Translumbar and Transsacral Magnetic Neurostimulation for the Assessment of Neuropathy in Fecal Incontinence

Abstract

Background Neurological dysfunction causes fecal incontinence, but current techniques for its assessment are limited and controversial. Objective To investigate spino-rectal and spino-anal motor evoked potentials simultaneously using lumbar and sacral magnetic stimulation in fecal incontinence and healthy subjects, and to compare motor evoked potentials and pudendal nerve terminal motor latency in fecal incontinence subjects. Design Prospective observational study. Settings Two Tertiary Care Centers. Patients Adult fecal incontinence and healthy subjects. Interventions Translumbar and transsacral magnetic stimulations performed bilaterally by applying a magnetic coil to the lumbar and sacral regions in 50 fecal incontinence (≥ 1 episode/week) and 20 healthy subjects. Both motor evoked potentials and pudendal nerve terminal motor latency were assessed in 30 fecal incontinence patients. Stimulation-induced motor evoked potentials were recorded simultaneously from rectum and anus with two pairs of bipolar ring electrodes. Main Outcome Measurements Latency and amplitude of motor evoked potentials after lumbosacral magnetic stimulation and agreement with pudendal nerve terminal motor latency. Results When compared to controls, one or more lumbo-anal, lumbo-rectal, sacro-anal, or sacro-rectal motor evoked potentials were significantly prolonged (p<0.01) and were abnormal in 44/50 (88%) fecal incontinence subjects. Positive agreement between abnormal motor evoked potentials and pudendal nerve terminal motor latency was 63% whereas negative agreement was 13%. motor evoked potentials were abnormal in more (p <0.05) fecal incontinence patients than pudendal nerve terminal motor latency, 26/30 (87%) versus 19/30 (63%) respectively, and in 24% of patients with normal pudendal nerve terminal motor latency. No adverse events. Limitations Anal electromyography was not performed. Conclusions Translumbar and transsacral magnetic stimulation–induced motor evoked potentials provide objective evidence for rectal or anal neuropathy in fecal incontinence patients and could be useful. Test was superior to pudendal nerve terminal motor latency and appears to be safe and well tolerated.

Epidemiology, Pathophysiology, and Classification of Fecal Incontinence: State of the Science Summary for the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) Workshop

“…Moreover, recent studies suggest that even asymptomatic older nulliparous women have anal sphincter neurogenic injury, which partly explained weak squeeze pressures (85). Since needle EMG is the only available technique for documenting neurogenic injury, newer, and preferably less invasive approaches are necessary (95). …”

High‐resolution anorectal manometry: An expensive hobby or worth every penny?

“…Anal resting and squeeze pressures measured with non‐HRM and HDM are lower in incontinent patients than in healthy persons . Endoanal imaging, electromyography, and translumbar or transsacral magnetic stimulation are useful for determining the contribution of nerve and sphincter/pelvic floor injury to reduced squeeze pressure …”

Comprehensive Clinical Approach to Fecal Incontinence

“…Novel neurophysiological investigations can be used to assess the spino-anorectal neuropathy with higher sensitivity. These include translumbar and trassacral magnetic neurostimulation (TLMS, TSMS), which induce motor evoked potential in the anal and rectal areas by using magnetic stimulation at the lumbar and sacral levels [82]. The magnetic stimulation induces the electrical current in the lumbosacral motor nerve roots and then the conduct along the peripheral nerves.…”