The Relationship Between Magnetic Resonance Imaging (MRI) Scores and Sensory Testing in Axial Spondyloarthritis

The sacroiliac PPT scores will be obtained bilaterally from four measurement points; the first point is located 1 cm medially and caudally from spina iliaca posterior superior (SIPS) and 3 more laterally, medially and cranially.The left trapezius muscle will be used to evaluate distant control point .The 1 cm2 algometer probe will be placed vertically in the each selected point and pressure will be increased with 0.1 kg/sc until the participant reporting pressure became painful. The pressure value at which the pain is first felt will be accepted as the PPT of that point.

Standardized questionnaire to determine the level of central sensitization

SPARCC scoring consists of two subcomponents to detect sacroiliitis activation and structural damage. In the short tau inversion recovery (STIR) sequence, 6 consecutive coronal sections will be examined and the signal increase will be scored as 0 = normal signal and 1 = increased signal. In this way, the maximum score can be 12 in a single coronal section. Evaluations Total maximum score of 72 in 6 consecutive coronal sections. In structural scoring, similar to sacroiliitis scoring, the SI joint is divided into four quadrants to evaluate whether there is fatty change, erosion, backfill and ankylosis. Each lesion is scored as 0=absent or 1=present. In this way, fatty change and erosion can be scored between 0-40 and backfill and ankylosis can be scored between 0-20 in 5 consecutive sections in total scoring.

TS will be evaluated over the trapezius muscle and sacroiliac joints with manuel algometer. In the evaluation of TS, a pressure as much the PPT value of each point will be applied with pain pressure algometer ten times with a 1-second interstimulus interval. Patients will be asked to rate their pain using on a 0 to 10 visual analogue scale (VAS) at 0, 5, and 10 seconds. TS will be calculated by subtracting the rating at 0 seconds from the rating at 10 seconds. The point that is located 1 cm medially and caudally from SIPS was used for SI joint TS measurement on both sides.

First stimulus will be applied to trapezius with the pressure that induced a pain intensity of 4 point on a 10 point VAS as called a test stimulus. After that the right hand of the patient will be immersed in 7 Celsius water for 20 seconds to create a conditioning stimulus. Second test stimulus with the same intensity of first one will be applied to trapezius after the conditioning stimulus and patients will be asked to rate their pain. If the patients cannot hold their hand in the water for 20 seconds, the test stimulus will be applied immediately after the patients removed their hands out of water. The ratio between the first and second VAS values multiplied by 100 will be defined as CPM score