Hashimoto encephalopathy is a rare condition that affects the brain. The disease’s symptoms, severity, and progression may vary between affected people. Some experts believe it has links to another condition called Hashimoto’s thyroiditis.

The condition can lead to various symptoms, including stroke-like episodes, seizures, confusion, and tremors. It can also affect mental health.

While the precise causes remain unknown, doctors believe Hashimoto encephalopathy is an autoimmune condition. Antibodies that typically fight pathogens, such as harmful bacteria and viruses, mistakenly attack the brain instead. This leads to an inflammatory response, causing damage and dysfunction in different parts of the brain.

There is no cure for Hashimoto encephalopathy, but treatment can help reduce its effects. Typically, this involves a combination of medications, such as anti-seizure drugs, to reduce inflammation and manage symptoms.

Many people enter remission and experience no further symptoms for years or decades.

This article explores the symptoms, causes, and treatments for Hashimoto encephalopathy.

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Hashimoto encephalopathy is a rare autoimmune disorder that affects brain function. Experts named the condition for its potential association with Hashimoto’s thyroiditis, a common autoimmune thyroid disease.

However, they remain unsure about the relationship between the disorders, but affected individuals have antithyroid antibodies in their bodies.

Antithyroid antibodies are immune cells that mistakenly target thyroid tissue. However, health experts are unsure if the antibodies contribute to the development of Hashimoto encephalopathy or are a coincidental finding.

People with Hashimoto encephalopathy may experience some neurological symptoms and changes to their mental health, such as:

  • seizures
  • confusion
  • personality changes
  • hallucination or delusion
  • schizophrenia
  • depression
  • cognitive impairment, or reduced ability to think

However, doctors can typically treat the condition and successfully reduce or eliminate symptoms.

Learn more about Hashimoto’s thyroiditis.

Hashimoto encephalopathy is rare. Experts estimate that it affects fewer than 1,000 people in the United States or 2.1 per 100,000 individuals.

The condition affects females more frequently than males. It can also affect children, but less frequently — there are only 60 reported cases in the medical literature.

Doctors do not know the exact cause of Hashimoto encephalopathy. However, it may most likely occur due to an atypical immune system response to an infection or other trigger.

Some believe it is an autoimmune disorder, where the immune system mistakenly attacks healthy tissue instead of harmful bacteria or viruses. In Hashimoto encephalopathy, the immune cells may attack the central nervous system, causing neurological symptoms.

There is no definitive test for Hashimoto encephalopathy. Therefore, doctors use a combination of medical history, physical evaluation, and various tests to diagnose the disorder.

Before diagnosing Hashimoto encephalopathy, doctors may first rule out the following:

Then doctors may use the following tests to help them diagnose the condition:

  • blood tests
  • MRI scans
  • electroencephalogram (EEG) recordings

Blood tests can detect antithyroid antibodies, which are immune cells that attack the thyroid gland. However, these antibodies are fairly common in the general population. Therefore, doctors must pair them with other symptoms relating to Hashimoto encephalopathy once they have ruled out other potential diagnoses.

Doctors may use an EEG to measure the brain’s electrical activity and show changes in brain function. The EEG can also help detect seizures.

An MRI scan can exclude other causes of symptoms. An MRI uses a magnetic field and radio waves to create a 3D image of the brain. It can show widespread or specific changes to the brain that may point to Hashimoto encephalopathy.

Treatment for Hashimoto encephalopathy may vary from person to person. In the first instance, doctors may recommend corticosteroids, such as prednisone (Rayos) and methylprednisolone (Medrol). These medications reduce inflammation in the brain.

Doctors may recommend other immunosuppressants to reduce the activity of the immune system. They can help reduce inflammation throughout the body. Some examples include:

  • cyclophosphamide (Cytoxan)
  • azathioprine (Azasan)
  • mycophenolate mofetil (CellCept)

If these approaches do not help, intravenous immunoglobulin (IVIG) and plasma exchange may be suitable alternatives.

In IVIG therapy, the person receives large doses of antibodies from donor blood. The antibodies target the immune cells that cause inflammation in the brain.

In plasma exchange, a doctor removes some of the person’s blood and separates the red blood cells. They then replace the missing component with healthy donor plasma. This technique helps reduce antithyroid antibody levels in the body.

Most people respond well to treatment with medications and can expect symptoms to improve or resolve completely within a few months. A 2016 study found that more than 9 in 10 people responded completely or by at least 50% to steroid treatment.

Although doctors cannot cure Hashimoto encephalopathy, it is highly treatable and has a positive outlook. Following initial treatment, it frequently lapses into remission. In the same review, only 16% of participants had one or more relapses.

With proper treatment, a person with Hashimoto encephalopathy should expect a typical life expectancy.

Hashimoto encephalopathy is a rare disorder that affects the central nervous system. It is more common in females.

Doctors do not know the exact cause of Hashimoto encephalopathy, but it may be due to an atypical immune response. They will use a combination of medical history, physical evaluation, and tests such as blood analyses, MRI scans, and EEG recordings to diagnose the disorder.

Treatments include corticosteroids to reduce inflammation, medications that dampen the immune response, and IVIG therapy. Most people respond well to treatment and have a positive outlook for recovery.