Hashimoto's encephalopathy

Hashimoto's encephalopathy, also known as steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT), is a neurological condition characterized by encephalopathy, thyroid autoimmunity, and good clinical response to corticosteroids. It is associated with Hashimoto's thyroiditis, and was first described in 1966. It is sometimes referred to as a neuroendocrine disorder, although the condition's relationship to the endocrine system is widely disputed. It is recognized as a rare disease by the NIH Genetic and Rare Diseases Information Center.

Up to 2005, almost 200 case reports of this disease were published. Between 1990 and 2000, 43 cases were published. Since that time, research has expanded and numerous cases are being reported by scientists around the world, suggesting that this rare condition is likely to have been significantly undiagnosed in the past. Over 100 scientific articles on Hashimoto's encephalopathy were published between 2000 and 2013.

The onset of symptoms tends to be fairly gradual and to occur over 1-12 years. ^{[citation needed]}

Symptoms of Hashimoto's encephalopathy may include:^{[citation needed]}

The mechanism of pathogenesis is not known, but is thought to be an autoimmune disorder, similar to Hashimoto's thyroiditis, as its name suggests.^{[citation needed]}

Consistent with this hypothesis, autoantibodies to alpha-enolase have been found to be associated with Hashimoto's encephalopathy. Since enolase is the penultimate step in glycolysis, if it were inhibited (for example by being bound by autoantibodies), one would expect decreased energy production by each cell, leading to resulting atrophy of the affected organ.^{[citation needed]}

This would occur most likely through each cell shrinking in size in response to the energy deficit (and/or in extreme situations from some cells dying via either apoptosis or necrosis, depending on location). This may occur as a result of enough ATP not being available to maintain cellular functions - notably, failure of the Na/K ATPase, resulting in a loss of the gradient to drive the Na/Ca antiporter, which normally keeps Ca⁺
₂ out of cells so it does not build to toxic levels that will rupture cell lysosomes leading to apoptosis. An additional feature of a low-energy state is failure to maintain axonal transport via dynein/kinesin ATPases, which in many diseases results in neuronal injury to both the brain and/or periphery.

Very little is known about the pathology of Hashimoto's encephalopathy. Autopsies of some individuals have shown lymphocytic vasculitis of venules and veins in the brainstem and a diffuse gliosis involving gray matter more than white matter.^{[citation needed]}