Acute confusional state caused by Hashimoto's encephalopathy in a patient with hypothyroidism: a case report

INTRODUCTION: Hashimoto's Encephalopathy is an unusual condition associated with Hashimoto's Thyroiditis. This immune-mediated, steroid-dependent entity was first described thirty years ago. In this case report, we discuss the importance of considering this diagnosis in the evaluation of confusion. CASE PRESENTATION: The patient is a 55-year-old African-American woman residing in United States, who was admitted to the hospital with a four-day history of mental status changes. Her past medical history was significant for type II Diabetes Mellitus, Hypertension, and Hypothyroidism. There was no reported seizure activity. The patient's vital signs were stable on admission. On examination, the patient was awake, alert, oriented to place and time. Her neurological examination revealed agraphia and dyslexia. Her speech showed lack of fluency and hesitation. Her complete blood count and electrolytes were within normal limits. The patient's brain CT scan did not reveal any significant findings. Her Magnetic Resonance Imaging only revealed mild chronic microangiopathy, which caused by “small vessel disease.” Her Electroencephalogram did not reveal any finding consistent with seizure activity. Cerebral spinal fluid analysis was likewise did not reveal a cause for this patient's acute onset of confusion. In contrast to the above negative finding, this patient's Thyroid stimulating hormone was discovered to be 15 UIU/ml. She was subsequently given 1000 mg of intravenous Methylprednisolone daily for 3 days. This three-day course of high-dose, intravenous steroids resulted complete resolution of the patient's symptoms. She was then discharged on an eleven-day course of oral prednisone 60 mg. CONCLUSION: Hashimoto's Encephalopathy should be considered in the differential diagnosis of an acute confusional state since it is responsive to steroid therapy and represents a readily reversible cause acute mental status changes. Clues to this diagnosis include elevated antithyroid antibodies, abnormal Thyroid stimulating hormone values, and exclusion of other causes of acute mental status changes.