A Case of Hashimoto's Encephalopathy

Lee, Tai Yeon; Shin, Dong Ick; Park, Kye Yeon; Lee, Sung Hyun; Lee, Sang Soo; Han, Seol Heui

Abstract

Hashimoto's encephalopathy (HE) is a steroid-responsive disorder of persistent or relapsing neurological or neu-ropsychological deficits associated with elevated serum concentrations of antithyroid antibody that frequently presents with myoclonus, seizures, and stroke-like episodes. We report a 55-year-old woman who presented with an altered men-tality associated with generalized tonic-clonic seizure. She was diagnosed with Hashimoto's thyroiditis 3 years prior. Serum antithyroglobulin antibody and antimicrosomal antibody were elevated. Electroencephalography (EEG) showed generalized slowing. Brain magnetic resonance imaging (MRI) with T2-weighted sequence and fluid-attenuated inver-sion- recovery (FLAIR) image revealed a high signal intensity in both mesial temporal areas. Single photon emission computed tomography (SPECT) demonstrated decreased perfusion in multiple areas. With the impression of HE, she was placed on high dose steroid and thyroid hormone replacement therapy which ameliorated her neurological symp-toms. We suggest that HE should be included in the differential diagnosis of decreased mentality, especially when patients with Hashimoto's thyroiditis show altered consciousness, seizure disorder, or cognitive decline.