No abstract

Childbirth appeared to induce both quantitative and qualitative changes in the pelvic floor which jeopardized the continence mechanism. Sphincter weakness appeared to result not only from the loss of motor units but also from altered activation patterns in the remaining units: shorter activation periods, lack of response or paradoxical inhibition. Kinesiological EMG recordings revealed behavioural abnormalities which appeared relevant for planning treatment.

No abstract

Simultaneous electromyographic (EMG) recordings from the left and right pubococcygeal muscles were obtained in 10 continent nulliparous women (aged 22-32 years) via wire electrodes inserted percutaneously. During relaxation, sustained motor unit firing was obtained in 14 and no EMG activity in 4 of the 20 recorded muscle sites. During voluntary squeeze, stopping urine in midstream and coughing there was always bilateral recruitment of motor units that was gradual in the recording sites with ongoing EMG activity and brisk in the sites without EMG activity; the 2 different patterns of activity were called "tonic" and "phasic" respectively. Voluntary squeeze led to activation of motor units sustained for 26 to 647 s (median 193.9) with the bladder empty and 25 to 600 s (median 198.4) with a full bladder. A marked decrease in ongoing tonic motor unit activity was seen during the attempt to urinate. Bladder filling caused an increase in tonic activity in 7 females bilaterally and in 1 unilaterally, whereas there was no change in 3 women. During the Valsalva manoeuvre, simultaneous motor unit recruitment was seen in all subjects bilaterally with the bladder empty and in all but one with the bladder full: in the latter case the motor unit recruitment with an empty bladder changed into simultaneous bilateral inhibition of firing of motor units with a full bladder (both in the supine and erect position); this pattern changed to bilateral recruitment of motor units again after bladder emptying. It is important to be familiar with the normal patterns of activity of the pubococcygeal muscles in continent nulliparous women since the denervation injury caused by childbirth might not only weaken these muscles but also influence their behaviour.

The influence of intravesical administration of PGE2 (1,500 micrograms) and sulprostone, a PGE2 derivative (1,000 micrograms) on urodynamic parameters of the lower urinary tract was tested on six healthy female patients. PGE2 and sulprostone significantly decreased the urethral closure pressure at rest. PGE2 increased the detrusor opening pressure as well as the detrusor pressure during maximum flow. Sulprostone, in contrast, slightly decreased these parameters. Both substances caused a strong urgency sensation resulting in an equally reduced bladder capacity and leading to a measurable bladder instability in both cases. This gives rise to the assumption that frequency, urgency and bladder instability may be the result of intravesical relaxation. By 24 h after administration all urodynamic parameters had returned to pretreatment values, thus indicating that long-term changes in urodynamic parameters are not found after either prostaglandin.