Tuberculous optochiasmatic arachnoiditis: a devastating form of tuberculous meningitis

Tuberculous meningitis is primarily a disease of the meninges of brain and spinal cord along with adjacent brain parenchyma. The characteristic pathological changes are meningeal inflammation, basal exudates, vasculitis and hydrocephalus. Tuberculous meningitis has a strong predilection for basal parts of the brain. Exudates, if dominantly present in the interpeduncular, suprasellar and Sylvian cisterns, result in optochiasmatic arachnoiditis and tuberculoma. Optochiasmatic arachnoiditis and tuberculoma are devastating forms of tuberculous meningitis and often associated with profound vision loss. This clinical entity more frequently affects young adults. In a recent study, on the multivariate logistic regression analysis, female sex, younger age and raised cerebrospinal fluid protein content were identified as predictors for developing optochiasmatic arachnoiditis. Frequently, optochiasmatic tuberculoma and optochiasmatic arachnoiditis develop paradoxically while a patient is being treated with anti-TB drugs. MRI reveals confluent enhancing lesions that are present in the interpeduncular fossa, pontine cistern, and the perimesencephalic and suprasellar cisterns. Management of tuberculous optochiasmatic arachnoiditis and optochiasmatic arachnoiditis tuberculoma has been variable. Treatment of optochiasmatic arachnoiditis continues to be a challenge and the response is generally unsatisfactory. In isolated case reports and in small series, corticosteroids, methyl prednisolone, thalidomide and hyaluronidase have been used with variable success. The benefit from neurosurgery is controversial and deterioration may follow the initial temporary improvement. Management of paradoxical optochiasmatic arachnoiditis is also controversial. Some patients regain vision following treatment with anti-TB drugs and continued usage of corticosteroids. Neurosurgery may be considered in the patients with either treatment failure or when diagnosis is in doubt. In conclusion, presence of optochiasmatic arachnoiditis or tuberculoma has important therapeutic and prognostic implications for patients of tuberculous meningitis.