Yuji Koyama

Premotor potential study in carpal tunnel syndrome

Introduction: Premotor potentials (PMPs) precede compound muscle action potentials evoked from the second lumbrical muscle after median nerve stimulation. Although PMP has been identified as a median sensory nerve action potential, few reports have documented the significance of PMP parameters for diagnosing carpal tunnel syndrome (CTS). Methods: We investigated the relationships between PMP parameters and results of 6 standard median nerve conduction studies in 74 CTS hands. Results: Significant correlations were noted in all comparisons. PMP conduction velocity was strongly correlated with the sensory conduction velocity between wrist and digit 2 (r2 = 0.91). Moreover, PMP parameters were significantly correlated with neurophysiological severity of CTS. Conclusion: Measuring PMP parameters with a second lumbrical–interosseous study may be useful for diagnosing CTS. Muscle Nerve, 2012

Effect of antagonistic voluntary contraction on motor responses in the forearm

OBJECTIVE We investigated the effects of voluntary contraction of agonist and antagonist muscles on motor evoked potentials (MEP) and on myoelectric activities in the target (agonist) muscle following transcranial magnetic stimulation (TMS). METHODS The left extensor carpi radialis (ECR) and flexor carpi radialis (FCR) muscles were studied in 16 healthy subjects. H reflexes, MEP induced by TMS, and background electromyographic (EMG) activity were recorded using surface electrodes at rest and during voluntary contraction of either agonist or antagonist muscles. RESULTS Voluntary contraction of antagonist muscles (at 10% of maximum contraction) enhanced the amplitudes of MEP for both muscles. The H reflex of the FCR muscle was inhibited by contraction (10% of maximum) of the ECR muscle. Background EMG activity did not differ between H-reflex trials and TMS trials. Enhancement of MEP amplitudes and background EMG activity during voluntary antagonist contraction was comparable in the two muscles. Appearance rate of MEP recorded by needle electrodes in response to subthreshold TMS was increased by antagonistic voluntary contraction. CONCLUSION Facilitation occurs during voluntary contraction of antagonist muscles. Differences between the effects of voluntary contraction of the ECR muscle for the MEP and the H reflex of the FCR suggest that cortical facilitatory spread occurs between agonist and antagonist muscles.

Effect of low-frequency repetitive transcranial magnetic stimulation combined with physical therapy on L-dopa-induced painful off-period dystonia in Parkinson's disease.

Previous research has shown that low-frequency repetitive transcranial magnetic stimulation over the primary motor area and supplementary motor area can reduce l-dopa-induced dyskinesias in Parkinsons disease; however, it involved only patients with peak-dose or diphasic dyskinesia. We report a case of a patient with severely painful off-period dystonia in the unilateral lower limb who underwent 0.9-Hz subthreshold repetitive transcranial magnetic stimulation over contralateral primary motor area and supplementary motor area. Repetitive transcranial magnetic stimulation over the primary motor area significantly reduced the painful dystonia and walking disturbances but repetitive transcranial magnetic stimulation over the supplementary motor area did not. The cortical silent period also prolonged after repetitive transcranial magnetic stimulation over the primary motor area. At 5 mos of approximately once a week repetitive transcranial magnetic stimulation over the primary motor area, the Unified Parkinsons Disease Rating Scale motor score also improved. This report shows that repetitive transcranial magnetic stimulation over the inhibitory primary motor area can be useful for rehabilitating patients with Parkinsons disease with off-period dystonia and suggests that this treatment should be further verified in such patients.

The nature of facilitation of leg muscle motor evoked potentials by knee flexion.

