EVALUATION OF LATE RESPONSE INDICES IN PATIENTS WITH LUMBOSACRAL RADICULOPATHY

Abstract

Background: Lumbosacral radiculopathy arises from compression or irritation of spinal nerve roots from L1 to S5. Diagnosis typically combines clinical evaluation, imaging, and electrodiagnosis. F-waves and H-reflexes-late responses in nerve conduction studies-offer functional insight into nerve-root integrity. Objectives: To assess the relationship between F-wave and H-reflex parameters and the severity of nerve-root compression on lumbosacral MRI. Subjects and Methods: In this cross-sectional study, 41 patients with MRI-confirmed lumbosacral nerve-root compression underwent nerve-conduction studies, F-wave, and H-reflex testing at the EMG Laboratory, Department of Functional Exploration, Hue University Hospital from April to December 2023. Results: Patients aged 40-59 years comprised 65.9% of the cohort. Degenerative disc disease accounted for 88.5% of compressive lesions. The L5 root was most frequently involved (40.4%), predominantly at grade 3 compression. The Fmax and Fmean wave indices exhibited significant differences according to the degree of nerve root compression observed on magnetic resonance imaging (p < 0.05). The latency and amplitude of the H-wave were prolonged and reduced, respectively, in relation to the severity of compression on lumbar–sacral MRI (p < 0.05). Conclusions: Late response indices may serve as supportive electrophysiological indicators in the assessment of lumbosacral nerve-root compression, although their diagnostic reliability remains limited.