Atypical Imaging Manifestations of Lateral Dural Tears with Arachnoid Herniations: A Multi-Institutional Study.

Lateral dural tears are a common cause of spontaneous intracranial hypotension. Frequently, these leaks are associated with an arachnoid diverticulum that herniates through the dural defect. CSF egress into the epidural space occurs from the margins of the dural tear rather than from the lateral portion of the herniated arachnoid diverticulum. Nonetheless, arachnoid diverticula can have secondary effects that alter the physiology and imaging appearance of lateral leaks. Specifically, we have anecdotally observed 3 unique variations of lateral dural tears, including 1) lateral dural tears in which the herniated arachnoid diverticulum is associated with a CSF leak that involves the facet joint, 2) lateral tears in which the arachnoid diverticulum is associated with a CVF, and 3) lateral tears in which there is contrast leaking into the epidural space on decubitus myelography without evidence of epidural CSF collections on preprocedural spine MRI. In this clinical report, we describe a multi-institutional retrospective case series of patients with these unique variations of lateral dural tears. We sought to elucidate the clinical and imaging features of these patients.