Knee flexion is a movement that initiates rising from a sitting position, which is a common therapeutic exercise for patients unable to ambulate. We investigated how voluntary isometric biceps femoris contraction affects motor evoked potential (MEP) amplitude following transcranial magnetic stimulation, background electromyographic (EMG) amplitude, and H-reflex amplitude in ipsilateral leg muscles. Subjects were seated on the edge of a bed with their hips and knees flexed at 90°, and the soles of their feet on the floor. MEP and background EMG were recorded from the tibialis anterior (TA) and soleus (SOL), and H reflexes from SOL of 30 volunteers. Background EMG and MEP also were recorded while voluntarily contracting tested muscles. Biceps femoris contraction increased MEP and background EMG for TA and SOL ( p < 0.01). Maximal background EMG and MEP increased with increasing voluntary contraction of tested muscles ( p < 0.005). Regression slope differed little between TA and SOL. Biceps femoris contraction facilitated MEP comparably for TA and SOL, while SOL background EMG exceeded that of TA ( p < 0.02). The relationship between MEP facilitation and background EMG changed to favor more efficient facilitation in TA ( p < 0.05), but not SOL ( p > 0.1). MEP recorded from TA and SOL with subthreshold stimuli using needle electrodes were more frequent with biceps femoris contraction ( p < 0.04). H-reflex amplitude of SOL decreased during biceps femoris contraction ( p < 0.001). We concluded that biceps femoris contraction affects leg muscle MEP, background EMG, and H reflexes differently.Knee flexion is a movement that initiates rising from a sitting position, which is a common therapeutic exercise for patients unable to ambulate. We investigated how voluntary isometric biceps femoris contraction affects motor evoked potential (MEP) amplitude following transcranial magnetic stimulation, background electromyographic (EMG) amplitude, and H-reflex amplitude in ipsilateral leg muscles. Subjects were seated on the edge of a bed with their hips and knees flexed at 90 degrees, and the soles of their feet on the floor. MEP and background EMG were recorded from the tibialis anterior (TA) and soleus (SOL), and H reflexes from SOL of 30 volunteers. Background EMG and MEP also were recorded while voluntarily contracting tested muscles. Biceps femoris contraction increased MEP and background EMG for TA and SOL (p < 0.01). Maximal background EMG and MEP increased with increasing voluntary contraction of tested muscles (p < 0.005). Regression slope differed little between TA and SOL. Biceps femoris contraction facilitated MEP comparably for TA and SOL, while SOL background EMG exceeded that of TA (p < 0.02). The relationship between MEP facilitation and background EMG changed to favor more efficient facilitation in TA (p < 0.05), but not SOL (p > 0.1). MEP recorded from TA and SOL with subthreshold stimuli using needle electrodes were more frequent with biceps femoris contraction (p < 0.04). H-reflex amplitude of SOL decreased during biceps femoris contraction (p < 0.001). We concluded that biceps femoris contraction affects leg muscle MEP, background EMG, and H reflexes differently.

Swallowing appliance: intraoral reshaping prosthesis for dysphagia secondary to oral floor cancer: a pilot study.

ABSTRACTPatients with oral floor cancer often have difficulty swallowing solid foods. The aim of this study was to improve the propulsion of solid foods using a swallowing appliance (SW-A). Subjects comprised three patients with oral floor cancer who had undergone curative surgery. Each participant was asked to swallow gelatin under three conditions: without an SW-A, with a maxillary SW-A, and with both maxillary and mandibular SW-As. This procedure was repeated thrice with three volumes of gelatin (2.5, 5, and 7.5 ml), with videofluorographic swallowing study. Swallowing was assessed on the basis of whether the participant could propel the gelatin from the oral cavity to the pharynx. No subject could propel 2.5 ml of gelatin to the pharynx without an SW-A or with only a maxillary SW-A in place. When both SW-As were used, all subjects could propel all three volumes of gelatin. The mandibular SW-A complemented the compensatory effects of the maxillary SW-A.

60. Changes in motor cortical excitability following electrical stimulation of the common peroneal nerve

acute sensory ataxia. The positive anti-Hu antibody suggested that he had anti-Hu-associated paraneoplastic subacute sensory neuropathy. The conventional nerve conduction studies and somatosensory evoked potentials revealed severe sensory neuropathy. For magnetic cerebellar stimulation, the test magnetic stimulus over the left primary motor cortex (M1) was preceded by the conditioning stimulus over the right cerebellum. Motor evoked potential was recorded from the right first dorsal interosseous muscle. The suppressive effect of magnetic cerebellar stimulation on the contralateral M1 was abnormally reduced. The results indicated that cerebellar efferent pathway or dentatothalamocortical pathway was involved in this patient, although cerebellar signs could not be evaluated due to severe sensory neuropathy. Magnetic cerebellar stimulation might be useful to reveal cerebellar dysfunction masked by coexisting sensory ataxia in patients with paraneoplastic sensory neuropathy.

