Outcome
Type |
Measure |
Description |
Time frame |
Safety issue |
Primary |
Modulation of Pressure Pain Threshold/Tolerance |
Pressure algometry is the most commonly used test for static mechanical pressure sensation in the skin and in deep tissues. Pressure algometers deliver a firm and quantifiable pressure through a flat base applied to the skin. The electronic pressure algometer that we will use (Wagner Instruments) is a hand-held algometer utilizing a pressure-sensitive strain gauge, covered by a 0.5 cm2 circular probe. The probe is covered with a soft polypropylene disk, to avoid injury to the skin. The pressure applied through the probe is transduced, amplified, and converted to electrical reading on a digital display. The pressure will be slowly increased (1 lb/s) and the participant will be asked to note when they first feel pain and when they want the pressure to stop , which will be recorded as the pressure pain threshold and tolerance, respectively. This process will be repeated on the trapezius and the forearm, alternating between sides of the body with 20 seconds between measurements. |
15 minutes |
|
Primary |
Modulation of Temporal Summation with Repeated Pinpricks |
Will be assessed using standardized weighted pinprick applicators using a range of forces (128 mN, 256mN and 512mN) which result in a painful sensation in most subjects. First, a single stimulation of the lower force pinprick will be applied to the dorsal aspect of the index finger between the first and second interphalangeal joints of each hand while resting palm down on the armrest, and then rated by the subject on a scale of 0-10. The weight probe that induces at least some pain, but not more than 3/10 pain will be determined, and this probe used for repeated testing. Then, a train of 10 stimuli will be applied at the same spot, at a rate of 1 stimulation/second. The subject will rate pain on a scale of 0-10 after the first, fifth and tenth stimulus, then rate any ongoing pain 15 seconds after cessation of the last stimulus (painful after-sensations). Temporal summation will be calculated as the change in pain score between the highest and lowest pain ratings in a train. |
15 minutes |
|
Primary |
Modulation of Temporal Summation with Pressure Cuff |
Will be assessed through response to cuff pressure algometry (CPA), in a similar manner to our previous studies.123 Tonic, deep-tissue, mechanical stimulation will be applied using a rapid cuff inflator (Hokanson) wrapped around the leg, centered around the middle of the gastrocnemius muscle. Pressure will then be increased at approximately 5-10 mmHg/s, at which time participants will be asked to note when they first start feeling pain and then when they feel as though the pain is a 5/10. At this point the cuff will be deflated. Participants will be given a 30 second break. The cuff will be re-inflated to this previously identified pressure and held for two minutes (or until participant asks to stop), at which point the cuff will be deflated. Participants will be asked to rate their pain every 30 seconds, as well as to rate any painful after sensations. Temporal summation will be calculated as the change in pain score between the highest and lowest pain ratings in the 2 minutes. |
15 minutes |
|
Primary |
Modulation of Heat Pain Threshold and Tolerance |
Heat pain responses will be assessed using a contact thermode, which delivers heat stimuli through a computer-controlled system (Medoc). The contact probe will be positioned on the skin and affixed in place on the volar aspect of the non-dominant forearm with a soft Velcro strap, after which an ascending method of limits paradigm will be employed, using a rate of rise of 2°C/sec, starting at a baseline of 35°C. For heat pain threshold, subjects are instructed to press a button when the thermal stimulation first becomes painful; pressing the button returns the thermode temperature to 35°C. Then the thermode will again increase in temperature, and this time the conductor will ask the participant to press the button when the thermal stimulation reaches 5/10 pain, which will return the thermode temperature to 35°C. |
15 minutes |
|
Primary |
Modulation of Heat Offset Analgesia |
In order to measure offset analgesia the thermode will be ramped up to a temperature that is 1 degree less than the temperature that they indicated produced 5/10 pain. The temperature will be held for 5 seconds and the participant will be asked to provide a pain rating from 0-10 at the timepoint approximately 2 seconds into the 5 second period. Then the temperature will ramp up 1 degree higher (to the patient's 5/10 temperature) and held for 5 seconds. The participant will be asked to provide a pain rating from 0-10 at the timepoint approximately 2 seconds into the 5 second period. Then the temperature will return back to 1 degree lower, be held here for 5 seconds, and the participant will be asked to provide a pain rating from 0-10 at the timepoint approximately 2 seconds into the 5 second period. Lastly, the thermode will return to baseline temperature, and be removed from the forearm. The conductor will ask for pain scores every 7 seconds for 21 seconds seconds(aftersensations). |
15 minutes |
|
Primary |
Modulation of Conditioned Pain Modulation |
CPM will be measured by adaptations of testing procedures used in our previous studies.
To measure CPM, pressure pain threshold and tolerance as measured earlier in the session will be compared to measurement in the presence of a conditioning stimulus (cold pain in hand). The participant will be asked to submerge their right hand (up to above the wrist) into a cold-water bath set at 6°C. Approximately 5 seconds after placing hand in cold water bath, a constant, increasing pressure (1lb/s) will again be applied to the contralateral trapezius with participant indicating when they start to feel pain (threshold) and when they want pressure to stop (tolerance). CPM defined as: CPM=((pressure pain in presence- pressure pain in absence of cold pain)/pressure pain in absence of cold pain)*100). Participants then asked to describe their worst cold pain, clinical pain, anxiety rating about testing and about the cold-water bath specifically, and if they experience any painful after sensations. |
15 minutes |
|
Primary |
Modulation of Anxiety |
Question assessing how much anxiety felt during session, using Likert Scale (0-10), with 0 being no anxiety and 10 being extremely anxious. |
10 Minutes |
|