Migratory Back Pain Mimicking Post-Intervention Infection Reveals Ankylosing Spondylitis: A Case Report

Case Diagnosis: A 37-year-old Uzbekistani male was initially misdiagnosed with post-intervention infection following spinal injections for back pain but was later diagnosed with ankylosing spondylitis (AS) after further evaluation.

Case Description or Program Description: The patient presented with severe migratory pain in multiple sites, including the posterior neck, lateral chest wall, mid-back, lower back, left buttock, and soles. Suspecting radiculopathy, he underwent medial branch blocks (MBB) with 10 mg of triamcinolone at the left L3-L4-L5 nerves, followed by dorsal root ganglion blocks (DRGB) with 5 mg of dexamethasone at both S1 nerve roots 2 months later due to persistent pain. 3 days post-DRGB, he developed low-grade fever ( < 38°C) and elevated C-reactive protein (CRP, 9.7 mg/L). He was transferred to a tertiary center for suspected iatrogenic infective spondylitis. Symptoms persisted despite prolonged, escalated antibiotic therapy and laminectomy with surgical debridement. Blood and intraoperative biopsy cultures were negative.
A subsequent MRI review confirmed sacroiliitis. Given his positive HLA-B27 and better response to nonsteroidal anti-inflammatory drugs (NSAIDs) than antibiotics, he was diagnosed with AS. While his symptoms improved significantly with NSAIDs, tumor necrosis factor-α (TNF-α) inhibitor therapy was initiated as well due to residual inflammation.

Setting: From primary care rehabilitation pain clinic to internal medicine department of tertiary care hospital

Assessment/Results: The patient’s symptoms and CRP levels improved significantly after TNF- α inhibitor initiation, leading to hospital discharge after 8 days of AS treatment.

Discussion (relevance): In primary care settings, it is appropriate to consider the common causes of back pain first. Similarly, when fever or signs of inflammation occur after injections, it is appropriate to rule out infection first. However, in both cases, when unusual treatment responses and persistent inflammation are observed, rheumatic diseases, including AS, should be considered.

Conclusions: Rheumatologic conditions such as AS should be considered in patients with atypical back pain and chronic inflammation unresponsive to spinal interventions and antibiotics.