Perineal electromyography

Perineal electromyography (EMG) is a neurophysiological test applied to the exploration of the pelvic floor. It records the electrical activity of the striated perineal muscles (external anal sphincter, urethral sphincter, levator ani muscles) in order to assess their innervation and function. Perineal EMG can be performed using surface electrodes (patches stuck to the skin of the perineum) or needle electrodes inserted directly into the muscles being explored. Surface electrodes are less invasive and are sufficient for the overall assessment of muscle activity during the urodynamic assessment. Needle electrodes provide a finer analysis of motor unit potentials. This test is essential for the diagnosis of detrusor-sphincter dyssynergia, a condition in which the sphincter paradoxically contracts during voiding instead of relaxing. It can also detect perineal denervation (after traumatic childbirth, pelvic surgery or neurological damage) and assess the quality of reinnervation. Perineal EMG is often combined with the other urodynamic tests to obtain a complete functional assessment. It provides valuable information on the neuromuscular coordination of the voiding cycle and guides the indications for pelvic floor rehabilitation or neuromodulation.