Gout is a common inflammatory arthritis that is characterized by the deposition of monosodium urate crystals in the synovium. An estimated 6.1 million adults in the United States have gout.Monosodium urate crystals have decreased solubility at lower temperatures, and consequently, the most commonly affected sites are peripheral joints. Other crystalline arthropathies include pseudogout. Pseudogout is the deposition of calcium pyrophosphate dihydrate crystals in the joints or periarticular structures, which leads to inflammation in joints. Pseudogout shows similar clinical findings to gouty arthritis although tophi are exclusive to gout.
Occurrence of gout in the spine is rare, with little over 70 cases reported in the literature. Not all levels of the spine are equally likely to be affected. One review of the literature found that the lumbar spine was most commonly affected (56% of cases), followed by the cervical and thoracic spine, which both occurred in 22% of cases. Out of these cases, the most common presenting symptoms were nonspecific paraparesis (39.0%), radiculopathy (27.0%), and back pain (18.0%). Given the rare incidence and nonspecific presentation, an inclusion of gout in the differential diagnosis of atypical neurocompressive pathologies is necessary for diagnosis. In the spine, gout may affect the epidural space, ligamentum flavum, intervertebral disc, pedicles, facet joint capsule, and neural foramen. This may present as spinal stenosis, lumbar radiculopathy, spondylolisthesis, or cauda equina syndrome.
Biopsy is the gold standard in confirming the diagnosis. Histologic findings show a granulomatous infiltrate of multinucleated giant cells, histiocytes, and fibroblasts. In addition, specimens examined under polarized light microscopy demonstrate the characteristic needle-shaped crystals with negative birefringence of gout. High serum urate levels, a concomitant history of advanced renal disease, previous gout attacks (podagra), and the cutaneous manifestation of tophi all point to the diagnosis.