Subarachnoid hemorrhage from a dissecting aneurysm of the middle cerebral artery. Case report

Spontaneous middle cerebral artery dissection: a series of six cases and literature review

Middle cerebral artery (MCA) dissection is rare, and various clinical presentations, including hemorrhage, ischemia, or comorbidities, and the changes in imaging findings over time hinder treatment decisions. The European Stroke Organization guidelines exclude MCA dissection. Few cases have been reported with no review of the relevant literature. Therefore, we reviewed the relevant literature and our own experience with non-traumatic MCA dissection cases to determine appropriate treatment strategies. At our institution and affiliated institutions, we encountered six cases of MCA dissection-five with infarction and one with hemorrhage. Two patients underwent revascularization, and one underwent an aneurysmectomy. We reviewed English and Japanese articles in PubMed and Medical Journal Web and summarized the results based on the relationships among age, sex, location, the presence of an aneurysm, the presence of angiography, history, treatment, and mode of onset. The clinical course, changes in imaging, treatment strategies, and prognosis were discussed. Eighty cases were included in the review. Cerebral aneurysms were more common distal to the M2 area (p = 0.00) and were correlated with hemorrhage (p < 0.001). Most hemorrhagic cases with aneurysms were treated surgically, while ischemic cases were treated with antithrombotic agents, and both had a similar neurological prognosis. There were some cases of rebleeding after antithrombotic therapy, especially in older adults.Surgical treatment is recommended in cases of hemorrhage and confirmed aneurysms, particularly for lesions distal to the M2 area. Patients with aneurysm-associated ischemia should be followed up, and antithrombotic treatment should be considered with particular care in older adults.

A rare intracranial fusiform thrombosed aneurysm of the distal middle cerebral artery: A case report

Background:

Intracranial aneurysms of the distal middle cerebral artery are rare, and most etiologies are infection or dissection. We present an extremely rare intracranial fusiform thrombosed aneurysm of the distal middle cerebral artery with histopathological confirmation of a pseudoaneurysm.

Case Description:

Our patient, a 68-year-old female, was previously healthy and had no history of infection or trauma. A fusiform thrombosed aneurysm of the distal middle cerebral artery was detected incidentally. The patient was treated successfully with trapping and resection of the aneurysm followed by superficial temporal artery to middle cerebral artery anastomosis. Xanthochromic and hypertrophic arachnoid membranes around the aneurysm were noticed, and a thrombus was detected inside the lesion. The aneurysmal wall had hyalinized connective tissue incompletely surrounded with intima, with no media or adventitia. Pathologically, it was a pseudoaneurysm.

Conclusion:

We report an extremely rare case of a pseudoaneurysm of the distal middle cerebral artery. We discuss the etiology of the lesion, with a literature review, and propose that the appearance and increase of the pseudoaneurysm was followed by microbleed of an aneurysm unrelated to the branching zone.

Treatment of pediatric intracranial dissecting aneurysm with clipping and angioplasty, and next-generation sequencing analysis: A case report and literature review

BACKGROUND

Large intracranial dissecting aneurysm (IDA) in the anterior cerebral circulation is rare in children. There has been no consensus on the diagnosis and treatment for IDA in children.

CASE SUMMARY

We report a 3-year-old boy with a large ruptured IDA in the right middle cerebral artery (16 mm × 14 mm). The IDA was successfully managed with clipping and angioplasty. Next-generation sequencing of the blood sample followed by bioinformatics analysis suggested that the rs78977446 variant of the ADAMTS13 gene is a risk for pediatric IDA. Three years after surgery, the boy was develop-mentally normal.

CONCLUSION

Clipping and angioplasty are effective treatments for ruptured IDA in the anterior cerebral circulation. ADAMTS13 rs78977446 is a risk factor for pediatric IDA.

