fully discussed.

Five cases of ruptured vertebral dissection located distally to the origin of posterior inferior cerebellar artery were occluded by platinum coil packing in the angiographical “pearl” portion or “fusiform dilatation” together with its proximal vertebral artery. All dissections were occluded completely together with occlusion of distal portion of vertebral artery to PICA's origin. No complications related to procedure were seen in this series.

Occlusion of rupture point with preserving tiny perforators arising from vertebral artery would be an ideal method for this lesion. The present cases suggest that the short segment occlusion by coil packing in the angiographical “pearl” portion or “fusiform dilatation” together with its proximal vertebral artery would be near to the ideal.

Late hemorrhage from persistent pseudoaneurysm in vertebral artery dissection presenting with ischemia: case report

BACKGROUND

Vertebral artery dissection lesions tend to resolve spontaneously, but abnormal findings such as aneurysmal-dilatation occasionally persist. However, the clinical features and pathological findings in such cases have never been verified.

CASE DESCRIPTION

A 62-year-old man presented with left cerebellar infarction. Angiography showed the "pearl and string sign" in the left vertebral artery, and he was diagnosed as having left vertebral artery dissection. Repeated angiography showed persistent aneurysmal dilatation with irregular stenosis. Eleven years after the cerebellar infarction, the patient presented with a subarachnoid hemorrhage from an aneurysm of the left vertebral artery, and the lesion was explored via the left suboccipital approach. The vertebral artery was firm, making the placement of a clip impossible, so the lesion was treated by coating of the bleeding point. The patient died of pneumonia and hyperglycemia on postoperative day 15. Postmortem examination revealed an organized intramural hematoma, thickening of the intima, and fibrous degeneration of the media of the vertebral artery, a fusiform, distended thin arterial wall with intimal disruption at the aneurysmal dilatation, and arteriosclerosis of all cerebral arteries.

CONCLUSION

This case indicates that persistent aneurysmal dilatation of a dissection is a pseudoaneurysm prone to rupture, and that healing of the affected vessels might be severely compromised in the presence of pathological conditions such as arteriosclerosis and disturbed intraluminal blood flow in the dissected lesions.

Subarachnoid hemorrhage from vertebrobasilar dissecting aneurysm treated with staged bilateral vertebral artery occlusion: the importance of early follow-up angiography: technical case report

OBJECTIVE AND IMPORTANCE

Vertebrobasilar dissecting aneurysms are an uncommon but increasingly recognized cause of subarachnoid hemorrhage (SAH). We describe a patient with SAH caused by a dissecting aneurysm involving both vertebral arteries as well as the basilar trunk. The patient was treated successfully with proximal occlusion of the vertebral arteries using endovascular balloon occlusion in two stages. The importance of early follow-up angiography to document progression or resolution of untreated dissections is emphasized. This approach is suggested as definitive treatment for vertebrobasilar dissection in appropriate circumstances.

CLINICAL PRESENTATION

A 41-year-old man presented with SAH from spontaneous vertebrobasilar dissection. Angiography revealed aneurysmal dilation of the right vertebral artery and basilar trunk and occlusion of the left vertebral artery.

INTERVENTION

The dissecting aneurysm was treated with balloon occlusion of the right vertebral artery. Repeat angiography 2 weeks later demonstrated resolution of the left vertebral occlusion, with restoration of antegrade flow in the basilar trunk and increased filling of the right vertebral and basilar dissecting aneurysms. Balloon occlusion of the left vertebral artery led to aneurysm thrombosis and excellent clinical outcome.

CONCLUSION

Bilateral vertebrobasilar dissecting aneurysms are an uncommon cause of SAH. If unilateral proximal vertebral artery occlusion is chosen as the initial treatment, it is essential to document the status of the contralateral vessel using follow-up angiography. Staged bilateral vertebral artery occlusion should be considered in the event of recurrent or progressive aneurysm enlargement. Endovascular balloon occlusion has advantages over proximal clipping of the parent vessel: cranial nerve manipulation is avoided, test occlusion in the awake patient can be performed at the site of permanent occlusion, and therapeutic levels of anticoagulation can be maintained throughout and after the procedure, thus diminishing the likelihood of thromboembolic complications.

