Bladder sphincter dyssynergia (also known as detrusor sphincter dysynergia (DSD) (the ICS standard terminology agreed 1998)  and neurogenic detrusor overactivity (NDO)) is a consequence of a neurological pathology such as spinal injury or multiple sclerosis that disrupts central nervous system regulation of the micturition (urination) reflex resulting in dyscoordination of the detrusor muscles of the bladder and the external urethral sphincter muscles. In normal lower urinary tract function, these two separate muscle structures act in synergistic coordination. But in this neurogenic disorder, the urethral sphincter muscle, instead of relaxing completely during voiding, dyssynergically contracts causing the flow to be interrupted and the bladder pressure to rise.  On cystography there is an irregular appearance of the bladder outline due to muscular contraction against the unrelaxed bladder sphincter.
The pathophysiology of the condition results from neuronal plasticity associated with bladder afferents and motor neurons innervating the external urethral sphincter. Symptomatically, people with this condition generally experience daytime and night time wetting, urinary retention, and often have a history of urinary tract and bladder infections. Constipation and encopresis are often associated with this condition.
^E Iu Stankovich, V V Borisov, T L Demina (1999). "Tamsulosin in the treatment of detrusor-sphincter dyssynergia of the urinary bladder in patients with multiple sclerosis". Urologiia: 48–51. ISSN1728-2985. Urination disorders occur in 80% patients with multiple sclerosis (MS). Most common of them is detrusor-sphincter dyssynergia (DSD).
^Corcos, Jacques; Schick, Erik (2004). Textbook of the neurogenic bladder: adults and children. Informa Health Care. pp. 163–168. ISBN1-84184-206-0.
^ Cystometry shows Neurogenic detrusor overactivity is overactivity in the presence of confirmed neuropathy in this case Multiple Sclerosis, Doug Small, Department of Urology, Southern General Hospital, Glasgow
^ Cystometry shows High detrusor pressure and interrupted. Can not diagnose dyssynergia without emg or radiology but this trace is suggestive of dyssynergic voiding; Doug Small, Department of Urology, Southern General Hospital, Glasgow