A study of dynamic F-waves in patients with symptomatic degenerative lumbar spinal stenosis.

Abstract

PURPOSE: To quantify the dynamic F-waves in patients with degenerative lumbar spinal stenosis (DLSS) and to analyze the relationships between dynamic F-wave abnormalities and both the severity and surgical outcomes of DLSS. METHODS: Preoperatively, peroneal F-waves were recorded bilaterally in 201 patients with DLSS and 52 healthy subjects before and after 10-minute walk tests, along with assessments of the Oswestry Disability Index (ODI), Zurich Claudication Questionnaire (ZCQ) and 36-Item Short Form Survey (SF-36). Questionnaire scores were re-evaluated 1 year after operation in all patients. RESULTS: Unlike normal controls, patients with DLSS had longer mean durations on both sides and lower F/M ratios on symptomatic side after the 10-minute walk test than before (P < 0.05). According to normal reference values from healthy subjects, a total of 129 (129/201, 64.2%) patients showed dynamic F-wave abnormalities. Preoperatively, these 129 patients had worse physical function according to both the SF-36 and ZCQ scores compared with the other patients (P < 0.05). Postoperatively, patients with dynamic F-wave abnormalities exhibited better patient satisfaction and greater improvements in physical function than did those without F-wave abnormalities. CONCLUSIONS: Comparisons of F-waves before and after the 10-minute walk test revealed clear dynamic F-wave abnormalities in patients with DLSS, even in those without neurogenic claudication. Equally important, the assessments of dynamic F-waves may offer additional insight into both the severity and postoperative outcomes, especially patient satisfaction, of DLSS.