A 34-year-old man complained of inflammatory back pain, alternating buttock pain and restriction in spinal mobility. Therefore, the man was referred for a full spine MRI examination.
Sagittal T1-weighted (Fig. 1) MR image shows a high-signal intensity in the intervertebral disc space of T8-T9. At the same level at the posterior aspect, there is a syndesmophytic ankylosis. All other intervertebral discs show a normal signal intensity and there are no abnormalities in vertebral stature, alignment and bone marrow signal.
Background:
Ankylosing spondylitis (AS) belongs to the family of spondyloarthritis (SpA). It is a chronic inflammatory disease causing axial arthritis, frequently resulting in inflammatory low-back pain and alternating buttock pain early in the disease course. Eventually, severe impairment of spinal mobility occurs, due to structural changes ultimately leading to fusion (ankylosis) of the spine and sacroiliac joints.
There is a male predilection and it usually manifests in young adults, with the first symptoms often becoming evident in the third decade. [1-5]
Clinical Perspective:
Ankylosing spondylitis predominantly affects the spine and sacroiliac joints by inflammation. Since magnetic resonance imaging (MRI) allows for early detection of inflammatory changes, it is the first choice of imaging for early diagnosis of ankylosing spondylitis. [1-3] If untreated AS may cause significant morbidity as the structured lesions will progress. Early diagnosis is particularly important as newer therapies are able to contain this condition and even induce remission. [3] When a physician has a patient with a suspected diagnosis he should refer for MRI. [1,3]
Imaging Perspective:
The key findings on MRI are localised in the spine and sacroiliac joints. Namely inflammatory or fatty Romanus lesions of the spine (early spondylitis), a high-signal intensity on T1-weighted MR images in the intervertebral disc associated with new bone formation, syndesmophytes, diffuse syndesmophytic ankylosis ("bamboo spine"), Andersson lesion and sacroiliitis [1,2,4].
The T1-weighted high-signal intensity in the intervertebral disc and the syndesmophytic ankylosis in combination with the clinical presentation (male, 34-year-old, inflammatory back pain, alternating buttock pain and restriction in spinal mobility) lead to the diagnosis of ankylosing spondylitis.
Take Home Message / Teaching Points:
When present in a patient with inflammatory back pain, an intervertebral disc high-signal intensity on T1-weighted MR images can be a sign of the presence of ankylosing spondylitis. [1,2]
Written patient consent for this case was waived by the Editorial Board. Patient data may have been modified to ensure patient anonymity.
Ankylosing spondylitis
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In the MRI examination of the patient’s spine, the main observations are as follows:
• T1WI hyperintensity is noted in certain sub-endplate or intervertebral disc regions, suggesting fatty infiltration or inflammatory changes;
• Mild signal abnormalities may appear at the vertebral margins, indicating chronic inflammation of the vertebral bodies and the facet joints;
• Possible local enthesitis at ligament attachment sites, requiring correlation with clinical symptoms and comparison with other imaging sequences;
• No evident vertebral collapse or severe structural destruction is observed, and no clear fracture is seen.
Based on the patient’s clinical presentation (inflammatory lower back pain, alternating buttock pain, limited spinal mobility) and the T1 hyperintense findings seen on MRI, the following differential diagnoses are considered:
1) Ankylosing Spondylitis (AS):
• Typically presents in young adult males with chronic inflammatory back pain, sacroiliitis, and a “bamboo spine” appearance;
• Early MRI findings may include inflammatory edema or fatty infiltration at the vertebral endplates, often showing T1WI hyperintense Romanus lesions.
2) Other Spondyloarthropathies (e.g., psoriatic arthritis, reactive arthritis, arthritis related to inflammatory bowel disease):
• May also involve the sacroiliac joints and the spine but are often accompanied by other characteristic skin, intestinal, or urogenital clinical features;
• Imaging can resemble AS, requiring clinical differentiation.
3) Infectious Spondylitis:
• Usually presents with pronounced destruction of the vertebral body or intervertebral disc, often accompanied by soft tissue abscess or marked enhancement;
• Current imaging lacks typical signs of infection, but clinical evaluation is needed to rule out etiologies causing vertebral and disc inflammation.
Considering the patient’s age (34 years), gender (male), clinical symptoms (inflammatory back pain, alternating buttock pain, decreased spinal mobility), and MRI findings (T1WI hyperintensity in the intervertebral disc area, possible early new bone formation, or fatty infiltration remodeling), the most likely diagnosis is:
Ankylosing Spondylitis (AS).
For further confirmation, additional tests such as sacroiliac joint MRI, HLA-B27 gene testing, and inflammatory markers (CRP, ESR) may be utilized.
(1) Treatment Strategy
• Medication: Nonsteroidal anti-inflammatory drugs (NSAIDs) are the first choice to relieve pain and suppress inflammation. For high disease activity or inadequate response to conventional therapy, biologics (e.g., anti-TNF-α agents or IL-17 inhibitors) can be considered to control disease progression, supplemented by disease-modifying antirheumatic drugs (DMARDs) if necessary.
• Physical Therapy: Modalities such as heat therapy and physical therapy can help reduce local inflammation and relax muscles.
• Surgical Indication: In cases of severe spinal kyphosis or significant loss of joint function, corrective surgery may be considered; however, conservative or medical management is generally preferred.
(2) Rehabilitation/Exercise Prescription
Based on the FITT-VP principle (Frequency, Intensity, Time, Type, Progression), the following is recommended:
• Frequency: Engage in rehabilitation exercise 3–5 times a week. Depending on individual tolerance, gradually increase to moderate daily exercise.
• Intensity: Light to moderate intensity (e.g., Borg scale of perceived exertion of 2–4). Avoid sudden high-load activities.
• Time: Each session can last 20–30 minutes, which can be broken down into segments (e.g., 10-minute sessions of stretching or posture correction exercises).
• Type: Start with gentle range-of-motion, stretching, and balance training, progressing to core strengthening exercises. Avoid excessive impact activities.
• Progression: As symptoms improve and function increases, add low-impact aerobic exercises (swimming, elliptical training, cycling), gradually increasing exercise intensity and duration. Monitor joint and spinal tolerance.
Throughout the rehabilitation process, close attention should be paid to bone health and exercise safety. Emphasize proper exercise form and adequate rest intervals, and avoid high-intensity training during acute inflammatory phases.
This report is a reference-based analysis derived from the current imaging and clinical information available and does not replace in-person medical consultation or professional physician advice. If questions arise, it is recommended to promptly consult specialists in rheumatology, orthopedics, or radiology to obtain an individualized diagnosis and treatment plan.
Ankylosing spondylitis
