Prognostic Value of Clinical and Radiological Signs in the Postoperative Outcome of Spinal Dural Arteriovenous Fistula

Study Design. Retrospective consecutive case series. Objective. To determine predictors of outcome in patients undergoing surgical treatment of spinal dural arteriovenous fistula (SDAVF). Summary of Background Data. Most previous studies assessing postoperative outcome in patients with SDAVF have been limited due to small population size, lack of sufficient information on presurgical variables, or short time of postoperative follow-up. Consequently, the most reliable predictors of functional outcome after treatment of SDAVF are not yet well established. Methods. Retrospective analysis of consecutive patients with SDAVF treated surgically between June 1985 and March 2008 in our institution. The Aminoff-Logue gait (G) and micturition (M) scores were used to stratify the degree of disability and the G + M score was used as the primary outcome measure. Demographics, clinical presentation, time to diagnosis, fistula level, presurgical motor and sphincter impairment, and magnetic resonance imaging findings were assessed as prognosticators for postoperative outcomes. Results. One hundred fifty-three patients were analyzed. Mean follow-up was 31 +/- 36.2 months. Most patients were improved (44%) or stable (34%) upon the last follow-up. Among preoperative variables, worsening weakness with exertion was associated with a better G + M score at the last follow-up (P < 0.001) and presence of pinprick level was associated with a worse G + M score at the last follow-up (P = 0.020). On multivariable analysis, worsening weakness with exertion was associated with better outcome at the last follow-up, and higher G score at presentation and higher G + M score at discharge were associated with worse outcome at the last follow-up. Magnetic resonance images obtained postoperatively for 104 patients (mean, 19.1 +/- 22.5 mo) showed complete resolution or improvement of the presurgical T2 signal abnormalities in 83.6% of cases. Changes in postoperative magnetic resonance image and fistula level did not correlate with functional outcomes. Conclusion. The degree of preoperative disability from SDAFV does not determine who will benefit most from surgery and even patients with severe deficits can improve after treatment. Patients with preoperative exertional claudication and without pinprick level on examination have greater chances of postsurgical improvement.