Variations in motor evoked potential latencies in the anal sphincter system with sacral magnetic stimulation

Sato, T Konishi, F Kanazawa, K

T. Sato et al., Variations in motor evoked potential latencies in the anal sphincter system with sacral magnetic stimulation, DIS COL REC, 43(7), 2000, pp. 966-970

14

INGLESE

Article

Gastroenerology and Hepatology

DISEASES OF THE COLON & RECTUM

0012-3706 → ACNP

43

7

2000

966 - 970

ISI

0012-3706(200007)43:7<966:VIMEPL>2.0.ZU;2-H

PURPOSE: The anal sphincter system of the skeletal musculature consists of various parts but functions as a single unit. The motor latencies measured at the puborectalis, deep external anal sphincter, superficial external ana l sphincter, and subcutaneous external anal sphincter have yet to be clearl y elucidated. This study was designed to measure the motor latencies of the se sphincters separately and to investigate the electrophysiologic heteroge neity of the anal sphincter system. METHODS: In 20 preoperative patients wi th colon cancer without either neurologic or anorectal diseases, motor evok ed potentials were taken separately bilaterally at levels measuring approxi mately 5, 3.8, 2.6, and 1.5 cm from the perineal skin using a concentric ne edle electrode after magnetic stimulation on the sacral region. These laten cies were considered to be separately measured at the puborectalis, deep, s uperficial, and subcutaneous external anal sphincter. RESULTS: The motor la tencies (median (95 percent confidence interval)) were 4.33 (4.1-4.93; righ t) and 4.24 (3.97-5.22; left) ms at the 5 cm lever; 5.96 (5.95-7.32; right) and 6.44 (5.49-8.20; left) ms at the 3.8 cm level, 9.28 (7.99-11.21; right ) and 8.88 (7.68-10.93; left) ms at the 2.6 cm level; and 11.06 (9.69-14.13 ; right) and 9.18 (8.03-10.31; left) ms at the 1.5 cm level Significant dif ferences were seen in the latencies bem een the 5 cm level and the other le vels and between the 3.8 cm level and the other levels. CONCLUSIONS: The mo tor latencies in the anal sphincter system significantly varied depending o n the distance from the skin. The latency may be shortest in the puborectal is and increasingly longer in the deep, superficial, and subcutaneous EAS, in that order.