Intermittent appearance of a ruptured cerebral aneurysm on sequential angiograms. Case report

Early reappearance of disappeared ruptured small aneurysm with concomitant vertebral artery dissection

Thrombosis of a previously ruptured intracranial aneurysm is a frequent event and it most commonly occurs in large or giant aneurysms. We present a dynamic short-term follow-up and management of thrombosis in a ruptured small posterior inferior cerebellar artery aneurysm with concomitant vertebral artery dissection (VAD). Clinical and radiological follow-up findings and reviewed literature on thrombosis of small ruptured aneurysms are the focus of this presentation. Early reappearance of a disappeared ruptured small cerebral aneurysm with a concomitant VAD may be attributed to the controlled ovarian hyperstimulation phase of in vitro fertilization and prolonged use of oral contraceptive pills.

Nonaneurysmal Perimesencephalic Hemorrhage Is Associated with Deep Cerebral Venous Drainage Anomalies: A Systematic Literature Review and Meta-Analysis

BACKGROUND AND PURPOSE

Mechanisms underlying bleeding in nonaneurysmal perimesencephalic SAH remain unclear. Previous investigators have suggested a relationship between nonaneurysmal perimesencephalic SAH and primitive venous drainage of the basal vein of Rosenthal. We performed a meta-analysis to evaluate the relation between primitive basal vein of Rosenthal drainage and nonaneurysmal perimesencephalic SAH.

MATERIALS AND METHODS

We performed a comprehensive literature search of all studies examining the prevalence of primitive basal vein of Rosenthal drainage in patients with aneurysmal SAH and nonaneurysmal perimesencephalic SAH. Data collected were primitive basal vein of Rosenthal drainage (direct connection of perimesencephalic veins into the dural sinuses instead of the Galenic system) in at least 1 cerebral hemisphere, normal bilateral basal vein of Rosenthal drainage systems, and the number of overall primitive venous systems in the nonaneurysmal perimesencephalic SAH and aneurysmal SAH groups. Statistical analysis was performed by using a random-effects meta-analysis.

RESULTS

Eight studies with 888 patients (334 with nonaneurysmal perimesencephalic SAH and 554 with aneurysmal SAH) and 1657 individual venous systems were included. Patients with nonaneurysmal perimesencephalic SAH were more likely to have a primitive basal vein of Rosenthal drainage in at least 1 hemisphere (47.7% versus 22.1%; OR, 3.31; 95% CI, 2.15-5.08; P < .01) and were less likely to have bilateral normal basal vein of Rosenthal drainage systems than patients with aneurysmal SAH (18.3% versus 37.4%; OR, 0.27; 95% CI, 0.14-0.52; P < .01). When we considered individual venous systems, there were higher rates of primitive venous systems in patients with nonaneurysmal perimesencephalic SAH than in patients with aneurysmal SAH (34.9% versus 15.3%; OR, 3.90; 95% CI, 2.37-6.43; P < .01).

CONCLUSIONS

Patients with nonaneurysmal perimesencephalic SAH have a higher prevalence of primitive basal vein of Rosenthal drainage in at least 1 hemisphere than patients with aneurysmal SAH. This finding suggests a venous origin of some nonaneurysmal perimesencephalic SAHs. A primitive basal vein of Rosenthal pattern is an imaging finding that has the potential to facilitate the diagnosis of nonaneurysmal perimesencephalic SAH.

Spontaneous Occluded Anterior Communicating Artery Aneurysm during Coil Embolization Treated with One Coil Insertion into Remaining Stump

Spontaneous thrombosis of a ruptured aneurysm during coil embolization is a rare event, and some reports on recanalization of a spontaneous occluded ruptured aneurysm have been published. We report on a case of a 54-year-old male who presented with a subarachnoid hemorrhage due to rupture of a small aneurysm of the anterior communicating artery (ACoA). Cerebral angiography confirmed the presence of the ACoA aneurysm, but, during coil embolization, the aneurysm was near completely occluded with a remaining small neck. A small coil was inserted into the remaining stump of the neck to prevent recanalization, and the angiographic result at 1 year after coil embolization showed complete obliteration of the aneurysm.

Thrombosis and recanalization of small saccular cerebral aneurysm : two case reports and a suggestion for possible mechanism

Reports of thrombosis and recanalization of cerebral aneurysm are rare. We report two cases of small, saccular aneurysms in which spontaneous thrombosis had occurred during the preparation for endovascular coiling. Also, we review reported cases and propose the presumed pathogenesis.

