[Electromyographic study of the striated urethral sphincter by using the bulbocavernosus reflex: study of the normal voluntary voiding and the involuntary sphincter relaxation].
OBJECTIVE
The aim of this study was to investigate the sacral reflex activity at the striated urethral sphincter relaxation by evoking the potential of the bulbocavernosus reflex (BCR).


METHODS
17 normal male subjects were investigated. BCR was elicited by electrical stimulation of dorsal nerve of the penis, and the evoked potential of the BCR (BCR-EP) was recorded by a concentric needle electrode at the periurethral striated muscle. In normal subjects BCR was performed at rest and during voluntary voiding. In 8 of the normal subjects electrical stimulation was increased gradually during voluntary voiding, and changes of BCR-EP were studied. 3 male patients with neurogenic bladder suffering from urinary incontinence caused by involuntary sphincter relaxation (IVSR) were also investigated. In these patients with neurogenic bladder, BCR was performed at rest and during voluntary voiding as well as during involuntary voiding.


RESULTS
In the normal subjects stable BCR-EP was elicited at rest and disappeared during voluntary voiding. But a gradually increased larger stimulation clearly demonstrated BCR-EP during voluntary voiding. In 3 patients with neurogenic bladder, stable ECR-EP was elicited at rest. During involuntary voiding caused by IVSR obvious BCR-EP was also elicited, but its amplitude was slightly less than the amplitude of BCR-EP at rest. During voluntary voiding in 2 of the 3 patients BCR-EP was recognized but the amplitude was much less, and in the third patient BCR-EP could not be recognized.


CONCLUSIONS
BCR-EP was suppressed during voluntary voiding in normal subjects, but insufficiently suppressed in the patients with neurogenic bladder. In these patients BCR-EP during voluntary voiding was suppressed more distinctly than BCR-EP during involuntary voiding due to IVSR. In urodynamic study, the detrusor contraction and the sphincter relaxation were common phenomenon in both voluntary voiding and involuntary voiding, but the difference in the degree of the BCR suppression depended on whether micturition was voluntary or involuntary. It was suggested that the measurement of BCR-EP could distinguish involuntary voiding caused by pathological urethral sphincter relaxation from voluntary voiding.
Kaiho
Y
Y
Department of Urology, Tohoku University School of Medicine.
Namima
T
T
Uchi
K
K
Nakagawa
H
H
Aizawa
M
M
Orikasa
S
S
D000328:Adult; D000368:Aged; D004576:Electromyography; D005071:Evoked Potentials; D006801:Humans; D008297:Male; D008875:Middle Aged; D009126:Muscle Relaxation / Q000502:physiology*; D009130:Muscle, Smooth / Q000502:physiology*; D010413:Penis / Q000502:physiology*; D011930:Reaction Time; D012018:Reflex / Q000502:physiology*; D012445:Sacrococcygeal Region; D013116:Spinal Cord / Q000502:physiology; D014521:Urethra / Q000502:physiology*; D001750:Urinary Bladder, Neurogenic / Q000503:physiopathology; D014554:Urination / Q000502:physiology*