Vertebro-basilar aneurysms: does delayed surgery represent the best surgical strategy?

Cooperative study of ruptured vertebrobasilar artery aneurysms in the Tohoku district in Japan

A multicenter study investigated the clinical characteristics and overall outcome of 342 cases of ruptured vertebrobasilar artery aneurysms among 6783 ruptured intracranial berry aneurysms in 73 hospitals across the Tohoku district in Japan between 1992 and 1996. The incidence of ruptured vertebrobasilar artery aneurysms was less frequent than previously reported. The incidence was 5% among all intracranial berry aneurysms. One hundred eleven patients had aneurysms of the basilar artery bifurcation, 98 had vertebral-posterior inferior cerebellar artery aneurysms, 44 had basilar-superior cerebellar artery aneurysms, and 28 had distal posterior inferior cerebellar artery aneurysms. Aneurysm clipping was performed in 238 cases (70%), intravascular treatment in 22 (6%), drainage in 22 (6%), and conservative treatment in 60 (18%). Approximately 50% of patients were in good condition at admission. At 3-month follow up, 46% had good recovery, 14% had moderate disability, 10% had severe disability, 4% were vegetative state, and 27% died. Vertebral artery aneurysms showed favorable outcomes compared to basilar artery bifurcation aneurysms. Surgical results in the 238 operated cases were good recovery in 60%, moderate disability in 18%, severe disability in 10%, vegetative state in 2%, and death in 11% of cases. Worse postoperative outcomes were observed in patients with high preoperative Hunt and Kosnik grades or aneurysms larger than 10 mm, and in patients over 70 years of age.

Perimesencephalic hemorrhage and CT angiography: A decision analysis

BACKGROUND AND PURPOSE

The method of choice for detecting or excluding a vertebrobasilar aneurysm still is a matter of debate in patients with a characteristically perimesencephalic pattern of subarachnoid hemorrhage (SAH) on CT. We used decision analysis to compare possible diagnostic strategies in these patients.

METHODS

A decision analytic model was developed to evaluate the effect of 4 different diagnostic strategies following a perimesencephalic pattern of SAH on CT: 1, no further investigation; 2, digital subtraction angiography (DSA) by catheter; 3, CT angiography as initial modality, not followed by DSA if negative; and 4, CT angiography as initial modality, followed by DSA. We used a 4% prevalence of a vertebrobasilar aneurysm given a perimesencephalic pattern of hemorrhage, a 97% sensitivity and specificity of CT angiography, and a 99.5% sensitivity and 100% specificity of DSA. In a prospectively collected series, the complication rate from DSA in patients with a perimesencephalic pattern of hemorrhage was 2.6%. We calculated the expected utility of each of the 4 diagnostic options and used sensitivity analyses to examine the influence of the plausible ranges of the various estimates used.

RESULTS

The expected utilities were 99.09 for CT angiography only, 98.96 for no further investigation, 98.22 for DSA, and 96.34 for CT angiography plus DSA. The results of the sensitivity analysis indicate that over a wide range of assumptions, CT angiography only is the most beneficial option. Only when the complication rate of catheter angiography is <0.2% is DSA the preferred strategy.

CONCLUSIONS

Our decision analysis shows that in patients with a perimesencephalic pattern of hemorrhage on CT, CT angiography only is the best diagnostic strategy. DSA can be omitted in patients with a perimesencephalic pattern of hemorrhage and a negative CT angiogram.

Oculomotor nerve palsy after surgery for upper basilar artery aneurysms

OBJECTIVE

The goals of this study were to evaluate the relationship between postoperative oculomotor nerve palsy and other clinical factors and to improve preoperative estimations of the risk. Such an evaluation has not been previously described in the literature.

METHODS

Patient records for 77 basilar tip aneurysm cases and 28 basilar superior cerebellar artery aneurysm cases treated between 1981 and 1997 were reviewed. Clinical and radiological parameters were separately analyzed using the chi2 test, and then multiple-regression analysis was used.

RESULTS

Postoperative oculomotor palsy occurred in 25 (32%) patients with basilar tip aneurysms and 11 (39%) patients with basilar superior cerebellar artery aneurysms, in addition to 2 patients with basilar tip aneurysms and 3 patients with basilar superior cerebellar artery aneurysms who exhibited oculomotor palsy before surgery. For both type of aneurysms, the size and direction of the aneurysms were closely related to oculomotor nerve palsy. The complication also tended to occur in early surgery cases, in younger patients, and in patients of poor-clinical grade status.

CONCLUSION

In this study, some clinical and radiological factors were found to be associated with postoperative oculomotor nerve palsy.

Surgical management of vertebrobasilar aneurysms

This paper reports a retrospective analysis of 50 patients who had 55 posterior circulation aneurysms treated surgically. Twenty-four patients presented with subarachnoid haemorrhage. Thirty-three of the lesions involved the basilar artery, predominantly at its bifurcation. There were 13 giant aneurysms in the series, 3 false aneurysms, 1 mycotic aneurysm and 3 associated with arteriovenous malformations. Forty-nine aneurysms (89%) were able to be treated surgically and 38 (69%) of these were directly clipped. Neurological assessment at discharge indicated that 38 patients (76%) had a good outcome. Moderate disability occurred in 7 patients (14%). Four patients (8%) were left severely disabled or vegetative. There was a single death in the series (2%).

Distal basilar perforator artery aneurysm: case report

OBJECTIVE AND IMPORTANCE

Distal basilar artery aneurysms represent 5 to 8% of intracranial aneurysms. It is crucial to preserve all of the basilar apex perforating vessels when dissecting in this region. This report is the first to describe a rostral basilar perforating artery that was the anatomic origin of a cerebral aneurysm.

CLINICAL PRESENTATION

A 56-year-old woman presenting with subarachnoid hemorrhage underwent initial four-vessel cerebral angiography that did not demonstrate the source of her hemorrhage. A follow-up cerebral angio-gram 9 days later suggested a small aneurysm in the region of the left superior cerebellar artery.

INTERVENTION

A left pterional craniotomy was performed. An aneurysm arising from the origin of a distal basilar perforating artery was identified and obliterated with a small vascular clip. Flow was preserved in the perforating vessel, and the patient had an excellent outcome.

CONCLUSION

The findings in the report illustrate the novel anatomic principle that a distal basilar perforating vessel can serve as the anatomic origin of a cerebral aneurysm. Knowledge of this entity would be helpful in avoiding complications at surgery, including perforator injury or aneurysmal rupture in such cases.