[A case of dementia with Lewy bodies and Hashimoto encephalopathy successfully treated with immunotherapy]

We report a 77-year-old woman suffering from dementia with Lewy bodies (DLB) who presented with Hashimoto encephalopathy. The patient began to mistakenly believe that another person was sleeping in her bed from approximately 70 years of age. She began to show symptoms of parkinsonism after 75 years of age. One night, the patient began to exhibit loitering behavior, and made incomprehensible comments while also exhibiting other abnormal behaviors. Clinical examination revealed rigidity and tremor of the limbs, as well as hallucination, abnormal speech and behavior. We first considered DLB. However, serum anti-thyroglobulin levels turned out to be elevated, indicating Hashimoto encephalopathy as well, and treated the patient with steroid pulse therapy. Her mental symptoms subsequently improved, but rigidity and tremor remained. ¹²³I-ioflupane SPECT demonstrated decreased accumulation in the bilateral caudal basal ganglia. Anti NH₂-terminal of α-enolase (NAE) antibody in the serum was positive. Therefore, we diagnosed the patient with the rare comorbidity of DLB and Hashimoto encephalopathy, successfully treated with immunotherapy.