Contralateral subdural effusion after aneurysm surgery and decompressive craniectomy: case report and review of the literature.

We report a complication of decompressive craniectomy in the treatment of aneurismal subarachnoid hemorrhage (SAH) and accompanying middle cerebral artery (MCA) infarction. A 56-year-old man presented with subarachnoid hemorrhage and right sylvian hematoma. He was diagnosed with high-grade SAH and medical therapy was employed. He showed rapid clinical deterioration on day 9 of his admission. Computed tomographic scans showed right MCA infarction and prominent midline shift. Because of the patient's rapidly worsening condition, further evaluation to find origin of SAH could not be obtained, and decompressive right hemicraniectomy was performed. During sylvian dissection, right middle cerebral and posterior communicant artery aneurysms were detected and clipped. One week after operation, a contralateral frontoparietal subdural effusion and left to right midline shift was detected and drained through a burr-hole. Through successive percutaneous aspirations, effusion recurred and complete resolution was achieved after cranioplasty and subduroperitoneal shunt procedures. Decompressive craniectomy is generally accepted as a technically simple operation with a low incidence of complications. In the light of this current case, we hypothesize that a large craniectomy may facilitate the accumulation of recurrent effusion on contralateral side creating a resistance gradient between two hemispheres. This point may be especially true for subarachnoid hemorrhage cases requiring aneurysm surgery. We conclusively suggest that subdural effusions may be resistant to simple drainage techniques if a large contralateral craniectomy does exist, and early cranioplasty may be required for treatment in addition to drainage procedures.