Hashimoto’s Encephalopathy Presenting with Acute Cognitive Dysfunction and Convulsion
A 65-year-old man visited the hospital due to a sudden onset of cognitive decline. Two weeks prior to visiting to the hospital, the patient caught a cold for one week. He couldn’t remember where the razor was and was unable to find the bathroom. He confirmed that he indeed brushed his teeth when asked in case certainly he didn’t brush his teeth and didn’t use toothpaste when brushing his teeth. At work, he was unable to find the office keys nor able to recognize his co-workers. As well, he was unable to recall the road he routinely walked along, where he parked his car and if he owned a car. He didn’t give the hospital staff proper attitude while saying there was something when he saw the electric light turned on. Besides, he showed the nervousness as serious as being restless and after that he presented urinary incontinence. He collapsed turning his body around to the left as neurological examination were performed and lost consciousness with the convulsion to move his head to the right for about 20 seconds when he visited the hospital. His medical records reported hypertension without thyroid disease or dementia.\nWhen he visited to the hospital, his vital signs showed a blood pressure of 135/80 mmHg, respiration rate of 22 times per minute, pulse of 80 times per minute and a body temperature of 36.5°C. His physical check-up showed no hair loss, edema, goiter, and etc. Neurological examination showed a clear consciousness with disorientation to time and place. Korean version of Mini-Mental State Examination (K-MMSE) showed a 2/5 point in time orientation, 4/5 in place orientation, 0/3 in the three word recall and 4/5 point in serial seven substraction test. The total score was 22. There were no abnormal results among complete blood count, serum chemistry and electrolytes, serum tumor markers, paraneoplastic syndrome antibodies, and autoimmune disease and connective tissue disease test. Erythrocyte sedimentation rate and C-reactive protein level were also normal. Thyroid function test confirmed the asymptomatic hypothyroidism; the level of triiodothyronine was 62.98 ng/dL (reference value: 65–150), that of thyroxine 0.88 ng/dL (reference value: 0.78–1.54), that of thyroid stimulating hormone 5.85 μIU/mL (reference value: 0.55–4.78 μIU/mL). The level of thyrotropin-releasing hormone was normal. According to the thyroid autoantibody tests, the level of anti-thyroglobulin antibody was 77 IU/mL (reference value: 0–60) and that of anti-thyroid microsomal antibody was >1,300 IU/mL (reference value: 0–60). The cerebrospinal fluid (CSF) showed a slightly increased level of protein (58 mg/dL) and the normal level of white blood cells. And there were no abnormalities in virus including herpes simplex, bacteria and Mycobacterium tuberculosis tests. CSF 14-3-3 protein was negative.\nSeoul Neuropsychological Screening Battery (SNSB) carried out 4 days after he was hospitalized revealed a decrease in language and visual memory and language fluency, but there were no abnormalities in the concentration and time and place orientation. Electroencephalography (EEG) during awake revealed inter mittent diffuse slow waves (). There was no abnormal signal in brain MRI (). Single photon emission computed tomography (SPECT) showed decreased in perfusion in the bilateral temporal lobes (). Ultrasonography demonstrated an increased vascularity and irregular echoing in the bilateral thyroid lobes. Chest and abdomen CT showed no abnormality. It was diagnosed as Hashimoto’s encephalopathy based on the clinical features and test results. After oral steroids (prednisolone 60 mg/day) and anticonvulsant (Levetiracetam 1,000 mg/day) administration, he showed a gradual recovery of cognitive function. Therefore, on the 14th day after he was hospitalized, the score of K-MMSE became normal to 30/30. Since then, the patient’s cognitive dysfunction gradually improved and showed no suffering from any convulsions.