THE SURGICAL-TREATMENT OF CHIARI-I MALFORMATION

A retrospective study was undertaken on 133 patients with a Chiari I m alformation treated within the last 16 years at the Departments of Neu rosurgery at the Nordstadt Hospital Hannover, Germany, and the Univers ity of California, Los Angeles, U.S.A. Ninety-seven patients presented with symptoms related to accompanying syringomyelia and 4 with associ ated syringobulbia. They underwent 149 surgical procedures and were fo llowed for a mean of 39 +/- 52 months. A decompression at the foramen magnum was performed in 124 patients, while 22 of those with syringomy elia were treated by shunting (7 syringosubarachnoid shunts, 15 syring operitoneal or -pleural shunts), and 3 by ventriculoperitoneal shunts for hydrocephalus. Except for ventriculoperitoneal shunting, at least a short-term decrease in size of an associated syrinx was observed for all procedures in the majority of cases. However, no long-term benefi t was observed for syrinx shunting operations. The best clinical long term results were obtained with decompression of the foramen magnum in patients with (86% free of a clinical recurrence) and without syringo myelia (77% free of a clinical recurrence). We advise against syrinx s hunting, a large craniectomy, and obex plugging which are associated w ith higher recurrence rates. Instead, surgery should consist of a smal l craniectomy, opening of the dura, archnoid dissection to establish n ormal cerebrospinal fluid (CSF) outflow from the 4th ventricle, and a fascia lata dural graft.