A type of inflammatory arthritis that usually begins before 40-years-old. If not treated, over the years, the spine will fuse in an abnormal bent-over posture, and the person will never be able to stand up straight. It usually affects the bottom of the spine, but can involve the neck.
The key symptom is spinal pain that is worst in the early morning on awakening, lasts an hour or more, & eases up somewhat throughout the day. Most muscle strains hurt more as the person moves around, but this is the opposite. Diagnosis is suspected if certain blood tests for inflammation are high (the sedimentation rate or CRP). X-rays may be positive; an MRI is better. The tests should look at the sacroiliac joint, not simply the spine.
Rheumatologists are specialists in treating this. The newer medicines have certain risks, but work very well. Older drugs barely helped with pain, and didn’t change the course of the disease.