Hashimoto's Encephalopathy
A Treatable Form of Dementia
Hashimoto's encephalopathy is an autoimmune neuroendocrine disorder caused when the thyroid antibodies seen in Hashimoto's thyroiditis affect brain tissue.
Autoimmune Dementia
Hashimoto's encephalopathy (HE), which has recently been designated steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT), is an autoimmune disorder that can cause memory impairment, cognitive changes, dementia and associated neurological symptoms. HE can occur in patients with hypothyroidism related to Hashimoto's thyroiditis and in patients with normal thyroid function.
In some cases, particularly when HE occurs in association with non-thyroid related disorders such as Sjogren's syndrome or systemic lupus erythematosus (SLE), it's called nonvasculitic autoimmune meningoencephalitis (NAIM).
History
The first cases of Hashimoto's encephalopathy were reported in 1966 when the existence of thyroid antibodies in the blood of patients with the autoimmune hypothyroid disorder Hashimoto's thyroiditis was first demonstrated. SREAT is caused by the same thyroid antibodies that cause Hashimoto's thyroiditis although in SREAT, rather than destroying thyroid tissue, these antibodies attack and destroy brain cells known as neurons.
Most experts believe that SREAT is under-diagnosed and that many patients thought to have Alzheimer's disease actually have SREAT, which is a treatable disorder. Hashimoto's encephalopathy has been reported worldwide, and cases have been documented in patients ranging from 12-82 years with women more likely to be affected than men.
Encephalopathy
Encephalopathy is a general term referring to an inflammatory brain disease that alters the brain's structure or function. Encephalopathy is suspected in patients showing signs of an altered mental state.
Symptoms
Common symptoms of encephalopathy include stroke-like symptoms of memory loss, difficulty concentrating, hallucinations, irritability, restlessness, amnesia, diminished cognitive ability, myoclonus (involuntary muscle twitching), tremors, nystagmus (rapid, involuntary eye movement), muscle weakness, dementia, seizures, convulsions, difficulty swallowing, impaired speech, confusion, disorientation, psychosis, headache, right-sided hemiparesis or partial paralysis, and fine motor problems, including incoordination of arms, hands and fingers.
Diagnosis
HE is diagnosed in patients with high titers of thyroid peroxidase (TPO) antibodies who show signs of cognitive impairment responsive to corticosteroids. Lymphocytic vasculitis of the veins and venules of the brain stem in HE supports the notion that HE may be an autoimmune vascular disorder. Vasculitis as a contributing factor to HE is also supported by the presence of anti-alpha-enolase antibodies in HE.
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