LUMBOSACRAL RADICULOPATHY SCREEN - OPTIMIZING THE NUMBER OF MUSCLES STUDIED

The literature is unclear as to which muscles and how many are require d for a sensitive lumbosacral radiculopathy (LSR) screen. A retrospect ive study of 247 electrodiagnostically confirmed LSRs in 201 patients over a 3-yr period was conducted to determine how many muscles were re quired to identify a LSR. All LSRs showed abnormal spontaneous activit y (positive waves or fibrillation potentials) in two or more muscles i nnervated by the same nerve root level but different peripheral nerves . All cases were categorized by radiculopathy level, and the most freq uently abnormal individual muscles were combined into different muscle screens. The frequency with which each muscle screen identified a rad iculopathy was the frequency with which one or more muscles in the scr een displayed abnormal spontaneous activity divided by the total numbe r of radiculopathies. The paraspinal muscles (PM) alone identified 88% of LSRs. Without PM, two muscle screens identified only 14-68%, three muscle screens identified 37-89% and four muscle screens identified 4 5-92%. Including PM, three muscle screens identified 86-94% of LSRs, f our muscle screens identified 91-97% and five muscle screens yielded 9 4-98% identification. Seven to ten muscle screens resulted in minimal improvements in identifying a LSR with 98-99% identification. We concl ude that five muscle LSR screens, including PM, are sufficient to iden tify LSRs while minimizing patient discomfort and examiner time.