Repeated neurovascular imaging in subarachnoid hemorrhage when initial studies are negative

Approximately 15% of patients with non-traumatic subarachnoid hemorrhage have no causative lesion identified on their initial angiogram. We present two patients with non-traumatic subarachnoid hemorrhage with negative initial angiograms who were subsequently found to have small basilar perforator aneurysms on delayed neurovascular imaging. We discuss the possible mechanisms for false negative diagnostic cerebral angiograms. These patients support the current standard of care with repeat angiography in cases of subarachnoid hemorrhage when no causative lesion can be identified on initial neurovascular imaging.

Disappearing saccular intracranial aneurysms: do they really disappear?

SUMMARY

Evolution and natural history of cerebral aneurysms is a dynamic process. Spontaneous regression in size or complete disappearance of an aneurysm is a known phenomenon, more commonly noted in giant intracranial aneurysms. However, reappearance or regrowth of such aneurysms is rare with few anecdotal reports. We report a series of four cases including one giant aneurysm, which either disappeared or regressed on sequential angiograms. Regrowth or reappearance of two of these previously disappeared or regressed aneurysms was noted and endovascularly treated while the other two cases are being followed up. The decision to follow up was crucial considering the nature of the aneurysms to change in morphology under the influence of various hemodynamic factors.

How does spontaneous hemostasis occur in ruptured cerebral aneurysms? Preliminary investigation on 247 clipping surgeries

BACKGROUND

Rupture of cerebral aneurysms results in subarachnoid hemorrhage. In many cases, bleeding from aneurysms spontaneously arrests. Although bleeding from cerebral aneurysms has been reported to arrest from outside, bleeding from some aneurysms can arrest in different ways.

METHODS

Between April 2002 and March 2004, we prospectively investigated mechanisms of spontaneous hemostasis in ruptured aneurysms by macroscopic examination when performing craniotomy and clipping surgeries.

RESULTS

Hemostatic mechanisms were investigated in 247 patients with ruptured aneurysm (77 men, 170 women; age range, 25-95 years). Hemostatic mechanisms were divided into 3 different patterns. In the most common pattern (79.4%), the surface of the aneurysm rupture point was sealed from the outside by a platelet plug or fibrin net (outside-arrest pattern). In some aneurysms (10.1%), a thrombus or platelet plug was attached to the rupture point from inside the aneurysm (inside-arrest pattern). In a very small number of aneurysms (1.6%), a naked thrombus covered the hole made on the arterial wall or small remnant of the aneurysmal dome (bursting pattern) The mechanism remained unclear in the remaining 8.9% of aneurysms. Multivariate analysis revealed that alert consciousness on admission (WFNS grade I) significantly associated with usual hemostasis (outside arrest pattern: OR, 3.8; 95% CI, 1.4-10.0; P = .008). Borderline association with usual hemostasis was found in aneurysms with a size of 5 or smaller than 5 mm (OR, 2.6; 95% CI, 0.99-7.1; P = .052).

CONCLUSIONS

The present preliminary study revealed that arrest of bleeding from a ruptured cerebral aneurysm does not always occur from outside the aneurysm. Unusual mechanisms of hemostasis are seen in approximately 12% of ruptured aneurysm. The outside-arrest-pattern aneurysm was more common for smaller aneurysms, and these patients tended to be of better grade. Further studies are necessary to explore the mechanism of hemostasis for ruptured cerebral aneurysms.

Subarachnoid Haemorrhage from a Large Cerebral Aneurysm Visible only on Repeat Angiography

SUMMARY

We report the case of a 49-year-old woman with a massive subarachnoid haemorrhage in conjunction with trauma. The initial cerebral angiography was normal. Three weeks later she had a second subarachnoid haemorrhage. A repeat angiography demonstrated an eight mm aneurysm of the internal carotid artery bifurcation, a region clearly normal in the previous angiography.

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.

Value of repeat-angiography in cases of unexplained subarachnoid hemorrhage (SAH)

PURPOSE

To investigate the rate of false negative initial cerebral angiography in spontaneous SAH and to ascertain why aneurysms remain undetected. Furthermore to validate CCT in predicting the presence and site of an angiographically missed aneurysm.

