Hashimoto encephalopathy

Other Names: Hashimoto's encephalopathy; Steroid-responsive encephalopathy associated with autoimmune thyroiditis

Hashimoto encephalopathy (HE) is a condition characterized by onset of confusion with altered level of consciousness; seizures; and jerking of muscles (myoclonus). Psychosis, including visual hallucinations and paranoid delusions, has also been reported.

Cause

The exact cause of Hashimoto encephalopathy (HE) is unknown, but is thought to relate to autoimmune or other autoinflammatory processes. While it is associated with Hashimoto's thyroiditis, the exact nature of the relationship between the two conditions is unclear. It does not appear to be directly related to hypothyroidism or hyperthyroidism.

Inheritance

Hashimoto encephalopathy (HE) typically is not inherited, occurring sporadically in people with no family history HE. It can occur in association with other autoimmune disorders however, so in some cases it may develop due to an interaction between genetic susceptibility and environmental triggers.

Signs and symptoms

The symptoms of Hashimoto encephalopathy can vary from person to person. They most often include sudden or subacute onset of confusion with alteration of consciousness. Some people have multiple, recurrent episodes of neurological deficits with cognitive dysfunction. Others experience a more progressive course characterized by slowly progressive cognitive impairment with dementia, confusion, hallucinations, or sleepiness. In some cases, rapid deterioration to coma can occur.

In addition to confusion and mental status changes, symptoms may include seizures and myoclonus (muscle jerking) or tremor. Psychosis, including visual hallucinations and paranoid delusions, has also been reported.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 100% of people have these symptoms

• Acute encephalopathy

80%-99% of people have these symptoms

• Cerebral vasculitis
• Hashimoto thyroiditis

30%-79% of people have these symptoms

• Abnormality of the cerebral white matter
• Confusion(Disorientation)
• Goiter(Enlarged thyroid gland in neck)
• Hyponatremia(Low blood sodium levels)
• Hypothyroidism(Underactive thyroid)
• Paralysis(Inability to move)

5%-29% of people have these symptoms

• Abnormal autonomic nervous system physiology
• Anxiety(Excessive, persistent worry and fear)
• Depressivity(Depression)
• Fever
• Focal-onset seizure(Seizure affecting one half of brain)
• Generalized-onset seizure
• Headache(Headaches)
• Immunodeficiency(Decreased immune function)
• Leukocytosis(Elevated white blood count)
• Myoclonus
• Nausea and vomiting
• Psychosis
• Status epilepticus(Repeated seizures without recovery between them)
• Thrombocytopenia(Low platelet count)

1%-4% of people have these symptoms

• Limited neck flexion(Limited neck flexibility)

Diagnosis

Diagnosis of Hashimoto encephalopathy can be made when all six of the following criteria have been met:

1. Encephalopathy with seizures, myoclonus, hallucinations, or stroke-like episodes

2. Subclinical or mild overt thyroid disease (usually hypothyroidism)

3. Normal brain MRI or with non-specific abnormalities

4. Presence of serum thyroid (thyroid peroxidase, thyroglobulin) antibodies

5. Absence of well-characterized neuronal antibodies in serum and CSF

6. Reasonable exclusion of alternative causes

A team of leading autoimmune encephalitis researchers have proposed that the term Hashimoto’s encephalopathy only be used when rigorous clinical assessment and comprehensive testing for well characterized neuronal antibodies exclude other potential causes of encephalopathy. The underlying cause of Hashimoto’s encephalopathy is unclear. Experts in the field recommend that cases of Hashimoto’s encephalopathy be classified as probable autoimmune encephalitis.

Treatment

Medical management of Hashimoto encephalopathy (HE) usually involves corticosteroids and treatment of thyroid abnormalities (if present). The optimal dose of oral steroids is not known. Most patients with HE respond to steroid therapy. Symptoms typically improve or resolve over a few months. Decisions regarding the length of steroid treatment and the rate of tapering off steroids are based on the individual's response to treatment. Treatment may last as long as two years in some patients.

People with HE who experience repeated HE relapses, do not respond to steroids, and/or cannot tolerate steroid treatment have been treated with other immunosuppressive medications such as azathioprine and cyclophosphamide. Intravenous immunoglobulin, and plasmapheresis have also been used.

NIH genetic and rare disease info

• NIH info on Hashimoto encephalopathy

Hashimoto encephalopathy is a rare disease.

Hashimoto encephalopathy Resources
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