Background Axial gout was first described in 1950, and, since then, only a few anecdotal cases with severe neurological manifestations and adverse outcomes have been reported. Although traditionally considered to be rare, some evidences suggest that axial lesions due to gout might be more common than previously thought. The true relationship of these lesions to symptoms or other gout-associated features is poorly understood.
Objectives We, therefore, aimed to describe the frequency of axial skeleton lesions in gout patients and to analyze the possible association of tomographically-identified axial gouty lesions and patients’ clinical or physiopathological characteristics.
Methods Forty-two patients with gout diagnosed according to the 1977 ACR criteria underwent thoracic and lumbar spine computerized tomographic (CT) scans. CT scans were read by an experienced radiologist who was blinded to the clinical features of the patients. Axial gout was defined when specific gout features such as bony erosions, facet joints or disc calcification and tophi were present in the axial skeleton. Patients were included and underwent the scans in a prospective fashion, and a cross-sectional analysis of data was performed. Epidemiologic and clinical data were collected from chart reviews. All patients were questioned about axial symptoms (back pain or neurological complaints) and examined clinically, in the inclusion visit, for subcutaneous tophi. Urate hypoexcretion was defined as a urate clearance of less than 7.5 ml/min. Hyperuricemia was defined as a serum uric acid higher than 7.0 mg/dL for men or higher than 6.0 mg/dL for women. Chi-square, Fisher’s exact test and Student’s T test were performed for statistical analyses of association between variables.
Results Patients were mainly male (93%). Mean age was 62.7 ± 11.1 years. Twelve (29%) of the 42 patients had CT evidence of axial gout, with axial tophi being identified in 5 (12%) subjects, interapophyseal joints erosions or calcifications in 7 (17%) and discal abnormalities (erosions or calcifications) in 9 (21%) subjects. Lumbar spine was always affected. Five (42%) had thoracic spine involvement and 2 (18%) had sacroiliac lesions as well. Despite the high prevalence of back pain and/or neurological manifestations (48% of the total population), no association was found between axial symptoms and axial gout (p=0,62). Duration of gout, mechanism of disease (hyperproduction vs. hypoexcretion) and metabolic commorbidities were also not related to the presence of axial involvement. Interestingly, a higher prevalence of axial gout was found between patients with current peripheral tophi (67% v. 30%; p=0,03), however no association was found with a past history of tophi that had already vanished due to therapy (p=0,72).
Conclusions Our study found out a striking 29% prevalence of spine lesions in gout patients. When dealing with axial lesions in these patients, a suitable differential diagnosis that should be remembered is axial gout itself, even in the absence of symptoms, since it might be more common than previously thought and no association with axial symptoms has been reported. The fact that axial lesions were associated to currently existing peripheral tophi but not to a previous history of tophi points out to the fact that gout treatment might be effective in preventing or solving axial lesions.
Disclosure of Interest None Declared
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