METHODS

Forty-two patients with spontaneous SAH were investigated, in whom initial cerebral angiography did not reveal any bleeding cause. Repeat-angiography was performed in all patients 5 to 55 days (mean 15 days) after the bleeding event. All patients underwent CCT scans within 48h after the ictus.

RESULTS

In 8 of 42 patients (19%) repeat-angiography revealed an aneurysm missed on initial angiography. The aneurysms were located on the AcomA (n = 2), the MCA (n = 2), the ACA (n = 1), the PICA (n = 2) and the junction of ICA and PcomA (n = 1). Presumable reasons for missing an aneurysm were spasms detected in four of eight cases on initial angiography and thrombosis of the aneurysm found in two cases at surgery. In two cases, multiple additional views just revealed the aneurysm appearing different in size and shape on repeat-angiography. CCT blood distribution pattern in four cases indicated presence and site of an aneurysm, while blood distribution was non-specific in the other four cases.

CONCLUSION

Repeat-angiography plays an important role in defining the site of an initially occult aneurysm and should be performed in all cases of unexplained SAH. It is of particular importance if vasospasm has compromised the initial angiogram or if one part of the vascular tree is not optimally seen.

Aneurysmal and microaneurysmal "angiogram-negative" subarachnoid hemorrhage

The source of bleeding remains obscure in most cases of subarachnoid hemorrhage (SAH) with a negative angiogram. From January 1, 1989, to July 1, 1993, 40 patients were admitted to the Massachusetts General Hospital with angiogram-negative SAH; 9 of these patients underwent surgical exploration. In seven of these explorations, an arterial source of the hemorrhage was discovered. These arterial sources included three anterior communicating artery complex lesions, two middle cerebral artery lesions, one internal carotid artery aneurysm arising at the origin of the posterior communicating artery, and one vertebral/posterior inferior cerebellar artery aneurysm. Three of these seven lesions had small aneurysmal sacs, but the other four were microaneurysms too small to accept a surgical clip. No source of hemorrhage could be found during surgery on one patient with a perimesencephalic pattern of blood. Two of the four patients with a microaneurysmal source of hemorrhage had two episodes of SAH. We propose that microaneurysms are the source of a significant percentage of nonperimesencephalic angiogram-negative SAH and suggest that these lesions may represent a forme fruste of saccular aneurysms. These findings lead us to propose a protocol for the management of angiogram-negative SAH based on the distribution of blood as seen on the patient's first computed tomogram.

Acute lacunar stroke in association with angiogram-negative subarachnoid hemorrhage. Mechanistic implications of two cases

BACKGROUND AND PURPOSE

Although there is much speculation regarding the source of bleeding in patients with subarachnoid hemorrhage when no angiographic abnormality is found, little direct evidence has been obtained to document a cause. We report two cases of stroke in the distribution of a perforating or lenticulostriate artery occurring at the time of angiogram-negative subarachnoid hemorrhage.

CASE DESCRIPTIONS

A 68- and a 60-year-old man each presented with acute onset of headache and meningismus. Computed tomography (CT) revealed subarachnoid hemorrhage in a perimesencephalic pattern and in the left sylvian fissure, respectively. In both instances, immediate CT revealed evidence of an early infarction in the distribution of a perforating artery originating at the site of the subarachnoid blood. Both of these strokes were demonstrated to be acute by evolution on serial imaging studies. No source for the subarachnoid blood could be found in either patient in cerebral angiograms repeated at 2 weeks.

CONCLUSIONS

These observations suggest that in some cases of angiogram-negative subarachnoid hemorrhage the source of blood may be a small artery that is obliterated at the time of hemorrhage. This observation provides an explanation for the low rate of rehemorrhage among patients with angiogram-negative subarachnoid hemorrhage.

The value of repeat cerebral angiography in subarachnoid haemorrhage

In 216 consecutive patients investigated for subarachnoid haemorrhage, 44 (20.3%) of cerebral angiograms were either normal or equivocal for the presence of aneurysm. Arteriography was repeated in 30 patients and an aneurysm was demonstrated in 10 cases. Repeat arteriography is recommended in proven subarachnoid haemorrhage even when the initial study is normal, and in this study achieved a reduction in overall negative rate to 15.6%.

