The lumbosacral electromyographic screen: revisiting a classic paper

Objective: Knutsson (Acta Orthopaed Scand (1961) 1) published a classic thesis comparing lower limb electromyography (EMG) results with intra-operative findings for 206 patients with sciatica. This unique and detailed work presented a rare opportunity to again use this data and determine the optimal number of muscles in a screening examination; a different study aim to that of the original investigator. Methods: Data from Knutsson (1961) were used to determine the identification rates and sensitivities with respect to clinical and intra-operative diagnostic standards, for various muscle screens. Results: Selected 4 muscle EMG screens identified over 97% of EMG confirmed radiculopathies and over 89% of surgically confirmed radiculopathies. Conclusions: These findings underscore the utility of 4 muscle EMG screens in the evaluation of patients with suspected lumbosacral radiculopathy.