Analysis on Surgical Outcome of Arnold-Chiari Malformation with Syringomyelia

ABSTRACT

The surgical outcomes of Arnold-Chiari malformation associated with syringomyelia have been reported with respect to improvement in symptoms and signs. But there are only a few studies about the changes of size in syrinx cavity after the era of magnetic resonance image. The authors employed two different surgical modalities and compared the difference in outcomes. Between 1988 and 1994, 17 patients suffering from Arnold-Chiari malformation associated with syringomyelia were treated by foramen magnum decompression(FMD), with or without shunt. Their ages ranged from 3 to 62 (median, 42) years; four were males and 13 were females. Eight were treated by FMD with syringosubarachnoid shunt (FMD with shunt group) and 9 by FMD only(FMD group). Changes in the extent of syrinx and clinical improvements were retrospectively compared between the two groups; the median follow-up period was 22(range 5-79) months. Changes in the extent of syrinx were analyzed by pre- and postoperative magnetic resonance images; improvements in symptoms or signs were classified by lower cranial nerves, the cerebellum and the spinal cord. The size of syrinx was decreased in 7/8 patients of FMD with shunt group(88%) and in 7/9 patients of FMD group (78%) and there was no significant difference in ratio statistically(p=0.54). Shrinkage of syrinx cavity was occurred regardless of its preoperative extent. In FMD with shunt group, 5/8 patients(63%) were improved in symptoms or signs and in FMD group, 6/9 patients(67%)(p=0.21). In all 3 cases which showed no collapse of syrinx cavity, the clinical improvements were not found. There was correlation between collapse of syringomyelia and improvement of clinical findings(p=0.035).