To assess the effect of motor imagery, as a rehabilitation method in stroke, on F-wave parameters that undergo changes during upper motor neuron involvement.
Twenty-one fully conscious hemiparetic stroke survivors with a completely plegic hand (power 0/5) and a minimum interval of 72 hours since stroke were recruited into this study. The mean F-wave latency, amplitude, and persistence in the median and ulnar nerves were measured in both the affected and non-affected sides at rest and in the paretic hand during a mental task. Comparison was made between data from the affected hand and the non-affected hand as well as between data from the affected hand at baseline and during motor imagery.
Patients had significantly different F-wave persistence between the affected and non-affected sides (paired t-test, p<0.001). Motor imagery could improve F-wave persistence in both the investigated nerves (paired t-test, p=0.01 for ulnar nerve and p<0.001 for median nerve) and F-response amplitude in the median nerve (paired t-test, p=0.01) of the affected limb.
The amplitude and persistence of F-wave were improved during motor imagery, representing F-wave facilitation. This result suggests that motor imagery can restore motor neuron excitability, which is depressed after stroke.
Citations
Objective: To estimate the motor unit numbers in normal adult hand muscles using manual incremental technique and F-wave technique.
Method: We estimated the motor unit numbers in abductor pollicis brevis muscles of twenty normal adults. In manual incremental technique, we estimated the motor unit numbers using motor unit count program setted in electrodiagnostic equipment (Dantec, Keypoint). In F-wave technique, we estimated the motor unit numbers dividing maximal M-potential amplitude by mean amplitude of surface motor unit action potential.
Results: There was no significant difference of motor unit numbers between right and left abductor pollicis brevis in both manual incremental and F-wave technique. Motor unit numbers using F-wave technique were significantly greater than motor unit numbers using manual incremental technique.
Conclusion: The difference of motor unit numbers using manual incremental technique and F-wave technique was considered as a difference of functional electrical stimulation. F-wave technique was more physiologic and functional method of motor unit numbers estimation than manual incremental technique.
Objective: To determine if stretching the sciatic nerve in control and patients with lumbosacral radiculopathy significantly alters F-wave parameters.
Method: We studied F-waves in the deep peroneal & posterior tibial nerves of 20 patients with unilateral lumbosacral radiculopathies and 22 controls. F-waves were recorded bilaterally in the neutral position and supine in 30o & 60o straight leg raising (SLR). F-wave parameters included minimal latency (F min), maximal latency (F max), mean latency (F mean), latency difference between F min and F max (chronodispersion), mean duration (F dur) and side to side difference in F min, F max, F mean and F dur.
Results: In controls, the F-wave latency was found to be longer in supine with SLR than in neutral position. In patients with lumbosacral radiculopathy, significant differences of F max, F mean and F dur between sides during 30o SLR were noted in the deep peroneal nerves, but all parameters in the posterior tibial nerves during SLR were not changed.
Conclusion: In this study, we observed significant changes in F-wave latency in control during straight leg raising, but no significant changes in patients with lumbosacral radiculopathy. For the clinical application to lumbosacral radiculopathy, further study is needed.
Objective: To explore the clinical value of postoperative follow-up examination of F-wave and H-reflex in patients with lumbosacral radiculopathy and to clarify optimal timing of follow-up examination.
Method: The subjects were 17 patients with unilateral lumbosacral radiculopathy caused by disc herniation. In patients with the L5 radiculopathy, F-waves were obtained from extensor digitorum brevis and six parameters including minimal latency per height were used. In patients with the S1 radiculopathy, H-reflexes were obtained from gastrocnemius and amplitude and minimal latency were used as parameters. These parameters were evaluated preoperatively and postoperatively at week 1, 3, 6. These changes of the parameters and clinical findings were related.
Results: The parameters of peroneal F-wave and tibial H-reflex showed significant improvement at 3 weeks and 6 weeks after surgery. The improvements of these parameters were not related with clinical improvement at 1 week after operation, but these were significantly related with improvement of pain and muscle weakness at 3 weeks after operation.