Pseudoaneurysm at M3 of the middle cerebral artery: Morphological changes on serial radiological examinations

A 20-year-old man presented with consciousness disturbance and hemiparesis, and computed tomography demonstrated subarachnoid and intracerebral hemorrhage. Angiography on admission demonstrated a slight irregularity of the middle cerebral artery (MCA) branch. Angiography on the 12th day showed a suspicious lesion at M3 of the left MCA. Angiography performed 24 days after the onset disclosed an aneurysm at M3. The aneurysm was trapped and resected after superficial temporal artery-MCA bypass. Pathological examinations revealed that this distal aneurysm was a pseudoaneurysm without vascular components in its dome. Although a lesion that may cause subarachnoid or intracerebral hemorrhage was not detected on the initial angiography, repeated examinations revealed the atypical vascular lesion in distal MCA.

Surgical Management of Intracranial Artery Dissection

Intracranial artery dissection (IAD) is a relatively rare cause of stroke, but it has been recognized increasingly with recent advances of the neuroimaging technique. Since rebleeding occurs frequently in the acute stage in the ruptured IAD, urgent surgical treatment should be performed to prevent rebleeding. On the other hand, surgical treatment for unruptured IAD is controversial because it has little risk for bleeding. However, surgical treatment for unruptured IAD may be considered if the formation or enlargement of the aneurysmal dilatation has been confirmed. Since there are several proposed surgical strategies for IAD, it is important to select an appropriate strategy on a case-by-case basis. If the risk of infarction due to vessel occlusion is high, combined bypass surgery should be considered.

Isolated middle cerebral artery dissection: a systematic review

Acute stroke can be missed in the emergency department, particularly in younger patients and in those with more vague symptoms such as headache or dizziness. Cervicocephalic dissections are one group of etiologies for acute stroke in the young. While cervicocephalic dissections are not uncommon in clinical practice, isolated middle cerebral artery dissection (MCAD) has been rarely reported as a cause for stroke. We sought to review the clinical implications and pathophysiology of an isolated MCAD. We searched the medical literature for isolated MCAD in clinical stroke patients using MEDLINE, HighWire, and Google Scholar databases from 1966 to 2013 using the keywords 'middle cerebral artery dissection,' 'intracerebral artery dissection,' and 'middle cerebral artery dissection stroke.' We reviewed cases to learn various characteristics of isolated MCAD. A total of 61 cases (62.3% male, mean age 44.16 ± 19.17 years) were reviewed from 54 publications. Most cases were reported from Asian countries (78.7%). Ischemic strokes were more common than hemorrhagic strokes (68.9%). Digital subtraction angiography was the most common imaging modality used to diagnose isolated MCAD (75.4%). Surgery was the preferred form of therapeutic intervention (39.3%). Males (n = 27/48, p = 0.0008) and those who presented with only ischemic syndromes (n = 22/48, p = 0.0009) had significantly higher rates of favorable outcome. Isolated MCAD is a rare disease that can contribute to the stroke burden of young patients. Further studies are needed to better characterize optimal treatment strategies and define outcomes for this rare condition.

Endovascular treatment of M2 dissecting aneurysm presenting with subarachnoid haemorrhage

A 63-year-old woman presented with a ruptured dissecting aneurysm (DA) at the right M2 region of the angular branches. This report describes a rare case of middle cerebral artery DA presenting with a subarachnoid haemorrhage (SAH); the patient was successfully treated with endovascular internal trapping of the DA, without a bypass surgery.

Intraarterial schwannoma in horizontal segment of middle cerebral artery causing subarachnoid hemorrhage

A spontaneous subarachnoid hemorrhage (SAH) from the middle cerebral artery is most commonly caused by the rupture of saccular aneurysms and rarely by fusiform aneurysms or arterial dissections/dissecting aneurysms. To the authors' knowledge, this is the first report of an intraarterial neoplasm causing an SAH. A 44-year-old woman presented with an SAH in the basal cisterns. Subsequent internal carotid artery angiography demonstrated a small bulge on the superior wall of the horizontal (M1) segment of the middle cerebral artery. However, a pterional craniotomy revealed a well-circumscribed solitary tumor with a diameter of 15 mm involving the superior wall of the M1 segment as the cause of the SAH. Pathological examination demonstrated typical findings of a schwannoma, elongated cells with tapered, spindle-shaped nuclei and indistinct cell borders, and diffuse immunoreactivity for the S100 protein.

