Crystalline spine: spinal gout causing back pain

A 54‐year‐old man was transferred to our unit for a magnetic resonance imaging (MRI) scan with a provisional diagnosis of spinal infection. He had initially presented with severe hip pain, but 2 weeks later he had lower back pain associated with fever, a white cell count of 13.1 and a C‐reactive protein of 191. A spinal computed tomography (CT) scan showed non‐specific irregularities of the L5/S1 disc. He also developed confusion, thought to be due to oxycodone treatment and inflammation of the right ankle, aspiration of which revealed urate crystals. There was a previous history of ankle gout but no history of risk factors for osteomyelitis, that is, intravenous drug use, ¹ extremes of age, pre‐existing inflammatory joint disease, immunosuppression or recent trauma. ²

On admission, he was afebrile; his right ankle was swollen and tender to palpation; his right knee was warm with an effusion. There was lower spinal tenderness, but neurological examination of his lower limbs was normal. Hip flexion was limited by pain. He did not have gouty tophi. His urate was low (<0.23).

Spinal MRI was ‘compatible with L5/S1 discitis/osteomyelitis’. No tophi were seen on CT or MRI.

Spinal, infectious disease and rheumatology consults were sought to consider the relative contributions of infection and gout. A unifying diagnosis of polyarticular gout including the spine was felt by all three consulted units to be unlikely.

A CT‐guided disc biopsy specimen did not grow any organisms. Despite the negative consults and resistance from the laboratory, the biopsy material was eventually examined and found to be positive for urate crystals. Even then, consulting teams continued to suggest ongoing IV antibiotics, and the patient received further doses of ceftriaxone prior to cessation by the home team.

The patient subsequently fully recovered, apart from mild residual ankle discomfort, with exposure to colchicine, ibuprofen and steroids. He has follow‐up in the gout clinic.

In Australia, there is only one case of spinal gout described in the literature ³ (88 cases worldwide ⁴ ). In this case, a 41‐year‐old male with a history of gout presented with severe thoracic pain and fevers. MRI scan was consistent with infection, and diagnosis was made with biopsy.

On the other hand, a study of non‐acute patients with poorly controlled gout showed CT evidence of spinal involvement in 35% of cases. ⁵

Our case was not atypical in that the symptom of back pain occurred in the context of earlier pain in other joints during this episode. However, the absence of positive microbiology and the patient's progress with minimal, interrupted antibiotics rendered unlikely the diagnosis of sepsis with incidental gout. A dual energy CT scan was not necessary in our case but may have also aided diagnosis. ⁶

Our experience suggests that familiarity with spinal gout remains low and supports claims that it may be underdiagnosed. ⁵ We therefore encourage the consideration of gout in the differential diagnosis of spinal infection even with suggestive radiological findings, particularly in patients with gout, no risk factors for infection or negative microbiology.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.