Benign arterial dissections of the posterior circulation

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 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.

[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.

Long-term follow-up study of unruptured vertebral artery dissection: clinical outcomes and serial angiographic findings

OBJECT

Although the spontaneous occurrence of an unruptured vertebral artery (VA) dissection has increasingly been recognized as a relatively common cause of stroke, and the clinical aspects of this lesion have gradually been determined, its natural course remains obscure. The main goal of this study was to clarify the management protocol for this condition by examining serial angiographic changes in patients with unruptured VA dissections.

METHODS

Seventeen patients with unruptured VA dissections, including 13 men and four women, were clinically and angiographically examined between 1993 and 1998. All patients were observed using serial angiography studies. The initial angiography examinations most frequently revealed stenotic lesions (appearance of a pearl-and-string sign or string sign) in eight (47.1%) of 17 cases. In 15 cases (88.2%), changes in the lesions were evident on follow-up angiography studies. Stenotic lesions resulted in occlusion in four cases, normalization in three, and subsequent formation of an aneurysm in one case, which was treated successfully by proximal occlusion of the affected vessel performed using a detachable balloon. Occluded lesions, which were initially observed in three patients, recanalized in two patients and remained unchanged in one patient. Fusiform dilation alone was demonstrated in three patients during the initial angiography session; these lesions became normalized or were unchanged on follow-up studies. Saccular aneurysms were observed in two patients. In one of these cases, proximal ligation of the parent artery was successfully performed because of subsequent aneurysm enlargement. A double lumen, which appeared in one patient with an extradural VA dissection, became occluded. Magnetic resonance T2-weighted imaging studies revealed infarction corresponding to the posterior circulation in seven cases. During long-term observation in this series, good or excellent recovery was obtained in 14 (87.5%) of 16 patients, and moderate or severe disability in two (12.5%); one patient was lost to follow up after the second angiography study.

CONCLUSIONS

A follow-up angiography study must be performed during the early stage (within approximately 3 weeks after onset of symptoms) to confirm the formation or enlargement of an aneurysm, because such conditions may be amenable to surgical treatment. Unruptured VA dissection could otherwise be treated and followed conservatively. Although the majority of dissected lesions seem likely to stabilize within a few months, as evidenced on angiography, in some cases a longer observation period is required.

[Basilar artery dissection: case report]

We report a case of basilar artery dissection. MRI and angiographic study could ascertain the diagnosis.

Clinicopathological features of non-atherosclerotic cerebral arterial trunk aneurysms

Internal elastic lamina (IEL) is the most vital structure of the cerebral arterial wall. Longstanding weakness of the IEL due to hemodynamic stress is compensated by adaptive intimal thickening. Formation of cerebral arterial trunk aneurysm is assumed to be the result of a break in the equilibrium between hemodynamic stress and the condition of the IEL and intima. Cerebral arterial trunk aneurysms unrelated to the branching zones have several lesional patterns of IEL and the state of intima. There is a strong relationship between the pathological features of aneurysms and their clinical courses. We attempt to delineate the concept of cerebral arterial trunk aneurysms including 'dissecting aneurysms' and 'fusiform aneurysms'.

Clinical picture of intracranial non-traumatic dissecting aneurysm

Non-traumatic intracranial arterial dissection has been accepted as a unique entity of 'cerebral infarction in otherwise healthy young adults', and is particularly prevalent in Western countries. A recent data collection and analysis have revealed additional clinical features. The nationwide study in Japan conducted in 1996 has provided new information on the natural history and current treatment of intracranial dissecting aneurysms in Japan. The incidence of symptomatic dissection was found to be much higher in the vertebrobasilar system than in the carotid system. The mean age of the patients was 51.3 years. Patients with carotid lesions were younger (mean 43.8 years). The male/female ratio was 2: 1. Fifty-eight percent of patients presented with subarachnoid hemorrhage. Recurrence was more frequent in patients with subarachnoid hemorrhage (14%) than in patients with no hemorrhage (4.2%). Common radiological findings were dilatation, 'pearl and string' sign and narrowing of the affected artery. Surgical treatment involved a variety of procedures including proximal occlusion, entrapment, wrapping and endovascular embolization. Patients with subarachnoid hemorrhage (61%) underwent surgical treatment more frequently than patients with no hemorrhage (17%). Good recovery was achieved in 64% of all patients. Outcome was better in patients with no subarachnoid hemorrhage compared with those with hemorrhage.

