[Syringomyelia, its pathogenesis and surgical treatment based on 4 cases' experience]

Four cases of syringomyelia, each were considered to have different pathogenesis of syrinx and presented different clinical and radiological pictures, are reported. Case I was associated with Chiari I malformation and the syrinx communicated with the fourth ventricle through the central canal, case 2 was associated with Chiari II malformation and the syrinx was not communicated with the fourth ventricle, case 3 was thought to be traumatic and case 4 to be arachnoiditis due to unknown etiology. Metrizamide CT myelography was most valuable diagnostic technique to disclose the syringomyelic cavity and its extension. The cases except case 1 showed central opacification without via fourth ventricle, suggesting transneural migration CSF as shown by Aubin et al. Surgical treatment, therefore, was different in each case to obtain normal CSF dynamics. Case 1 was treated by suboccipital craniectomy, muscle plugging to the obex and syringo-subarachnoid shunt. In case 2 syringo-cisternal shunt was done in addition to suboccipital craniectomy. In case 3 syringocisternal shunt was done after laminectomy. In case 4 syringo-peritoneal shunt was performed. All but case 4 were obtained favorable result and case 4 was unfavorable except the disappearance of girdle sensation. For traumatic or inflammatory syringomyelia with tight adhesion between pia and arachnoid membrane in subarachnoid space, syringocisternal shunt was good way to obtain normal CSF dynamics and was expected to relieve the neurological deterioration.