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Objective To explore the resonant frequencies of human spinal motor neurons.Methods Twenty healthy college students were recruited as the subjects.Each was put in a supine position and administered vibratory stimulation at 20 Hz,30 Hz,40 Hz,50 Hz and 60 Hz on the left distal fibula just above the lateral malleolus for 5 minutes.M-waves and F-waves were recorded before each intervention.F-waves were also recorded immediately after each intervention.Results The F-wave amplitude and the F/Mmax ratio after the 30 Hz stimulation were significantly larger than those at baseline and after stimulation at 50 or 60 Hz.However,20 Hz,30 Hz and 40 Hz stimulation produced no significantly different F-wave amplitudes or F/Mmax.Conclusion Human spinal motor neurons may have a resonant frequency around 30 Hz.
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Objective To investigate the value of nerve conduction studies (NCSs),F wave analysis,somatosensory evoked potential (SEP) and skin sympathetic response (SSR) in the early diagnosis of diabetic peripheral neuropathy (DPN).Methods A total of 110 patients with diabetes mellitus were recruited as the diabetic group and another 50 well-matched healthy volunteers as the normal controls.Sensory and motor NCSs of the median,ulnar,posterior tibial and common peroneal nerves were performed.F waves were recorded from the median and posterior tibial nerves.SEPs elicited by stimulation to nerves of both the upper and lower limbs as well as SSRs were measured,all in both the diabetic group and the normal controls.Results The total rate of nerve conduction abnormality was 74.5％ in the diabetic group,with sensory nerve conduction abnormalities more frequent and more severe among motor nerves in the extremities.The total rate of F wave abnormalities was 57.3％ in the diabetic group.The rate in patients with normal distal motor conduction in their median and posterior tibial nerves was 50.7％.The total SEP abnormality rate was 70.0％ with regard to the proximal peripheral nerve potentials in the diabetic group,but there was no obvious abnormality of the supraclavicular electrical potential in the upper limbs for those with normal sensory nerve conduction in the median nerve.The rate of occurrence of abnormality in the gluteus point potential in the lower limbs of those with normal posterior tibial sensory conduction was 62.5％.The total rate of SSR abnormalities was 80.0％ in the diabetic group but 72％ among those with normal nerve conduction in their extremities.Combining the NCS,SSR,SEP and F wave results,the total abnormality rate was 90.9％ in the diabetic group,which was much higher than with any single test used alone.Conclusion NCS is essential for diagnosing DPN.Early diagnosis of subclinical diabetic neuropathy will be significantly enhanced when nerve conduction,SSRs,SEPs and F waves are tested together.
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Objective To explore a new electrodiagnostic approach using the H reflex elicited by magnetic stimulation of the S1 nerve root and F waves to evaluate sensory nerve root function in patients with S1 radiculopathy.Methods Thirty normal subjects and 30 patients with unilateral S1 radiculopathy were recruited in this study.H reflex and M response were recorded from the bilateral soleus of all the subjects by magnetic stimulation of S1 nerve roots.F and M wave responses elicited by electrical stimulation of bilateral tibial nerves at the popliteal fossa were also recorded.The sensory root conduction time (SRCT) was calculated.Correlations of age and body height with SRCT in the healthy subjects,and between SRCT and pain in the patients with S1 radiculopathy were analyzed.Results The mean values of normal subjects were 3.10 ± 0.44 ms for SRCT,and 0.13 ± 0.19 ms for inter-side SRCT differences.In the 30 patients with S1 radiculopathy,H reflex could not be elicited from 4 patients.Among the remaining patients,the SRCT of the affected side was prolonged significantly (3.90 ±0.65 ms),and the mean value of the inter-side difference increased significantly (0.90 ±0.50 ms).A regression equation correlating SRCT with height was developed,but no significant correlation between SRCT and age in the normal subjects was revealed.There was positive correlation between SRCT and the severity of pain among the patients.Conclusion SRCT can be used as a new electrodiagnostic index in estimating sensory nerve root function in patients with S1 radiculopathy.
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OBJECTIVE: To investigate the effect of distant muscle contraction on the sensory and motor nerve conduction and F-wave studies. METHOD: During isometric contraction (10%, 25% and 50% of maximal voluntary contraction) of dominant hand using hand held dynamometer, sensory nerve action potentials (SNAPs), compound muscle action potentials (CMAPs) and F-waves were examined on contralateral upper and ipsilateral lower extremities in 20 healthy adult subjects. SNAPs of median and sural nerves, CMAPs and F-waves of median and tibial nerves were recorded with submaximal and supramaximal intensity stimulation. RESULTS: At submaximal stimulation the amplitudes and areas of median and sural SNAPs and median nerve CMAPs were significantly increased during distant muscle contraction (p<0.05). Distant muscle contraction did not effect on the parameters of SNAPs and CMAPs at supramaximal stimulation. The latencies of F-waves were significantly shortened and amplitudes of F-waves were increased during distant muscle contraction (p<0.05). Especially the amplitudes of F-waves were significantly positive correlated with the level of muscle contraction (p<0.05). CONCLUSION: SNAPs and CMAP were augmented by the distant muscle contraction only submaximal stimulation. Due to facilitation, the distant muscle contraction should be considered during routine F-wave studies.