A new classification of complications in neurosurgery.

Objective: To define and grade neurosurgical and spinal postoperative complications based on their need for treatment.

Methods: Complications were defined as any deviation from the normal postoperative course occurring within 30 days of surgery. A four-grade scale was proposed based on the therapy used to treat the complications: grade I, any non-life-threatening complications treated without invasive procedures; grade II, complications requiring invasive management such as surgical, endoscopic, and endovascular procedures; grade III, life-threatening adverse events requiring treatment in an intensive care unit (ICU); and grade IV, deaths as a result of complications.