Management of ruptured dissecting intracranial aneurysms in infants: report of four cases and review of the literature

BACKGROUND

Intracranial cerebral aneurysms in the pediatric population are infrequent, and those occurring in infants less than 1 year old are extremely rare. Of intracranial aneurysms in children, dissecting aneurysms are the most common type seen. While spontaneous dissecting aneurysms usually present with ischemia, hemorrhage can also occur.

METHODS

A retrospective review of our patients revealed that from July 1, 2007 to June 30, 2012, four infants were treated for ruptured distal dissecting intracranial aneurysms at Texas Children's Hospital. Mycotic aneurysms and collagen vascular disorder were excluded in all four cases. All patients presented in our series presented with subarachnoid hemorrhage, and three had intraventricular hemorrhage. All patients underwent conventional catheter angiography for diagnosis. All patients in this series were managed in the acute or subacute period with surgical or endovascular trapping without distal bypass procedures. All four patients tolerated sacrifice of the parent vessels feeding these distal aneurysms well.

CASE REPORT AND REVIEW OF LITERATURE

We describe the presentation and management of these rare cases and then review the current literature on the management of these dissecting aneurysms in infants.

Management of middle cerebral artery dissecting aneurysm

BACKGROUND

Dissecting aneurysms of the intracranial carotid circulation were previously thought to occur primarily in young people presenting with cerebral infarction caused by arterial stenosis and occlusion. The appropriate management of dissecting aneurysms in the anterior circulation remains controversial, especially in patients who also present with cerebral infarction. However, recent studies have reported better outcomes for patients with middle cerebral artery (MCA) dissecting aneurysms involving surgically treated subarachnoid hemorrhage (SAH). The purpose of this study is to describe a case of spontaneous SAH from rupture of a dissecting aneurysm in the M2 segment observed in a 79-year-old man with no sign of an ischemic neurological deficit, and also to review the clinical and radiological features of cases reported since 1990.

METHODS

Our review of the literature identified 24 cases of MCA dissecting aneurysms after 1990.

RESULTS

Of the patients in these cases, 15 (63%) presented with pure bleeding and 7 (29%) with ischemia, and two were detected incidentally. Our review also found that the outcome of patients presenting with pure bleeding differed from those with ischemia. Patients with an MCA dissecting aneurysm who presented with pure bleeding showed better outcomes if they had surgery than if they did not. In contrast, the appropriate management of patients with a dissecting aneurysm who present with ischemia remains controversial.

CONCLUSION

Our review found that the clinical course of patients presenting with ischemia differed from that of patients presenting with pure bleeding. Most of the patients with ischemia underwent progressive deterioration. However, while the outcome for patients with ischemia treated surgically was relatively good, it remained poor compared to the outcome for patients who had been bleeding.

Ruptured dissecting cerebral aneurysms in young people: report of three cases

Intracranial arterial aneurysms in the pediatric population are rare. Among these, dissecting aneurysms are the most frequent, followed by saccular, infectious, and posttraumatic. It is widely known that aneurysmal rupture is uncommon in the first two decades of life. Spontaneous dissecting aneurysms (SDAs) of the middle cerebral artery (MCA) affecting young individuals most frequently present as occlusive syndrome with ischemia, although bleeding and subarachnoid hemorrhage can also occur. Between March 2006 and January 2008, three young patients (20 months, 8 and 20 years old) were surgically treated for MCA SDA in the Neurosurgical Department of "12 de Octubre" Hospital of Madrid. These patients showed hemorrhage as primary radiological finding, and all of them underwent surgical operation. Aneurysms were always treated by trapping, with aneurysmectomy in one case, but no distal extra-intracranial (EC-IC) bypass was performed. In two cases, the histological examination of the aneurysm's wall evidenced signs of subintimal dissection with widespread disruption of the internal elastic lamina and media with neointima formation and intramural hemorrhage. Although bleeding is an uncommon presenting sign of SDAs, they should be suspected in young people showing hemorrhage at CT scan. Early surgical treatment and, if possible, preoperative neuroimaging evaluation of intracranial vessels should be performed to reduce the mortality in these patients despite a higher postoperative morbidity. From a technical point of view, surgical trapping of the aneurysm seems to be a reasonable treatment strategy especially in an emergency basis. However, whenever possible, an EC-IC bypass could help diminish the ischemic morbidity associated with these aneurysms.

