F-Wave Studies in L5 Radiculopathic Patients Receiving Automated Percutaneous Lumbar Disectomy

Background and purpose: Herniated intervertebral disc with radiculopathy may prolong F-latency and reduce F-persistence. The aim of this study was to investigate changes of F-waves in patients with L5 radiculopathy before and after automated percutaneous lumbar disectomy (APLD). Methods: Eight patients (aged 26 to 39 years) with L5 radiculopathy were recruited. The L5 radiculopathy was diagnosed by radicular pain and motor/sensory deficit and was confirmed by MRI. F-latency and persistence of the deep peroneal nerve were measured before and after APLD. To enhance the F-wave response, a stimulus duration of 0.3 ms was used, and patients were asked to contract the masseter muscles. Results: The F-persistence showed a significant increase (p ＜ 0.05) after APLD (42.5% ± 11.7% and 66.3 % ± 10.6% before and after APLD, respectively). The F-latencies of the deep peroneal nerve showed a decreasing trend after APLD (46.19 ± 3.58 ms and 44.76 ± 2.69 ms before and after APLD, respectively). The increase of F-persistence may be explained by increased nerve excitability after APLD. F-latency may lack the sensitivity to show the change after APLD because F-latency possibly reflects only a small portion of motor neuron fibers affected. Conclusions: We conclude that F-persistence is more sensitive than F-latency in monitoring nerve root decompression after APLD. Understanding the role of F-persistence in evaluating the nerve root condition requires further study.