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Dive into the research topics where Hideki Morita is active.

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Featured researches published by Hideki Morita.


Electroencephalography and Clinical Neurophysiology\/electromyography and Motor Control | 1996

The effect of current direction induced by transcranial magnetic stimulation on the corticospinal excitability in human brain

Kazuo Kaneko; Shinya Kawai; Yasunori Fuchigami; Hideki Morita; Akira Ofuji

Evoked spinal cord potentials (ESCPs) from the cervical epidural space and motor evoked potentials (MEPs) from the hand muscles were recorded simultaneously in 6 subjects following transcranial magnetic stimulation in two different coil orientations on motor cortex. The onset latency of the MEPs was approximately 1 ms shorter when the induced current flowed in a latero-medial direction (L-M stimulation) on the motor cortex as compared to a postero-anterior direction (P-A stimulation). Hence, L-M stimulation elicited an earlier component of the ESCPs than that induced by P-A stimulation. During general anesthesia with Sevoflurane, only the first component of the ESCPs could be elicited routinely following L-M stimulation. In contrast, all components of the ESCPs were dramatically attenuated following P-A stimulation. Moreover, first component latency of the ESCPs induced by L-M stimulation was almost the same as that induced by transcranial anodal electrical stimulation. These results suggest that if the induced current following transcranial magnetic stimulation flows in a latero-medial direction on motor cortex, it preferentially stimulates the corticospinal tract non-synaptically (producing a D-wave). However, if the induced current flows in a postero-anterior direction, it preferentially stimulates the corticospinal tract trans-synaptically (producing I-waves). Therefore, the direction of magnetically induced current is crucial in determining corticospinal excitability in the human brain.


Clinical Neurophysiology | 2001

Mechanism of prolonged central motor conduction time in compressive cervical myelopathy.

Kazuo Kaneko; Toshihiko Taguchi; Hideki Morita; Hiroshi Yonemura; Hideaki Fujimoto; Shinya Kawai

OBJECTIVE To investigate the mechanism of prolonged central motor conduction time (CMCT) in compressive cervical myelopathy, we compared the calculated CMCT following transcranial magnetic stimulation (TCM) and evoked spinal cord potentials (ESCPs) following transcranial electric stimulation (TCE). METHOD Motor evoked potentials following TCM were recorded from abductor digiti minimi and abductor hallucis brevis muscles in 16 patients with compressive cervical myelopathy. CMCT was calculated by subtracting peripheral conduction time using peripheral nerve stimulation from MEP latency. ESCPs following TCE were recorded intraoperatively from posterior epidural space. RESULTS CMCT was prolonged and significant attenuation of the ESCP amplitude following TCE was observed in all patients with cervical myelopathy. In 8 of 16 patients CMCT was significantly prolonged but ESCPs were recorded at the C6-7 level with normal negative peak latency. CONCLUSIONS Prolonged CMCT may occur with only a minor amount of conduction slowing in the corticospinal tract in compressive cervical myelopathy. Impaired temporal summation of multiple descending potentials following TCM produced delays of motor neuron firing that contribute to the mechanism of prolonged CMCT.