Basilar artery dissection in a young woman: a case report

The case of a young woman with basilar artery dissection, possibly precipitated by trauma, is presented, and the literature is reviewed.

Proposed classification of nonatherosclerotic cerebral fusiform and dissecting aneurysms

OBJECTIVE

The aim of this study is to classify nonatherosclerotic aneurysms unrelated to the branching zones (including fusiform aneurysms and dissecting aneurysms).

METHODS

Damage to the internal elastic lamina (IEL) is often an associated factor in the pathogenesis of aneurysm formation. In this study, 85 nonatherosclerotic aneurysms arising from an arterial trunk unrelated to the branching zones were classified into four different types, based on the lesional patterns of the IEL and the state of the intima. Type 1 corresponded to classic dissecting aneurysms, the pathogenesis of which was characterized by acute widespread disruption of the IEL without intimal thickening. Patients with Type 1 aneurysms had an ominous clinical course, and many presented with sudden subarachnoid hemorrhage with frequent rebleeding. Type 2 aneurysms were segmental ectasias, which had an extended and/or fragmented IEL with intimal thickening. Weakness of the arterial wall caused by the damaged IEL was assumed to be compensated by the intimal thickening. The luminal surface of the thickened intima was smooth without thrombus formation. The patients with Type 2 aneurysms had a placid clinical course. Type 3 aneurysms were dolichoectatic dissecting aneurysms, pathologically characterized by fragmentation of the IEL, multiple dissections of thickened intima, and organized thrombus in the lumen. Most of them were symptomatic and progressively enlarged over time. Type 4 aneurysms were saccular aneurysms unrelated to the branching zones. They arose in areas with minimally disrupted IEL without intimal thickening, and there was a risk of rupture.

CONCLUSION

There was a strong relationship between the pathological features of the aneurysms and their clinical courses. This classification may provide a rationale for modes of treatment.

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.

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.

Extracranial and intracranial vertebrobasilar dissections: diagnosis and prognosis

OBJECTIVES

To compare the diagnosis and prognosis of extracranial versus intracranial vertebral artery dissections without intracerebral haemorrhage.

METHODS

Twenty two vertebral artery dissections were defined by intra-arterial angiography and classified in two groups: group 1, nine extracranial dissections (seven patients) and group 2, 13 intracranial dissections (nine patients), involving the basilar artery in five cases. Bilateral dissections were found in 38% of the population. Before angiography, all the patients had been investigated by continuous wave Doppler, colour coded Doppler, and transcranial Doppler. Mean follow up was 44 months.

RESULTS

The two most important symptoms of both dissections (81% of patients) were unbearable pain preceding stroke and progressive onset of stroke within a few hours. Severe ultrasonic abnormalities were present in 94% of the patients whereas specific ultrasonic signs (segmental dilation with eccentric channel) were rare (19%) in both groups. Major strokes and brainstem strokes represented respectively 67% and 78% in intracranial versus 43% and 29% in extracranial dissections. Severe sequelae (permanent disabling motor or cerebellar deficit) were more often associated with intracranial (44%) than with extracranial dissections (14%). No recurrence of dissection and no cerebral haemorrhage were found under heparin. Significant factors of poor outcome (P< 0.05) were the initial severity of the stroke and the bilateral location of dissections.

CONCLUSION

The combination of a pain and a progressive onset of the stroke, corroborated by ultrasonic findings, could have helped to recognise most of these types of dissections. Intracranial dissections have a poorer prognosis than extracranial dissections.

Vertebral artery occlusion after subarachnoid hemorrhage from a dissecting aneurysm of the vertebral artery: case report

BACKGROUND

Generally speaking, occlusion of the vertebral artery is a finding of a dissecting aneurysm associated with completed stroke. We present a case of a vertebral dissecting aneurysm that produced subarachnoid hemorrhage (SAH). Angiography on the day of hemorrhage, however, demonstrated complete occlusion of the vertebral artery.

CASE PRESENTATION

A 44-year-old hypertensive woman suffered a sudden onset of headache and vomiting followed by loss of consciousness due to SAH. Angiography on the day of hemorrhage revealed a complete occlusion of the right vertebral artery just distal to the dissecting aneurysm. This is the first report of such a case. The patient was still considered to be at significant risk of rerupture. Craniotomy and clip occlusion of the right vertebral artery and the origin of the right posterior inferior cerebellar artery were carried out to trap the thin-walled sac. At discharge, the patient had recovered completely except for some left limb ataxia, which subsequently disappeared.

