Long-term results after posterior fossa decompression in syringomyelia with adult Chiari Type I malformation.

OBJECT

There is little information about the long-term effectiveness and complications following decompressive surgery for syringomyelia related to Chiari malformation Type I (CM-I).

METHODS

Examining long-term clinical and radiological follow-up, the authors studied a mixed retrospective and prospective single-institution cohort of 109 consecutive surgically treated adult patients with syringomyelia and CM-I. All patients underwent a standardized surgical protocol: decompression of the craniocervical junction, arachnoid exploration, and shrinkage of the cerebellar tonsils. Factors predicting outcome were investigated.

RESULTS

The retrospective arm consisted of 41 cases treated between 1990 and 1994, and the prospective arm comprised 68 patients treated between 1994 and 2001. The mean overall age was 45.9 years, and 58.8% of the population was female. The median follow-up period was 12.7 years. The most frequent initial symptoms were pain and sensory and gait disturbances. There was no perioperative death or neurological deterioration. The comprehensive perioperative complication rate was approximately 11%, with 3 cases (2.7%) of CSF leakage. Regression analysis showed that the best combination of clinical and radiological outcome predictors was age and duration of symptoms. Clinical follow-up confirmed surgical result stability with clinical improvement of greater than 90% of the spinal and cranial manifestations over a long-term period. Two patients had radiological recurrences of syringomyelia without clinical signs 85 and 124 months after surgery.

CONCLUSIONS

Certain clinical predictors of poor clinical and radiological prognosis were identified-namely, age at time of surgery and symptom duration. The results of the study provide additional long-term data that support the effectiveness and safety of relieving CSF block at the craniocervical junction in CM-I-related syringomyelia.