Endovascular therapy of traumatic injuries of the intracranial cerebral arteries

Traumatic intracranial arterial injuries represent uncommon complications of both closed-head injury and penetrating head trauma. These injuries include arterial dissections, pseudoaneurysms, and fistulas, both direct and indirect. Although these lesions may be identified while still asymptomatic, they usually present in a delayed fashion with intracranial hemorrhage, focal cerebral ischemia, or, occasionally, severe epistaxis. Endovascular therapy has assumed a major role in the management of this diverse group of lesions. Embolization of pseudoaneurysms with balloons or detachable coils, the use of embolic particles for small arterial injuries, and large vessel occlusion with detachable balloons represent current treatment strategies that have evolved over the past three decades. Angioplasty and stent deployment may have a future role to play in the management of arterial dissection. Principles of neurologic critical care that minimize secondary brain injury are essential adjuncts in the management of these patients before, during, and after endovascular treatment.

Fusiform vertebral artery aneurysms as a cause of dissecting aneurysms. Report of two autopsy cases and a review of the literature

Two autopsy cases of angiographically determined fusiform aneurysms of the vertebral arteries (VAs) are reported and the appropriate literature is reviewed to investigate the pathological characteristics of both fusiform and dissecting VA aneurysms and the pathogenesis of dissecting aneurysms. One patient had suffered a subarachnoid hemorrhage (SAH) due to dissection of a previously documented incidental fusiform aneurysm. The other patient had harbored incidental fusiform aneurysms coexistent with a ruptured aneurysm of the posterior inferior cerebellar artery. The location and pathological features of the aneurysms were similar in the two cases. The aneurysms in both cases displayed intimal thickening, disruption of the internal elastic lamina, and degeneration of the media. A mural hemorrhage and patchy calcification were also found in the case that included SAH. Based on their pathological investigation of these two cases and a review of reported cases, the authors propose that incidental fusiform aneurysms in the VAs are characterized by weakness in the internal elastic lamina and, therefore, have the potential to become dissecting aneurysms, resulting in a fatal prognosis. This suggests that long-term control of blood pressure is mandatory in patients with incidental fusiform aneurysms in the VAs.

Endovascular treatment of ruptured dissecting aneurysms aimed at occlusion of the dissected site by using Guglielmi detachable coils

OBJECT

Surgical or endovascular occlusion of the parent artery proximal to an aneurysm has been recommended for treatment of dissecting aneurysms of the intracranial posterior circulation. However, dissecting aneurysms may rupture even after proximal occlusion because distal progression of thrombus is necessary to occlude the dissecting aneurysm completely, and this may be delayed by the presence of retrograde flow. In this article the authors present their experience in treating six patients with ruptured dissecting aneurysms.

METHODS

The authors report on six patients with a ruptured dissecting aneurysm in the posterior fossa who were successfully treated by endovascular occlusion of the aneurysm by using Guglielmi detachable coils. The procedure was particularly aimed at occluding the dissected site.

CONCLUSIONS

At the present time, endovascular occlusion of the dissected site is a safe, minimally invasive, and reliable treatment for dissecting aneurysms when a test occlusion is tolerated and adequate collateral circulation is present.

Clinical and neuroradiological features of intracranial vertebrobasilar artery dissection

BACKGROUND AND PURPOSE

We sought to determine the clinical and neuroradiological features of intracranial vertebrobasilar artery dissection.

METHODS

The clinical features and MR findings of 31 patients (20 men and 11 women) with intracranial vertebrobasilar artery dissections confirmed by vertebral angiography were analyzed retrospectively. The vertebral angiography revealed the double lumen sign in 11 patients (13 arteries) and the pearl and string sign in 20 patients (28 arteries).

RESULTS

The patients ranged in age from 25 to 82 years (mean, 54.8 years). Clinical symptoms due to ischemic cerebellar and/or brain stem lesions were common, but in 3 cases the dissections were discovered incidentally while an unrelated disorder was investigated. Headache, which has been emphasized as the only specific clinical sign of vertebrobasilar artery dissection, was found in 55% of the patients. Intramural hematoma on T1-weighted images has been emphasized as a specific MR finding. The positive rate of intramural hematoma was 32%. Double lumen on 3-dimensional (3-D) spoiled gradient-recalled acquisition (SPGR) images after the injection of contrast medium was identified in 87% of the patients. The 3-D SPGR imaging method is considered useful for the screening of vertebrobasilar artery dissection.