CONCLUSIONS

Two options are available for the treatment of such a case: surgical or medical treatment. We employed surgery. Which is the preferred approach, however, is a difficult judgment to make at this juncture.

Unruptured intracranial vertebral artery dissection. Clinical course and serial radiographic imagings

BACKGROUND AND PURPOSE

Intracranial vertebral artery dissection is an increasingly recognized cause of stroke. However, little is known about its natural history and clinical manifestations, and appropriate management protocol has not yet been established. This study was performed to clarify its clinical course and determine the best management protocol.

METHODS

This study is a retrospective clinical and radiographic review of 11 patients with 13 lesions who presented between 1990 and 1996. Patients with a history of trauma and those who presented with subarachnoid hemorrhage were excluded. The 11 patients comprised seven men and four women, who ranged in age from 34 to 71 years, with a mean age of 47 years. Ten patients presented with ischemic symptoms.

RESULTS

Although recurrent ischemic attacks were observed in two patients, most (90%) subsequently made a good recovery and returned to their previous lifestyle. Five arteries showed the typical "string sign" or "pearl and string sign" on initial angiography. They changed in the follow-up examinations, which demonstrated either resolution of the stenosis or progression to complete occlusion. In contrast, the angiographic signs of complete occlusion (three arteries) or aneurysmal dilatation without luminal stenosis (four arteries) remained unchanged during the observation period of 5 months to 2.5 years. MRI was a sensitive tool for diagnosing intracranial vertebral artery dissection; intramural thrombus and intimal flap were the two major findings. MR angiography was also useful for demonstrating abnormalities of the arterial signal column such as pseudolumen or aneurysmal dilatation.

CONCLUSIONS

The natural history of unruptured intracranial vertebral artery dissection seems relatively benign, with a high probability (62%) of spontaneous angiographic cure. Some persistent aneurysmal dilatation may be amenable to intravascular coil embolization.

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.

Dissection of the vertebral arteries: case report and discussion

Vertebral artery dissection is an unusual condition with potentially protean neurologic presentations. It may occur spontaneously or follow apparently minor neck trauma. Ischemic symptoms related to the posterior circulation ensue and may be due to obstruction or embolization. The ensuing stroke is ischemic, although subarachnoid hemorrhage may be a complication as well. A case of vertebral artery dissection in a young woman who developed symptoms approximately one week after mild neck injury is reported, and the topic is reviewed.

Nonsurgical treatment of unruptured intracranial vertebral artery dissection with serial follow-up angiography

The question of whether unruptured intracranial vertebral artery dissections should be treated surgically or nonsurgically still remains unresolved. In this study, six consecutive patients with intracranial vertebral artery dissection presenting with brain-stem ischemia without subarachnoid hemorrhage (SAH) were treated non-surgically with control of blood pressure and bed rest, and five received follow-up review with serial angiography. No further progression of dissection or associated SAH occurred in any of the cases, and all patients returned to their previous lifestyles. In the serial angiograms in five patients, the findings continued to change during the first few months after onset. Four cases ultimately showed "angiographic cure," while fusiform aneurysmal dilatation of the affected vessel persisted in one case. In one patient, arterial dissection was visualized on the second angiogram despite negative initial angiographic findings. These results indicate that intracranial vertebral artery dissection presenting without SAH can be treated nonsurgically, with careful angiographic follow-up monitoring. Persistent aneurysmal dilatation as a sequela of arterial dissection seemed to form a subgroup of fusiform aneurysms of the posterior circulation. These aneurysms may be prone to late bleeding and may require surgical treatment.