Surgery for angiographically occult cerebral aneurysms

In 15% of patients with spontaneous subarachnoid hemorrhage (SAH), the source of bleeding cannot be determined despite repeated cerebral angiography. However, some patients diagnosed as having "SAH of unknown cause" actually harbor undetected aneurysms. The authors report six patients with SAH who, despite multiple negative cerebral angiograms, underwent exploratory surgery due to a high clinical and radiographic suspicion for the presence of an aneurysm. Brain computerized tomography (CT) scans revealed blood located mainly in the basal frontal interhemispheric fissure in four patients, in the sylvian fissure in one patient, and in the interpeduncular cistern in one patient. The patients were evaluated as Hunt and Hess Grades I to III, and had undergone at least two high-quality cerebral angiograms that did not reveal an aneurysm. Vasospasm was visualized in two patients. Three patients rebled while in the hospital. Exploratory surgery was performed at an average of 12 days post-SAH. Five aneurysms were discovered at surgery and were successfully clipped. All four patients with interhemispheric blood were found to have an anterior communicating artery (ACoA) aneurysm. The patient with blood in the sylvian fissure was found to have a middle cerebral artery aneurysm. These aneurysms were partially thrombosed. No aneurysm was detected in the patient with interpeduncular SAH, despite extensive basilar artery exploration. Five patients had an excellent outcome and one patient developed diabetes insipidus. These results show that exploratory aneurysm surgery is warranted, despite repeated negative cerebral angiograms, if the patient manifests the classical signs of SAH with CT scans localizing blood to a specific cerebral blood vessel (particularly the ACoA) and if a second SAH is documented at the same site.

Clinical studies of de novo aneurysms

Although multiple cerebral aneurysms ae well recognized, a new aneurysm has only rarely been documented after successful treatment for an aneurysm elsewhere. In our consecutive series of 986 patients with intracranial saccular arterial aneurysm collected from 1975 to 1990, nine patients who had previously unverified (hence, de novo) intracranial aneurysms and ruptures at intervals of 4 to 7.5 years after clipping of an initial aneurysm are presented here. All nine had undergone successful treatment of a previous aneurysm; preoperative and postoperative angiography showed not only successful clipping of the first aneurysm but also no incidence of multiple aneurysms. These patients had suffered from hypertension before their second admission. Seven of the nine patients were treated surgically. All patients had experienced angiographical or symptomatic vasospasm after the first subarachnoid hemorrhage. In the second admission however, seven patients who underwent the surgery for a new aneurysm suffered from no vasospasm in spite of the prominent second subarachnoid hemorrhage. Two of the nine patients died of primary brain damage due to the hemorrhage and underwent necropsy. A histological study of a new aneurysm demonstrated the same findings as that of a usual saccular aneurysm. This clinical study of our patients suggests that it is important to control blood pressure for protection against a new aneurysm formation.

Histopathological study of balloon embolization: silicone versus latex

Bilateral, symmetrical, experimental aneurysms were produced with anastomosed vein flap in the carotid arteries of 24 mongrel dogs. Aneurysms were occluded with latex or silicone balloons on each side and observed angiographically from 2 weeks to 2 months. A histopathological study was performed subsequently using light and scanning electron microscopy. Rupture after balloon embolization occurred in five aneurysms; all of which were incompletely occluded by a silicone balloon. On subsequent angiograms, four silicone balloons and one latex balloon were found to have migrated into the aneurysm, resulting in aneurysmal expansion. Parent artery occlusion was more common with latex balloons than silicone balloons. Histopathologically, residual fresh thrombi, decreased proliferation of fibroblasts within the aneurysmal cavity, and poor endothelialization were present around the silicone balloon. These results suggest that the intra-aneurysmal organization, as seen in the aneurysm occluded by the silicone balloon, will be delayed because the balloon is not fixed within the aneurysm, and that this free-floating and rotating balloon causes repeated trauma to the aneurysm wall, contributing to subsequent enlargement and rupture of the aneurysm. The superior antithrombogenic nature of silicone may be responsible for the bias of such phenomena toward the silicone balloon.

