[Sphincter function disorders. physiopathology and neurophysiological study].
Miction and defecation disturbances are very frequent in the general population and far more so among neurological patients. It is essential to know the physiopathology of these disorders in clinical practice. The neurological control of these functions is carried out by automatisms that are regulated in the nuclei of the brain stem through somatic and vegetative peripheral structures that act simultaneously. The cortical, hypothalamic and reticular levels play a part in the activation or inhibition of the pontine nuclei. Continence depends on the integrity of the anatomical structures and the sensory, pressure and mechanical systems that enable the automatisms to develop. Neurological examination must be combined with studies conducted by other specialists on patients in which no neurological illness is known, but who have this kind of dysfunction. Adding a neurophysiological examination allows us to complete the clinical study and to check objectively for the existence of external anal sphincter denervation or disorders involving the exteroceptive reflexes of the sacrum. The recent appearance of techniques for treating incontinence that make use of the repeated and continuous stimulation of the sacral roots has revolutionised the way these patients are treated and calls for greater involvement of neurologists in dealing with these problems.