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Neurology India, Vol. 51, No. 3, July, 2003, pp. 422-424 Intracranial aneurysms causing spontaneous acute subdural hematoma Shenoy SN, Kumar MG, Raja A Correspondence Address: Code Number: ni03143 ABSTRACT Acute subdural hematoma is an uncommon presentation of the rupture of an intracranial aneurysm. We report two cases of intracranial aneurysms causing spontaneous acute subdural hematoma. INTRODUCTION Spontaneous acute subdural hematoma is an uncommon manifestation of the rupture of a cerebral aneurysm. Aneurysms of the internal carotid artery and middle cerebral artery are more commonly associated with the presentation of subdural hematoma.[1],[2],[3],[4] During the last 15 years, 348 cases of intracranial aneurysms were operated at the Kasturba Hospital, Manipal. Of these, two patients had acute subdural hematoma secondary to the rupture of an intracranial aneurysm. We report these two cases of acute subdural hematoma and review the literature on the subject. CASE REPORTS Case1 DISCUSSION The various types of intracranial bleeding due to the rupture of a cerebral aneurysm are: subarachnoid hemorrhage (about 60%), intracerebral hematoma (30 to 40%) and intraventricular hematoma (12 to 17%).[2],[34] The incidence of spontaneous acute subdural hematoma due to aneurysm rupture varies from 0.5% to 7.9%.[1],[4],[5],[6] Various mechanisms have been proposed to explain the causation of acute subdural hematoma after the rupture of saccular aneurysm. Firstly, the aneurysm adherent to the arachnoid may bleed directly into the subdural space when the arachnoid tear occurs after aneurysm rupture.[7] Secondly, the stream of blood may rupture through the arachnoid at some distant weak point.[8] Lastly, the subdural hematoma may develop secondary to the decompression of intracerebral hematoma into the subdural space following disruption of the arachnoid covering the cerebral cortex.[9] Acute subdural hematoma has been described in association with aneurysms at almost all the branches of intracranial arteries.[2] Fox analyzed the world literature and found 56 reports containing 146 cases of subdural hematoma that were published between 1895 and 1978.[2] The commonest aneurysm associated with subdural hematoma was internal carotid artery aneurysm, followed by middle cerebral artery aneurysm.[2],[5] Similar to our cases, about 80% of the cases of subdural hematoma due to the rupture of cerebral aneurysms reported in the literature were seen in females.[2],[5] The majority of these patients presented with features suggestive of transtentorial herniation such as anisocoria, hemiplegia and altered consciousness.[4],[5],[9],[10] On the other hand, both the cases reported here presented in good clinical grade and had no lateralizing deficit. An acute subdural hematoma in the absence of head trauma requires further neuro-radiological investigation to define its possible cause.[5],[10],[11] Weir et al reported various criteria to differentiate subdural hematoma due to a ruptured aneurysm from trauma in the CT scan.[4],[5],[10] If the patient is stable enough to allow further investigations before craniotomy, then angiographic study to define the vascular lesion must be considered. If the patient is in poor clinical grade, a 3D-CT angiography is the best investigation to detect the presence of an aneurysm. Certain criteria must be assessed with regard to the timing of the operation in patients with aneurysm-related acute subdural hematoma.[5],[11] If the subdural hematoma is well tolerated like in the cases reported here, then relatively elective clipping of the aneurysm under optimal operating conditions along with evacuation of the subdural hematoma can be performed. However, in the face of rapid clinical deterioration, an emergency craniotomy for subdural evacuation should be performed before further investigations.[5],[10] Both cases reported here underwent early operation and improved postoperatively. The incidence of delayed ischemic deficit in these patients is reported to be low as compared to those patients who had subarachnoid hemorrhage.[2] REFERENCES
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