Outcome in patients with subarachnoid haemorrhage and negative angiography according to pattern of haemorrhage on computed tomography

15% of patients with spontaneous subarachnoid haemorrhage have normal cerebral angiograms; they fare better than patients with demonstrated aneurysms, though rebleeding and cerebral ischaemia can still occur. In patients with a normal angiogram and accumulation of blood in the cisterns around the midbrain--"perimesencephalic nonaneurysmal haemorrhage"--outcome is excellent. To test the hypothesis that rebleeding and disability in angiogram-negative subarachnoid haemorrhage might be limited to those with other patterns of haemorrhage on initial computed tomography (CT), complications and long-term outcome were studied in 113 patients with angiogram-negative subarachnoid haemorrhage, admitted between January, 1983, and July, 1990. All patients were investigated with third-generation CT scans within 72 h of the event, and with cerebral angiography. The mean follow-up period was 45 (range 6-96) months. None of 77 patients with a perimesencephalic pattern of haemorrhage on CT died or was left disabled as a result of the haemorrhage (0% [95% confidence interval 0-5%]). Among the other 36 patients, who had a blood distribution on CT indistinguishable from that in proven aneurysmal bleeds, 4 had rebleeds and 9 died or were left disabled as result of the haemorrhage (25% [14-43%]). Thus, two distinct subsets of patients with angiogram-negative subarachnoid haemorrhage should be recognised. Patients with a perimesencephalic pattern of haemorrhage have an excellent prognosis. Rebleeding, cerebral ischaemia, and residual disability occur exclusively in patients with aneurysmal patterns of haemorrhage on initial CT. Repeated angiography in search of an occult aneurysm is justified only in the patients with aneurysmal patterns.

Hemodynamic mechanism in the angiographic disappearance of ruptured cerebral aneurysm

Failure of unilateral carotid angiography to opacify a saccular aneurysm of the anterior communicating artery was observed; this occurred despite excellent visualization of the parent artery with spontaneous cross-filling and adequate demonstration of the intracranial carotid system bilaterally. In the absence of thrombosis of the aneurysm (which was discounted by contralateral carotid angiograms), vasospasm, and hypoplasia of the afferent arteries, a hemodynamic mechanism involving velocity of blood flow and intravascular turbulence is considered.

Delayed angiographic appearance of a large basilar aneurysm

A technically adequate four-vessel cerebral angiogram was normal on the first day after a typical episode of subarachnoid hemorrhage. The study was repeated 40 days later showing a large aneurysm of the basilar bifurcation. Hypothetically, the first attempt to visualize the aneurysm was negative due to early transitory thrombosis of the aneurysmal sac. In some cases of subarachnoid hemorrhage it is beneficial to repeat previously normal angiographic studies.

Spontaneous thrombosis of an intracranial aneurysm

A case of spontaneous thrombosis of a previously ruptured anterior communicating artery aneurysm is reported. The patient was referred by another hospital to our service 4 months after the bleeding episode. He had developed a symptomatic normal pressure hydrocephalus, successfully treated by ventriculoperitoneal shunt. Follow-up angiographies, the first performed 4 months and the second 1 year after the bleeding, did not show the aneurysm. Furthermore, the parent artery was not occluded. The literature relative to the subject is reviewed and the possible mechanisms of spontaneous thrombosis are discussed.

Angiographic disappearance and reappearance of an arteriovenous malformation of the cerebellum and brain stem, and its surgical excision. A case report

A case of arteriovenous malformation (AVM) of the cerebellum and brainstem at the cerebellopontine angle is reported. Though a postoperative angiogram after the first operation indicated complete excision of the lesion, the patient returned with subarachnoid haemorrhage, and an angiogram indicated reappearance of the lesion. Total excision was carried out at the second operation.

Spontaneous cure of ruptured intracranial arterial aneurysms

The case of a patient who had spontaneous cure of an intracranial saccular aneurysm, documented by angiography, is reported. This occurred in a 41-year-old patient, admitted four months after recurrent subarachnoid hemorrhage due to an angiographically verified supraclinoid internal carotid artery aneurysm. The relevant literature is reviewed, and the possible mechanism of spontaneous aneurysmal thrombosis is briefly discussed. It is concluded that repeating angiography is not without merit in patients with already documented cerebral aneurysms who are referred for surgical treatment some time after a subarachnoid hemorrhage.

The changing angiographic appearance of an arteriovenous malformation after subarachnoid hemorrhage

The changing angiographic appearance of a cerebral arteriovenous malformation (AVM) illustrated hemodynamic changes that can occur following subarachnoid hemorrhage and antifibrinolytic therapy. Decreased size of this lesion suggested thrombosis of the AVM. This appearance actually represented a transient, vasospastic phenomenon which reversed with time. Although the AVM underwent significant changes acutely, little changed in the long term.