Choroidal tubercles in neurotuberculosis: prevalence and significance

Neurotuberculosis is a relatively common form of tuberculosis and may be seen in 1-10% of patients of systemic tuberculosis and may present in several forms. Ocular lesions are frequently seen, most commonly optic nerve lesions. Limited data are available for choroidal tubercles. We conducted a prospective study 1) to determine the prevalence of choroidal tubercles in a cohort of patients of neurotuberculosis as well as its relative prevalence in the various morphological manifestations and 2) to study the role of co-existent systemic tuberculous infection.

IRB-approved prospective cross-sectional observational study. A hospital-based cohort of patients underwent a detailed physical, laboratory and ocular evaluation.

A total of 52 (20 male, 32 female) patients were evaluated with tubercles being seen in 23 eyes (18 patients, 34.6%). Twenty four patients (46.12%, 16 female, 8 male) presented with intracranial granulomas and 28 (53.8%, 16 female, 12 male) presented with tuberculous meningitis. Tubercles were seen in 10 eyes of 8 (28.5%) patients with tuberculous meningitis and in 13 eyes of 10 patients (41.6%) with intracranial granulomas. This result is not statistically significant. Twenty seven patients (51.9%) had neurotuberculosis without systemic infection, whereas 25 (48.1%) patients had systemic foci. Tubercles were seen in 18 eyes (13 patients) with systemic foci and in 5 eyes (5 patients) of neurotuberculosis alone. The odds ratio for the presence of systemic tuberculosis when choroidal tubercles are present is 5.6 (95% confidence interval: 1.39-24.49, statistically significant [p = 0.005]).

Tubercles were equally likely to occur in either manifestation of neurotuberculosis, and their presence was related to the presence of systemic focus of tuberculous infection. The presence of choroidal tubercles may serve as a diagnostic marker for the presence of an underlying systemic infection.