CONCLUSIONS

Intracranial vertebrobasilar artery dissection is probably much more frequent than previously considered. Such patients may present no or only minor symptoms. Neuroradiological screening for posterior circulation requires MR examinations, including contrast-enhanced 3-D SPGR. Angiography may be necessary for the definite diagnosis of intracranial vertebrobasilar artery dissection because the sensitivity of the finding of intramural hematoma is not satisfactory.

Risk factors and precipitating neck movements causing vertebrobasilar artery dissection after cervical trauma and spinal manipulation

STUDY DESIGN

Potential precipitating events and risk factors for vertebrobasilar artery dissection were reviewed in an analysis of the English language literature published before 1993.

OBJECTIVES

To assess the literature pertaining to precipitating neck movements and risk factors for vertebrobasilar artery dissection in an attempt to determine whether the incidence of these complications can be minimized.

SUMMARY OF BACKGROUND DATA

Vertebrobasilar artery dissection and occlusion leading to brain stem and cerebellar ischemia and infarction are rare but often devastating complications of cervical, manipulation and neck trauma. Although various investigators have suggested potential risk factors and precipitating events, the basis for these suggestions remains unclear.

METHODS

A detailed search of the literature using three computerized bibliographic databases was performed to identify English language articles from 1966 to 1993. Literature before 1966 was identified through a hand search of Index Medicus. References of articles obtained by database search were reviewed to identify additional relevant articles. Data presented in all articles meeting the inclusion criteria were summarized.

RESULTS

The 367 case reports included in this study describe 160 cases of spontaneous onset, 115 cases of onset after spinal manipulation, 58 cases associated with trivial trauma, and 37 cases caused by major trauma (3 cases were classified in two categories). The nature of the precipitating trauma, neck movement, or type of manipulation that was performed was poorly defined in the literature, and it was not possible to identify a specific neck movement or trauma that would be considered the offending activity in the majority of cases. There were 208 (57%) men and 158 (43%) women (gender data not reported in one case) with an average age of 39.3 +/- 12.9 years. There was an overall prevalence of 13.4% hypertension, 6.5% migraines, 18% use of oral contraception (percent of female patients), and 4.9% smoking. In only isolated cases was specific vascular disease such as fibromuscular hyperplasia noted.

CONCLUSIONS

The literature does not assist in the identification of the offending mechanical trauma, neck movement, or type of manipulation precipitating vertebrobasilar artery dissection or the identification of the patient at risk. Thus, given the current status of the literature, it is impossible to advise patients or physicians about how to avoid vertebrobasilar artery dissection when considering cervical manipulation or about specific sports or exercises that result in neck movement or trauma.

A giant dissecting aneurysm mimicking serpentine aneurysm angiographically. Case report and review of the literature

Intracranial dissecting and giant serpentine aneurysms are rare vascular anomalies. Their precise cause has not yet been completely clarified, and the radiological appearance of such lesions can be different in each case according to the effect of hemodynamic stress on a pathologic vessel wall. For berry aneurysms, available evidence overwhelmingly favors their causation by hemodynamically induced degenerative vascular disease and there is an obvious need to determine the hemodynamic parameters most likely to induce the precursor atrophic lesions. In this study, a case of a giant dissecting aneurysm angiographically mimicking serpentine aneurysm of the right ophthalmic artery is reported and the relevant literature is reviewed to investigate the pathological characteristics and pathogenesis of this lesion. In the present case, radiological investigation of the lesion suggested a serpentine aneurysm, but the diagnosis was corrected to dissecting aneurysm subsequent to the pathological examination of the resected aneurysm. A giant dissecting aneurysm angiographically mimicking serpentine aneurysm and developing as the result of a circumferential dissection located between the internal elastic lamina and media is of particular interest when the etiology of these aneurysms is considered. To our knowledge this is the first report on intracranial dissecting aneurysm mimicking serpentine aneurysm angiographically. Our case illustrates the importance of careful serial section studies for a better understanding of the vascular pathology underlying the processes involved in intracranial serpentine aneurysms. We conclude that serpentine, dissecting and berry aneurysms may all arise by way of similar pathophysiological mechanisms.

