Clinical neurophysiological tests have been introduced to test motor and sensory parts of the somatic and autonomic nervous system involved in control of uro-ano-genital functions, pelvic floor muscles and sensory innervation of perineum and pelvic organs. The whole gamut of different EMG techniques, tests of conduction, and autonomic nervous system tests has thus become available for use in the patient with uro-ano-genital dysfunction. The aim of the presentation is to review available tests and stress which ones are useful in clinical practice.
Needle EMG and conduction studies (particularly the bulbocavernosus reflex) are useful in diagnosing lesions within the lower (S2-S4) sacral reflex arcs. EMG and electrophysiological recording of reflexes are more sensitive than clinical examination to detect abnormalities, and provide additional information, whereas pudendal SEP is as a rule less sensitive then clinical examination of sensitivity.
Application of urethral sphincter EMG has revealed myogenic urethral sphincter hyperactivity as cause for urinary retention in women, thus defining a new clinical syndrome (Fowler syndrome). Neurophysiological methods have demonstrated the (partly) neuropathic cause of “genuine” stress urinary and anal incontinence. The tests of conduction (bulbocavernosus reflex testing, pudendal SEP, sphincter MEP) are particularly promising as intraoperative monitoring techniques. Autonomic nervous system testing of the lower thoracic – upper lumbal sympathetic and the sacral parasympathetic, as well as testing visceral afferents from pelvic organs, has so far remained mostly a research area.
Kinesiological sphincter EMG is routinely used in functional testing and demonstrates detrusor /and bowel / sphincter discoordination.
To summarize: clinical application of pelvic EMG has been particularly helpful in urodynamic studies and in diagnosing denervation and reinnervation of pelvic floor muscles in patients with sacral nervous system involvement due to dysraphism, disease, and trauma. Urethral sphincter EMG studies have revealed a new syndrome of myogenic urethral sphincter hyperactivity (Fowler syndrome), and have contributed to the understanding of the pathophysiology of “genuine” stress urinary and anal incontinence. The tests of conduction are auxiliary in testing the lower sacral reflex arcs and the central connections of the sacral nervous system lesions, and are used increasingly for intraoperative mapping and monitoring.
In conclusion, concentric needle EMG and bulbocaverosus reflex testing are useful particularly in diagnostics of patients with suspected lesions of the peripheral sacral nervous system (segments S2 – S 4); clinical neurophysiological tests in general remain interesting for research of neurogenic uro-ano-genital dysfunctions, and, in particular, in extending the possibilities of clinical neurophysiological intraoperative monitoring.
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Wyndaele JJ and Vodušek DB: Approach to the male patient with lower urinary tract dysfunction. In: Vodušek DB and Boller F. NEUROLOGY OF SEXUAL AND BLADDER DISORDERS, Elsevier, Amsterdam 2015; 143 -164.
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