Conventional TENS will be applied for 20 minutes. The cathode will be placed on the carpal ligament, and the anode electrodes on the palmar area of the hand, with a layer of conductive gel applied to the area (the set will be turned on for 20 minutes)..

The transcranial stimulation will be applied by a constant current device (tdcs) with an intensity of 2 mA for 20 minutes (the set will be turned off after 30 seconds).

Conventional TENS will be applied for 20 minutes. The cathode will be placed on the carpal ligament, and the anode electrodes on the palmar area of the hand, with a layer of conductive gel applied to the area (the set will be turned off after 30 seconds).

A simple and objective tool, primarily designed to screen for neuropathic pain, differentiating between neuropathic and nociceptive pain conditions in clinical practice and research studies. In total, it contains 10 questions with a binary answer (no/yes). The total score, ranging from 0 to 10, is obtained by adding the number of affirmative answers, a total score > 4 out of 10 suggests neuropathic pain.

A simple and objective tool, primarily designed to screen for neuropathic pain, differentiating between neuropathic and nociceptive pain conditions in clinical practice and research studies. In total, it contains 10 questions with a binary answer (no/yes). The total score, ranging from 0 to 10, is obtained by adding the number of affirmative answers, a total score > 4 out of 10 suggests neuropathic pain.

The Semmes-Weinstein Monofilament test kit will be used to evaluate sensory thresholds of the tips of the thumb, the index, and the middle fingers. The kit consists of 20 flexible nylon monofilaments of varying diameter and length to measure the level of skin touch sensation. The monofilaments have log numbers from 1.65 to 6.65 which begins with the light filaments (1.65-3.61) and progresses to heavy filaments of increasing diameter (3.84-6.65). Heavy filaments need increased pressure for touch to be recognized by patients. The tester applies each monofilament to the surface area of the skin with a perpendicular angle, then applies slight and steady pressure until the monofilament begins to bend, which is the end point of the test. The monofilament number 2.83 was defined as cut-off for normal sensation.

The Semmes-Weinstein Monofilament test kit will be used to evaluate sensory thresholds of the tips of the thumb, the index, and the middle fingers. The kit consists of 20 flexible nylon monofilaments of varying diameter and length to measure the level of skin touch sensation. The monofilaments have log numbers from 1.65 to 6.65 which begins with the light filaments (1.65-3.61) and progresses to heavy filaments of increasing diameter (3.84-6.65). Heavy filaments need increased pressure for touch to be recognized by patients. The tester applies each monofilament to the surface area of the skin with a perpendicular angle, then applies slight and steady pressure until the monofilament begins to bend, which is the end point of the test. The monofilament number 2.83 was defined as cut-off for normal sensation.

Pressure pain threshold (PPT) is defined as the minimal amount of pressure where a sense of pressure first changes to pain. An electronic algometer will be used to measure PPT levels. The algometer consists of a 1 cm2 rubber-tipped plunger mounted on a force transducer. The pressure is applied approximately at a rate of 30 kPa/s, with the algometer placed perpendicular to the application point. Participants will be instructed to press switch when the sensation changed from pressure to pain. The mean of three trials (intra-examiner reliability) will be calculated and used for main analysis. A 30 s resting period will be allowed between each measure.

Pressure pain threshold (PPT) is defined as the minimal amount of pressure where a sense of pressure first changes to pain. An electronic algometer will be used to measure PPT levels. The algometer consists of a 1 cm2 rubber-tipped plunger mounted on a force transducer. The pressure is applied approximately at a rate of 30 kPa/s, with the algometer placed perpendicular to the application point. Participants will be instructed to press switch when the sensation changed from pressure to pain. The mean of three trials (intra-examiner reliability) will be calculated and used for main analysis. A 30 s resting period will be allowed between each measure.

A CPM paradigm with the cold pressor test will be was used. Participants will submerge one foot into an insulated container filled with cold water with the medial malleolus ~3 cm below the water line. The foot contralateral to the affected hand (or most affected hand in case of bilateral CTS) will be submerged. Participants will rate the cold-induced foot pain on a numric pain rating scale (NPRS), ranging from 0 (no pain) to 10 (worst pain imaginable). Immediately after maintaining the NPRS within the target score for 30 seconds, the test stimulus will be given. Pressure pain threshold (PPT) testing will be applied as a test stimulus. PPTs will be measured with a digital algometer. The participants will press a button as soon as the sensation of pressure changed to pain. PPT measurements will be taken on the thenar and hypothenar eminence of both hands, before cold water immersion and during cold water immersion.

A CPM paradigm with the cold pressor test will be was used. Participants will submerge one foot into an insulated container filled with cold water with the medial malleolus ~3 cm below the water line. The foot contralateral to the affected hand (or most affected hand in case of bilateral CTS) will be submerged. Participants will rate the cold-induced foot pain on a numric pain rating scale (NPRS), ranging from 0 (no pain) to 10 (worst pain imaginable). Immediately after maintaining the NPRS within the target score for 30 seconds, the test stimulus will be given. Pressure pain threshold (PPT) testing will be applied as a test stimulus. PPTs will be measured with a digital algometer. The participants will press a button as soon as the sensation of pressure changed to pain. PPT measurements will be taken on the thenar and hypothenar eminence of both hands, before cold water immersion and during cold water immersion.

Patient's Clinical Global Impression of Change scale, subjects select one of seven options describing response to treatment, ranging from 1-7 where 1 indicates "very much improved" and 7 indicates "very much worse.".

Patient's Clinical Global Impression of Change scale, subjects select one of seven options describing response to treatment, ranging from 1-7 where 1 indicates "very much improved" and 7 indicates "very much worse.".

To assess quality of Life, it consists of 36 items divided into eight domains range from reflecting predominantly physical well-being, that include physical function, the ability to perform expected physical roles, the degree of bodily pain and overall sense of general health to those reflecting predominantly social and emotional well-being that include overall sense of vitality, ability to function in social roles, ability to perform expected emotional and social roles and overall sense of mental health. Each item has 5 response choices, a high score (response choice 5) and a low score (response choice 1).

To assess quality of Life, it consists of 36 items divided into eight domains range from reflecting predominantly physical well-being, that include physical function, the ability to perform expected physical roles, the degree of bodily pain and overall sense of general health to those reflecting predominantly social and emotional well-being that include overall sense of vitality, ability to function in social roles, ability to perform expected emotional and social roles and overall sense of mental health. Each item has 5 response choices, a high score (response choice 5) and a low score (response choice 1).

A self-assessment scale in which subjects rate their own emotions, including anxiety, depression, stress, and sleepiness along a 100 mm line.

A self-assessment scale in which subjects rate their own emotions, including anxiety, depression, stress, and sleepiness along a 100 mm line.

Cognition will be analyzed using Mini-Mental Status Examination, a brief screening of cognitive abilities.

Cognition will be analyzed using Mini-Mental Status Examination, a brief screening of cognitive abilities.

At each stimulation session and all follow-ups, participants will be administered a questionnaire to evaluate the potential adverse effects of stimulation on a 5-point scale from 0-4 (0 indicates no adverse events and 4 indicates extreme adverse effects. The main potential adverse effects include headache, neck and scalp pain, tingling, sleepiness, and acute mood change.