Conclusion: These findings suggested that follow-up examination of F-wave and H-reflex were valuable for objective assessment of lumbosacral radiculopathy after operation and the optimal timing for follow-up study was 3 weeks after operation.
Objective: The purpose of this study was to examine the sensitivity and characteristics of F-wave abnormalities detected by various parameters in patients with lumbosacral radiculopathies and to evaluate the relationship of F-wave with needle EMG.
Method: The study was performed on 37 patients with lumbosacral disc herniation, which was confirmed by MRI and the patients with clinical lumbosacral radiculopathies (single lesion of L5 in 28 cases, S1 in 1 case, double lesion of L5 and S1 in 8 cases). F-waves were recorded by stimulating peroneal and tibial nerves at the ankle. Minimal latency (F min), maximal latency (F max), latency difference between F min and F max (F dif), mean duration (F dur) and side to side difference between sides in F min and F max were measured. Conventional nerve conduction study and needle EMG were also examined.
Results: The abnormal parameters of F-wave were so varied that the results could not lead any apparent conclusions as to which parameters were the most sensitive. However, F min and F dur seemed to be abnormal more frequently than F max and F dif. While the needle EMG showed abnormalities in 28 patients (75.7%), at least one of the different F-wave parameters was found to be abnormal in 18 patients (48.6%). Moreover, no significant relationship was observed between the abnormal findings of EMG and F-wave (p＞0.05).
Conclusion: The conventional needle EMG appears to be the more useful electrophysiological technique in the diagnosis of lumbosacral radiculopathies. Concerning the additional usefulness of F-wave, further study will be necessary.
The F wave has been thought to be useful in assessing the proximal neuropathy such as radiculopathy. However the sensitivity of F wave in radiculopathy is varying from 18% to 65%. The aim of this study is to compare the relative diagnostic value of 20 averaging technique and 20 sequential stimulation technique in recording the F waves and to determine the usefulness of F wave for the evaluation of radiculopathy.
Animals employed were rabbits that were divided into a study group of 17 rabbits(31 legs) and control group of 14 rabbits(25 legs). In the study group, the sciatic nerve was exposed after the dissection of gluteus maximus muscle and the nerve trunk was traced up to reach the spinal canal level. One of the two nerve roots composing the sciatic nerve was dissected randomly. F wave parameters were measured using both of 20 averaging technique and 20 sequential stimulation technique.
The parameters which showed significant change after the root dissection were the amplitude by employing 20 electronic averaging technique, and mean latency, minimal latency, mean amplitude by employing 20 sequential stimulation technique.
We concluded that 20 electronic averaging technique had no benefit over the 20 sequential stimulation technique and F wave measurement was not useful for the electrodiagnosis of radiculopathy because of the wide range of control values.
It has been reported that the electrical stimulation of nerves can cause the changes of anterior horn cell excitability and conduction velocity of the nerves in vivo and vitro studies. The purpose of this study is to evaluate the electrophysiologic changes of the peripheral nerves near the spinal cord by the electrical stimulation. Subjects were 20 healthy volunteers, with the age of 21 to 27 years. The conditioning current was an interferential current of 10 Hz and 100 Hz with the maximal tolerable intensity (18∼20 mA). Conditioning stimulation was applied to the paraspinal area between T9 and T12 for 15 minutes. Before and after the conditioning stimulation, we measured the peripheral nerve conduction, H-reflex, F-wave, and somatosensory evoked potential (SEP) of the tibial nerve. The results after the conditioning revealed that the tibial motor and sensory conductions were unchanged but the latency of the H-reflex was significantly prolonged with a significant reduction of H amplitude and H/M ratio (p＜0.01). The latency, duration, and F-ratio of the F-wave were significantly increased and the amplitude of the F-wave was significantly reduced (p＜0.01). P1 latency was significantly prolonged in the cortical tibial SEP (p＜0.01). Change of N1P1 amplitude was not meaningful (p＞0.05). There was no statistical difference between the changes by a high or low frequency stimulation. These results suggest that a certain conditioned electrical stimulation of peripheral nerves near the spinal cord may cause the decrement of anterior horn cell excitability, and the inhibition of the alpha motor nerve and sensory nerve conductions near the spinal cord.
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