Transient electromyographic findings in serotonergic toxicity due to combination of essitalopram and isoniazid
A Forty-three-years-old female developed acute onset fever and confusion. She was receiving corticosteroids with the diagnosis of Takayasu arteritis for the recent three years. She was also taking isoniazid cause of a suspicious positive result in tuberculin skin test (PPD) for the last three months.\nNeurological examination revealed fever, rigidity, clonus, bilateral positive Babinsky and Hoffman signs, and hyperactive deep tendon reflexes. Cranial and spinal magnetic resonance imaging (MRI) showed no abnormalities nor contrast enhancement. Nerve conduction studies were normal, but needle electromyography (EMG) demonstrated spontaneous neurogenic changes (fibrillation and positive waves) in her extensor digitorum brevis (EDB), tibialis anterior (TA), and gastrocnemius muscles. There were no chronic neurogenic signs.\nFurther investigations for toxic, nutritional, and infectious spinal cord diseases revealed nothing.\nWe learned that she had been taking essitalopram 20 mg/day for last month from her relatives.\nWith the help of this medical history, she was diagnosed as serotonergic toxicity, essitalopram was stopped, and the patient was hydrated. In her follow-up, she started to get better on the third day of drug-free period. After one week, she was completely improved. No rigidity, clonus, or pyramidal sign was detected. Repeated EMG was completely normal.