RESUMEN
Marchiafava-Bignami disease is a rare disorder characterized by demyelination and necrosis of the central nervous system. Dystonia is a movement disorder characterized by sustained or intermittent muscle contractions. Herein, we present the case of a patient with Marchiafava-Bignami disease who developed acute oromandibular dystonia after receiving a very low dose of olanzapine. He was a 60-year-old Japanese man who was diagnosed with demyelinating lesions in the corpus callosum associated with Marchiafava-Bignami disease. At one point, he became agitated at night and was administered olanzapine 2.5 mg, resulting in the onset of oromandibular dystonia; however, the symptoms disappeared upon discontinuation of the drug. Primary dystonia is believed to arise solely from abnormal basal ganglia function in the absence of apparent morphological changes, according to the traditional view. However, recent studies suggest the involvement of lesions beyond the basal ganglia and organic factors, including ultrastructural changes. Rare side effects that develop following small doses of olanzapine indicate that demyelinating lesions of the corpus callosum may be partially responsible for oromandibular dystonia. This case report supports previous reports that the corpus callosum is involved in dystonia and provides insights into the pathophysiology underlying oromandibular dystonia.