Urinary incontinence may result from neurological disease. Neurological pathways subserving the appropriate control of micturition encompass the medial frontal lobes, a micturition centre in the dorsal tegmentum of the pons, spinal cord pathways, Onuf ’s nucleus in the spinal cord segments S2-S4, the cauda equina, and the pudendal nerves. Thus the anatomical differential diagnosis of incontinence is broad. Moreover incontinence may be due to inappropriate bladder emptying or a consequence of loss of awareness of bladder fullness with secondary overflow. Other features of the history and/or examination may give useful pointers as to localization. Incontinence of neurological origin is often accompanied by other neurological signs, especially if associated with spinal cord pathology (see Myelopathy). The pontine micturition centre lies close to the medial longitudinal fasciculus and local disease may cause an internuclear ophthalmoplegia. However, other signs may be absent in disease of the frontal lobe or cauda equina.
Causes of urinary incontinence include:
- Idiopathic generalized epilepsy with tonic-clonic seizures; how- ever, the differential diagnosis of "loss of consciousness with incontinence" also encompasses syncopal attacks with or with- out secondary anoxic convulsions, nonepileptic attacks, and hyperekplexia
- Frontal lobe lesions: frontal lobe dementia; normal pressure hydrocephalus
- Spinal cord pathways: urge incontinence of multiple sclerosis; loss of awareness of bladder fullness with retention of urine and overflow in tabes dorsalis
- Sacral spinal cord injury; degeneration of the sacral anterior horn cells in Onuf ’s nucleus (multiple system atrophy)
- Cauda equina syndrome; tethered cord syndrome (associated with spinal dysraphism)
- Pelvic floor injury.
Neurogenic incontinence may be associated with urgency, which results from associated abrupt increases in detrusor pressure (detrusor hyperreflexia); this may be helped by anticholinergic medication (e.g., oxybutynin). In addition there may be incomplete bladder emptying, which is usually asymptomatic, due to detrusor sphincter dyssynergia; for post-micturition residual volumes of greater than 100 ml (assessed by in-out catheterization or ultrasonography), this is best treated by clean intermittent self-catheterization.
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