A dissecting aneurysm of the posteroinferior cerebellar artery: case report

OBJECTIVE AND IMPORTANCE

We present a patient who experienced a subarachnoid hemorrhage secondary to a dissecting aneurysm of the right posteroinferior cerebellar artery (PICA). The use of an encircling clip in treating the aneurysm while preserving supply to brain stem perforators originating near the dissecting segment and the distal PICA territory was key in the operative management.

CLINICAL PRESENTATION

A 48-year-old patient with a history of hypertension presented with subarachnoid hemorrhage confirmed by computed tomography of the brain. Successive cerebral angiography revealed a dynamic change in the configuration of the dissection, with expansion of the associated focal ectasia.

OPERATIVE MANAGEMENT

At surgery, three brain stem perforators adjacent to the aneurysm were visualized. The dissecting segment was reconstructed with an encircling Sundt clip and muslin wrap, which preserved the flow through the PICA and brain stem perforators.

CONCLUSION

A patient suffering from a dissecting PICA aneurysm and subarachnoid hemorrhage was successfully treated with direct surgical reconstruction of the parent artery, sparing the perforators to the medulla.

Follow-up evaluation of dissecting aneurysms of the vertebrobasilar circulation by using gadolinium-enhanced magnetic resonance imaging

The authors assessed the reliability of magnetic resonance (MR) imaging contrast enhancement for the detection and follow-up evaluation of dissecting aneurysms of the vertebrobasilar circulation. Twenty consecutively admitted patients who underwent both gadolinium-enhanced MR imaging and conventional angiography were reviewed. Enhancement of the dissecting aneurysm was seen in all but one of the 20 patients, including 10 (71%) of 14 patients examined in the chronic phases, when the T1-hyperintensity signal that corresponded to the intramural hematoma was unrecognizable. The enhanced area corresponded to the "pearl sign" or aneurysm dilation noted on the comparable angiogram. On follow-up MR studies enhancement had spontaneously disappeared in four patients at a time when comparable vertebral angiograms revealed disappearance of the aneurysm dilation. The enhancement persisted in five of nine patients examined more than 24 weeks after symptom onset; in all five patients the aneurysm dilation remained on comparable angiograms. Dynamic MR studies showed rapid and remarkable enhancements with their peaks during the immediate dynamic phase after injection of the contrast material. The authors conclude that gadolinium-enhanced MR imaging is useful for the detection and follow-up evaluation of dissecting aneurysms of the vertebrobasilar circulation.

Coil embolization of ruptured vertebral dissection in acute stage with interlocking detachable coils

BACKGROUND

Although dissecting aneurysm of vertebral artery is known as one of the causes of subarachnoid hemorrhage (SAH) in the posterior circulation, the best surgical treatment method remains controversial.

METHOD AND RESULT

This 64-year-old woman was admitted to our service with headache due to SAH caused by a ruptured vertebral dissecting aneurysm in the distal portion of the posterior inferior cerebellar artery. After confirming tolerance of parent artery occlusion by temporary balloon occlusion, both the dissection site and the proximal portion of the parent artery were occluded completely by interlocking detachable coils (IDCs) without any ischemic complications. The patient was discharged without any neurologic deficit on the 25th day after the therapy.

CONCLUSION

The goal of treatment for the ruptured dissecting aneurysm is isolation of the dissection site from the circulation to prevent rerupture. In our case, endovascular occlusion with IDCs was sufficient to reach the goal. In cases with difficulties in the surgical approach, embolization of the dissection site with IDCs should be considered.

Tissue plasminogen activator in a vertebral artery dissection

BACKGROUND

Spontaneous dissection of the vertebral artery is uncommon.

METHOD

Case study.

RESULTS

We report a 49-year-old woman who presented with the rapidly progressing basilar artery syndrome who was given an intravenous dose of tissue plasminogen activator seven hours after the onset of first symptoms. Thirty minutes after the injection, a dramatic recovery of the patient's consciousness and neurological signs was noted.

CONCLUSION

To our knowledge, this is the first reported case of intravenous tissue plasminogen activator use in acute vertebral artery dissection.

