Introduction: Idiopathic herniation of the spinal cord is a rarely diagnosed condition. It is important since this cause of paraparesis is potentially curable if diagnosis is made early. Our aim is to report a new case, review the relevant literature, describe the radiological findings and consider the etiopathogenic findings.
Clinical case: We report the case of a 56 year old man with increasing difficulty in walking attributed to stenosis of the lumbar spinal canal, which did not improve after laminectomy. On examination he had sensory and motor deficits compatible with the Brown-Séquard syndrome. Dorsal MR showed ventral displacement of the thoracic spinal cord with disappearance of the anterior subarachnoid space together with a posterior arachnoid cyst at the same site. A further operation was done at the same place and the cyst removed. However, it was impossible to free the spinal cord since there was severe spinal arachnoiditis. The patient made little improvement.
Conclusions: Herniation of the spinal cord is a rarely diagnosed condition. After careful study of the literature it seems that all patients present in a similar manner. Clinically there is a disorder of gait compatible with the Brown-Séquard syndrome. On MR there is sudden ventral displacement of the thoracic spinal cord, associated in some cases with an arachnoid cyst. When surgery is effective there is great improvement, so this diagnosis should be remembered in all cases of progressive paraparesis.