Sensory Afferents for Deep Pressure Sensation
Condition: Normal Physiology
Study type: Interventional

Summary: 
      Background:

      Much is known about how people perceive light touch, temperature, and pain. But less is known
      about how deep pressure is perceived. Deep pressure is an important part of many touch
      therapies, like massage therapy. Researchers want to learn more to help people with chronic
      pain and other disorders.

      Objective:

      To find out which sensory nerve fibers are involved in feeling the sensation of deep
      pressure.

      Eligibility:

      Healthy people ages 18 50 enrolled in study number 16-AT-0077

      Design:

      Participants will be screened under study number 16-AT-0077

      Participants will have 1 visit that lasts about 2 hours.

      Participants will have a brief medical interview. They will have a urine test.

      Participants will have ischemic nerve block on 1 arm. A blood pressure cuff will be inflated
      until the arm is numb for up to an hour.

      Participants will have tests to see how they perceive different sensations. They will rate
      gentle brushing on the hands and forearms. They will rate gentle pressure squeezing from a
      hand massager on the hands and forearms.

      Participants will receive other sensations such as vibration, cool, warm, pinprick without
      piercing the skin, finger movement, and pressure. They will be asked to rate or respond to
      the sensations. They will be asked to rate any pain or discomfort from the nerve block on an
      ongoing basis.
    

Detailed description: 
      Objective:

      The sensory basis of non-painful deep pressure sensation is not known. We recently found that
      innocuous pressure sensation is eliminated in rare sensory neuronopathy patients with a
      specific loss of A-beta fibers, strongly suggesting that A-beta fibers underlie the ability
      to sense deep pressure. In addition, we and others have shown that deep pressure touch
      (observed in hugs and massage) frequently conveys a sense of pleasantness. The current study
      aims to examine the role of A-beta fibers in the perception of deep pressure touch including
      both its intensity and the pleasant affect it often elicits. This study constitutes the
      second study of the K99 phase of a K99/R00 grant application awarded to Dr. Laura Case by
      National Center for Complementary and Integrative Health (NCCIH).

      Study Population:

      Up to 24 healthy participants will be enrolled in the study with a goal of 12 completers.
      Participants will be invited based on previous screening and participation in our studies.

      Design: Participants will undergo an ischemic-compression block. Sensory stimuli will be
      administered at frequent intervals to capture the loss of sensation related to A fibers as
      the block progresses. Before and after A-beta-associated sensations have been lost, the
      perception of deep pressure will be tested. Participants will rate the intensity and
      pleasantness of the pressure. Ratings of pain and discomfort will be collected throughout the
      study session.

      Outcome measures: Primary outcome; Rating of intensity of deep pressure on the blocked arm
      before versus after loss of A-beta sensation, compared to ratings on the unblocked arm.

      Secondary outcomes: 1) Rating of pleasantness of deep pressure on the blocked arm after loss
      of A-beta sensation, compared to ratings on the unblocked arm; 2) Ratings of intensity and
      pleasantness of gentle brushing on the blocked arm after loss of A-beta sensation, compared
      to ratings on the unblocked arm.
    

Intervention name(s): Deep pressure block
Intervention type(s): Behavioral
Intervention description(s): Apply deep pressure block by using blood pressure cuff.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Somatosensory