Hashimoto's Encephalopathy: What You Need to Know

hashimoto's encephalopathy, he, autoimmune encephalopathy, steroid-responsive encephalopathy
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Hashimoto's Thyroiditis and Hashimoto's Encephalopathy

Hashimoto's thyroiditis is the autoimmune thyroid disease that is, in the United States, the most common cause of hypothyroidism, an underactive thyroid.

A rare condition associated with Hashimoto's thyroiditis is Hashimoto's encephalopathy (abbreviated as HE). Hashimoto's encephalopathy is a neuroendocrine disorder whose mechanisms are not well understood by doctors and researchers.

It's thought that like Hashimoto's disease, Hashimoto's encephalopathy is autoimmune in nature, and caused by an aggressive but mistaken immune system targeting the body's own organs, glands and tissues. In the case of Hashimoto's encephalopathy the target is the brain.

Note: Because not all patients have evidence of Hashimoto's disease, some experts are suggesting that the condition​ should be renamed to remove the link to Hashimoto's, and instead be called "steroid-responsive encephalopathy associated with autoimmune thyroiditis.' 

We do know that in Hashimoto's encephalopathy, high levels of antithyroid antibodies (thyroid peroxidase antibodies, or TPO) appear to be related to a swelling in the brain that can then manifest in a variety of debilitating symptoms . 

How Often Does Hashimoto's Encephalopathy Occur?

Hashimoto's encephalopathy is considered rare (there are several dozen diagnosed patients in the United States) but it is likely that there are many more undiagnosed sufferers who are undiagnosed or misdiagnosed.

Because it is not well known and its symptoms are primarily neurological, it is easy to misdiagnosis or overlook and Hashimoto's encephalopathy symptoms frequently lead to mistaken neurological diagnoses.

The average age of onset of Hashimoto's encephalopathy is around 47 years old. The vast majority of HE patients patients are women.

HE can also show up in adolescents, when it is even more likely to be overlooked. The symptoms in adolescents include seizures, confusion and hallucinations. A drop in school performance is also a common symptom, along with progressive cognitive decline. Thyroid antibody levels should be evaluated in any adolescents with these symptoms, even when other thyroid function tests are normal.

Some of the most common symptoms in adults with Hashimoto's encephalopathy include the following:

  • disorientation
  • psychosis and delusional behavior
  • tremors
  • concentration and memory problems
  • spasms and jerks in the muscles known as myoclonus
  • lack of physical coordination
  • headaches
  • partial paralysis
  • speech problems
  • personality changes.
  • aggression.
  • delusional behavior.
  • concentration and memory problems.
  • seizures
  • sleep abnormalities

HE often progresses along two avenues: either as an acute, stroke-like attack or seizure; or through progressive movement into dementia, or even coma. Sometimes, patients are mistakenly diagnosed as having had a stroke, Creutzfeldt-Jakob disease, dementia, or Alzheimer's disease.

At present, there is not a definitive test for Hashimoto's encephalopathy.  While thyroid antibodies may be high, they may also not be present.

Similarly, TSH levels could be of concern, or could be normal. Treatment with thyroid hormone replacement medication does not resolve HE.

HE is diagnosed by ruling out other causes of the symptoms. 

Treatment of Hashimoto's Encephalopathy

The primary treatment for Hashimoto's encephalopathy is oral corticosteroid drugs, like prednisone. Many patients respond dramatically to drug treatment, with an average acute treatment period of four to six weeks. Like most autoimmune disorders, HE is not considered curable, but rather treatable. After initial treatment, the disorder often lapses into remission.

Some patients are able to discontinue drug therapy for a number of years, though there is a risk of future relapse. 

In addition to steroid therapy, other treatments such as intravenous immunoglobulin and plasma exchange are considered options.

While rare, Hashimoto's encephalopathy could be the culprit behind depression, sporadic seizure, or even anxiety. It is not until the condition presents itself by acute, or unresponsive neuropsychiatric symptoms, that many doctors look for thyroid issues, nodules, or a family history of immune dysfunction.

Patients who experience Hashimoto's encephalopathy face a diagnostic challenge and a potentially debilitating disease. Fortunately, most people respond to readily available treatment.  If you suffer acute neurocognitive symptoms your doctor cannot explain, be sure to mention your personal or family history of Hashimoto's thyroiditis or other thyroid conditions.

Sources:

Carbone A, et. al. "Hashimoto's encephalopathy (HE): an under diagnosed autoimmune-mediated encephalopathy." Endocrine. 2016 Nov;54(2):572-573. 

Kaczmarczyk A, et al. "Hashimoto's encephalopathy - rare encephalopathy with good prognosis." Wiad Lek. 2016;69(6):768-772. 

Laurent C et al. "Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT): Characteristics, treatment and outcome in 251 cases from the literature." Autoimmun Rev. 2016 Dec;15(12):1129-1133. doi: 10.1016/j.autrev.2016.09.008. Epub 2016 Sep 15.

Litmeier S, et al. "Initial serum thyroid peroxidase antibodies and long-term outcomes in SREAT." Acta Neurol Scand. 2016 Dec;134(6):452-457. doi: 10.1111/ane.12556.
PMID: 26757046

 

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