Orgasmic headache and middle cerebral artery dissection

A patient with a 20 year history of primary orgasmic headache is described who, after suffering an unusually severe episode of orgasmic headache was found to have a middle cerebral artery dissection. This unusual association of primary and secondary orgasmic headache emphasises the need for a thorough diagnostic examination when the orgasmic headache differs from that of previous episodes or is associated with neurological symptoms.

Middle cerebral artery dissections: Differences between isolated and extended dissections of internal carotid artery

Isolated middle cerebral artery dissection (MCAD) has rarely been encountered clinically and few have reviewed it systemically. The etiologies, clinical manifestations, natural clinical course and prognosis of MCAD remain poorly understood. From 1995 to 2004, there were 5 cases diagnosed clinically and angiographically to have MCAD (isolated MCAD in 1, ICAD-MCAD in 4) from a medical center in Taiwan. MEDLINE (1966-2003) was searched for published articles in English that concerned the diagnosis of MCAD. Clinical presentations, stroke types, angiographic findings, etiologies, treatment strategies and outcomes were compared between cases with isolated MCAD or ICAD-MCAD. There were 23 cases (male, 46%; mean age, 22.9+/-19.5 years) with 24 events of isolated MCAD and 31 cases (male, 47%; mean age, 22.2+/-12.9 years) with 35 events of ICAD-MCAD. The types of stroke in isolated MCAD group included subarachnoid hemorrhage (12%) and cerebral infarction (88%); and in ICAD-MCAD group were subarachnoid hemorrhage (6%) and cerebral infarction (94%). The presenting symptoms were similar between both groups. Fluctuating course was more often in isolated MCAD than in ICAD-MCAD (17% vs. 3%, p=0.061). Recurrence of dissection events in both groups was infrequent (4% vs. 9%, p=0.56). Both groups had high case-fatality rates (MCAD, 48%; ICAD-MCAD, 58%). The cause of dissection in both groups was idiopathic in the majority. Congenital vessel wall defects were found in 26% of ICAD-MCAD, but in only 4% of isolated MCAD (p=0.066). In contrast, preceded trauma was more often found in isolated MCAD than ICAD-MCAD (35% vs. 19%, p=0.085). Arteritis was noted in 16% of ICAD-MCAD patients, but none in isolated MCAD. Angiography revealed segmental stenosis in 72% of isolated MCAD and 96% of ICAD-MCAD. Aneurysmal dilatation of the involved cerebral arteries was noted in 28% of isolated MCAD, but none in MCAD-ICAD. Both isolated MCAD and ICAD-MCAD can cause vascular events with high mortality rates. Several aspects differed between 2 groups, including clinical course, underlying etiologies and angiographic findings.

Cerebral infarction and fluid collection due to an enlarged dissecting aneurysm of the middle cerebral artery--case report

A 53-year-old man presented with cerebral infarction associated with a dissecting aneurysm of the left middle cerebral artery (MCA), with enlargement and fluid collection. Anticoagulant therapy was performed as the first stage treatment for cerebral infarction. Serial magnetic resonance imaging showed that the dissecting aneurysm had enlarged and fluid collection adjacent to the aneurysm had developed since the first admission. Surgery was performed to ligate the MCA proximal to the aneurysm. Intraoperative findings showed the branch of the MCA was obstructed by intramural hemorrhage of the aneurysm dome. Histological examination showed direct obstruction of the MCA branch artery by intramural hemorrhage of aneurysm dome had caused the cerebral infarction and the fluid collection surrounding the aneurysm resulted from minor leakage or exudation of intramural hemorrhage to the outer surface of the dissecting aneurysm.

