X-ray and ultrasound studies as well as pressure measurements are not able to determine the etiology of dysfunctional voiding in women because these techniques are not able to differentiate between the various muscular structures surrounding the urethra. For this reason it is necessary to combine different EMC; techniques. 12 women with unexplained, severe symptoms of urinary outlet obstruction, with a mean age of 41.7 years (range 18 - 61) and an average follow-up of 30.5 months were examined. Urodynamic evaluation included kinesiologic EMC recordings of the right and left pubococcygeus muscle (the most prominent part of the levator ani) and the external urethral sphincter. For the kinesiologic EMG recordings, unipolar wire electrodes were inserted percutaneously. The concentric needle EMG examination of the external urethral sphincter was performed as a separate study. All women showed prolonged, intermittent flow in the primarily performed uroflow examination diagnosed in general as detrusor-sphincter externus-dyssynergia. Kinesiologic EMC recordings revealed differences between the activity patterns of the two muscle groups (the external urethral sphincter and the pubococcygeus m.) during bladder filling, different maneuvers and micturition. In 9 women, dysfunctional voiding was due to the pubococcygeal muscles only. In these women, the concentric needle EMG examination of the urethral sphincter showed no evidence of spontaneous activity oder denervation/reinnervation. In three women, abnormal pseudomyotonic-like EMG activity could be demonstrated by concentric needle examination of the external urethral sphincter. The kinesiologic EMG examination of this muscle revealed no modulation of activity during voluntary or reflex maneuvers, and bursts of activity during voiding decreasing the uroflow. In our patients we were able to differentiate two groups of women, one group with dysfunctional voiding due to the pelvic floor (a change of the motor program of the muscle) and one group with dysfunction of the external urethral sphincter (bizarre high frequency discharges). The described EMG recordings are considered relevant for therapeutic decisions.