Treatment of dissecting basilar artery aneurysm by flow reversal

Dissecting aneurysm of the basilar artery is a rare but increasingly recognized entity, with a frequently fatal or morbid outcome. Unlike the well established proximal occlusion and trapping approaches to vertebral artery dissections, surgical intervention for basilar lesions has been limited to wrapping techniques for arterial wall reinforcement. We report a case of midbasilar dissecting aneurysm successfully treated by clipping the proximal basilar artery below the level of the anterior inferior cerebellar arteries, allowing retrograde flow via the posterior communicating arteries to provide continued basilar perfusion. With the growing recognition of basilar dissection and pseudoaneurysm formation there is a need for improved therapeutic options. We suggest that definitive treatment can be achieved using the principle of proximal occlusion and flow reversal, and review the pertinent literature on basilar artery dissection.

Reconstruction of the posterior inferior cerebellar artery in the treatment of giant aneurysms. Report of two cases

Two techniques of revascularizing the posterior inferior cerebellar artery (PICA) during aneurysm surgery are presented. One involves transposition of the PICA to the vertebral artery proximal to the aneurysm using a superior temporal artery (STA) as a graft. This is used in cases in which the PICA has branched off from the wall of the giant vertebral artery aneurysm. The other technique involves end-to-end anastomosis of the PICA after excision of a giant distal PICA aneurysm located at the cranial loop near the roof of the fourth ventricle. The reconstructions of the PICA described here are surgical procedures designed to preserve normal blood flow in the PICA in patients treated for giant aneurysms involving that artery.

Treatment of aneurysms by excision or trapping with arterial reimplantation or interpositional grafting. Report of three cases

The authors report three cases of ruptured, large or giant aneurysms that were treated by excision or trapping, followed by revascularization of distal vessels by means of arterial reimplantation or superficial temporal artery interpositional grafting. In the first case, a large serpentine aneurysm arising from the anterior temporal branch of the right middle cerebral artery (MCA) was excised and the distal segment of the anterior temporal artery was reimplanted into one of the branches of the MCA. In the second case, a giant aneurysm, fusiform in shape, arose from the rolandic branch of the MCA. This aneurysm was totally excised and the M3 branch in which it had been contained was reconstructed with an arterial interpositional graft. In the third case the patient, who presented with a subarachnoid hemorrhage, had a dissecting aneurysm that involved the distal portion of the left vertebral artery. In this case the posterior inferior cerebellar artery (PICA) arose from the wall of the aneurysm and coursed onward to supply the brainstem. This aneurysm was managed by trapping and the PICA was reimplanted into the ipsilateral large anterior inferior cerebellar artery. None of the patients suffered a postoperative stroke and all recovered to a good or excellent postoperative condition. These techniques allowed complete isolation of the aneurysm from the normal blood circulation and preserved the blood flow through the distal vessel that came out of the aneurysm. These techniques should be considered as alternatives when traditional means of cerebral revascularization are not feasible.

A fatal, chronically growing basilar artery: a new type of dissecting aneurysm

A long-term follow-up study (minimum duration 2 years) was made of 13 patients with tortuous dilated basilar arteries. Of these, five patients had symptoms related to the presence of such arteries. Symptoms present at a very early stage included vertebrobasilar insufficiency in two patients, brainstem infarction in two patients, and left hemifacial spasm in one patient. Initial magnetic resonance (MR) imaging in serial slices of basilar arteries obtained from the five symptomatic patients showed an intimal flap or a subadventitial hematoma, both of which are characteristic of a dissecting aneurysm. In contrast, the basilar arteries in the eight asymptomatic patients did not show particular findings and they remained clinically and radiologically silent during the follow-up period. All of the lesions in the five symptomatic patients gradually grew to fantastic sizes, with progressive deterioration of the related clinical symptoms. Dilation of the basilar artery was consistent with hemorrhage into the "pseudolumen" within the laminated thrombus, which was confirmed by MR imaging studies. Of the five symptomatic patients studied, two died of fatal subarachnoid hemorrhage (SAH) and two of brainstem compression; the fifth patient remains alive without neurological deficits. In the three patients who underwent autopsy, a definite macroscopic double lumen was observed in both the proximal and distal ends of the aneurysms within the layer of the thickening intima. Microscopically, multiple mural dissections, fragmentation of internal elastic lamina (IEL), and degeneration of media were diffusely observed in the remarkably extended wall of the aneurysms. The substantial mechanism of pathogenesis and enlargement in the symptomatic, highly tortuous dilated artery might initially be macroscopic dissection within a thickening intima and subsequent repetitive hemorrhaging within a laminated thrombus in the pseudolumen combined with microscopic multiple mural dissections on the basis of a weakened IEL. The authors note and caution that symptomatic, tortuous dilated basilar arteries cannot be overlooked because they include a group of malignant arteries that may grow rapidly, resulting in a fatal course.

