Central Sensitization and Clinical Parameters in Chronic Neck Pain

Central sensitization was assessed using the CSI, a tool applicable in cases of chronic pain. The CSI has two parts. Part A evaluates symptoms and is scored from 0 to 100; higher scores reflect greater central sensitization. A score of 30 or higher suggests the presence of central sensitization. Part B asks if the individual has ever been diagnosed with any central sensitization syndromes.

Pain intensity will be assessed using the Visual Analog Scale (VAS). The VAS is commonly employed in clinical practice because it is simple to use and consistent. The scale ranges from 0 to 10, where "0" indicates no pain and "10" signifies the worst possible pain. Patients are informed that pain severity increases from 0 to 10 and are asked to mark the number that best reflects their pain level.

Pain catastrophizing was measured with the PCS. This 13-item self-report questionnaire includes three subscales: rumination, magnification, and helplessness. Higher scores indicate more pain and greater functional impairment, with a total score above 30 signifying a clinically significant level of pain catastrophizing.

Participants' neck disability levels were evaluated using the Neck Disability Index (NDI).

The scale includes 10 items that address neck pain intensity, personal care, lifting, reading, headaches, concentration, driving, sleep, and recreational activities.

Each item is scored from 0 to 5. The total score ranges from 0 to 50, with higher scores indicating greater disability.

Disability levels are classified as follows:

0-4: No disability

5-14: Mild disability

15-24: Moderate disability

25-34: Severe disability

35 and above: Complete disability

Sleep quality was measured using the Pittsburgh Sleep Quality Index (PSQI). The PSQI was created by Buysse et al. in 1989. The scale's validity and reliability in Turkish were tested by Agargün et al. in 1996.

The questionnaire features 24 items related to both nighttime and daytime sleep. Nineteen items are self-rated, while five are answered by a bed partner or roommate. The five partner-rated items and the question asking whether the person has a sleep partner or roommate are not included in the scoring.

Responses are rated on a 0-3 scale:

0 = Not during the past month

• = Less than once a week
• = Once or twice a week
• = Three or more times a week

Eighteen of the 24 items are scored, resulting in a total score from 0 to 21. A score of 5 or below indicates good sleep quality, while a score above 5 suggests poor sleep quality.

The Jaw Functional Limitation Scale-20 (JFLS-20) will be used to assess the level of temporomandibular joint function in individuals. The JFLS-20 is a questionnaire designed to measure disability in people with temporomandibular disorders.

Each item is scored on a scale from 0 to 10, where 0 indicates no limitation and 10 indicates severe limitation. The total score ranges from 0 to 200, with higher scores indicating greater impairment. The JFLS-20 is a valid and reliable tool for clinical use.

Pressure pain sensitivity will be assessed using a digital pressure pain threshold (PPT) algometer (Wagner Instruments, Greenwich, USA). Measurements will be taken bilaterally from the upper trapezius, sternocleidomastoid, masseter, and temporalis muscles.