Dorsal arachnoid web and scalpel sign: a diagnostic imaging entity

Abstract

In patients with presumed idiopathic syringomyelia, imaging studies should be closely inspected for the presence of transverse arachnoid web. This extramedullary transverse band of arachnoid tissue extends to dorsal surface of the spinal cord, resulting in mass effect and dorsal indentation, known as scalpel sign because of its apparent resemblance to a scalpel on sagittal imaging. Early diagnosis with early intervention may benefit greatly patients. Surgical resection of transverse arachnoid web is a minimally invasive procedure with low morbidity, and can result in resolution of syringomyelia and improvement in neurological function.