Visceral Pain Sensation and Nav1.8
We wish to investigate the role of a specific gene in visceral pain sensation and perception. This gene, Nav1.8 has a known change present in 10% of the population which may affect the way we feel inflammatory pain in the gut. This is an important symptom in inflammatory bowel disease (IBD). Some patients feel high levels of pain we would like to control, other patients feel little to no pain in the presence of very active disease, which can lead to dangerously under-treated disease. In this study, we will use healthy volunteers of a known genotype for Nav1.8, and test their sensitivity using rectal balloon dilation. Research subjects will be asked to fast, skipping solid foods and opaque liquids for 6 hours before the testing. Usually this means skipping 1 meal. At the beginning of the study visit. they will use an over the counter enema to clear their rectum of any stool. Then. a trained physician on the research team will insert a thin, lubricated tube into the rectum, which will be inflated to specific pressures. Most of these tests will be designed to measure any change in sensation, then the need to use the toilet, followed by urgent need or discomfort, and lastly the lower threshold of pain. Patients will be able to stop testing at any time, should they become too uncomfortable. The testing takes between 1 and 1 and a half hours, and volunteers are compensated $200 for their time.
To simulate abdominal pain, we use a thin tube placed in the rectum that inflates a small balloon to very precise and safe pressures. Our bodies interpret these pressures (in ascending order) as the need to go to the bathroom; first just a little, then with increasing urgency and eventually discomfort and pain. During these experiments, we only measure the lower threshold of pain, and stop immediately when you tell us to stop. We have significant experience using this approach and we have found it consistently informative while causing the least amount of discomfort possible. The whole thing takes about an hour and we’re paying volunteers $200 for participating. We'll ask that you skip a meal before the study visit, and perform an over-the-counter enema at the start of the visit.
Had a colonoscopy in HMC health record within the past 6 months (UC or Crhon's) or 5 years (healthy control)
Healthy control: any diagnosed lower GI disease (such as IBS or active diverticulitis) or significant abdominal pain in the last 12 months.
Any peripheral neuropathy or neuromodulating/opioid medications
Any Autoimmune disease (except Crohn's disease or ulcerative colitis)