Case Presentation: A 66 year-old male with hypothyroidism was admitted for a COPD exacerbation, however his neurological exam was markedly abnormal. He had suffered multiple falls due to gait instability in years past, and recently experienced progressive symptoms of dizziness, slurred speech, tremors, and weakness. His symptoms were now so severe that he could no longer ambulate, despite assistance of a walker. On exam, he was noted to have horizontal nystagmus, dysarthric speech, sensorineural hearing loss, upper extremity spasticity, and ataxia. An MRI of the brain showed no acute abnormalities. A lumbar puncture was notable for increased protein (58mg/dL). All other CSF studies were unrevealing. Autoimmune, vasculitis, paraneoplastic, infectious, toxic, and nutritional work-up were also unremarkable. Antithyroglobulin (2.2 IU/mL) and anti-TPO antibodies (41 IU/mL) were notably elevated, however TSH (2.89mIU/mL) and free T4 (1.5ng/dL) levels were within normal limits as he was on levothyroxine repletion. Hashimoto’s Encephalopathy (HE) was suspected based on the laboratory and CSF findings as well as the improvement in his neurological symptoms after the initiation of steroids.
Discussion: Hashimoto’s encephalopathy is a neurological disorder first diagnosed by Lord Brain and encompasses a heterogenous collection of clinical findings, which include movement disorders, seizures, and psychiatric manifestations. It is presumed to have an autoimmune association and is associated with high anti-thyroperoxidase (TPO) antibody titers but typically subclinical hypothyroidism to normal thyroid function. No pathognomonic clinical, laboratory, or imaging finding exists. CSF studies are variable as are MRI findings, however the most commonly reported CSF patterns include high protein levels without notable pleocytosis. Another hallmark feature is the response to steroid therapy, such that it is often referred to as “steroid responsive encephalopathy associated with autoimmune thyroiditis (SREAT).” In a recent review, 96% of patients improved on glucocorticoid therapy.
Conclusions: In patients with encephalopathy of unclear etiology with associated neurologic findings and elevated anti-TPO antibodies, Hashimoto’s encephalopathy should be considered, as this is a potential reversible debilitating illness with the simple administration of glucocorticoids.