The value of sphincter electromyography in urodynamics.

Multichannel urodynamic evaluation combined with sphincter electromyography was done on 102 patients. Normal and abnormal activity was defined. When detrusor hyperreflexia occurred in patients with obstruction, idiopathic detrusor hyperreflexia and upper motor neuron disease there was a reflex relaxation of the pelvic floor in 52 per cent of the cases. Electromyographic evidence of dyssynergia was associated with other evidence of sphincter obstruction in 50 per cent of the patients who voided by detrusor contraction and in 9 per cent of the patients who voided by Valsalva's maneuver. A diagnosis of dyssynergia should not be made from the electromyographic evidence alone, especially if the patient strains to void.