Posterior fossa decompression in syringomyelia associated with a Chiari malformation: a retrospective analysis of 22 patients

Background: The technique of posterior fossa decompression, nowadays prefer red by most neurosurgeons as the first surgical option in the treatment of hindbrain associated syringomyelia, was reintroduced in our center in 1989. We present a retrospective analysis of 22 patients with this pathology who underwent the procedure since then. Methods: In all patients diagnosis was made by MRI of the craniospinal junction. The operation consisted of a sub occipital craniectomy, removal of the posterior are of C1, laminectomy of C 2 or C3 when necessary and a wide duraplasty at the end. The intradural man ipulations (opening of the arachnoid membrane, coagulation or resection of the tonsils) were not uniform. Postoperatively short- and long-term clinica l outcome and MRI findings were assessed. Results: Sixteen out of 21 patien ts (76%) experienced an improvement in the early follow-up period. In the l ate follow-up period 13 out of 19 patients (68%) were improved, whereas fiv e patients (26%) experienced a marked deterioration. There was no unequivoc al effect on all symptoms and signs. Postoperative MR images showed a favor able result in 16 out of 20 patients (80%), consisting of syrinx collapse o r reduction of the syrinx diameter. Conclusions: We conclude that decompres sion of the posterior fossa is a safe procedure with a considerable chance of clinical improvement. Although total syrinx collapse is not as frequentl y seen as in syrinx shunting procedures, the clinical outcome may be better . Moreover, there seemed to he no unequivocal correlation between clinical outcome and postoperative syrinx size in the present study. (C) 2000 Elsevi er Science B.V. All rights reserved.