Long-term utility and complication profile of open craniotomy for biopsy in patients with idiopathic encephalitis

Neurosurgeons are often asked to perform open biopsy for diagnosis of encephalitis after medical investigations are non-diagnostic. These patients may be critically ill with multiple comorbidities. Patients and their families often request data regarding the success rates and complication profile of biopsy, but minimal literature exists in this area. Retrospective chart review of all patients undergoing open brain biopsy (burr hole or craniotomy) for encephalitis refractory to medical diagnosis between January 2009 and December 2013 was undertaken. Pathology records and outpatient follow-up were reviewed to determine most recent clinical status of each patient. A total of 59 patients were included with mean follow up of 20months. The average age at biopsy was 55years. The most common unconfirmed diagnoses leading to biopsy were vasculitis (44%), neoplasm (27%), infection (12%), autoimmune (12%), amyloidosis (5%). Tissue pathology was diagnostic in 42% of all cases. Overall, biopsy confirmed the preoperative diagnosis in 46% of cases and refuted the preoperative leading diagnosis in 25% of cases. At last follow-up, the tissue pathology resulted in a medical treatment change in 25% of cases. There was a 14% major neurological complication rate (postoperative stroke, hemorrhage, or neurological deficit) and 9% cardiopulmonary complication rate (delayed extubation and re-intubation) attributable to surgical intervention. In this limited series, diagnostic utility of biopsy in patients with idiopathic encephalitis is less than 50% and the major complication rate is 23%. Patients and providers must be counseled accordingly and weigh the risks and benefits of open biopsy for encephalitis cautiously.