Latency of compound muscle action potentials of the anal sphincter after magnetic sacral stimulation

2005

Muscle and Nerve

Motor evoked potentials (MEPs) can be recorded in the external anal sphincter in response to magnetic stimulation of the cerebral cortex or sacral roots. However, the magnitude of the stimulus artifact may alter the reliability of anal MEP recording. An intrarectal ground electrode substantially reduces stimulus artifact and technical failure, improving MEP latency determination to sacral root stimulation in particular.

Section: Resultssupporting

confidence: 62%

Intrarectal ground electrode improves the reliability of motor evoked potentials recorded in the anal sphincter

2005

Muscle and Nerve

“…133,135 Failure rates of 14%-25% have been observed for sacral magnetic stimulation, because the long recovery of the stimulus artifact interfered with latency measurement. 57,73,86,133 Intrarectal placement of the ground electrode led to a substantial reduction of the stimulus artifact and improves the reliability of the technique. 65 Finally, compared to electrical stimulation, magnetic stimulation permits the assessment of both peripheral and central anal sphincter motor pathways at the same examination.…”

Section: Terminal Motor Latency Measurementmentioning

confidence: 97%

“…57 In particular, sacral magnetic stimulation has advantages for measuring peripheral motor conduction time to the anal sphincter, because it is less painful and uncomfortable than intrarectal stimulation and allows for study of the anal/pudendal nerve along its entire length. 85,86,[133][134][135] Latency differences between sacral magnetic stimulation and intrarectal electrical stimulation range from 1.0 to 1.6 ms. 42,65,86,158 Results also depend on the type of recording electrodes. Surface recordings performed within the anal canal, using electrodes mounted on a glove, 42,56,57,158 a sponge, 86 a 12-F catheter, 73,135 or a plug, 46 provide shorter latencies than adhesive electrodes placed at the anal verge.…”

Section: Terminal Motor Latency Measurementmentioning

confidence: 99%

Neurophysiological testing in anorectal disorders

2005

Muscle and Nerve

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.

“…Aussi, d'autres techniques d'enregistrement des LDM pudendales ont été proposées, comme en réponse à la stimulation magnétique appliquée au niveau des trous sacrés [24,25]. Cette dernière méthode est particulièrement intéres-sante, car elle permet d'explorer la conduction des fibres motrices du nerf anal/pudendal depuis l'émergence des racines sacrées jusqu'aux muscles innervés sans l'invasivité d'un toucher rectal.…”

Section: Latence Distale Motrice (Ldm)unclassified

Exploration neurophysiologique périnéale des atteintes de la queue-de-cheval et du cône terminal

Ahdab

2010

Pelv Perineol

Le syndrome de la queue-de-cheval résulte de lésions concomitantes (généralement d'origine compressive) de plusieurs racines sacrées et/ou lombaires dans le canal rachidien, alors que le syndrome du cône terminal correspond à l'atteinte des structures centrales médullaires sacrées. Ces deux entités sont proches sur le plan de leur expression clinique, leurs symptômes comprenant notamment des troubles mictionnels et une anesthésie en selle. Même si le tableau clinique est complet et typique, le bilan radiologique (imagerie par résonance magnétique) est incontournable, en particulier pour établir le diagnostic étiologique. En complément de l'imagerie, le bilan électrophysiologique peut être justifié pour confirmer le diagnostic, notamment en cas de discordance clinicoradiologique, pour mieux comprendre la physiopathologie des lésions et en apprécier la sévérité fonctionnelle, voire le pronostic. Dans ce texte, nous détaillons plus spécifiquement les techniques applicables dans le cadre du bilan électrophysiologique périnéal : électromyographie de détection à l'aiguille, mesure des latences distales motrices, potentiels évoqués moteurs et somesthésiques, réponses réflexes sacrées et cutanées sympathiques, quantification des seuils de sensibilité. L'utilité et les limites de ces techniques seront discutées, notamment dans le cadre du diagnostic différentiel qui reste difficile à établir entre atteinte du cône terminal et de la queue-de-cheval.Mots clés Cône terminal · Électromyographie · Latence distale motrice · Potentiel évoqué · Quantification des seuils de sensibilité · Queue-de-cheval · Réflexe sacré · Réponse cutanée sympathique Abstract Cauda equina syndrome results from concomitant lesions of several sacral or lumbar roots within the spinal canal, whereas sacral conus syndrome more specifically relates to the damage of central nervous structures within the sacral spinal cord. Both entities have close but heterogeneous clinical presentation, including voiding disturbances and saddle anesthesia. Radiological investigation (magnetic resonance imaging) is required, at least to assess the etiology of the lesions, even if clinical features leave no room for doubt concerning the diagnosis. Electrophysiological examination is complementary to imaging and can be useful to confirm the diagnosis, to better understand the underlying mechanisms, to assess the severity of the damage, or to establish a prognosis of recovery at the follow-up. In this article, we describe the various techniques that are more specifically applicable in the electrophysiological investigation of the perineum: needle electromyography, terminal motor latency measurement, motor and somatosensory evoked potentials, sacral and sympathetic skin reflex responses, and quantitative sensory testing. The utility and limitations of these techniques will be discussed, in particular regarding the differential diagnosis between cauda equina and sacral conus syndrome, which is usually hard to establish.