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

OBJECT

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

METHODS

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

CONCLUSIONS

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

Acute surgery for ruptured dissecting aneurysm of the M3 portion of the middle cerebral artery

A 65-year-old woman presented with a ruptured dissecting aneurysm of the M3 portion of the middle cerebral artery (MCA) manifesting as disturbance of consciousness and motor aphasia. Computed tomography revealed subarachnoid hemorrhage. Emergent angiography demonstrated segmental aneurysmal dilatation of the M3 portion of the left MCA. Infectious aneurysm was excluded. Surgery was performed to prevent repeated hemorrhage from the aneurysm. The lesion was excised and flow to the distal MCA was preserved with an anastomosis of the superficial temporal artery to the MCA. Histological examination confirmed that the aneurysmal dilatation was due to arterial dissection caused by disruption of the internal elastic lamina. Distal dissecting aneurysm may occur in the absence of infectious disease. Such ruptured distal dissecting aneurysm should preferably be treated surgically in the acute stage, immediately after detection of the aneurysm. The parent artery of the proximal and distal sides of the aneurysm should be trapped because of the probable weakness of the arterial wall, and bypass surgery performed to preserve the distal circulation.

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

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

Spontaneous dissecting aneurysms of anterior and middle cerebral artery associated with brain infarction: a case report and review of the literature

BACKGROUND

Intracranial dissecting aneurysms have been reported with increasing frequency and are recognized as a common cause of stroke. In some reviews and case reports, attempts have been made to compare the outcomes of surgical and medical treatments. However, the appropriate management of dissecting aneurysms in the anterior circulation remains controversial, especially in patients who also manifest cerebral infarction.

CASE DESCRIPTION

A 45-year-old male was diagnosed as having a dissecting aneurysm of the right middle cerebral artery (MCA) with cerebral infarction. In the course of conservative treatment, he developed a new cerebral infarction in the territory of the right anterior cerebral artery (ACA). Repeat cerebral angiograms revealed an increase in the aneurysmal dilatation of the right M2 and the appearance of a segmental dilatation of the right A2. He continued to be treated conservatively and his course was satisfactory. On subsequent angiograms, we observed resolution of the right A2 dissection and no further progression of the dilatation of the right M2.

CONCLUSION

This is the first reported case of simultaneous idiopathic dissecting aneurysms of different major arterial branches in the anterior circulation. Our review of the literature disclosed 36 and 23 cases, respectively, of dissecting aneurysms of the ACA and MCA. Many previously reported patients with these dissecting aneurysms involving subarachnoid hemorrhage (SAH) underwent surgery, which resulted in better outcome. More than half of the patients with ACA and MCA dissecting aneurysms had cerebral infarction. All ACA dissecting aneurysms involving ischemia occurred in the A2 region. The outcomes of both surgical and conservative management were equally satisfactory. On the other hand, in patients with MCA dissecting aneurysms, the area of ischemia frequently involved the M1 region; in these patients, conservative treatment resulted in poor outcomes. Therefore, revascularization distal to the compromised artery should be considered in patients with MCA-dissecting aneurysms who have ischemia. Careful interpretation of serial angiograms and/or magnetic resonance (MR) images is necessary because of the possibility of disease progression. If the aneurysmal size increases or there is progression of ischemic symptoms in the course of conservative treatment, surgery must be urgently evaluated.

Dissecting aneurysm of the middle cerebral artery manifesting as subarachnoid hemorrhage and hemorrhagic infarctions--case report

A 46-year-old woman presented with a dissecting aneurysm of the right middle cerebral artery manifesting as subarachnoid hemorrhage followed by hemorrhagic infarctions. The aneurysm was clipped and wrapped. However, serial angiography showed progression of the lesion, which was probably responsible for the clinical course of this patient. Intracranial dissecting aneurysms are less common, and the natural history of these lesions is unclear. Conservative management might be preferable in this patient.

Transient ischemic attack due to dissection of the middle cerebral artery--case report

A 57-year-old man presented with a transient ischemic attack due to dissection of the middle cerebral artery. He suffered total aphasia and clouding of consciousness for several minutes. On admission, he was alert without neurological deficit. Magnetic resonance (MR) angiography and conventional angiography depicted irregularity and double lumen of the left middle cerebral artery. The diagnosis was dissection of the middle cerebral artery. After 1 month, he left our institute with no neurological deficit. Transient ischemic attack associated with dissection of an intracranial artery is unusual. The source images of MR angiography are useful for the essential follow up of dissection.