P30-2 The origin of the premotor potential recorded from the second lumbrical (2): investigation in patient with carpal tunnel syndrome

Purpose: Recently, a premotor potential (PMP) recording from a second lumbrical muscle (2L) has been identified as a median sensory nerve action potential (SNAP), but the origin of that has remained uncertain. The purpose of this study was to investigate the latency of PMP-2L and the correlation with the latency of digital SNAP in patients with carpal tunnel syndrome (CTS). Methods: In 36 CTS hands, the PMP-2L was recorded with the palm active electrode following median nerve stimulation at the wrist. The median SNAPs activating antidromically from 1st, 2nd and 4th digits were also recorded, and the latencies of those were verified the correlations with the latency of PMP-2L. Results: PMP-2L could be recorded in 28 patients but no evoked in 8 patients. In severe affected CTS patients that the median SNAPs did not recorded in each digit, it was difficult to record with the PMP-2L either. The significant correlations with the latencies of all three digital SNAPs were observed. The correlation (R-square) with the SNAP recorded from 1st, 2nd and 4th digit was 0.65, 0.91 and 0.38 respectively. Conclusions: We considered that the origin of the PMP-2L is a nearfield SNAP arising from antidromically activated median 2nd digit sensory branch.

P30-1 The origin of the premotor potential recorded from the second lumbrical (1): in normal subject

Objective: To investigate the involvement of primary motor cortex (M1) while observing handwritten known or unknown letters using motor evoked potentials (MEPs) induced by transcranial magnetic stimulation (TMS). Methods: 11 right-handed healthy volunteers with written informed consents were involved. Hand written and block letter images of 30 characters were prepared as stimuli; 10 alphabets, 10 hiragana, and 10 kanji of daily use in Japan (Experiment 1). Arabic letters were used as a control condition of unknown letters (Experiment 2). Subjects look at a screen, where letter stimuli appear in a random order. MEPs were recorded from right FDI muscle, TMSs were given at the timing 100, 200, 300, 400 or 500 ms following each stimulus onset. Results: For handwritten condition, MEPs were significantly small at 300 and 400 ms in comparison to block-letter condition. The result was dependent on the subjects’ knowledge of letters. Conclusion: This result suggests the involvement of M1 hand area in the neural network associated with letter recognition.

114. A case of polyneuropathy with hypertrophic spinal radiculopathy mimicking neurofibromatosis

This report illustrate a case of polyneuropathy masquerading as neurofibromatosis due to multifocal enlargements of spinal nerve roots. The patient complained of numbness and pain of the hands and leg weakness from six years later at age 67, but could gait with cane independently and draw picture with intention tremor. Magnetic resonance imaging (MRI) T2 weighted image through cervical spine demonstrated C6-7 spinal cord compression bilaterally by cervical root tumors like neurofibromatosis and enlargements of spinal nerve roots and brachial, lumbosacral plexus of nerves. Nerve conduction studies were almost no evoked response but median nerve which demonstrated prolonged distal latency and reduced compound muscle action potential with temporal dispersion, suggesting a diagnosis of demyelinating neuropathy. Somatosensory evoked potential of the median nerve revealed prolonged latency, and motor evoked potentials obtained from abductor pollicis brevis, and abductor digiti minimi by transcranial magnetic stimulation have prolonged latency and temporal dispersion. Sural nerve biopsies showed segmental demyelination, remyelination, lymphocyte infiltration and onion-bulb formation, suggesting chronic inflammatory demyelinating polyneuropathy. The patient did not have family history and reject furthermore genetic study, we could not deny the possibility of hereditary hypertrophic neuropathy like Charcot– Marie–Tooth disease.