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Paper text:
emergence of resistant strains and human immunodeficiency virus infection has made the situation even more complicated .
in addition to above , paradoxical reactions to anti - tuberculous therapy have created difficulties in the diagnosis and management of extrapulmonary tuberculosis , particularly central nervous system tuberculosis .
we present a case of a child with tuberculous meningitis who developed optic neuritis as a paradoxical reaction to anti - tuberculous therapy ( att ) .
a 5 year - old - boy presented with complaints of loss of vision in both eyes since 4 days .
it started as blurring of vision with an inability to recognize faces which gradually progressed to complete blindness . on examination
, there was no perception of light and the pupillary response was sluggish , ill - sustained to light in both eyes .
three months ago the patient was diagnosed as tuberculous meningitis in a private hospital on the basis of prolonged fever , convulsion , positive tuberculin test , history of tuberculous contact and cerebrospinal fluid analysis .
computed tomography ( ct ) scan of the brain showed mild dilatation of all ventricles with periventricular ooze and exudates along tentorium cerebelli .
he was started on four - drug att , consisting of isoniazid ( 5 mg / kg / day ) , rifampicin ( 10 mg / kg / day ) , pyrazinamide ( 25 mg / kg / day ) , and ethambutol ( 20 mg / kg / day ) , all taken once daily per orally .
prednisolone ( 2 mg / kg / day ) and oral phenytoin ( 10 mg / kg / day ) were also given in divided doses .
after 4 weeks of stopping ethambutol and pyrazinamide , he developed visual complaints and presented to our hospital .
although the patient had visual loss , there was no worsening of his systemic condition . also , he developed bilateral optic neuritis despite being off ethambutol . due to the above factors ,
isoniazid and rifampicin were continued and oral prednisolone was re - started at a dose of 2 mg / kg / day in divided doses . on follow up after 2 weeks the patient showed gradual improvement in his vision .
steroids were continued for four weeks and then gradually tapered . on follow up after six months the child 's vision had improved and fundoscopy was normal .
recurrence or appearance of fresh symptoms , physical and radiological signs in a patient who had previously shown improvement with appropriate att is called as paradoxical reaction .
various cases of neurotuberculosis showing expansion of previous tuberculoma or development of multiple new brain lesions during att have been reported .
clinicians may experience difficulty in differentiating between paradoxical deterioration , relapse of the disease or development of secondary resistance to att .
paradoxical reactions has been reported as early as 2 weeks and as late as 18 months after the initiation of att . in our case ,
the interval between the institution of therapy and appearance of paradoxical response was 3 months .
paradoxical reaction to att , side - effects of att , tuberculous neuritis , and secondary resistance to att were the different possibilities considered in our patient .
it is unlikely that he had tuberculous optic neuritis , as this rare condition is usually associated with chorioretinitis , uveitis , or military tuberculosis .
further , when the patient developed visual loss , there was no worsening of the systemic condition . thus , secondary resistance to att is also less likely .
the anti - tuberculous drugs causing optic neuritis include isoniazid , ethambutol , and streptomycin .
our patient did not receive streptomycin and was off ethambutol at the time of visual loss .
the fact that he improved with steroids despite continuing isoniazid suggests that optic neuritis was possibly an immunological - mediated response to att .
paradoxical reactions occur due to complex interplay between host 's immune response and the direct effect of mycobacterial antigens .
activation and accumulation of lymphocytes and macrophages at the site of bacterial deposition or toxin production occurs when bacilli die . in patients with paradoxical reaction to att
the rationale behind the use of adjuvant steroids lies in reducing the harmful effects of inflammation as the att kill the organisms . in conclusion
, there is a need for clinicians to be aware of the occurrence of paradoxical reactions to att .
we report a 5-year - old boy who developed optic neuritis as a paradoxical reaction to anti - tuberculous therapy . 
 steroids were re - started in the patient with gradual recovery of his vision . 
 the case emphasizes the importance of recognizing paradoxical reactions in patients on anti - tuberculous therapy . 
 prompt recognition and treatment of such reactions will reduce the associated morbidity .