Muscle & Nerve | 1997

Cutaneous silent period in syringomyelia

Kazuo Kaneko; Shinya Kawai; Yasunori Fuchigami; Hideki Morita; Akira Ofuji

Painful cutaneous nerve stimulation can suppress measured. F waves over 100 mV in peak-to-peak amplitude were considered significant. electromyographic activity in voluntarily contracting muscle.3–5,10,11 This phenomenon is designated the cuMotor evoked potentials (MEPs) following transcranial magnetic stimulation were recorded from the taneous silent period (CSP). In the present study we investigated a clinical application of CSP in syringoAPB during 30% of maximal contraction. The center of a round coil 14 cm in diameter (Magstim, Whitmyelia associated with Chiari I malformation, where the loss of pain sensation is the most common early land, UK, Model 200) was held over the vertex. Induced current was applied to target motor cortex in neurologic sign.7,8 a posteroanterior direction. The stimulus intensity was set at 30% above the threshold of the MEPs. MATERIALS AND METHODS Somatosensory evoked potentials (SSEPs) followFive male patients (mean age 18 years) with cervical ing median nerve stimulation at the wrist were resyringomyelia were studied. Dysesthesias and recorded. Spinal responses were recorded with active duced pain sensation were the only symptoms in all electrodes placed over the spinous process of the patients. Fifteen healthy subjects (12 men, 3 women; sixth cervical vertebra (Cv6) and reference electrodes mean age, 32 years) were studied as controls. The placed above the thyroid cartilage.9 Peripheral nerve experimental procedure was explained and informed potentials from Erb’s point were recorded with the consent was obtained. same reference. Cortical responses were recorded Several CSPs following index finger stimulation from the parietal scalp with both ears connected as were recorded from the abductor pollicis brevis a reference (A1 1 A2). (APB) using self-adhesive electrodes over the belly All potentials except for SSEPs were recorded and tendon. Electrical stimuli were applied randomly with a bandpass filter between 20 Hz and 5 kHz. from ring electrodes using 0.5 ms square pulses at 10 SSEPs were filtered between 20 Hz and 3 kHz. The times the sensory threshold. The degree of isometric parameters of all the responses were expressed as contraction was maintained at about 30% of maximean 6 SD. mum using an audiovisual biofeedback system. From sagittal and axial T1and T2-weighted magCompound muscle action potentials (CMAPs) netic resonance imaging (MRI), the location and and F waves following supramaximal stimulation to laterality of the syrinxes was confirmed. the median nerve at the wrist were recorded. Onset latency and baseline-to-negative peak amplitude of RESULTS CMAPs were measured. The persistence and shortest latency for F waves among 20 responses also were Controls. The onset and duration of CSPs were 74.7 6 8.1 ms and 44.9 6 10.6 ms, respectively. CMAPs latency and amplitude were 3.5 6 0.3 ms and 7.2 6 2.8 mV, respectively. F-wave latency was 26.8 6 2.2 ms with 40.3 6 10.5% persistence. MEPs *Correspondence to: Dr. K. Kaneko latency and amplitude (peak-to-peak) were 19.5 6 CCC 0148-639X/97/070884-03  1997 John Wiley & Sons, Inc. 1.5 ms and 4.0 6 2.5 mV, respectively. For SSEPs,


Journal of the Neurological Sciences | 1998

Correlation between spinal cord compression and abnormal patterns of median nerve somatosensory evoked potentials in compressive cervical myelopathy: comparison of surface and epidurally recorded responses.

Kazuo Kaneko; Shinya Kawai; Toshihiko Taguchi; Yasunori Fuchigami; Takashi Ito; Hideki Morita

To investigate the correlation between the level of spinal cord lesion and the abnormal pattern of median nerve somatosensory evoked potentials (SSEPs), evoked spinal cord potentials (ESCPs) were also recorded from the posterior epidural space intraoperatively in 18 patients with compressive cervical myelopathy. Levels of symptomatic spinal cord compression were determined by ESCP findings. Spinal N13 potential of the SSEPs was recorded from the surface of the posterior neck with anterior neck reference. Brainstem P14 and cortical N20 potential were recorded from the parietal scalp contralateral to the stimulated side. Spinal N13, P14, and N20 potentials were all normal when the ESCPs were abnormal at localized segmental region (C4-5 or C5-6 level alone). Spinal N13 potential was significantly attenuated in all of patients with abnormal ESCP findings at widespread segmental area of the median nerve territory. In four of these seven patients, brainstem P14 potential was also prolonged or diminished, but three patients showed normal P14 and N20 potentials. Isolated P14 abnormality with normal spinal N13 potential was characteristic in patients with abnormal ESCP at the C3-4 lesion. Although sensitivity of abnormal ESCP was higher than that of the SSEPs, abnormal patterns of spinal N13, P14 and N20 potentials following median nerve stimulation were useful in detecting not only the pathology (posterior horn and/or posterior column) but also symptomatic spinal compression level in compressive cervical myelopathy.


Journal of the Neurological Sciences | 1998

New method to measure central motor conduction time using transcranial magnetic stimulation and T-response

Akira Ofuji; Kazuo Kaneko; Toshihiko Taguchi; Yasunori Fuchigami; Hideki Morita; Shinya Kawai

Measuring central motor conduction time (CMCT) is one of the useful methods to detect an impaired level of the spinal segment in cervical myelopathy patients. We modified a new technique to calculate the CMCT using tendon reflex latency (T-response) and investigated its accuracy. Motor-evoked potentials (MEPs) following transcranial stimulation were recorded in 19 patients with cervical myelopathy caused by a single level of spinal cord compression. CMCT was measured by subtracting the peripheral conduction time, which was calculated by using the T-response for the biceps brachii muscle (Biceps), the compound muscle action potentials (CMAPs) and the F-wave of the abductor digiti minimi muscle (ADM). In the control subjects, the mean value of CMCT of the Biceps and ADM was 3.8 and 7.0 ms, respectively. The accuracy of the determination of the CMCT for Biceps using T-response was investigated beforehand in the unilateral brachial plexus palsy patients and thoracic spinal cord myelopathy patients. The calculated CMCT (3.88+/-0.65 ms) for Biceps was close to the N2 latency (4.06+/-0.3 ms) of the evoked spinal cord potentials which were recorded from the epidural space on the C3-4 vertebral level following transcranial magnetic stimulation. The CMCT of both the Biceps and ADM was delayed in all cases of C1-2 cord compression. In patients with cord compression on the C3-4 level, two of four patients showed CMCT prolongation in Biceps. The prolongation of CMCT was observed only in ADM in patients with C4-5 or C5-6 cord compression. Measurement of the CMCT using T-responses was useful in proximal limb muscles. Comparison of the CMCT in Biceps and ADM could allow us to better detect the functional level diagnosis for compressive cervical myelopathy.


