RESEARCH REPORT POSTER DISPLAY

VALIDATING THE RELATIONSHIP BETWEEN THE SOMATOSENSORY EVOKED POTENTIALS AND RECOVERY OF SENSATION AND MOTOR ABILITY IN STROKE PATIENTS. Shiratani T¹, Murakami T², Arai M³, Shimizu M⁴, Shimizu H², Yanagisawa K⁵; ¹Graduate student, Institute of Health Sciences, Faculty of Medicine, Hiroshima University. ²Division of Occupational Therapy, Institute of Health Sciences, Faculty of Medicine, Hiroshima University. ³PNF Society of Japan. ⁴Department of Physical Therapy, Faculty of Health and Welfare, Prefectural University of Hiroshima. ⁵Department of Physical Therapy, Tokyo Metropolitan University of Health Sciences

PURPOSE: Clinically, we have experienced how exercising the involved extremity improves the compensation of sensory and motor impairment by the sound side in stroke patients. Iwamura et al (1994) indicated that the interhemispheric transfer of information occurs at higher levels of hierarchical processing in each hemisphere. If ipsilateral responses are transmitted through the contralateral hemisphere, compensation by the sound side may be related to the recovery of sensory and motor impairment in stroke patients. The measurement of compensation by the sound side may be measured by tibial somatosensory evoked potentials (SEPs), which is an objective method of assessing the integrity of sensory and motor pathways and areas of the central nervous system. The purpose of this study was to find the relationships between the SEPs sound side parameters (latency and amplitude) and the clinical parameters (kinetic sense of the great toe, sensory discrimination of the planta pedis, Brunnstrom stage motor function test, and Barthel Index activities of daily living test). RELEVANCE: If a relationship exists between the SEPs sound side parameters and clinical parameters, the improvement of ability on the sound side may be related to the recovery of the sensory and motor impairment in stroke patients. PARTICIPANTS: Fourteen patients (6 women, 8 men) with hemiplegia (mean age: 73.9±10.4; range 28-57 years) participated. Four cases had right hemisphere damage, and ten cases had left hemisphere damage. METHODS: The study was approved by the ethics review board of Hiroshima University, and all subjects were given a written informed consent. Tibial nerve SEPs were recorded after stimulation at the ankle, using a frequency of 2Hz, a pulse duration of 0.2 ms, and enough current to produce minimal twitches of the thenar muscles. A total of 500 responses were averaged twice for the sound sides. The following parameters were determined for both sides: P40 latency, N50 latency, P60 latency, N75 latency, P40-N50 peak-to-peak amplitude, N50-P60 peak-to-peak amplitude, and P60-N75 peak-to-peak amplitude. After measuring the SEPs, each subject was evaluated for the clinical parameters. ANALYSIS: To assess the correlation between the SEPs and clinical parameters, we used a regression analysis (Pearson’s correlation coefficients). RESULTS: The P60 latency of the sound side had a moderate negative correlation with the Brunnstrom stage (−0.60; P = 0.03). The P40-N50 amplitude of the sound side had a moderate correlation with the discrimination sense of the affected side (0.68; P = 0.007). CONCLUSIONS: The integrity of sensory and motor pathways and areas of the central nervous system may improve through latency shunting and amplitude enhancement. IMPLICATIONS: Exercise of the involved side may promote the general recovery of the sensory and motor impairment in stroke patients. KEYWORDS: SEPs, CVA, compensation. FUNDING ACKNOWLEDGEMENTS: Unfunded. CONTACT: M060982@hiroshima-u.ac.jp

ETHICS COMMITTEE: The study was approved by the ethics review board of Hiroshima University.