Can patients with brain herniation on cranial computed tomography have a normal neurologic exam?

Herniation of the brain outside of its normal intracranial spaces is assumed to be accompanied by clinically apparent neurologic dysfunction. The authors sought to determine if some patients with brain herniation or significant brain shift diagnosed by cranial computed tomography (CT) might have a normal neurologic examination.

This is a secondary analysis of the National Emergency X-Radiography Utilization Study (NEXUS) II cranial CT database compiled from a multicenter, prospective, observational study of all patients for whom cranial CT scanning was ordered in the emergency department (ED). Clinical information including neurologic examination was prospectively collected on all patients prior to CT scanning. Using the final cranial CT radiology reports from participating centers, all CT scans were classified into three categories: frank herniation, significant shift without frank herniation, and minimal or no shift, based on predetermined explicit criteria. These reports were concatenated with clinical information to form the final study database.

A total of 161 patients had CT-diagnosed frank herniation; 3 (1.9%) had no neurologic deficit. Of 91 patients with significant brain shift but no herniation, 4 (4.4%) had no neurologic deficit.

A small number of patients may have normal neurologic status while harboring significant brain shift or brain herniation on cranial CT.