Middle cerebral artery dissecting aneurysm with persistent patent pseudolumen. Case report

The extremely rare condition of an ischemic right middle cerebral artery dissecting aneurysm with persistent patent pseudolumen is described. In the majority of cases of dissecting aneurysms, the pseudolumen persists for a very short time, probably because reentry from the pseudolumen is minimal or nonexistent. In contrast, the present case was assumed to have sufficient reentry from the bypass flow in the pseudolumen. Endothelial formation both in the true lumen and the pseudolumen was suggested as the possible mechanism of the stabilized double lumen.

Dissecting aneurysm of the anterior cerebral artery causing hemorrhagic infarction

BACKGROUND

Dissecting aneurysms of the cerebral arteries are infrequent, and they occur preferentially in the middle cerebral, internal carotid, and vertebrobasilar arteries. The anterior cerebral artery (ACA) is usually involved in association with dissection in other locations, but a lesion confined to the ACA is an extremely rare event. No previous reports have well documented the clinical and pathological features of the ACA dissection. Moreover, surgical management for this lesion has not been reported.

CASE REPORT

A case of dissecting aneurysm confined to the ACA causing hemorrhagic infarction is presented. To prevent subsequent rupture, we employed a trapping procedure 12 days after the onset. A dark purplish discoloration of the right A2 portion was encountered, with an intact anterior communicating complex. The involved vessel was partly sectioned for further pathological examination.

RESULTS

Pathologically, subintimal clots dissected the vascular lumen in the inner layer of the media. Other abnormalities such as deficiency of the internal elastic lamina and medial defects were not found. The postoperative clinical course was not eventful.

CONCLUSIONS

This is the first case to document an ACA dissecting aneurysm treated by a direct surgical approach. Spontaneous resolution is not infrequent in cerebral dissection, but subsequent rupture has commonly resulted in poor outcome. Surgical management is thought to be the most effective method to prevent further hemorrhagic event, even for an ACA dissection. Revascularization distal to the compromised artery should be considered whenever necessary.

Iatrogenic dissecting aneurysm of the internal carotid artery

A secondary dissecting aneurysm after arterial injury has been reported as a complication of surgery. We encountered this phenomenon in a patient with a meningioma of the sphenoid ridge. Despite successful clipping of a small rupture in the anterior wall of the proximal portion of the internal carotid artery, the patient became drowsy 30 days after surgery and developed right hemiparesis followed by fatal bleeding from the internal carotid artery. Histological examination revealed a traumatic dissecting aneurysm which had developed from the tear in the intima and extended into the dural ring and the bifurcation of the carotid artery. The characteristic clinical and histopathologic findings are shown. Methods for early recognition and the possibility of immediate treatment are briefly discussed.

Recurrent subarachnoid hemorrhage from untreated ruptured vertebrobasilar dissecting aneurysms

The clinical characteristics of vertebrobasilar dissecting aneurysms occurring with subarachnoid hemorrhage (SAH) were reviewed in 42 patients, with particular focus on the time, incidence, and outcome in association with subsequent rupture. Twenty-nine patients underwent 31 surgical procedures, and the remaining 13 patients were managed without surgery. Surgical details included 19 proximal vertebral artery obliterations (including 1 case of endovascular surgery using balloon occlusion), 9 trappings, 1 wrapping, 1 bleb clipping, and 1 bleb clipping combined with wrapping. Surprisingly, subsequent rupture occurred in 30 (71.4%) of the 42 patients. Excluding one patient with postoperative rupture, 29 patients suffered a subsequent rupture in the unsecured stage. Of these 29 patients, 19 were operated on after the subsequent rupture and 10 were not operated on because of deteriorated clinical condition (9 patients) or anatomic considerations (1 patient). Of the 30 patients that suffered a subsequent rupture, 14 died. Twelve of the deaths were directly related to the second episode of rupture. Of the 12 patients who did not suffer a subsequent rupture, 10 underwent operations and there were no operative deaths. Only one patient died as the result of the initial critical SAH. The mortality (46.7%) of the patients with subsequent rupture was significantly higher (P < 0.05) than that (8.3%) of the patients without subsequent rupture. Seventeen (56.7%) of the 30 subsequent ruptures occurred within 24 hours after the first SAH, and 24 (80%) occurred within the first week. Six (66.7%) of the 9 patients operated on within 24 hours after the first SAH and 11 (68.8%) of the 16 patients operated on within a week suffered preoperative subsequent ruptures.(ABSTRACT TRUNCATED AT 250 WORDS)

