Background Axial gout is an atypical presentation characterized by the deposition of monosodium urate crystals in the spine. Unlike peripheral joints, spinal gout can pose diagnostic challenges due to its nonspecific presentation and the inability to obtain joint fluid for crystal analysis. This case highlights severe subacute back pain where dual-energy computed tomography (DECT) was crucial in diagnosing spinal gout.

Case Presentation A 73-year-old male with a history of gout, chronic kidney disease, hypertension, and hyperlipidemia presented with worsening subacute back pain. Initial MRI imaging revealed phlegmonous changes with elevated inflammatory markers. IR-guided drainage was performed, and the cultures were negative. He was treated with analgesics, resulting in symptom improvement. Two weeks later, he experienced worsening back pain, limiting his ambulation to using a wheelchair, and even the slightest movement exacerbated the pain. Repeat MRI imaging revealed features concerning osteomyelitis/discitis. Given the negative cultures, episodic nature of the disease, symptom improvement with NSAIDs, and elevated uric acid on admission, there was a high suspicion for gout and low suspicion for infection. A DECT scan of the lumbar spine was performed, showing monosodium urate crystal deposition with erosive arthritis consistent with lumbar spinal gout. The patient was started on allopurinol and colchicine, resulting in only mild improvement in back pain. As cultures were negative, infection was ruled out. He was then started on prednisone, resulting in significant pain relief.

Discussion Spinal gout can be confused with pathologies like vertebral osteomyelitis, malignancy, epidural abscess, and spondylarthritis. Features such as elevated inflammatory markers, fever, and leukocytosis are common to both infection and gout. MRI and CT can show phlegmonous changes and erosions, but these findings can be non-specific. DECT, using two energy levels of X-ray beams (80 kV and 140 kV), differentiates structures based on their attenuation characteristics. After post-processing, materials are color-coded for identification, with urate often coded green. DECT’s sensitivity and specificity for gout are 90% and 83%, respectively, and it can diagnose gout even with negative synovial fluid analysis. An accurate diagnosis with DECT helps avoid unnecessary interventions like biopsy and drainage. Early and accurate detection is crucial for preventing severe complications, including neurological deficits from the compressive effects of tophi. Sudden onset back pain, elevated uric acid, and improvement with NSAIDs should prompt consideration of spinal gout. Aggressive uric acid control is needed to avoid recurrence, with a target level of <6 mg/dL.

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