SURGICAL TREATMENT OF POST-TRAUMATIC SYRINGOMYELIA BY ARACHNOID BYPASS OR RELEASE

Abstract

Purpose: The purpose of this retrospective study was to report outcome after surgical treatment of posttraumatic syringomyelia (PTS) and examine the different techniques.

Material and methods: Between 1984 and 2001, 31 patients underwent surgery for cyst derivation (group D, n= 21) or arachnoid release (group R, n = 10). Outcome was assessed on the basis of postoperative changes in clinical presentation (pain) and function (measure of functional independence, MFI). Morphology results were assessed using the Vaquero index (VI) measured on the magnetic resonance images (MRI).

Results: After surgery, aggravation of posterior cord sensitivity was observed in 24% of the patients in group D and in 10% in group R. At last follow-up, there was a statistically significant improvement in pain in the supra- and infra-lesion levels. The Frankel score was stable in 77% and the MFImotor score was stable in 76%. Morphologically, there was a significant diminution in the VI in both groups. MRI velometric studies were performed in seven patients. Cystic systolic and diastolic flow rates were higher preoperatively in patients with more severe clinical grade. Postoperatively (mean 14 months), intra-cystic systolic flow rates decreased significantly (p=0.017). Perimedullary systolic flow rates, which were initially very low reached high levels postoperatively due to re-circulation in the perimedullary subarachnoid space. Re-operation rate was 43% at 39 months for patients in group D (man follow-up 36 months), and 20% in group R (mean follow-up 31 months). The complication rate was 11% (two scar infections, one meningitis, one pneumonia, one acute derivation dysfunction).

Discussion: Arachnoid release yielded a lower re-operation rate than derivations with a lower rate of postoperative posterior cord involvement and an identical functional and morphological outcome. We propose a schema for determining the indication for intra- and extra-dural interventions in the treatment of PTS.