Quantitative Analysis of Bulbocavernosus Reflex Activity in Patients with Spinal Cord Injury

ABSTRACT

OBJECTIVE: To quantify activities of bulbocavernosus reflex (BCR) using root mean square (RMS) value of motor unit action potentials in power spectrum analysis. METHOD: Twenty-six male patients with spinal cord injury were studied. The BCRs were evaluated by one examiner. The patients were assigned into absent, hypoactive and normal reflex groups according to the degree of BCR activity. The electrophysiological activities of the BCRs were evaluated by the RMS value of the motor unit action potentials in power spectrum analysis recorded from the bulbocavernosus muscle using concentric needle electrode. RESULTS: The BCR by clinical examination was absent in 6 patients, hypoactive in 10 patients and normal in 10 patients. RMS values of absent, hypoactive and normal BCR groups were 15.1+/-3.6 uV, 26.7+/-13.2 uV and 36.3+/-4.8 uV, respectively. RMS values of three groups were significant different (p=0.028) and showed significant correlation (r=0.714, p= 0.005). CONCLUSION: There was strong correlation between RMS value of motor unit action potentials of bulbocavernosus muscle and degree of BCR activities estimated by clinical examination in patients with spinal cord injury.