An unusual case of focal seizures after a therapeutic dose of isoniazid: a case report

Tuberculosis remains a major cause of morbidity in endemic areas. Isoniazid (INH) is an important first-line agent for its treatment. Its major adverse effects include hepatotoxicity and neurotoxicity. Neurological side effects usually occur at toxic doses; however, few cases have reported generalized seizures at therapeutic doses. Focal seizures after therapeutic doses are rare. Here, we present the case of a 78-year-old male diagnosed with squamous cell carcinoma of the lung and pulmonary tuberculosis who experienced focal seizures after INH administration. No structural, metabolic, or infectious cause was found. The seizures stopped after discontinuation of the drug, which confirmed the diagnosis.