The Neurophysiological Testing
Neurophysiological testing has an important role in the evaluation of patients affected by neurogenic or dysfunctional bladder. The tests present limits related to age and child compliance. Despite the utility the tests are not used routinely. Electromyog
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Giorgio Selvaggio and Roberto Cordella
The neurophysiological testing plays an important role in evaluation of patients affected by detrusor sphincter dysfunction. Despite this concept the tests are not used routinely. These studies require particular and expensive equipment and clinical experience of neurophysiologist. In addition to this, the neurophysiological tests present in pediatric patient limits related to age, child, and parents compliance. Electromyography (EMG), nerve conduction latency studies, reflex latencies, and sensory evoked potential are classic tests. In pediatric patients their service is not all indicated. EMG and sensory evoked potential have clinical application.
10.1 Electromyography The EMG is recording related electrical potentials to the depolarization of striated muscle fibers. The striated urethral sphincter keeps continuous motor unit activity. During bladder storage phase, the activity has an increment as coughing and other maneuvers that increases intra-abdominal pressure. In voiding phase the first step is an inhibition of motor unit activity by detrusor contraction and urine emission. The EMG should be used during cystometry, pressure/flow study, and noninvasive urodynamic study (Fig. 10.1). The study could be used to detect either detrusor/ sphincter dyssynergia in neurological patients or dyscoordination in functional patients. In non-neurological patients, who present a dysfunctional voiding, the
G. Selvaggio, M.D. (*) Department of Pediatric Surgery, Children’s Hospital “V.Buzzi”, Milan, Italy e-mail: [email protected] R. Cordella, M.Sc., Ph.D. Department of Neurosurgery, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy © Springer International Publishing AG, part of Springer Nature 2018 G. Mosiello et al. (eds.), Clinical Urodynamics in Childhood and Adolescence, Urodynamics, Neurourology and Pelvic Floor Dysfunctions, https://doi.org/10.1007/978-3-319-42193-3_10
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G. Selvaggio and R. Cordella
Fig. 10.1 Noninvasive urodynamic study: dyscoordinated micturition in functional patient. External sphincter contraction during the flow
EMG could be used as a part of biofeedback to improve the pelvic floor relaxation during the micturition. Detrusor sphincter dyssynergia (DSD) is characterized by involuntary contractions of the external urethral sphincter during a hyperreflexic detrusor contraction. It is caused by neurological lesions above the sacral levels to the pontine micturition center. Three main types of DSD are well established. In type 1 there is an increase of sphincter EMG activity during detrusor contraction. At the peak of the detrusor contraction, the sphincter suddenly relaxes and voiding occurs. Type 2 DSD is characterized by clonic contractions of the external urethral sphincter during the detrusor contraction (Fig. 10.2). In type 3 DSD, there is a crescendo-decrescendo pattern of sphincter contraction, which results in urethral obstruction throughout the entire detrusor contraction [1]. The perfect EMG study
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