Journal of Neurology

, Volume 240, Issue 7, pp 427–429 | Cite as

The utility of F wave chronodispersion in lumbosacral radiculopathy

  • Samson Mebrahtu
  • Michael Rubin
Original Communications

Abstract

The sensitivity of F wave chronodispersion (Fc) in evaluating nerve root pathology is unknown. We compared Fc in 91 patients with clinical and EMG evidence of L5 or S1 radiculopathy with Fc in 81 controls in order to evaluate its sensitivity in lumbosacral radiculopathy. F waves were obtained by stimulating the peroneal and tibial nerves behind the knee and recording from the extensor digitorum brevis (L5 predominant) and flexor hallucis brevis (S1 predominant) muscles, respectively. Fc was calculated by subtracting the shortest F wave latency from the longest and, in controls, ranged from 0.2 to 23.4 ms in the peroneal nerve, and from 1.2 to 13.4 ms in the tibial nerve (95th percentile = 13 ms for the peroneal nerve and 9.2 ms for the tibial nerve). In the patient group, Fc also ranged from 0.2 to 23.4 ms in the peroneal nerve, and from 0.4 to 18.2 ms in the tibial nerve. Only 5 (5.5%) and 8 (11.3%) patients for the peroneal and tibial nerves, respectively, had Fc values which fell beyond the 95th percentile, a percentage far below the sensitivity of F wave latency measurement and not substantially different from chance. Thus we conclude that Fc has no substantial additional value in evaluating lumbosacral radiculopathy over that of F wave latency.

Key words

Electromyography Lumbosacral radiculopathy F wave F chronodispersion 

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Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • Samson Mebrahtu
    • 1
  • Michael Rubin
    • 1
  1. 1.Department of Neurology, Division of Clinical Neurophysiology (EMG)Hospital for Special Surgery and The New York Hospital-Cornell Medical CenterNewYorkUSA

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