Sensory Afferents for Deep Pressure Sensation

Not Applicable

Completed

Conditions: Normal Physiology

Interventions: Behavioral: Deep pressure block

Registration Number: NCT03937778

Lead Sponsor: National Center for Complementary and Integrative Health (NCCIH)

Brief 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.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 7

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

Study Type: INTERVENTIONAL

Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Tourniquet block to left upper arm	Deep pressure block	Participants underwent \~10 minutes of baseline testing followed by a tourniquet placement to left upper arm and inflated to 80-100 mmHG above systolic blood pressure. Participants repeatedly rated a variety of sensory stimuli after tourniquet was placed. Participants rated intensity and pleasantness of slow brushing and deep pressure on both hands/forearms at baseline and after loss of A-beta sensation.

Primary Outcome Measures

Name	Time	Method
Difference Between Arms in the Change of Pressure Intensity From Baseline to After Loss of A-beta Sensation	From baseline to after loss of A-beta sensation, within one-hour session	Difference between left (blocked) and right (control) arms in the change from baseline to after loss of A-beta sensation from nerve block. Measurement of perceived pressure intensity was assessed using a visual analog scale ranging from "no sensation" (0) to "highest possible intensity" (100).

Secondary Outcome Measures

Name	Time	Method
Difference Between Arms in the Change of Brushing Intensity From Baseline to After Loss of A-beta Sensation	From baseline to after loss of A-beta sensation, within one-hour session	Difference between left (blocked) and right (control) arms in the change from baseline to after loss of A-beta sensation from nerve block. Measurement of perceived brushing intensity was assessed using a visual analog scale ranging from "no sensation" (0) to "highest possible intensity" (100).
Difference Between Arms in the Change of Brushing Pleasantness From Baseline to After Loss of A-beta Sensation	From baseline to after loss of A-beta sensation, within one-hour session	Difference between left (blocked) and right (control) arms in the change from baseline to after loss of A-beta sensation from nerve block. Measurement of perceived brushing pleasantness was assessed using a visual analog scale ranging from "no sensation" (0) to "highest possible intensity" (100).
Difference Between Arms in the Change of Pressure Pleasantness From Baseline to After Loss of A-beta Sensation	From baseline to after loss of A-beta sensation, within one-hour session	Difference between left (blocked) and right (control) arms in the change from baseline to after loss of A-beta sensation from nerve block. Measurement of perceived pressure pleasantness was assessed using a visual analog scale ranging from "no sensation" (0) to "highest possible intensity" (100).