Subarachnoid haemorrhage: diagnosis, causes and management

The incidence of subarachnoid haemorrhage (SAH) is stable, at around six cases per 100 000 patient years. Any apparent decrease is attributable to a higher rate of CT scanning, by which other haemorrhagic conditions are excluded. Most patients are <60 years of age. Risk factors are the same as for stroke in general; genetic factors operate in only a minority. Case fatality is approximately 50% overall (including pre-hospital deaths) and one-third of survivors remain dependent. Sudden, explosive headache is a cardinal but non-specific feature in the diagnosis of SAH: in general practice, the cause is innocuous in nine out of 10 patients in whom this is the only symptom. CT scanning is mandatory in all, to be followed by (delayed) lumbar puncture if CT is negative. The cause of SAH is a ruptured aneurysm in 85% of cases, non-aneurysmal perimesencephalic haemorrhage (with excellent prognosis) in 10%, and a variety of rare conditions in 5%. Catheter angiography for detecting aneurysms is gradually being replaced by CT angiography. A poor clinical condition on admission may be caused by a remediable complication of the initial bleed or a recurrent haemorrhage in the form of intracranial haematoma, acute hydrocephalus or global brain ischaemia. Occlusion of the aneurysm effectively prevents rebleeding, but there is a dearth of controlled trials assessing the relative benefits of early operation (within 3 days) versus late operation (day 10-12), or that of endovascular treatment versus any operation. Antifibrinolytic drugs reduce the risk of rebleeding, but do not improve overall outcome. Measures of proven value in decreasing the risk of delayed cerebral ischaemia are a liberal supply of fluids, avoidance of antihypertensive drugs and administration of nimodipine. Once ischaemia has occurred, treatment regimens such as a combination of induced hypertension and hypervolaemia, or transluminal angioplasty, are plausible, but of unproven benefit.

Serial angiography and endovascular treatment of dissecting aneurysms of the anterior cerebral and vertebral arteries. Case report

This 47-year-old man was admitted to the hospital with disturbance of consciousness due to subarachnoid hemorrhage caused by a ruptured dissecting aneurysm of the left anterior cerebral artery (ACA). Conservative treatment resulted in improvement in the patient's consciousness; however, repeated rupture occurred during the chronic stage. Endovascular coil embolization of the parent artery was successful. Serial angiography demonstrated all stages in the development of the aneurysm. Follow-up angiography demonstrated an incidental dissecting aneurysm of the right vertebral artery. This aneurysm was also treated by endovascular embolization. No new neurological deficit appeared during or after the treatment. Multiple dissecting aneurysms are rare, especially those involving both supra- and infratentorial regions. A ruptured dissecting aneurysm of the ACA is also an uncommon vascular disorder. This case shows that rebleeding may occur, even during the chronic stage, and thus appropriate treatment for the prevention of subsequent bleeding is essential. Incidental dissecting aneurysms can be treated using the endovascular technique, but further study is necessary.

Subarachnoid hemorrhage associated with angiographic "stenotic" or "occlusive" lesions in the carotid circulation

BACKGROUND

It has been assumed that dissecting aneurysms presenting with subarachnoid hemorrhage (SAH) are extremely rare in the carotid circulation. This may be partially attributed to the difficulty in their diagnosis. The documented angiographic findings include arterial narrowing or occlusion. The purpose of the present study is to investigate the origin of SAH associated with "stenotic" or "occlusive" lesions, which might have been categorized into "SAH of unknown origin."

METHODS

Between April 1984 and June 1994, 580 patients underwent thorough angiographic investigation to determine the origin of their nontraumatic SAH. Of these patients, five patients had as the only lesion suspected as the source of SAH a single stenosis or occlusion in the carotid circulation that was revealed at the first angiography performed within 48 hours following the onset. We detail these five patients and discuss the current strategy for the treatment of SAH associated with stenotic or occlusive lesions in the carotid circulation.

