OBJECTIVEWith the increasing use of magnetic resonance imaging, terminal syringomyelia (segmental cystic dilation of the caudal one-third of the spinal cord) in association with the tethered cord syndrome has become an appreciable finding. This study attempted to define the clinical significance of this associated pathological condition by describing its clinical and radiological characteristics and its contribution to the clinical status of patients with tethered spinal cords.METHODSOf 132 consecutive patients with tethered cord syndrome who presented to our department between 1990 and 1997, 32 patients with terminal syringomyelia were enrolled in this study. Clinical findings were correlated with syrinx morphological features, as defined using magnetic resonance imaging. Surgical treatment used two basic approaches, i.e., simple untethering or untethering with concurrent syrinx drainage.RESULTSAnalysis of the neurological deficits established a contribution of segmental symptoms, which were correlated with the extension and dilation of the syrinx cavity. Magnetic resonance imaging scans revealed the frequency of sacral tethering (40.6%), the intramedullary paracentral position of the syrinx (75%), and disturbances in regional cerebrospinal fluid flow (42%). The clinical outcomes seemed to be correlated with syrinx shrinkage; all patients who experienced collapse of the cavity achieved better symptom resolution.CONCLUSIONRadiologically significant terminal syringomyelia affects the clinical presentation of tethered cord syndrome, by increasing or inducing neurological deficits. Better clinical outcomes after syrinx decompression emphasize the importance of the recognition and treatment of this pathological condition.