Abstract
Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT), frequently termed as Hashimoto’s encephalopathy (HE), is characterized by reversible encephalopathy with the presence of elevated antithyroid antibodies. The condition was initially described due to its association with Hashimoto’s thyroiditis. We report a case of euthyroid HE presenting as subacute dementia. A 50-year-old woman presented with progressive memory decline for six weeks. Thyroid function tests, thyroid ultrasound, and cerebrospinal fluid analysis were unremarkable. Electroencephalogram showed generalized slowing with triphasic waves. On magnetic resonance imaging, T1 weighted images revealed hyperintensity in bilateral basal ganglia. Antithyroglobulin and antithyroid peroxidase were markedly elevated. She improved remarkably on tablet prednisolone 60 mg once daily, confirming the suspicion of steroid-responsive encephalopathy. Thus, we conclude that patients with subacute cognitive decline could be screened for antithyroid antibodies in the dementia workup despite their euthyroid status.
Highlights
Hashimoto’s encephalopathy (HE) is a rare cause of reversible cognitive decline [1]
After excluding the above causes with laboratory investigations and imaging, we evaluated HE as the possible etiology, the diagnosis of which traditionally requires the presence of encephalopathy with neurologic manifestations, the presence of increased antithyroid antibodies, exclusion of infectious and metabolic disorders, and rapid clinical improvement after immunomodulation [9]
We attempt to contribute to the literature by presenting this case of subacute dementia in a euthyroid case with elevated antithyroid antibodies, normal thyroid ultrasound, and normal cerebrospinal fluid (CSF) analysis with marked response to oral steroids
Summary
Hashimoto’s encephalopathy (HE) is a rare cause of reversible cognitive decline [1]. The first case was reported in 1966 by Brain et al with symptoms of hallucinations, altered mental status, tremor, and elevated thyroid antibodies [antithyroglobulin (anti-TG) antibodies-normal < 4 IU/mL and antithyroid peroxidase (anti-TPO) antibodies-normal < 4 IU/mL] [2]. A 50-year-old right-handed woman with a history of diabetes and hypertension was brought into the clinic by her husband with progressive memory loss for the past six weeks She had amnesia of recent daily activities like bathing, having meals, and difficulty in finding words. She reported further improvement in memory and cognition, with a complete return to normal activity and no symptoms of recurrence after tapering the dosage of steroids. She has been on a maintenance dose of oral prednisolone 10 mg once daily, and no relapse was noted on her yearly follow-up. We plan to add immunosuppressants if she relapses or significant adverse effects of prolonged steroids poses a risk
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