Terminal Syringomyelia and Occult Spinal Dysraphism

Abstract

Terminal syringomyelia is traditionally defined as a cystic dilatation in the caudal third of the spinal cord. It is commonly associated with occult spinal dysraphism (OSD), with its incidence better recognized since the advent of magnetic resonance imaging. While the underlying pathophysiologic mechanism is not fully understood, several theories exist regarding the development of terminal syrinx in patients with OSD. The independent clinical significance of OSD-associated terminal syringomyelia and the role for direct surgical treatment of the syrinx beyond standard detethering of the OSD remains controversial. Isolated terminal syrinx is almost always a benign, nonprogressive clinical entity and typically requires no treatment. Terminal myelocystocele may represent an extreme version of terminal syrinx and should be repaired in a timely manner to avoid neurological worsening secondary to cord tethering.