Defining Central Circuits of Pain
Condition: Dyspepsia
MeSH terms: Dyspepsia
Study type: Interventional

Summary: 
      The purpose of the study is to use functional Magnetic Resonance Imaging (MRI) to help us
      understand what parts of the subject's brain are involved when he experiences visceral pain,
      or pain in the gut. To stimulate the brain, he will be infused with a liquid meal (Ensure)
      into his stomach until he is maximally full. Magnetic resonance imaging (MRI) is a technique
      for making images (pictures) of the brain; it uses magnetic fields and radio waves and is not
      harmful. This study uses a new investigational technique called functional MRI (fMRI), which
      is a very fast MRI technique that will allow the investigators to evaluate changes in how
      blood flows to parts of his brain.
    

Detailed description: 
      Dyspepsia, a condition characterized by upper abdominal discomfort, is one of the most common
      types of pains in clinical practice and is one of the most common reasons for visits to
      primary care physicians and gastroenterologists. But relative to somatic pain, little
      fundamental information is known about visceral pain syndromes such as dyspepsia and
      irritable bowel syndrome. Recent exciting advances in neuroimaging such as functional
      magnetic resonance imaging (fMRI) have allowed investigators to interrogate neural signal
      changes in humans in a wide variety of pain conditions. But to date neuroimaging has not
      provided details of activation in specific neural circuits that are important in visceral
      pain. In these experiments we will focus on specific regions of interest (ROI's) that have
      shown to be relevant in animal models of pain circuitry including the dorsal column nuclei,
      the thalamus, the hypothalamus, the amygdala and the periaqueductal gray.

      The specific aims of our proposed project are:

        1. To measure fMRI signal in primary visceral afferent pain pathways (dorsal column nuclei
           and thalamus) in normal human subjects and in patients with dyspepsia following
           instilling a liquid meal at a fixed rate into the stomach until maximal satiety, a
           surrogate model of dyspepsia.

        2. To measure fMRI signal in autonomic pathways (hypothalamus and amygdala) and in
           endogenous analgesic pathways (periaqueductal gray/PAG) in normal human subjects and in
           patients with dyspepsia using the above model.

        3. To correlate physiological parameters (heart rate, skin conductance, respiratory rate)
           to hedonic ratings (ratings on a visual analogue scale of satiety, nausea, bloating, and
           pain) during the liquid meal stimulus in normal human subjects and patients with
           dyspepsia.

      In all these experiments we will correlate alterations in psychophysical measures which have
      traditional measures of pain response (e.g., pain and other hedonic ratings, physiological
      monitoring such as heart rate, etc) with the changes in fMRI signal in specific areas of the
      brain.
    

Intervention name(s): fMRI
Intervention type(s): Procedure
Intervention description(s): A liquid meal (Ensure 1Kcal/cc) will be infused into the stomach via a nasogastric tube at a rate of 60cc/min till the subject reaches maximal satiety. The amount of liquid meal will differ per subject.
Allocation: Non-Randomized
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Diagnostic
Keywords: Dyspepsia, fMRI