Clinical evaluation of the bulbocavernosus reflex is very important in patients with voiding difficulty and sexual dysfunction because the physiologic micturition center is located in the S₂-S₄, spinal cord level which is also associated with the mechanism of sexual reflex, especially of erection.

However, accurate assessment was difficult because: (1) with clinical examination alone, only the presence of reaction could be assessed (2) reaction may not be definite (3) often false negative reactions appeared, and (4) degree of injury could not be assessed in cases with partial nerve injury.

The objectives of this study were to demonstrate the diagnostic value and the clinical usefulness of the electrodiagnostic test in measurement of latency time of the bulbocavernosus reflex.

Thirteen normal adult males served as controls for this study. 119 patients with sexual dysfunction and spinal cord injury who were referred to the EMG laboratory of Rehabilitation Medicine Department, Severance Hospital, Yonsei University, were studied from June 1984 to January 1986.

The results were as follows;

1) The latency time of the bulbocavernosus reflex in normal subjects was 33.9±3.04 msec (normal ranger : 27.9~40.0 msec) and there were no significant difference between right and left sides (P>0.05).

2) The mean bulbocavernosus reflex latency time in cases of functional sexual dysfunction and suprasacral spinal cord injury was not significantly different compared with normal mean values (P<0.01).

3) 46.2% of diabetic patients with sexual dysfunction showed abnormality in latency time and the main cause of sexual dysfunction in this group might be due to diabetic neuropathy. The mean in latency time of the diabetic group showed a significant difference (P<0.01).

4) 36.0% of patients with pelvic and perineal area injury and sexual dysfunction showed an abnormality in latency time and could be diagnosed to have peripheral nerve injury

5) electrodiagnostic study in the patients with conus medullaris and/or cauda equina lesion was useful in classifying th types of sexual dysfunction and neurogenic bladder and the degree of injury.