Surgical treatment of syringomyelia with Chiari malformation type I

Several surgical procedures have been used for the treatment of syringomyelia associated with Chiari I malformation in our institute. The purpose of this paper is to evaluate the results of two major surgical procedures, foramen magnum decompression (FMD) and syringosubarachnoid (SS) shunting. The series consisted of 111 patients with syringomyelia associated with Chiari I malformation who were surgically treated. Their ages ranged from 3 to 59 years (median, 29 years). FMD was performed on 53 patients and SS shunting on 58 patients. The follow-up period ranged from 6 months to 18 years. The clinical and radiological outcomes were analyzed comparing the two groups. We principally performed FMD in patients with symptoms of Chiari I malformation or a small syrinx or both. We prefer to use SS shunting in patients with a large syrinx. Postoperative magnetic resonance imaging demonstrated that the syrinx had collapsed or decreased in size in 93% of the patients who underwent FMD and in 100% of the patients who underwent SS shunting. Neurological improvements were observed in 82% and in 97%, respectively, of the patients who underwent FMD and SS shunting. The average time for the syrinx to collapse was 5.6 weeks after surgery in the FMD group and 1.5 weeks in the SS shunting group. These results indicate that clinical symptoms and radiological findings improved much more quickly in the SS shunt group than in the FMD group.