Response of Syrinx Associated with Chiari I Malformation to Posterior Fossa Decompression with or without Duraplasty and Correlation with Functional Outcome: A Prospective Study of 22 Patients.

Background: The aim of the study is to correlate the surgical outcome with radiological changes in patients with Chiari I malformation (CMI) with syrinx. We also compared long-term functional and radiographic outcome in CM1 patients treated with posterior fossa decompression (PFD) with or without duroplasty.

Patients and Methods: From December 2013 to October 2015, 22 patients who underwent surgery with the diagnosis of CMI and syrinx were included in the study. Measurements were performed on preoperative and postoperative magnetic resonance (MR) scans using the same software. All patients underwent PFD with or without duroplasty. Clinical results were evaluated on the basis of the Chicago Chiari Outcome Scale (CCOS). We assessed the degree of resolution of syrinx and outcome of Chiari decompression with PFD versus PFD with duroplasty. Mean duration of follow-up was 12.4 ± 5.37 months (range: 6-24 months).

Results: Out of 19 patients in whom syrinx diameter decreased on postoperative MR imaging, 17 (89.5%) improved based on CCOS and 2 (10.5%) were unchanged while out of three patients in whom syrinx worsened, 2 (66.7%) improved and 1 (33.3%) was unchanged ( P = 0.37). The cord diameter was found to have decreased in 12 patients and of these 11 (91.7%) improved. The cord diameter increased in 10 patients, but 8 (80%) improved ( P = 0.57). The mean changes in syrinx, cord, and syrinx/cord ratio were studied in both groups with and without duroplasty, were not statistically significant. In this study, radiological parameters failed to predict functional outcome.

Conclusions: The outcome does not correlate with change in any of the syrinx-related factors. Surgical decompression with or without duroplasty does not have a statistically significant relationship in the degree of syrinx resolution. Surgical decompression without duroplasty provides the benefits of surgical decompression while avoiding the complications of intradural techniques.