Objective: The aim of this study is to identify the ipsilateral motor evoked potentials (iMEPs) from unaffected cerebral hemisphere after stroke via transcranial magnetic stimulation, especially in acute stage (within 1 week from attack), and to evaluate the characteristics of iMEPs compared with the crossed contralateral motor evoked potentials (cMEPs).

Method: Thirty patients were recruited, who had suffered their first ischemic stroke and consequent motor deficits and mean duration from attack to examination was 6.0⁑3.3 days. They were tested with round coil stimulator in order to record motor evoked potentials from both contralateral and ipsilateral abductor pollicis brevis (APB) muscles. For the purpose of hand motor cortex mapping, we designed specialized cap, which was marked using international 10∼20 systems by 1 cm interval. In addition, we observed the changes in onset latency and amplitude of MEPs during the isometric contraction of thenar muscle guided by visual and auditory feedback.

Results: iMEPs were generally absent in normal subjects, but they were obtained in 17 (56.7%) of 30 patients by stimulating the unaffected hemisphere. Different from contralateral MEPs, ipsilateral MEPs were obtained with higher stimulation intensity, significantly delayed latencies and lower amplitudes. And we noticed shorter latencies and larger amplitudes of MEPs by the isometric contraction of thenar muscle.

Conclusion: Our results will reflect the compensatory role by the unaffected cerebral hemisphere with respect to motor recovery, if contralateral route is damaged. We provided neurophysiologic evidences of cerebral neuroplasticity, proven by the ipsilateral unaffected hemispheric activation in early phase stroke patients.

Objective: To observe the ipsilateral upper limb function after stroke comparing proximal with distal part and to determine how they recover after stroke.

Method: Cohort study of 72 patients with stroke in the middle cerebral arterial territory undergoing multidisciplinary stroke rehabilitation program. The main outcome was assessed by the Manual Function Test (MFT) for upper limb function, weekly.

Results: The recovery time of the ipsilateral upper limb to maximum function was 32.4 ⁑ 15.4 days. The functions of the ipsilateral shoulder and hand after stroke decreased significantly. Even at the maximum recovery, complete recovery was not seen. For ipsilateral shoulder, more severe functional deficits were seen with subcortical lesion than with cortical lesion, whereas for ipsilateral hands, no difference was seen between them.

Conclusion: Therefore, the fact that recoveries of the shoulders and hands were different according to the presence of cerebral cortical or subcortical lesions suggests that the brain structures that control these areas or the recovery mechanisms might be different.

Objective: We observed the nature of ipsilateral weakness, not hemiplegic side after stroke. And we studied correlation between ipsilateral weakness and neurologic recovery of hemiplegia.

Method: This study was prospective, follow-up clinical trial. Ipsilateral motor power was checked serially in 20 subjects using Nicholas Manual Muscle Tester (NMMT) (shoulder abduction, wrist extension, hip flexion, ankle dorsiflexion). The subjects are first attacked hemiplegic stroke patients. Other outcome measures are Mini-mental Status Examination (MMSE) and National Institutes of Health Stroke Scale (NIHSS). We studied correlations between motor power recovery in ipsilateral limbs and recovery of neurologic impairment in hemiplegic limbs of stroke patients through SPSS 7.0 program.

Results: Ipsilateral motor power in early stage stroke patients is significantly low compared with that of normal subject except ankle dorsiflexion (p＜0.05). Comparing ipsilateral proximal with distal limbs power in pre and post multidisciplinary rehabilitation program, upper proximal part recovered faster than the distal part, but which was not statistically significant. Recovery of ipsilateral upper proximal and distal limb weakness is associated with neurologic recovery in hemiplegic side.

Conclusion: After the stroke, ipsilateral upper limb motor weakness does occur and which follows similar neurologic recovery pattern to the hemiplegic side. Ipsilateral cortical and subcortical tracts take effect on the neurologic recovery of contalateral side.

Objective: To identify the existence of ipsilateral responses by magnetic stimulation, and to elucidate the influences of ipsilateral tonic contraction on bilateral MEP responses, and to attain the proper facilitation technique for bilateral MEP responses.

Method: Ten normal healthy volunteers who were right handed, were recruited. They performed the voluntary contraction of thenar muscle via lateral prehension with three stage, contralateral, bilateral, ipsilateral contraction by 70 mm bipolar coil stimulator (figure-of-eight shaped). The excitability threshold (ET) at rest was determined, and then, three facilitation techniques with combination of both voluntary contraction and stimulus intensity were also performed: A technique, minimal facilitation (10% of MVC) with ET intensity; B technique, moderate facilitation (30% of MVC) with 110% of ET intensity; C technique, minimal facilitation (10% of MVC) with 140% of ET intensity. Contralateral, bilateral and ipsilateral voluntary contractions were performed in each technique. In 90 mm circular coil stimulator, same procedure as above was followed.

Results: There were no differences of ET between the two coil stimulators. Ipsilateral MEP responses were not detected after bipolar coil stimulation except one case in C technique, but they were developed over 70% in B and C technique with ipsilateral muscle contraction. However, only 2 cases of ipsilateal responses could be detected in C technique, and not detected in A and B technique. The latency of ipsilateral responses were similar to that of contralateral responses, but the amplitude was much lower than that of contralateral responses. Ipsilateral muscle contraction reduced the amplitude of contralateral MEP in moderate facilitation (B technique). Especially, ipsilateral response was never evoked in B technique with contralateral contraction.

Conclusion: In normal subjects, ipsilateral MEPs can't be obtained in focal magnetic stimulation. Ipsilateral tonic contractions are regarded as reducing facilitative effects of contralateral MEP responses. Bilateral responses should be attained when contralateral target muscle is contracted with moderate facilitation (30% of MVC and 110% of threshold intensity). In this facilitation, the stimulation by circular coil is no less effective than focal stimulation by 70 mm bipolar.

Objective: The objective of this study is to determine the effect of unilateral brain lesion on hand strength and dexterity of ipsilateral side in hemiplegic patients and the change of strength and dexterity of ipsilateral hand after rehabilitation according to the side of brain lesion.

Method: Sixty four hemiplegic patients with unilateral brain lesion underwent hand function tests for the ipsilateral hand to the brain lesion. Grip strength, tip pinch, lateral pinch, and palmar pinch strength were measured, and Purdue pegboard test was performed. Results were compared with a group of forty age-matched healthy volunteers.

Results: There was significant decrement of hand strength and dexterity of ipsilateral side except grip strength in patients with unilateral brain lesion in the begining of rehabilitation compared with the controls. Hand strength and dexterity of ipsilateral hand was significantly improved after rehabilitation. There was no significant difference in hand strength and dexterity of ipsilateral side according to the side of hemispheric lesion.

Conclusion: Ipsilateral upper extremity function in hemiplegic patients may also be affected adversely, and therefore rehabilitation treatment for ipsilateral upper extremity function should be involved.