Identifying lumbosacral radiculopathies - An optimal electromyographic screen

Objective: The objective of this study was to determine prospectively the o ptimal electromyographic screening examination of the lower limb that ensur es identification of those lumbosacral radiculopathies that can be electrod iagnostically confirmed, yet minimizes the number of muscles studied. Design: A prospective multicenter study was conducted from May 1996 to Sept ember 1997, Patients with suspected lumbosacral radiculopathy referred to p articipating electrodiagnostic laboratories were recruited and examined by needle electromyography using a standard set of muscles. Patients with elec trodiagnostically confirmed lumbosacral radiculopathies were selected for a nalysis. Various muscle screens were tested against this group of patients with radiculopathies to determine the frequency with which each screen iden tified the patient with radiculopathy. Results: There were 102 patients identified. When paraspinal muscles were o ne of the screening muscles, four-muscle screens identified 88-97% of the r adiculopathies, five-muscle screens identified 94-98%, and six-muscle scree ns 98-100%, When paraspinal muscles were not part of the screen, identifica tion rates were lower for all screens, and eight distal muscles were necess ary to identify about 90% of the radiculopathies. Conclusions: Six-muscle screens with paraspinal muscles yielded consistentl y high identification rates. Studying additional muscles produced no improv ements in identification.