In the literature, we found only one study evaluating the thickness of the cervical paraspinal muscles (multifidus, semispinalis cervicis, semispinalis capitis, splenius capitis, and trapezius) in patients with AS. This study examined the morphology of all neck extensor muscles (multifidus, semispinalis capitis, semispinalis cervicis, splenius capitis, and trapezius muscles) using ultrasound and their relationship to activities of daily living and compared them with a control group. As is well known, the user's experience is crucial in ultrasound. Furthermore, ultrasound cannot accurately assess the deep paravertebral muscles. Therefore, inspired by this study, we decided to use Magnetic Resonance Imaging (MRI) to evaluate the cervical muscle planes in AS patients in more detailed and objective ways. In this study, in addition to cervical muscle volumes in AS patients, we also aimed to evaluate cervical fat infiltration and cervical alignment, which have not been previously evaluated in AS patients.

Inclusion Criteria:

• For the study group:
• Patients diagnosed with ankylosing spondylitis, aged 18-50.
• Patients who underwent a cervical MRI between January 2020 and September 2023. Control Group Patients aged 18-50 who underwent cervical MRI between January 2020 and September 2023 due to nonspecific neck pain, who did not have an AS diagnosis and whose cervical MRI was reported as normal.

Exclusion Criteria:

• Patients over 50 years of age
• History of spine surgery;
• Presence of pain, numbness, and weakness in the upper extremities
• History of cervical injury or neck injury
• Presence of tuberculosis, tumor, fracture, infection, instability, cervical myelopathy, cervical disc herniation (protrusion, extrusion) (will be considered cervical bulging)
• Presence of cervical radiculopathy
• Those with a detectable pathological spinal condition related to neck pain, including spinal deformity; inflammatory or rheumatic diseases other than AS, malignancies, or neurological diseases
• A cognitive or psychological disorder

For the study group:

• Patients diagnosed with ankylosing spondylitis, aged 18-50.
• Patients who underwent a cervical MRI between January 2020 and September 2023. Control Group Patients aged 18-50 who underwent cervical MRI between January 2020 and September 2023 due to nonspecific neck pain, who did not have an AS diagnosis and whose cervical MRI was reported as normal.