The prevalence of Hashimoto Encephalopathy is estimated to affect 2.1 per 100,000 individuals in the general population. The male to female ratio of afflicted individuals is 1:4. The average age of onset is 44. Because rare disorders are typically misdiagnosed, it is difficult to estimate the true frequency of the disease.

            The exact cause of Hashimoto Encephalopathy is unknown, but researchers believe it is likely a result of an abnormal immune system. A marker for the disease is the presence of anti-thyroid antibodies and, recently discovered, anti-alpha enolase antibodies. Antibodies are molecules secreted by immune cells which normally target bacteria or viruses invading the body. But in immune system disorders, antibodies mistakenly attack the body’s own tissue, leading to inflammation.

It is unclear if the anti-thyroid antibodies are the cause or the result of Hashimoto encephalopathy, or if it is just a coincidental finding. There is no evidence to suggest that the anti-thyroid antibodies play a role in the brain damage seen in HE patients. Additionally, the level of anti-thyroid antibodies is not correlated to the severity of the disease. It is possible for HE patients to have anti-thyroid antibodies, and yet have completely normal functioning thyroid glands. At this point, the presence of anti-thyroid antibodies simply means the person’s immune system is not functioning properly.  

No genetic cause for Hashimoto Encephalopathy has been identified, and the disease is not inherited. HE can occur in people with no family history of the disorder.

The symptoms for Hashimoto Encephalopathy vary greatly person to person. Some individuals have a sudden onset of confusion with cognitive dysfunction. Other individuals have a slow progressive cognitive impairment combined with dementia, confusion and hallucinations. A rapid deterioration to coma can occur. Patients may also exhibit behavioral changes, such as depression, anxiety, social withdrawal or changes in personality.

In addition to the mental status changes, individuals may also have seizures or abnormal jerky muscle movements.  

A correct diagnosis can only be made by a medical professional. Hashimoto Disease is a diagnosis of exclusion-- meaning a whole range of other conditions need to be ruled out first. Once other diseases have been ruled out, doctors make a diagnosis for HE if the following criteria have been met:

1.     Impaired brain function with seizures, hallucinations or stroke

2.     Mild or unobservable thyroid disease

3.     Normal brain MRI

4.     Presence of anti-thyroid antibodies

5.     Absence of neuronal antibodies

6.     Reasonable exclusion of alternative causes

Individuals with Hashimoto encephalopathy are treated with medications called corticosteroids to reduce inflammation. Affected individuals typically respond well to this treatment. The optimal dose is dependent on the individuals’ age, overall health and tolerance for medication. Individuals begin with a high dose of corticosteroid to get the disease under control, then doctors slowly lower the dose. Duration of the treatment can last a few months or up to 2 years until symptoms improve.

If a patient fails on corticosteroids, alternative immunosuppressive medications, such as azathioprine, cyclophosphamide or methotrexate, may be given. If a patient still does not respond to treatment, they then undergo plasma exchange, where the individual’s blood is removed, unwanted substances are removed, and the blood is then put back in the individual.

Anti-seizure and anti-psychotic medications are given to help relieve other symptoms if present.

Prognosis with corticosteroid treatment is generally good. Treatment may continue for a few months to up to 2 years. Relapse is possible after discontinuation of treatment. Left untreated, this condition can result in coma or death.

https://rarediseases.info.nih.gov/diseases/8570/hashimoto-encephalopathy

https://rarediseases.org/rare-diseases/hashimoto-encephalopathy/

https://en.wikipedia.org/wiki/Hashimoto%27s_encephalopathy

https://www.encephalitis.info/hashimotos-encephalopathy

https://www.verywellhealth.com/hashimotos-encephalopathy-overview-3231700