Self Cranial Electrical Stimulation (CES) for Pain in Older Adults With Knee Osteoarthritis (Self CES for Knee Pain)

The NRS total score ranges from 0 (no pain) to 100 (most intense pain imaginable).

The WOMAC ranges from 0 to 96, with higher scores indicating worse osteoarthritis (OA) pain-related symptoms

In order to measure experimental pain sensitivity, a multimodal Quantitative Sensory Testing (QST) battery will be completed: heat pain threshold (HPTH), heat pain tolerance (HPTO), pressure pain threshold (PPT), and Conditioned Pain Modulation (CPM).

To assess HPTH, heat stimuli were delivered to the participant's knee using a computer-controlled TSAII NeuroSensory Analyzer. From a baseline of 32 degrees Celsius, the temperature increased by 0.5 degrees Celsius per second until the participants responded by pressing a button to stop heat stimuli. Participants were instructed to press the button when the sensation ''first becomes painful" to assess the heat pain threshold (HPTH).

In order to measure experimental pain sensitivity, a multimodal Quantitative Sensory Testing (QST) battery will be completed: heat pain threshold (HPTH), heat pain tolerance (HPTO), pressure pain threshold (PPT), and Conditioned Pain Modulation (CPM).

To assess HPTO, heat stimuli were delivered to the participant's knee using a computer-controlled TSAII NeuroSensory Analyzer. From a baseline of 32 degrees Celsius, the temperature increased by 0.5 degrees Celsius per second until the participants responded by pressing a button to stop heat stimuli. Participants were instructed to press the button when they ''no longer feel able to tolerate the pain" to assess their heat pain tolerance (HPTO).

In order to measure experimental pain sensitivity, a multimodal Quantitative Sensory Testing (QST) battery will be completed: heat pain threshold (HPTH), heat pain tolerance (HPTO), pressure pain threshold (PPT), and Conditioned Pain Modulation (CPM).

To assess PPT, a handheld digital pressure algometer (Wagner, Greenwich, CT) was applied at a constant rate of 0.3 kilograms force per centimeter squared (kgf/cm^2) per second to the participant's knee. Participants were asked to notify the experimenter when the pressure sensation ''first becomes painful" to assess pressure pain threshold (PPT).

In order to measure experimental pain sensitivity, a multimodal Quantitative Sensory Testing (QST) battery will be completed: heat pain threshold (HPTH), heat pain tolerance (HPTO), pressure pain threshold (PPT), and Conditioned Pain Modulation (CPM).

CPM was assessed as the change in PPT on the trapezius immediately after the immersion of the contralateral hand up to the wrist in a cold-water bath (Neslab, Portsmouth, NH) at 12 degrees C for one minute. [To assess PPT, a handheld digital pressure algometer (Wagner, Greenwich, CT) was applied at a constant rate of 0.3 kilograms force per centimeter squared (kgf/cm^2) per second to the participant's trapezius. Participants were asked to notify the experimenter when the pressure sensation ''first becomes painful" to assess pressure pain threshold (PPT).]

The 7-item PROMIS Anxiety Short Form assesses the pure domain of anxiety in individuals age 18 and older, and each item on the measure is rated on a 5-point scale (1=never; 2=rarely; 3=sometimes; 4=often; and 5=always) with a range in score from 7 to 35 with higher scores indicating greater severity of anxiety.

The 8-item PROMIS Depression Short Form assesses the pure domain of depression in individuals age 18 and older, and each item on the measure is rated on a 5-point scale (1=never; 2=rarely; 3=sometimes; 4=often; and 5=always) with a range in score from 8 to 40 with higher scores indicating greater severity of depression.

The 8-item PROMIS Sleep Disturbance Short Form assesses the pure domain of sleep disturbance in individuals age 18 and older, and each item on the measure is rated on a 5-point scale (1=never; 2=rarely;3=sometimes; 4=often; and 5=always) with a range in score from 8 to 40 with higher scores indicating greater severity of sleep disturbance.

The Pain Catastrophizing Scale (PCS) consists of 13 items assessing three components of catastrophizing: rumination, magnification, and helplessness. It is measured using the 0 (not at all) to 4 (all the time) scale. Total score ranges from 0 to 52, with higher scores indicating greater pain catastrophizing.

Pain-related cortical response will be measured using a continuous-wave, multichannel fNIRS imaging system (LIGHTNIRS, Shimadzu, Kyoto, Japan) with three semiconductor lasers at 780, 805, and 830 nm. Optical recordings will be collected during thermal pain stimulation.

The CSQ-8 comprises eight items that are summed to yield an overall score of 8-32, with higher scores indicating greater satisfaction.

CES experience will be measured on a 10-item scale, with each item rated 0-10 and 0 being strongly disagree and 10 being strongly agree. Total score ranges from 0 to 100, with higher scores indicating a better CES experience.

Question 1. It was easy to prepare the device and accessories Question 2. The device was unnecessarily complex Question 3. The device was easy to use Question 4. I felt the video conferences with a technical person were helpful Question 5. I would imagine that most people would learn to use this device quickly Question 6. The device was cumbersome to use Question 7. I felt confident using the device Question 8. I needed to learn a lot of things before I could get going with this device Question 9. The effectiveness of the treatment increased over the course of treatment Question 10. I felt that transcranial electrical stimulation treatment benefited me

Measurement of presence and severity of possible side effects of treatment on a 0 (not at all) to 10 (highest degree) scale.If any side effects are reported, the degree of relatedness to the intervention will be assessed on a 5-point scale.