Investigation of Cortico-Rectal Pathways in Healthy Subjects and Constipated Patients

Biofeedback therapy improves bowel symptoms and anorectal function in patients with dyssynergic defecation, however its mechanism of action is not known. The investigators hypothesize that biofeedback therapy enhances gut-brain-gut communication by altering cortical processing of information and improving cortically mediated neuromuscular function of the gut. However, in order to better understand these mechanisms in patients, the investigators need to examine and establish normative data and compare findings with healthy subjects. The investigators specific aims are to examine and evaluate the following 40 normal subjects; (1) To evaluate the afferent cortical evoked potentials in response to the electrical stimulation of the anorectum and (2) To evaluate the corticofugal tracts (efferent) by recording the anal and rectal electromyographic responses following noninvasive lumbosacral and transcranial magnetic stimulation.

Study Overview

• Status: Unknown
• Conditions: Constipation; Healthy Volunteers
• Intervention / Treatment: Procedure: Cortical Evoked Potentials; Procedure: Transcranial motor evoked potentials; Procedure: Translumbosacral motor evoked potentials

Detailed Description

1. Cortical evoked potentials:A probe with 2 ring electrodes is placed in anus and rectum. A small amount of electrical current is passed. The cortical evoked responses to the anal and rectal electrical stimulation is measured from the scalp using a neurophysiology recorder.
2. Motor evoked potentials: A magnetic coil is placed on the scalp at the anorectal cortical site and discharged using magnetic energy. The anal and rectal motor evoked potentials are then measured using a probe with 2 ring electrodes.

• Study Type: Observational
• Enrollment (Anticipated): 150

Contacts and Locations

Study Locations

• United States
  • Iowa
    • Iowa City, Iowa, United States, 52242
      • University of Iowa Hospitals and Clinics

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 85 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Probability Sample

Study Population

40 Healthy volunteers. 110 patients with chronic constipation and dyssynergic defecation and rectal hyposensitivity and rectal hypersensitivity

Description

Inclusion criteria:

• Right-handed adults between ages 18 years and 99 years, who are free of bowel disorders or other medical illnesses.

Exclusion Criteria:

• Potential subjects with comorbid illnesses; severe cardiac disease, chronic renal failure or previous gastrointestinal surgery except cholecystectomy and appendectomy.
• Neurologic diseases e.g.; head injury, epilepsy, multiple sclerosis, strokes, spinal cord injuries.
• People who have metal in their skull or under the skull, or have metal in the back or hips.
• People who have a cardiac pacemaker, implanted defibrillator or medication pump.
• Impaired cognizance (mini mental score of < 15) and/or legally blind.
• Pregnant or likely to conceive during the course of the study. Women with potential for pregnancy must be willing to use contraceptive measures during the study.
• Previous pelvic surgery, rectocele repair, bladder repair, radical hysterectomy.
• Rectal prolapse or anal fissure or anal surgery.

Study Plan

How is the study designed?

Design Details

• Observational Models: Case-Control
• Time Perspectives: Prospective

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Healthy Volunteer; healthy volunteers will serve as controls. In each subject the cortical evoked potentials, transcranial motor evoked potentials and translumbosacral motor evoked potentials will be measured.	Procedure: Cortical Evoked Potentials; A probe with 2 ring electrodes is placed in the anorectum. A small amount of electric current is passed separately through the anal and rectal electrodes.. The cortical evoked potentials from the anal and rectal sites are measured.; Procedure: Transcranial motor evoked potentials; A probe with 2 ring electrodes is placed in the anorectum. A magnetic coil is placed on the scalp at the anorectal site on each side, and discharged using magnetic energy. The motor evoked potentials at the anal and rectal sites are measured.; Procedure: Translumbosacral motor evoked potentials; A probe with 2 ring electrodes is placed in the anorectum. A magnetic coil is placed on the back at the lumbar plexus and sacral plexus levels and discharged using magnetic energy. The motor evoked potentials at the anal and rectal sites are measured.
Constipated patients; Patients with chronic constipation and rectal hypersensitivity or hyposensitivity and/or dyssynergic defecation.In each subject the cortical evoked potentials, transcranial motor evoked potentials and translumbosacral motor evoked potential will be measured	Procedure: Cortical Evoked Potentials; A probe with 2 ring electrodes is placed in the anorectum. A small amount of electric current is passed separately through the anal and rectal electrodes.. The cortical evoked potentials from the anal and rectal sites are measured.; Procedure: Transcranial motor evoked potentials; A probe with 2 ring electrodes is placed in the anorectum. A magnetic coil is placed on the scalp at the anorectal site on each side, and discharged using magnetic energy. The motor evoked potentials at the anal and rectal sites are measured.; Procedure: Translumbosacral motor evoked potentials; A probe with 2 ring electrodes is placed in the anorectum. A magnetic coil is placed on the back at the lumbar plexus and sacral plexus levels and discharged using magnetic energy. The motor evoked potentials at the anal and rectal sites are measured.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Describe latencies and amplitudes between the brain and gut in healthy volunteers	Measurements & Analysis: The latency, inter-peak latency and amplitude of each component of the cortical evoked potentials will be averaged to obtain group mean data. Statistical Analysis: The paired t-test or Wilcoxon signed-rank test will be used to compare the latencies. Lumbosacral and Transcranial Magnetic Stimulation (TMS) Data and Statistical Analysis: Mean latency and mean amplitude for each individual will be calculated.	1 visit of 3 hours

Collaborators and Investigators

• Sponsor: Augusta University
• Investigators: Principal Investigator: Satish SC Rao, MD, PhD, Augusta University

Study record dates

Study Major Dates

• Study Start (Actual): August 1, 2005
• Primary Completion (Actual): December 1, 2015
• Study Completion (Anticipated): December 1, 2018

Study Registration Dates

• First Submitted: August 18, 2010
• First Submitted That Met QC Criteria: February 22, 2011
• First Posted (Estimate): February 23, 2011

Study Record Updates

• Last Update Posted (Actual): July 23, 2018
• Last Update Submitted That Met QC Criteria: July 20, 2018
• Last Verified: July 1, 2018

More Information

Terms related to this study

• Keywords: cortical evoked potentials, motor evoked potential responses
• Additional Relevant MeSH Terms: Signs and Symptoms, Digestive; Constipation
• Other Study ID Numbers: 5R01DK057100-2; 5R01DK057100 (NIH)