Background:
PIEZO2 Deficiency Syndrome (PDS) is a genetic disorder that affects a person s ability to feel touches and pain. Researchers want to know more about how PDS changes nerve function.
Objective:
To compare nerve function in people with PDS to that in people without PDS.
Eligibility:
People aged 18 years and older with PDS enrolled in protocol 16-AT-0077. Healthy volunteers are also needed.
Design:
Participants will have at least 1 clinic visit. They will undergo a test that measures activity in the nerves.
For the test:
Participants will place their arm or leg in a comfortable position.
Ultrasound will be used to locate nerves. A smooth wand will be slid over the skin to capture images of the structures below.
Two thin needles will be inserted through the skin. These needles are much smaller than the kind used to draw blood.
The needles will record nerve activity as different sensations are applied to the skin. These include mild electrical pulses; heat and cold; bending of the knee or elbow; vibration; air puffs; pulling a hair; and tapping, stroking (brushing), stretching, pinching, and pushing on the skin at different levels of force.
Each test takes 5 to 10 minutes. Participants will describe the sensations they feel.
Participants may opt for an additional test that measures how nerves respond after heat pulses are used to create mild redness on the skin.
Researchers would like at least 2 tests from each person. Participants may return for up to 3 additional visits, if desired, to complete all the testing.
Stated willingness to comply with all study procedures and availability for the duration of the study
Male or female, aged 18 years and over.
The ability to provide written informed consent.
Enrolled in 16-AT-0077, "Clinical and Scientific Assessment of Pain and Painful Disorders".
Difficulties with communication that make subjective innocuous and pain assessments impossible or unreliable.
Unable to comply with study procedures or visits.
Has a dermatological condition that might influence cutaneous sensitivity.
Congenital limb deficiency or amputation of any limb.
All participants will be screened and selected from an existing NCCIH protocol, 16-AT-0077. PDS participants will be referred to 16-AT-0077 for screening from an existing NINDS protocol, 12-N-0095.
Case-control
Cross-sectional
Not listed
Firing rate (Hz) in response to fast and slow brushing.
PDS patients have major deficits in touch detection. Therefore, we predict the response (firing rate) to gentle brush stimuli to be reduced by at least 50% (compared to healthy controls), corresponding to decreased sensitivity to mechanical stimuli. The neural measure of firing rate (Hz) captures both the magnitude of the response and its temporal pattern and has been shown to reliably distinguish between normal and pathological responses and the effects of pharmacological manipulations.
Firing rate (Hz) in response to other sensory modalities, e.g., thermal, and other mechanical stimuli.
Our secondary endpoint is the emergence of a differential effect of the loss of PIEZO2 on mechanoreceptor subclasses. Mechanoreceptor subclasses will be identified using established criteria (e.g., stimulus sensitivity, receptive field size, spike morphology and axon conduction velocity). The effect of the loss of PIEZO2 on the responsiveness of single-unit subclasses will be quantified by firing rate measures on single-unit data. In addition, the percept evoked to intraneural electrical stimulation of single-unit subclasses will be noted.
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