Brief Article
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World J Gastroenterol. Nov 21, 2010; 16(43): 5440-5446
Published online Nov 21, 2010. doi: 10.3748/wjg.v16.i43.5440
Cortical and spinal evoked potential response to electrical stimulation in human rectum
Brian Garvin, Lisa Lovely, Alex Tsodikov, Danielle Minecan, Shaungson Hong, John W Wiley
Brian Garvin, John W Wiley, Shaungsong Hong, Department of Internal Medicine, University of Michigan, Michigan Clinical Research Unit, Level 1, Room 1702, Cardiovascular Center, 1500 E Medical Center Drive, Ann Arbor, MI 48109, United States
Lisa Lovely, Danielle Minecan, Department of Neurology, University of Michigan, Ann Arbor, MI 48109, United States
Alex Tsodikov, Department of Biostatistics, University of Michigan, Ann Arbor, MI 48109, United States
Author contributions: Garvin B contributed to data analysis and manuscript preparation; Lovely L contributed to data collection and figure preparation; Tsodikov A contributed to statistical analysis; Minecan D contributed to data interpretation; Hong S contributed to figure preparation; Wiley JW contributed to experimental design, performance of research studies, data analysis and manuscript preparation.
Supported by Grants from the National Institutes of Health M01-RR-00042 and UL1RR024986 (to Wiley JW)
Correspondence to: John W Wiley, MD, Professor, Department of Internal Medicine, University of Michigan, Michigan Clinical Research Unit, Level 1, Room 1702, Cardiovascular Center, 1500 E Medical Center Drive, Ann Arbor, MI 48109-5872, United States. jwiley@umich.edu
Telephone: +1-734-9368080 Fax: +1-734-9364024
Received: April 17, 2010
Revised: June 5, 2010
Accepted: June 12, 2010
Published online: November 21, 2010
Abstract

AIM: To study a novel technique to record spinal and cortical evoked potentials (EPs) simultaneously in response to electrical stimulation in the human rectum.

METHODS: Eight male and nine female healthy volunteers participated. Stimulating electrodes were attached to the rectal mucosa at 15 cm and 12 cm above the dentate line. Recording skin electrodes were positioned over vertebrae L4 through S2. The electrical stimulus was a square wave of 0.2 ms duration and the intensity of the stimulus varied between 0 and 100 mA. EP responses were recorded using a Nicolet Viking IV programmable signal conditioner.

RESULTS: Simultaneous recording of cortical and spinal EPs was obtained in > 80% of the trials. The EP responses increased with the intensity of the electrical stimulation, were reproducible overtime, and were blocked by application of Lidocaine jelly at the site of stimulation. The morphology (N1/P1), mean ± SD for latency (spinal N1, 4.6 ± 0.4 ms; P1, 6.8 ± 0.5 ms; cortical N1, 136.1 ± 4.2 ms; P1, 233.6 ± 12.8 ms) and amplitude (N1/P1, spinal, 38 ± 7 μV; cortical 19 ± 3 μV) data for the EP responses were consistent with those in the published literature. Reliable and reproducible EP recordings were obtained with the attachment of the electrodes to the rectal mucosa at predetermined locations between 16 and 8 cm above the anal verge, and the distance between the attachment sites of the electrodes (the optimal distance being approximately 3.0 cm between the two electrodes).

CONCLUSION: This technique can be used to assess potential abnormalities in primary afferent neural pathways innervating the rectum in several neurodegenerative and functional pain disorders.

Keywords: Spinal evoked potentials; Cortical evoked potentials; Rectum; Electrical stimulation; Primary afferent neurons; Visceral sensation