Journal of the Neurological Sciences | 1997

Effect of coil position and stimulus intensity in transcranial magnetic stimulation on human brain

Kazuo Kaneko; Yasunori Fuchigami; Hideki Morita; Akira Ofuji; Shinya Kawai

Evoked spinal cord potentials (ESCPs) from the cervical and high thoracic epidural space following transcranial magnetic stimulation were recorded from eight subjects in awake and anesthetized condition. Motor evoked potentials (MEPs) from the right abductor digiti minimi (ADM) and rectus femoris (RF) muscles were simultaneously recorded during voluntary contraction. The stimulus intensity was at 30% above the MEPs threshold of the ADM when the coil center was fixed on 10-20 international Cz position. In awake condition, multiple ESCP components (greater than 3) were recorded from the cervical epidural space but no or minimal components were recorded from the upper thoracic epidural space. When the coil was moved anteriorly so that the posterior edge of the coil was positioned on Cz, the amplitude of the first ESCP component was significantly increased (P < 0.02) and shortened (not significant) at cervical levels. In addition, several ESCP components were more evident at high thoracic levels. Although the amplitude of the ADM was not enhanced, that of the RF was enhanced. During general anesthesia with volatile anesthetics (sevoflurane), only the first component of the ESCPs (D-wave) was elicited. Its amplitude was enhanced (P < 0.02) when the coil edge was fixed on Cz, similar to results in awake condition. This enhancement of the first ESCP component was accompanied by enhancement of those recorded from the high thoracic epidural space. However the amplitude of D-wave was the same in the two different coil positions when the stimulus intensity was set a 100% of the output. These results suggest that at low stimulus intensity, positioning the coil edge on Cz is optimal in inducing D-wave effectively but at high stimulus intensity, D-wave generation can be achieved in either if the two different coil position.


Journal of the Neurological Sciences | 1997

Spatial distribution of corticospinal potentials following transcranial electric and magnetic stimulation in human spinal cord

Kazuo Kaneko; Shinya Kawai; Toshihiko Taguchi; Yasunori Fuchigami; Hideki Morita; Akira Ofuji; Hiroshi Yonemura

To investigate the spatial distribution of the human corticospinal tract in the spinal cord, evoked spinal cord potentials (ESCPs) following transcranial electrical and magnetic stimulation were recorded simultaneously from both the anterior and posterior epidural space in five anesthetized patients. One ESCP component following transcranial electrical stimulation (D-wave) and at least two ESCP components (initially D-wave and later I-wave) following transcranial magnetic stimulation were recorded in all subjects. The negative peak latency of all the potentials recorded from the posterior epidural space was the same as that recorded anteriorly. The amplitude ratio of the ESCP following electrical stimulation (posterior/anterior) was 1.10+/-0.12, while that of ESCPs following magnetic stimulation was 1.08+/-0.12 (N1) and 1.15+/-0.16 (N2). These results suggest that lateral corticospinal tract descending dorsolateral fasciculus in the spinal cord is main corticospinal pathway and spatial distribution of D and I-waves are similar in the human cervical cord.


Orthopaedics and Traumatology | 2000

Iatrogenic Accessory Nerve Injury Report of Two Cases

Hironobu Yamasaki; Akira Matsuoka; Tosikatsu Tominaga; Yosihiko Kunishi; Hisashi Yamamoto; Tooru Okumura; Seiji Tsuchida; Hideki Morita; Yosikazu Seki


Orthopaedics and Traumatology | 1998

Microsurgical Reconstruction in the Elderly

Yukio Abe; Kouzou Sunago; Takashi Itoh; Eiichi Shiigi; Hideki Morita


Orthopaedics and Traumatology | 1998

Functional Recovery after Surgery for Unstable Distal Radial Fractures

Yukio Abe; Kouzou Sunago; Takashi Itoh; Eiichi Shiigi; Hideki Morita

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