The Significance of Evoked Potentials according to the Injury Severity of Spinal Cord Contusive Rat Model

OBJECTIVE: To investigate the prognostic values of somatosensory evoked potential (SEP) and electric motor evoked potential (eMEP) studies according to the varying spinal cord injury by incremental height of weight-drop impactor and progress of functional recovery METHOD: Thirty Sprague-Dawley rats (300+/-50 grams, male) were used. The spinal cord injury was made by weight-drop device from 12.5, 25.0 and 50.0 mm height at T10 cord segment. The three groups of each drop-height (n=10) and laminectomized sham group (n=10) were subjected to functional analysis using inclined plane test and Basso Beattie Bresnahan (BBB) locomotor scales at the 1, 3, 5, 7, 14, 21 and 28th day after the contusive injury. SEP by sciatic nerve stimulation and eMEP at the gastrocnemius muscle were recorded. RESULTS: Maximal angle of inclination and BBB scales had an inverse relation with the contusion severity (p <0.05). There were significant correlations among the changes of peak latencies and amplitudes of SEP, contusion severity, and the motor recovery (p <0.05). The changes of onset latencies and amplitudes of eMEP were significantly correlated with the contusion severity and the motor recovery (p <0.05). CONCLUSION: The SEP and eMEP studies had significant values according to the contusion severity and functional recovery in contusive rat model of the spinal cord.

The Jaw Jerk in Normal Young Adults

OBJECTIVE: To obtain the mean value of parameters of the jaw jerk and to investigate gender difference on the jaw jerk in normal young adults in Korea. METHOD: In young 40 subjects (20 males and 20 females), the jaw jerks were elicited by chin tapping in the relaxed masseter muscles of both sides. RESULTS: The jaw jerks were recorded in 100% of the total number of chin-taps. The mean latency was 5.39 ms in the males and 5.14 ms in the females (p>0.05). The mean amplitude was 0.75 mV in the males and 0.59 mV in the females (p>0.05). The mean duration was 8.18 ms in the males and 7.85 ms in the females (p>0.05). CONCLUSION: No significant differences were found in the parameters of the jaw jerk between males and females in this study.