Management of dissecting aneurysms of the posterior circulation

We analysed the clinical presentation, treatment and outcome of our own 36 cases of posterior circulation dissecting aneurysms (DA) and discussed the surgical indications and procedures regarding posterior fossa DA. Twenty one cases were male, 15 cases were female. Their mean age was 54 +/- 14 years. Clinical manifestations were subarachnoid haemorrhage (SAH) in 14 cases (39%) and ischaemic attacks in 22 cases (61%). Three of 14 SAH cases had rebleeding in the acute stage. Angiographic findings were aneurysmal dilatation in 16 cases, retention of contrast medium in 12 cases, string sign in 9 cases, double lumen in 4 cases, pearl and string sign in 3 cases, and occlusion of parent artery in 2 cases. Surgical treatment was performed on nineteen cases (53%). The operation was carried out in the acute stage on the SAH group; in the subacute or chronic stage on the ischaemic group. The surgical procedure was the proximal ligation, trapping and removal of DA with or without revascularization of the parent artery. 84% of the surgically managed patients and 71% of the nonsurgical cases had a favourable outcome (good recovery or moderate disability). Poor prognosis was revealed from the rebleeding and primary neurological stage. We recommend surgical treatment in the acute stage on the SAH group. On the ischaemic group surgical treatment in the subacute or chronic stage is recommended, if the DA has the risk of rupture or progression of the dissection.

Extracranial-intracranial saphenous vein bypass for carotid or vertebral artery dissections: a report of six cases

The management of carotid or vertebral artery dissections has generally been either conservative (with anticoagulation) or surgical (by proximal ligation or trapping procedures). However, identification and management of those patients with a high risk of stroke recurrence have been difficult. Six patients with carotid or vertebral artery dissections underwent a total of seven surgical procedures involving intracranial interpositional saphenous vein bypass grafts anastomosed distally beyond the point of dissection with trapping of the intermediate diseased section of the artery. It is suggested that this procedure be used in patients who have bilateral carotid or vertebral artery disease, persistent angiographic abnormalities (particularly aneurysms), or recurring ischemic events while undergoing anticoagulation therapy, or in whom anticoagulation is undesirable. This procedure has benefits over current surgical options because of the maintenance of high flow, the avoidance of abnormal watershed areas of flow, and the elimination of the risk of emboli. The procedure is compared to previous techniques of extracranial-intracranial bypass.

Dissecting aneurysms of the vertebrobasilar system: study of 16 cases

In the last 14 years we have encountered 16 patients with spontaneous intracranial dissections of the vertebrobasilar (VB) system (mean age was 46 years and male/female ratio was 10/6). VB dissections presented in eight cases with subarachnoid bleeding and in eight with brainstem, cerebellar, or cerebral ischemia. Three patients had multiple dissections. Ten dissections occurred in the vertebral artery (two extended to the basilar artery), three in the posterior cerebral artery (one bilateral), two in the basilar artery, and one in the posterior inferior cerebellar artery. The angiographic configuration included "string" sign, "pearl and string" sign, fusiform dilation, and double lumen. The following angiographic evolution (available in 11 cases) was that of complete healing (three cases), partial resolution (five cases), progression (one case), and unimproving (two cases). Three patients died (two due to recurrent subarachnoid hemorrhage): two patients were explored surgically (one had further intravascular therapeutic embolization), and the rest were treated conservatively. Not all dissecting aneurysms fared in the same manner, depending either on the location in the VB circulation or on the variable vascular configuration: treatment should be fitted to the timing of diagnosis.

Dissecting aneurysm of the posterior inferior cerebellar artery

Dissecting aneurysms of the posterior inferior cerebellar artery are an uncommon cause of stroke in the vertebrobasilar system, but they may also present with subarachnoid bleeding into the posterior fossa in 70% of the cases. Neither magnetic resonance imaging nor vertebral angiography show specific signs. Treatment should be neurosurgical to prevent rebleeding, although few cases have been reported. The authors report a tenth case and the literature is reviewed.

Dissecting aneurysm of the posterior inferior cerebellar artery: case report

A patient with a dissecting aneurysm of a posterior inferior cerebellar artery who presented with Wallenberg's syndrome is reported. A 31-year-old man suddenly experienced an occipital headache, vertigo, and vomiting, followed by dysphagia. A neurological examination revealed partial Wallenberg's syndrome. Vertebral angiography revealed aneurysmal dilatation at the origin of the left posterior inferior cerebellar artery, with distal luminal narrowing. T1-weighted magnetic resonance imaging demonstrated an area of high-signal intensity, indicating an intramural hemorrhage in the arterial wall of the narrowed lumen. The dissecting aneurysm with a typical intramural hematoma of the posterior inferior cerebellar artery was entrapped with clips after an anastomosis of the left occipital artery to the distal posterior inferior cerebellar artery. The diagnosis and the treatment of dissecting aneurysms of the posterior inferior cerebellar artery are discussed.

