Abstracts

Rationale: Hashiomoto’s encephalopathy (HE) is also known as steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT). The terms HE or SREAT describe a broad constellation of neuropsychiatric and sometimes peripheral nervous system symptoms attributed to elevated titers of anti-thyroid peroxidase antibodies (TPO Ab), anti-thyroglobulin antibodies (TG Ab) or both. The pathogenic mechanisms of HE are poorly understood with multiple postulated hypotheses, but the TPO Ab and TG Ab are thought to play a pathologic role. When TG Ab are elevated, usually TPO Ab are elevated as well. However, this is not always the case. Furthermore, high levels of TG Ab are present only about 35% of the time when TPO Ab are elevated. We hypothesized that clinical presentation of HE may vary according to which antibody titers were elevated.Methods: This is a descriptive case series of 11 subjects diagnosed with HE according to clinical presentation and elevated serum titers of TPO Ab or TG Ab. The clinical presentation, EEG findings, MRI findings, and response to high-dose steroids are described.Results: Of the 11 subjects, 8 were female (73%). The age at the time of diagnosis ranged from 16-78 years with mean age 37.8 years. A combination of elevated TPO Ab and TG Ab was seen in 5 subjects. TPO Ab alone were elevated in 4 subjects, and TG Ab alone were elevated in 2 subjects. Presenting symptoms, EEG findings, MRI findings, and response to high-dose steroids are described in Table 1. Briefly, common presenting symptoms in those with TPO Ab (with or without TG Ab) included focal seizures, transient encephalopathy, memory impairment, anxiety, and headaches. Clinical presentation in the 2 subjects with TG Ab only was distinct from those with TPO Ab. One subject with TG Ab presented with gastrointestinal and bladder dysmotility, hyperreflexia, and sub-cortical myoclonus. The other subject presented with persistent delirium, diffuse hyperreflexia, generalized weakness and bulbar weakness causing dysarthria and dysphagia. Of the 9 subjects with TPO Ab present, 6 were clinically improved after treatment with high-dose steroids. No clinical improvement was seen following treatment with high-dose steroids in either 2 subjects with TG Ab alone.Conclusions: Our small case series suggests that the clinical presentation in HE may vary according to which antithyroid antibodies are elevated. In particular, the clinical picture in those TG Ab alone appears distinct from those with TPO Ab with or without TG Ab. Response to high-dose steroids in those with TPO Ab may be more favorable. These finding suggests that the pathogenic processes marked by these 2 antibodies may be different. Further study with larger sample size may be necessary to validate our results.