PELVIC FLOOR ACTIVITY PATTERNS - COMPARISON OF NULLIPAROUS CONTINENT AND PAROUS URINARY STRESS INCONTINENT WOMEN - A KINESIOLOGICAL EMG STUDY

Objective To introduce neurophysiological methods to search for damage to neuromuscular structures involved in sustaining continence in wome n who experienced stress urinary incontinence during pregnancy and/or after delivery. Patients and methods Eight stress urinary incontinent parous women (mean of 2.75 vaginal deliveries [range 2-4] median age 4 5.3 years [range 31-60]) were examined using simultaneous electromyogr am recordings of the left and right pubococcygeus muscle via wire elec trodes. Comparisons were made with 10 nulliparous continent women (med ian age 27.2 years [range 22-32]). Results Individual muscle activatio n patterns in stress urinary incontinent parous women were in principl e similar to those observed in the continent nulliparous women, with t wo significant exceptions: (i) voluntary 'squeeze' showed significant differences in the holding time between the parous stress urinary inco ntinent 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 activa tion patterns were demonstrated in four of eight parous stress inconti nent women, i.e. inhibition of motor unit firing on coughing (n=3) and dissociated recruitment of motor units during voluntary and reflex ac tivation (n=1). Conclusion Childbirth appeared to induce both quantita tive 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 beha vioural abnormalities which appeared relevant for planning treatment.