Reevaluation of syringosubarachnoid shunt for syringomyelia with Chiari malformation

OBJECTIVE: The purpose of this study was to evaluate the effectiveness of s yringosubarachnoid (S-S) shunting for syringomyelia with Chiari malformatio n. The authors describe the technical methods of performing the S-S shunt a nd the clinical results, including shunt malfunction, METHODS: Forty-nine patients underwent S-S shunting. These patients were di vided into three groups according to differences in the surgical technique used. Group I patients underwent laminectomy plus midline myelotomy and had a shunt tube placed in the dorsal subarachnoid space. Group II patients un derwent laminectomy plus dorsal root entry zone myelotomy and had a shunt t ube placed in the dorsolateral subarachnoid space. Group III patients under went hemilaminectomy plus dorsal root entry zone myelotomy and had a shunt tube placed in the ventrolateral subarachnoid space. RESULTS: Clinical results were generally satisfactory, especially in terms of pain relief, in all three groups. However, 10 patients among Groups I an d II required follow-up surgery because of shunt problems; no second surger y was necessary for any patient in Group III. CONCLUSION: The S-S shunt was very effective in deflating the syrinx, and t he clinical results were satisfactory. Therefore, even though foramen magnu m decompression is a very effective treatment, S-S shunting should be reeva luated and not rejected; it should be considered as one of the major surgic al options. To prevent the possibility of cord injury by myelotomy or shunt malfunction, the dorsal root entry zone should be selected as the myelotom y site, and the shunt tube should be inserted into the ventral subarachnoid space at the cervical level.