Neurophysiological testing in anorectal disorders

Abstract

The neurophysiological techniques currently available to evaluate anorectal disorders include concentric needle electromyography (EMG) of the external anal sphincter, anal nerve terminal motor latency (TML) measurement in response to transrectal electrical stimulation or sacral magnetic stimulation, motor evoked potentials (MEPs) of the anal sphincter to transcranial magnetic cortical stimulation, cortical recording of somatosensory evoked potentials (SEPs) to anal nerve stimulation, quantification of electrical or thermal sensory thresholds (QSTs) within the anal canal, sacral anal reflex (SAR) latency measurement in response to pudendal nerve or perianal stimulation, and perianal recording of sympathetic skin responses (SSRs). In most cases, a comprehensive approach using several tests is helpful for diagnosis: needle EMG signs of sphincter denervation or prolonged TML give evidence for anal motor nerve lesion; SEP/QST or SSR abnormalities can suggest sensory or autonomic neuropathy; and in the absence of peripheral nerve disorder, MEPs, SEPs, SSRs, and SARs can assist in demonstrating and localizing spinal or supraspinal disease. Such techniques are complementary to other methods of investigation, such as pelvic floor imaging and anorectal manometry, to establish the diagnosis and guide therapeutic management of neurogenic anorectal disorders.

Midline sensory nerve supply to the anoscrotal junction: a study using human male fetuses

“…Nerves of the anoscrotal junction has been one of major interests of researchers because they should contain an afferent route for autonomic nerve reflexes in the pelvic floor involving the urinary and anal sphincter functions (Bird and Hanno, 1998;Lefaucheur, 2006;Yilmaz et al, 2009;Hotta et al, 2012). The posterior part of the human scrotum is innervated by a branch of the pudendal nerve, i.e., the posterior scrotal nerve.…”

Neurophysiology of the pelvic floor in clinical practice: a systematic literature review

“…Although clinical neurophysiology is practiced in almost all neurology departments, pelvic floor neurophysiology requires specific knowledge about neurophysiological techniques and a sound anatomo-clinical background (Fowler et al, 2002). A number of relevant critical reviews discuss the methodological aspects and diagnostic value of neurophysiological tests in pelvic floor disease (Fowler et al, 2002;Vodusek, 2005;Lefaucheur, 2006), but the actual clinical usefulness of these tests is not yet completely clarified. We performed a systematic literature review to provide clinicians with evidence-based recommendations on the use of neurophysiological tests in clinical practice.…”

“…Conversely, in other clinical scenarios, for example in the presence of syndromes or symptoms having a different etiology or pathogenetic mechanism (e.g., 'generic' urgency or urinary retention, fecal incontinence or constipation, and pelvic pain), or when no clearly defined independent a priori criteria for the 'neurogenic' origin of the symptoms are met, the pathogenetic relevance of an altered test result can often only be assumed. Most of the literature reviews on pelvic floor neurophysiology published to date suggest recommendations on the clinical use of diagnostic tests that are based on expert opinion (Olsen and Rao, 2001;Lefaucheur, 2006;Podnar, 2007). However, a systematic literature analysis involving a selection of the most relevant studies and evaluation of their methodological quality is lacking.…”

Executive summary: The International Consultation on incontinence 2008—committee on: “Dynamic Testing”; for Urinary or fecal incontinence. Part 3: Anorectal physiology studies

“…PNTML is reported to be a fairly reproducible but inherently insensitive measure of neuropathy. 25,26 The ICI-CDT has concluded that, like other neuro-electrophysiological testing, PNTML shows substantially different published ''cut-off'' values to discriminate normal from abnormal. This demonstrates that PNTML is operator and laboratory dependent.…”