Central Sensitization and Ultrasound in Lateral Epicondylitis

The pressure pain threshold is defined as the lowest pressure level that causes pain. The measurement will be taken from the anterior-medial region of the tibia (a distant, painless, and irrelevant area) using a Wagner manual pressure algometer (1 cm² probe-10 kg/20 lb). The measurement will be applied twice at 1-minute intervals, and the average of these applications will be recorded. A trial test will be conducted on the patient before the actual test. Pressure will be applied to the selected points with a pressure algometer until pain is induced, and the test in that area will be terminated when the patient feels pain.

CSI scores range from 0-100, with higher scores indicating greater severity of central sensitization-related symptoms.

The TSK consists of a total of 17 items, and individuals evaluate each item using a 4-point Likert scale (1=strongly disagree, 4=strongly agree). The total score obtained from the scale reflects the individual's level of kinesiophobia. Increasing TSK scores indicate an increase in avoidance behaviors and fear related to pain.

The PCS consists of a total of 13 items, and each item is evaluated on a 5-point Likert scale (0=never, 4=always). The total and subscale scores obtained from the scale reflect the individual's level of catastrophic thinking toward pain. High PCS scores indicate an increase in negative cognitive and emotional responses to pain.

To evaluate upper extremity functionality, it is a questionnaire specifically designed for patients with lateral epicondylitis, providing patient follow-up and being condition-specific, with scoring ranging from 0 (no pain/disability) to 100 (possible worst pain and disability), and containing pain and function sub-scales. The total score is calculated out of 100 by summing the pain and function subscales. Low scores indicate better function.

It is a 14-item self-report scale that quickly, reliably, and independently of medical conditions assesses patients' anxiety and depression symptoms over the past week.

The health-related quality of life of the participants will be evaluated using the Short Form-12 (SF-12) Quality of Life Scale. SF-12 is a 12-item self-report scale that assesses individuals' physical function, physical role limitations, pain, general health perception, vitality, social function, emotional role limitations, and mental health status over the past four weeks. From the scale, the physical component score (Physical Component Summary, PCS) and the mental component score (Mental Component Summary, MCS) are obtained.

Pressure pain threshold is defined as the minimal pressure level that causes pain. The measurement will be applied twice for each region with a 1-minute interval, and the average of these applications will be recorded. A trial test will be conducted on the patient before the actual test. Pressure will be applied to the selected point with a pressure algometer until pain is induced, and the test for that area will be terminated when the patient feels pain. The measurement will be taken from the symptomatic common extensor tendon area, and a Wagner manual pressure algometer (1 cm² probe-10 kg/20 lb) will be used.

The cross-sectional area of the radial nerve will be measured in the antecubital fossa and spiral groove. In the spiral groove, the measurement will be taken with the patient's arm resting on the table, the elbow bent at 90°, the forearm in a pronation position, and the hand loosely resting on the table, with the probe perpendicular to the arm axis and placed on the lateral side of the distal third of the humerus. If measuring from the antecubital fossa, the patient will have their arm resting on the table, elbow extended, and forearm in a supine position; the probe will be placed transversely to the arm axis at the front of the elbow flexion, observing the elbow joint space. The radial nerve, located between the brachioradialis muscle and the anterior brachialis muscle, will be visualized before it divides into two branches. Two measurements will be taken for the nerve cross-sectional area, and the average will be calculated.

For the measurement of common extensor tendon thickness, the probe will be placed on the lateral epicondyle, and the evaluation will be conducted with the elbow in 90 degrees of flexion and the forearm in mid-supination. To determine the evaluation point, a horizontal line of 1 cm will be placed from the upper edge of the lateral epicondyle. At this point, a vertical line will be drawn from the upper edge of the tendon tissue to the hyperechoic line of the humerus for measurement. The Sonosite M-Turbo device will be used for ultrasonography and it will be performed by a physical therapy and rehabilitation specialist with 10 years of experience.

It will be measured using a modified sphygmomanometer test (MST). a manual aneroid sphygmomanometer (gauge manometer + inflation bulb + cuff) will be used. First, the blood pressure measurement device will be transformed into a cylinder that the patient can comfortably grasp while resting. then the cuff will be inflated to 20 mmHg and the patient will apply maximum grip strength to the cuff. Grip measurements will be taken while the participant sits in a chair without armrests, with their feet supported, shoulders internally rotated, forearms in a neutral position, and elbows flexed at 90°. Before the assessment, information about the procedures and a trial will be conducted. They will be instructed to perform maximum isometric contraction for 5 seconds, and the highest force value (mmHg) will be recorded. The measurement will be taken 3 times with a 15-second rest interval, and the average will be calculated.