Isolated subarachnoid hemorrhage after evacuation of chronic bilateral subdural hematoma: Case report and review of the literature

Background: Chronic subdural hematoma (CSDH) is frequently encountered in neurosurgical practice. Evacuation through one or two burr holes is the most common surgical treatment. Hemorrhagic complications such as acute subdural hematoma (ASDH) or intracerebral hemorrhage (ICH) has been reported as rare but severe complications. Nonetheless, isolated subarachnoid hemorrhage (SAH), developed after burr-hole evacuation of CSDH, without other hemorrhagic complications, is an extremely rare finding reported only in two previous reports. Case description: A 64 year's old man was referred to our department for mental confusion, disorientation, dizziness and walking disability. CT scans showed a bilateral fronto-parietal CSDH. He underwent bilateral parietal burr-hole craniectomy and subdural drainage positioning. The day after surgery, the patient developed intense headache and vomit and a CT scan revealed a SAH in the temporal and parietal lobe located in both hemispheres. A CT angiogram excluded the presence of intracranial aneurysms. The drainage systems were removed and the patient underwent conservative management with clinical improvement. He was discharged in day 7 without neurological deficits. The one-month follow-up showed the patient was in good conditions and the CT scan revealed complete resolution of the previous hemorrhagic findings. Conclusion: We suppose the rapid brain shift occurred during surgery was the main cause of development of SAH in our patient, but several possible pathological mechanisms are discussed. Although CSDH evacuation is considered a routinely procedure, neurosurgeons must be aware of this rare complication avoiding perioperative overdrainage of subdural hematomas.