The electrical activity of the paraurethral and perineal muscles in normal and pathological conditions
TL;DR: Electromyographical activity of various perineal striated muscles during bladder filling and voiding has been studied and it is found that a inco-ordination of various striated pelvic floor muscles may also be present.
Abstract: SUMMARY
Electromyographical activity of various perineal striated muscles during bladder filling and voiding has been studied. These muscles provoke a urethral pressure of 10 to 20 mm. Hg. Initiation of micturition can be characterised either by a progressive or an abrupt inhibition of perineal muscle activity or by a transient promotion of activity. The former features are more frequently observed in spontaneous voiding, the latter in voluntary voiding efforts with low vesical volumes. Voiding is possible without complete inhibition of myographical activity. In pathological cases (obstruction and neurogenic bladders) dyssynergy between the detrusor and the external striated sphincter may occur. Moreover, we found that a inco-ordination of various striated pelvic floor muscles may also be present. Such dyssynergism may cause functional obstructions with residual urine, spurting, dysuria and pseudo-incontinence.
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TL;DR: The anatomical location and fibre characteristics of the levator ani muscle suggest that these fibres actively assist in urethral closure, particularly during events which cause elevation of intra-abdominal pressure.
Abstract: Specimens from the human male and female external urethral sphincter and the periurethral levator ani muscle have been examined using histochemical and electron microscopic techniques. In both sexes the external sphincter consists of a single population of type I (slow twitch) fibres with a mean diameter of 17.47 +/- 0.7 micrometers in the absence of muscle spindles. In contrast, the periurethral levator ani possesses muscle spindles and the constituent fibres form a heterogeneous population of type I and type II (fast twitch) fibres, with mean diameters of 45.5 +/- 0.8 micrometer and 59.5 +/- 3.4 micrometers respectively. These findings indicate that the external urethral sphincter is functionally adapted to maintain tone over prolonged periods and may be of considerable importance in producing active urethral closure during continence. The anatomical location and fibre characteristics of the levator ani muscle suggest that these fibres actively assist in urethral closure, particularly during events which cause elevation of intra-abdominal pressure. In view of the differences in fibre characteristics between the external urethral sphincter and the levator ani, EMG activity recorded from a single site in the levator ani may not be representative of the functional status either of other levator ani muscle fibres or of the external urethral sphincter.
410 citations
TL;DR: Childbirth appeared to induce both quantitative and qualitative changes in the pelvic floor which jeopardized the continence mechanism, and kinesiological EMG recordings revealed behavioural abnormalities which appeared relevant for planning treatment.
Abstract: Objective To introduce neurophysiological methods to search for damage to neuromuscular structures involved in sustaining continence in women who experienced stress urinary incontinence during pregnancy andlor after delivery.
Patients and methods Eight stress urinary incontinent parous women (mean of 2.75 vaginal deliveries [range 2–41 median age 45.3 years [range 31–60]) were examined using simultaneous electromyogram recordings of the left and right pubococcygeus muscle via wire electrodes. Comparisons were made with 10 nulliparous continent women (median age 2 7.2 years [range 22–32]).
Results Individual muscle activation patterns in stress urinary incontinent parous women were in principle similar to those observed in the continent nulliparous women, with two significant exceptions: (i) voluntary ‘squeeze’ showed significant differences in the holding time between the parous stress urinary incontinent patients and the nulliparous Continent controls, with an empty bladder (49.0 s versus 193.9 s median value) and a full bladder (39.2 s versus 198.4 s); (ii) asymmetrical and uncoordinated levator activation patterns were demonstrated in four of eight parous stress incontinent women, i.e. inhibition of motor unit firing on coughing (n = 3) and dissociated recruitment of motor units during voluntary and reflex activation (n= 1). Conclusion 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.
124 citations
TL;DR: Bladder symptoms in multiple sclerosis patients should serve more to alert the clinician to the need for urodynamic testing than to mandate specific treatment.
110 citations
TL;DR: Based on the clinical experience with more than 200 spinal cord subjects and serial urodynamic observations on some of these individuals from the time of injury, various grades of dyssynergia (1 to 3) were recognized and the duration and completeness of suprasacral cord injury essentially determined the degree of Dyssynergy.
106 citations
TL;DR: Simultaneous electromyographic recordings from the left and right pubococcygeal muscles were obtained in 10 continent nulliparous women via wire electrodes inserted percutaneously to familiarise them with the normal patterns of activity of these muscles in continent nullipsity since the denervation injury caused by childbirth might not only weaken these muscles but also influence their behaviour.
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.
103 citations
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