A Case Report of Neuroleptic Malignant Syndrome during Methadone Therapy

Methadone is an opioid agonist used for the treatment of addiction to opioid drugs. Toxic leukoencephalopathy can cause serious problem and even be life-threatening. Methadone-induced leukoencephalopathy is a rare condition of this toxicity. Because of the importance of this situation and its treatment, we aim to report a case who is diagnosed as Methadone-induced leukoencephalopathy.

Case Report:

A 63-year-old man referred with non-persistent fever, drowsiness, rigidity and suspected of neuroleptic malignant syndrome (NMS). He was addicted to opioid from young age. He was on maintenance therapy with 80 mg methadone syrup from 2 months ago. After the appearance of symptoms including delirium, impaired attention and consciousness, treatment was performed with half a tablet of haloperidol 0.5 mg twice a day before rigidity and fever. Multiple lesions were seen in baseline CT-Scan and MRI. Toxic laboratory examination showed methadone was positive and other toxins and opioids were negative. After two weeks, second MRI showed rapid progressive lesions in white matter. Thus, it was diagnosed as Methadone-induced leukoencephalopathy in addition to NMS. Hydration, bromocriptine tablets 2.5 mg twice a day, methadone tapering and haloperidol discontinuation were performed. After two months, the patient's consciousness was better and his CPK and LDH tests were normal.

Methadone-induced leukoencephalopathy is a very rare condition, but it is important for physicians to consider this diagnosis in patients using methadone, especially when they show neurological and psychiatric signs and symptoms. That’s because early methadone tapering can reduce and stop toxicity on the white matter of the brain.