Lecture Details

EMG of the urogenital system
David Vodusek

David Vodušek is Emeritus Professor of Neurology at the University of Ljubljana,
Slovenia. Born in Slovenia he received his MD and PhD from the University of
Ljubljana. He spent time in the Department for Clinical Neurophysiology,
Uppsalla, Sweden, Institute of Neurology, Queen Square, London, Baylor
College, Houston, and at NYU, NY USA. In 1997 he was appointed full Professor
of Neurology at the University of Ljubljana. He served as Head of the Institute of
Clinical Neurophysiology in Ljubljana, as Chair of Neurology, Medical Faculty, University of Ljubljana and from 1996-2017 as Medical Director of the Division of Neurology, University Medical Center Ljubljana, where he continues to work as consultant. Dr. Vodušek is a member of the Slovene and German Neurological Association, BSCN, and the European Academy of Neurology (EAN-Chair of the International Liaison Group).Through EAN he is also active in the Bio Med Alliance where he chairs the CME Experts Permanent Committee. He serves on the editorial boards of Neurology and Urodynamics, Neurological Sciences and JECME. During his career, Dr. Vodušek has authored more than 100 articles in international journals and has co-edited the 130th volume of the Handbook of Clinical Neurology series (Neurology of Sexual and Bladder Disorders).

The bladder, bowel and sexual functions are neurally controlled and have striated and smooth muscles involved in their complex functioning. They are not readily amenable to clinical "observation" but functional tests for their objective assessment have been developed. The neural elements controlling these functions comprise (somatic) motor control of pelvic floor muscles, sensory input from the anogenital region, and autonomic nerve fibres. Clinical examination provides some data on motor function (the presence of voluntary and reflex contraction), and data on sensation. Morphological data obtained by imaging can provide only indirect data of potential dysfunction of neuromuscular structures. To test the integrity of the sacral segmental reflexes, the individual components of the reflex arcs and their suprasegmental connections, several neurophysiological methods have been introduced. Of the many published methods, EMG, sacral reflex studies, sensory and motor evoked potentials (SEP, MEP) have been most often studied (cf. 1, 2). All these methods have conveniently been called "uroneurophysiological". The International Continence Society has suggested standards regarding the general and technical information that needs to be stated when performing and reporting uroneurophysiological tests, to assure transparency and reproducibility of published reports (3). In the context of urodynamics, electromyography (EMG) describes the pattern of muscle activity (i.e. the timing and quantity of motor unit activity). This kind of EMG has also been called "kinesiological" and is used to demonstrate detrusor-sphincter dyssynergia. Most often, however, EMG is used for its ability tom distinguish normal from neuropathic striated sphincter / pelvic floor muscles. Wider experience is only available for the concentric needle electrode (CNEMG). CNEMG demonstrates both pathological spontaneous activity and changes in motor unit potentials (MUAPs). MUAP changes are specific and sensitive to diagnose reinnervation in sphincter muscles in individual patients. CNEMG has been found helpful in diagnosing involvement of lower sacral segments in different traumatic and compressive lesions, and malformations involving the thoraco-lumbo-sacral spine or the pelvis, because it provides data not obtainable by other methods (4).

Sacral reflex, SEP and MEP testing have, on the other hand, shown poor ability to distinguish accurately between neurogenic and non-neurogenic bladder, bowel, and/or sexual dysfunction (in other words their lack of sensitivity and specificity for this purpose in individual patients). These functions depend more on autonomic than on somatic nerve fibres, and then on several other non- neurogenic factors. Therefore, the sensitivity and specificity of neurophysiological tests should only be considered with reference to the particular underlying neurological lesion, not in direct reference to the bladder, bowel, and/or sexual dysfunction. Bulbocavernosus reflex, SEP and MEP recording has, however, been introduced to intraoperative monitoring in selected patient groups.
In routine diagnostics CNEMG and bulbocavernosus reflex testing are suggested as useful in selected individual patients with suspected lesions in the peripheral lower sacral reflex arc. CNEMG reveals muscle denervation and reinnervation, and bulbocavernosus reflex recording by EMG is more sensitive to demonstrate the preservation of the reflex arc than clinical testing. Demyelination lesions (such as in inflammatory polyradiculoneuropathy and multiple sclerosis), will show abnormalities in latencies of responses obtained in the uro-ano-genital region (sacral reflex, SEP, MEP), but the necessity to investigate such patients only rarely arises as data obtained by other means are considered sufficient. In axonal type lesions sensory involvement will be more readily demonstrated by clinical exam than by electrophysiological testing.