Proximal balloon occlusion for dissecting vertebral aneurysms accompanied by subarachnoid hemorrhage

Five patients with spontaneous dissecting vertebral aneurysms presenting with subarachnoid hemorrhage were treated with endovascular proximal balloon occlusion after a successful balloon Matas' test. Occlusion was performed in the extracranial portion of the vertebral artery after the potentially dangerous period of cerebral vasospasm. Two patients rebled preoperatively during the waiting period. Although angiograms demonstrated residual aneurysmal dilatation for four of the five patients, postoperative hemorrhages or progression of the dissection were not observed during the 19- to 48-month follow-up period. Only one patient experienced transient postoperative ischemic complication. Although the timing of the procedure and the site of occlusion remain controversial, proximal balloon occlusion of the vertebral artery appears to be a safe and effective therapy for patients with dissecting vertebral aneurysms presenting with subarachnoid hemorrhages. This method provides an important, less invasive alternative for this condition.

Dissecting aneurysms of the basilar artery

Ten patients (six men and four women; mean age, 40 yr) with spontaneous dissection of the basilar artery are reported. Clinically, six were admitted with subarachnoid hemorrhage (SAH) and four were admitted with brain stem ischemia. Angiography demonstrated string sign in four patients, pearl reaction in four, double lumen in one, and arterial ectasia with mural retention of contrast medium in one. Magnetic resonance imaging was performed in two patients. Follow-up angiograms or magnetic resonance angiography in six patients showed spontaneous healing in two patients, improvement in two, progression in one, and no change in one. Nine patients were treated medically, and one underwent selective intravascular occlusion of the dissecting aneurysm. One patient died after further SAH, two remain severely disabled, three have residual neurological deficit, and four are in good clinical condition. The most interesting observations in this series include a relatively good course in a substantial number of patients and low further bleeding potential after SAH, the late "globular" evolution, which may be favorable for reconstructive treatment, and the diagnostic value of associated computed tomographic/angiographic findings. Surgical options in basilar dissection are very poor; in some reported cases, wrapping has been tried with disappointing results. In light of the possibility of spontaneous healing or improvement, wrapping should be reserved for only those patients with recurrent SAH or angiographic progression of the dissection.

Treatment of vertebral artery dissecting aneurysm by aneurysm trapping and posterior inferior cerebellar artery reimplantation. Case report

The author presents the case of a patient with a ruptured vertebral artery dissecting aneurysm in which the posterior inferior cerebellar artery (PICA) arose from the wall of the aneurysm. The aneurysm was treated by trapping and the PICA was anastomosed to the vertebral artery proximal to the dissection. This technique allows intraoperative obliteration of the aneurysm while maintaining normal blood flow to the PICA.

Ruptured dissecting vertebral artery aneurysm detected by repeated angiography: case report

A case of a ruptured dissecting aneurysm of the vertebral artery, which was detected by repeated angiography (third time), is reported. A 59-year-old woman, whose preoperative angiogram showed no abnormality, underwent a bifrontal craniotomy and the total removal of the right frontal glioma. However, a subarachnoid hemorrhage was detected by computed tomography the day after the surgery. Conventional angiography performed on the same day revealed no definite abnormality. Nevertheless, 9 days after surgery, a second subarachnoid hemorrhage occurred. The dissecting aneurysm of the vertebral artery was revealed by angiography. It is important to suspect this type of aneurysm as a differential diagnosis when the cause of the subarachnoid hemorrhage is not clarified in the first angiogram.