Cremasteric reflexes of boys with descended, retractile, or undescended testes:: An electrophysiological evaluation

Background/Purpose: Retractile testis traditionally has been regarded as suprascrotal location of testis resulting from hyperactivity of the cremasteric reflex (CR). However, the activity of CR is evaluated poorly in the literature. Electrophysiological characteristics of CR in boys with various testicular localizations have been evaluated comparatively. Methods: Cremasteric responses that were evoked by electrical stimulation of the upper-inner aspect of thigh were recorded using a concentric needle electromyography (EMG) electrode inserted into the cremaster muscle. Evoked EMGs of groups, each consisting of 10 boys with bilateral descended (DT), unilateral retractile (RT), or unilateral undescended testes (UT) were compared for response latencies and durations. Results:Three components with different onset latencies (R1, R2, and R3) were identified in EMG responses. In patients with UT, the latency of the R1 was shorter than that of the patients with DT, and the duration of R2 was longer than those of the patients with DT and RT. The differences between patients with RT and DT regarding the latency and duration of R1 and R2, although similar to those differences between UT and DT, were not significant. There were no significant differences of the latencies of R3 between groups, in patients with RT and UT, response latency and duration in the descended and retractive-undescended sides were similar. Conclusions: Defined by shortened latency and prolonged activity of cremasteric responses, which probably reflect a diminished neuronal inhibitory control, CR is hyperactive in UT. Dysinhibited motor neurons leading to overactivity of cremaster muscle might have hampered the descent of testis. Our results do not provide a definite support for or against the hypothesis of CR hyperactivity in RT. Copyright (C) 1999 by W.B. Saunders Company.