CLINICAL-VALUE OF F-WAVE RECORDINGS IN TRAUMATIC CERVICAL SPINAL-CORDINJURY

F-waves and motor/sensory nerve conduction (NCS) of the median and uln ar nerves were examined in 66 patients with traumatic motoneurone lesi on due to acute and chronic cervical spinal cord injury (SCI). The exa minations were performed in parallel in chronic tetraplegics once and in acute tetraplegic patients monthly for the first 3 months, after 6 months and 1 year post-trauma. A pathological reduction of the compoun d muscle action potential (CMAP) (in 10% even a complete loss of the C h?AP) was present in about 50% of the patients. The mean CMAP values o f tetraplegic patients with either acute or chronic SCI were significa ntly (P < 0.001) reduced compared to normal subjects. Because sensory nerve conduction in these patients was normal, the reduction of CMAP s hould be due to damage of intramedullar motoneurones or anterior nerve roots. While in all chronic SCI patients with preserved CMAP F-waves could be elicited, 50% of the acute SCI patients showed a complete los s of F-waves of both nerves during the initial examination due to spin al shock. After 6 months all acute SCI patients with preserved motor p otentials regained F-waves. Therefore, the excitability of F-waves is influenced by spinal shock in acute SCI. The mean F-wave latencies (Fm in-response, Fmin-M response) revealed no significant difference betwe en healthy subjects and SCI patients. However, the frequency of F-wave production was related to the severity of the motoneurone lesion. Fur thermore, while the F-wave latencies and CMAP values did not change si gnificantly with time after acute SCI, the frequency of F-wave product ion increased, but remained reduced compared to normal subjects. (C) 1 997 Elsevier Science Ireland Ltd.