Repeat angiography and magnetic resonance imaging (MRI) of dissecting aneurysms of the intracranial vertebral artery. Report of four cases

We here present 4 cases with dissecting aneurysm (DA) of the intracranial vertebral artery, who were followed up by repeat cerebral angiography and MRI. The patients consisted of 2 males and 2 females, and the mean age was 43 years. Two cases were associated with polyarteritis nodosa (PN) and hypertension, respectively. Three of the cases developed subarachnoid haemorrhage (SAH), while the other one suffered from lateral medullary syndrome. In cerebral angiography, "pearl and string" signs were revealed in all cases, while a "double lumen" indicating a true diagnostic sign of DA was demonstrated in only one case. Repeat angiography showed that a bleb formation with a bulging of the aneurysmal sac was seen in 2 cases, and an irregularity of the wall in one case. On the other hand in one case, the ectatic part shrank, while the stenotic part was restored. In magnetic resonance imaging (MRI), a hyperintensity mass on T 1-weighted image (T 1-WI) adjacent to flow void suggesting either an intramural haematoma or a linear shape hyperintensity on T 1-WI were demonstrated in 3 cases. In the follow up MRI done in 2 cases, a serial change in the intensity from iso-intensity to hyperintensity on T 1-WI was observed in one case suggesting intramural haemorrhage, while an enlargement of the ectasic flow void was seen in the other case. Three of 4 cases were operated on by trapping of the aneurysms. One, who had systemic vascular diseases due to PN, and repeat angiography showed a regression of the aneurysm, was conservatively treated.(ABSTRACT TRUNCATED AT 250 WORDS)

Endovascular treatment of vertebral artery dissections and pseudoaneurysms

Sixteen patients with dissecting aneurysms or pseudoaneurysms of the vertebral artery, 12 involving the intradural vertebral artery and four occurring in the extradural segment, were treated by endovascular occlusion of the dissection site. Patients with vertebral fistulas were excluded from this study. The dissection was caused by trauma in three patients (two iatrogenic) and in the remaining 13 no obvious etiology was disclosed. Nine patients presented with subarachnoid hemorrhage (SAH), two of whom had severe cardiac disturbances secondary to the bleed. The nontraumatic dissections occurred in seven women and six men, with a mean age on discovery of 48 years. Fifteen patients were treated with endovascular occlusion of the parent artery at or just proximal to the dissection site. One patient had occlusion of a traumatic pseudoaneurysm with preservation of the parent artery. Four patients required transluminal angioplasty because of severe vasospasm produced by the presenting hemorrhage, and all benefited from this procedure with improved arterial flow documented by transcranial Doppler ultrasonography and arteriography. In 15 patients angiography disclosed complete cure of the dissection. One patient with a long dissection of extracranial origin extending intracranially had proximal occlusion of the dissection site. Follow-up angiography demonstrated healing of the vertebral artery dissection but persistent filling of the artery above the balloons, which underscores the need for embolic occlusion near the dissection site. No hemorrhages recurred. One patient had a second SAH at the time of therapy which was immediately controlled with balloons and coils. This patient and one other had minor neurological worsening resulting from the procedure (mild Wallenberg syndrome in one and minor ataxia in the second). Symptomatic vertebral artery dissections involving the intradural and extradural segments can be effectively managed by endovascular techniques. Balloon test occlusion and transluminal angioplasty can be useful adjuncts in the management of this disease.

Recurrent ischemic events in two patients with painless vertebral artery dissection

BACKGROUND AND PURPOSE

Vertebral artery dissection causes endothelial changes and stenosis that may lead to recurrent ischemic neurological events. The diagnosis may not be obvious because the dissection may be painless and "spontaneous" (no obvious trauma). Magnetic resonance angiography has increasingly been used to screen patients for this disorder, but its accuracy has not yet been established.

CASE DESCRIPTION

Two patients were admitted with repeated transient ischemic attacks and strokes over 11 months and 1 month, respectively. Neither had a history of trauma, cervical pain, or headache. Magnetic resonance angiography failed to visualize vertebral artery dissections that were later revealed by conventional angiography. One patient's events were stopped by balloon occlusion of the vertebral artery proximal to the posterior inferior cerebellar artery branch.

CONCLUSIONS

Magnetic resonance angiography is not yet sensitive enough to always visualize vertebral artery dissection. Vertebral artery dissection is a life-threatening condition that requires aggressive evaluation and treatment.