JRSM >
Volume 96, Number 11 >
Pp. 550-551
Department of Neurosurgery, Shiga National Hospital, 255 Gochi-cho, Yokaichi, Shiga 527-8505, Japan
When a de novo intracranial saccular aneurysm is detected at a site where angiography was previously negative, the interval between angiographies is usually a matter of years1,2 rather than days.
CASE HISTORY
A woman of 76 with a history of hypertension developed headache with mild disturbance of consciousness. There was no personal or family history of inflammatory, collagen or cerebrovascular disease. On neurological examination there were no localizing features and laboratory data were all within the normal range. Urgent cranial CT revealed diffuse subarachnoid haemorrhage in the interpeduncular and ambient cisterns, and a magnetic resonance angiogram disclosed a single aneurysm, 12 mm in diameter, at the bifurcation of the basilar artery (Figure 1). Eight days later, the patient suddenly vomited and became comatose with neck rigidity. 30 minutes after this, CT revealed a dense subarachnoid haemorrhage localized in the left sylvian fissure. Next day the basilar artery aneurysm, which was then thought to be responsible for both vascular events, was successfully occluded by endovascular coiling. At that time a new aneurysm (Figure 2), 10 mm in diameter, was observed at the bifurcation of the left middle cerebral artery; the artery itself was not clearly visualized owing to vasospasm. Because of the patient's clinical state (semi-comatose and dyspnoeic) the new aneurysm was left untreated. 7 days later, magnetic resonance angiography showed the left middle cerebral artery to be completely occluded proximal to the aneurysm, which was no longer visible (Figure 3). Thereafter the patient remained stuporose with a right hemiplegia.
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COMMENT
The shortest reported interval between an angiography and the demonstration of a de novo aneurysm at further angiography is 47 days.3 In the present case the interval was 9 days. The arteriographic appearance was suggestive of a true saccular aneurysm rather than a mycotic, dissecting or arteriosclerotic aneurysm.
Could the middle cerebral artery aneurysm have been missed at the original magnetic resonance angiography? Digital subtraction arteriography is certainly more sensitive; however, a basilar bifurcation aneurysm and the first and second portion of the left middle cerebral artery are clearly seen in the first magnetic resonance angiogram. Moreover, on examination of the published work4-6 I could find no report of false-negative magnetic resonance angiography for an aneurysm greater than 10 mm in diameter. On this evidence I conclude that this aneurysm did not exist at the time of initial study 9 days earlier.
REFERENCES
De
novo
formation of intracranial aneurysms: who is at risk?
Neuroradiology1999; 41:674
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