RESULTS

Arterial narrowing or occlusion were located in the internal carotid artery (ICA) in two patients, in the middle cerebral artery (MCA) in two patients, and in the posterior communicating artery in one patient. Three patients underwent operation (circumferential wrapping with cotton gauze), and dissecting aneurysms were confirmed in all of them. They all attained good recovery without rebleeding over a long-term period. Two patients died of fatal rebleeding on day 8 and on day 9 while awaiting the second angiography. In one of the patients with ICA stenosis, autopsy revealed a lacerated ICA without a definite saccular aneurysm. In the last patient with M2 occlusion, dissecting aneurysm was strongly suspected from the clinical course.

CONCLUSION

To prevent early fatal rebleeding, exploratory craniotomy for angiographic stenotic and occlusive lesions associated with SAH may be justified if all underlying conditions are met, because they may likely include dissecting aneurysms: (1) single stenotic or occlusive, (2) surgically accessible, and (3) consistent with the localization of SAH from CT scan.

Ruptured dissecting aneurysm as a cause of subarachnoid hemorrhage of unverified etiology

BACKGROUND AND PURPOSE

The clinical features of "aneurysmal" subarachnoid hemorrhage (SAH) of angiographically unverified etiology were reviewed to clarify the incidence and natural history of dissecting aneurysms as the hemorrhagic source of SAH.

METHODS

We reviewed 30 patients with SAH of unverified etiology in whom initial CT scan showed a diffuse or anteriorly distributed subarachnoid blood clot. Ten of the patients had stenotic or occlusive lesions (SOCL) on initial angiography, and these were the main focus of this study.

RESULTS

Among the 10 patients with SOCL on initial angiography, the lesions were located on the anterior circulation in 6 and on the posterior circulation in 4. Ruptured dissecting aneurysms were confirmed by exploratory surgery or autopsy in 6 patients. Subsequent rupture occurred in 6 of the 10 patients (60%), and all 6 of these patients died as a result.

CONCLUSIONS

The incidence (6/30) of dissecting aneurysms as the cause of SAH of unverified etiology was unexpectedly high, especially when initial angiography disclosed SOCL (6/10). The moribund patients with SOCL showed a high rate of rebleeding, and the untreated recurrent hemorrhages were fatal. Further MRI study is indicated for these patients to demonstrate the intramural hematoma. Compared with the devastating mortality caused by the subsequent ruptures, the extent of surgical morbidity was minor. Surgical intervention could therefore be justified when the following neuroradiological findings are present: (1) SOCL evident on angiography, (2) distribution of SAH on CT compatible with the location of the SOCL, and (3) intramural hematoma on MRI in the same region as the SOCL.

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.

Subarachnoid hemorrhage without detectable aneurysm. A review of the causes

BACKGROUND

In 15% to 20% of patients with a spontaneous subarachnoid hemorrhage, no aneurysm is found on the first angiogram. This review emphasizes that this group of patients is in fact heterogeneous and describes the clinical features, pattern of hemorrhage on early computed tomographic (CT) scan, prognosis, and proposed management in the several and distinct subsets of these patients.

SUMMARY OF REVIEW

Patients in whom no aneurysm is revealed on the initial angiogram can be subdivided mainly according to the pattern of hemorrhage on an early CT scan. In two thirds of these patients the CT scan shows a perimesencephalic pattern of hemorrhage (ie, blood confined to the cisterns around the midbrain); these patients invariably have a good prognosis, which obviates the need for a second angiogram. Patients with diffuse or anteriorly located blood on CT scan are at risk of rebleeding. In most of these patients the source of hemorrhage is an occult aneurysm, but intracranial artery dissections, dural arteriovenous malformations, mycotic aneurysms, trauma, bleeding disorders, substance abuse, or a cervical origin of the hemorrhage should also be considered. Patients with no blood revealed on an early CT scan but with xanthochromic cerebrospinal fluid are extremely rare. These patients deserve a second reading of the scan for blood in the prepontine cistern, which can be the only site of hemorrhage in perimesencephalic hemorrhage.

CONCLUSIONS

The prognosis and management of patients in whom no aneurysm is found on the initial angiogram depends on the pattern of hemorrhage on the initial CT scan. Patients should no longer be designated with the umbrella term "angiogram-negative subarachnoid hemorrhage."