No abstract available.
Evoked Potentials, Motor* ; Stroke*

No abstract available.
Evoked Potentials, Motor* ; Paresis*

No abstract available.
Evoked Potentials, Motor*

No abstract available.
Animals ; Evoked Potentials, Motor* ; Rats*

OBJECTIVE: The purpose of our study is to evaluate the success rate and feasibility of intraoperative neuromonitoring (IONM) focusing on transcranial motor evoked potential (TcMEP) monitoring for patients with preoperative motor weakness in spine surgery. METHODS: Between November 2011 and December 2013, TcMEP and somatosensory evoked potential (SSEP) monitoring were attempted in 130 consecutive patients undergoing spine surgeries for cervical or thoracic cord lesions. Patients ranged in age from 14 to 81 years (mean±standard deviation, 56.7±14.8 years), and 84 patients were male. The success rates of both SSEP and MEPs monitoring were assessed according to the preoperative Medical Research Council (MRC) and Nurick grades. RESULTS: TcMEP was recorded successfully in 0%, 28.6%, 72.3%, and 100% of patients with MRC grades 1, 2, 3, 4, and 5, respectively. SSEP was obtained from 0%, 37.5%, 21.5%, 61.4%, and 85.4% of patients with MRC grades 1, 2, 3, 4, and 5, respectively. TcMEP was recorded successfully in 84% of patients with Nurick grades 1-3 and 26% of patients with Nurick grades 4-5. SSEPs were recorded successfully in 76.3% of patients with Nurick grades 1-3 and 24% of patients with grades 4-5. CONCLUSION: IONM during spine surgery may be useless in patients with MRC grades 1-2, applicable MRC grade 3, and useful MRC grades 4-5. MRC grade 3 is a critical point of indication for application of MEPs. In unmonitorable cases with MRC grade 3, increasing stimulus intensity or facilitation techniques may be considered to improve the usefulness of TcMEP.
Evoked Potentials, Motor ; Evoked Potentials, Somatosensory ; Humans ; Male ; Spine*

This study was undertaken to evaluate the clinical usefulness of magnetic motor evoked potential (MEP) in the diagnosis of stroke and predicting the motor improvement following stroke. The cortical, cervical and lumbar stimulations were performed in the case of 24 healthy controls and 24 to a target muscle between after transcranial stimulation and after cervical or lumbar stimulation. There was no case showing no response in controls. But in 11 out of 24 ischemic patients, we could not get cortical MEP. Mean CMCT of abductor pollicis brevis muscle was not significantly different in controls and stroke patients in whom MEPs were recorded. There were significant differences between mean CMCT of normal controls and that of stroke patients showing MEPs in AH Muscle. MEP Results from testing the stroke patients were correlated with site of lesion, degree of motor weakness and motor improvement after 1 to 2 months. These results suggest that magnetic MEP is easy and useful in electrophysiological test of central motor pathway and is useful indicator for representing the motor weakness and predicting the motor outcome in acute ischemic stroke patients.
Diagnosis ; Evoked Potentials, Motor* ; Humans ; Stroke*

Motor evoked potentials (MEP) were elicited with transcranial cortical stimulation using a magnetic coil in 33 normal subjects and 12 ischemic stroke patients with variable degree of motor weakness. Significant side effects or pain were not encountered. Normal thenar and tibialis anterior (TA) MEP latency measured 20.9+1.4msec and 29.3+1.9msec respectively. Thenar latency correlated with arm length more than height and TA latency correlated with height. The variability of MEP amplitude was great but thenar MEP amplitude exceeded 11% of the maximum thenar M wave. Thenar and TA MEP were evoked in all uninvolved site of ischemic stroke patients to contralateral cortical stimulation. No potentials were noted in involved site of 6 among 12 patients studied thenar MEP and 5 among 7 patients studied TA MEP and their motor powers were lower than those with elicited MEP. All involved site with motor power grade 2 or less in arm and grade 3 or less in leg elicited no potential. These findings suggest that the MEP is very sensitive to ischemic injury.
Arm ; Evoked Potentials, Motor* ; Humans ; Leg ; Stroke*

Evoked Potentials, Motor ; Humans ; Spine ; surgery

OBJECTIVES: To analyze the motor evoked potential (MEP) responses to a degree of voluntary contraction and stimulus intensity and to suggest the standardized optimal stimulation for MEP responses. METHODS: MEPs induced by a cortical stimulation were elicited at the thenar muscles in 15 normal subjects during the rest and gradual voluntary contraction, using the 10% of maximal voluntary contraction (MVC), 30%, 50%, and MVC. During rest and during each contraction, excitability threshold at rest (RET) and at contraction (CET) were determined. Consecutive stimuli were applied, according to the intensity of ratio increment (110% to 150% of excitation threshold). RESULTS: The RET showed a remarkable decrease (57.1+/-8.2% --> 47.4+/-8.7%) after the voluntary contraction (P<0.05). Shortening of latency reached the saturation level with 10% of MVC, irrespective of stimulus intensity. Amplitude reached a saturation level at 30% of MVC with 62.7% intensity of maximal output, which is equal to 140% intensity of its CET, and to 110% of RET. MEP amplitude at rest and at 10% of MVC were influenced by the excitation threshold (P<0.05), but those at above 30% of MVC were not related. CONCLUSION: The procedure for optimal facilitation for the MEPs is as follows; for minimal latency of MEPs, minimal contraction (10% of MVC) with RET intensity is enough. For maximal amplitude of MEPs, moderate contraction (30% MVC) with 110% intensity of RET is adequate.
Evoked Potentials, Motor ; Muscles ; Transcranial Magnetic Stimulation*

No abstract available.
Animals ; Evoked Potentials, Motor* ; Rats* ; Spinal Cord*