Isoniazid-induced neuropathy in a pre-pubertal child.

Isoniazid (INH)-induced peripheral neuritis is not uncommonly reported in adults, especially those with malnutrition and alcoholism, but it is very rare in children. INH leads to peripheral neuritis by causing a deficiency in the serum level of pyridoxine which depends on the dose of INH, duration of treatment and the patient's nutritional and acetylator status. A 12-year-old girl developed tingling and numbness of the lower limbs after commencing anti-tuberculous therapy which included INH 10 mg/kg/day. The symptoms continued despite the dose being reduced to 5 mg/kg/day. Nerve conduction velocity was normal. Her diet was poor: she consumed little or no fruit and vegetables and ate mostly dal and rice. Discontinuation of INH was advised and her therapy was changed to ofloxacin, rifampicin, ethambutol and pyrazinamide along with a high dose of pyridoxine and multi-vitamins. The tingling and numbness subsided within 15 days, after which INH was prescribed at the dose of 10 mg/kg/day. Although INH-induced neuropathy is rare in children, the World Health Organization recommends pyridoxine prophylaxis for children on INH who are malnourished or have HIV infection.