Detrusor-external sphincter dyssynergia (DESD) is characterized by involuntary contractions of the external urethral sphincter during an involuntary detrusor contraction. It is caused by neurological lesions between the brainstem (pontine micturition centre) and the sacral spinal cord (sacral micturition centre). These include traumatic spinal cord injury, multiple sclerosis, myelodysplasia and other forms of transverse myelitis. There are three main types of DESD. In Type 1 there is a concomitant increase in both detrusor pressure and sphincter EMG activity. At the peak of the detrusor contraction the sphincter suddenly relaxes and unobstructed voiding occurs. Type 2 DESD is characterized by sporadic contractions of the external urethral sphincter throughout the detrusor contraction. In Type 3 DESD there is a crescendo-decrescendo pattern of sphincter contraction which results in urethral obstruction throughout the entire detrusor contraction. In patients with sufficient manual dexterity the most reasonable treatment option is to abolish the involuntary detrusor contractions (to ensure continence) and then to institute intermittent self-catheterization (in order to empty the bladder). The bladder may be paralysed pharmacologically or may be surgically converted to a low pressure urinary reservoir by the technique of augmentation enterocystoplasty. In quadriplegic men, transurethral external sphincterotomy may be performed and the incontinence managed with an external urinary appliance. Without proper treatment over 50% of men with DESD develop serious urological complications within about five years. In women these complications are much less common.