Also known as:
Hashimoto's Encephalopathy, Non-vasculitic Autoimmune Meningoencephalitis, Steroid-responsive Encephalopathy associated with Autoimmune Thyroiditis
Hashimoto's encephalitis (inflammation/swelling of the brain)
was first described in 1966. It is a rare, probably autoimmune
condition (a disorder in which the immune system mistakenly attacks
and destroys healthy body tissues). It is usually associated with
high levels of thyroid antibodies in the blood. Hashimoto's
encephalitis has been reported in children, adults and the elderly
all over the world. It is more common in females than males.
What are the symptoms?
Patients with Hashimoto's encephalitis often present with a
depression of brain function (meaning that function is reduced),
drowsiness and sometimes coma. Two types of Hashimoto's
encephalitis have been described:
- the relapsing and remitting type (where symptoms at times worse
and other times better) - which manifests with encephalopathy (a
change in function or structure of the brain) and 'stroke-like'
- the diffuse progressive (widely dispersed) type - which has a
slow onset and a progressive course with occasional fluctuations
and manifests with psychiatric symptoms, such as confusion,
disorientation and psychosis.
Either of these may present with tremors, jerks or epileptic
What are the causes?
Currently, the exact cause is unknown. High levels of thyroid
antibodies are a marker of Hashimoto's encephalitis rather than the
cause of the condition. Thyroid function is usually normal.
How is it diagnosed?
It is a diagnosis of exclusion and the differential (alternative
diagnoses that are similar to the condition) is wide, ranging from
stroke-like episodes, Alzheimer's diseases, Creutzfeldt-Jacob disease, to
rare inborn errors of metabolism (see entry Inherited Metabolic
disease). Useful tests to detect the presence of Hashimoto's
encephalitis include magnetic resonance imaging (MRI) of the brain,
electroencephalogram (EEG), examination of the cerebrospinal fluid
(CSF), endocrine and metabolic screens, and viral studies.
How is it treated?
Most patients with Hashimoto's encephalitis improve after
treatment with high-dose steroid, such as prednisolone. However,
improvement may take weeks or even months. Because of the
improvement with steroids, some experts refer to the condition as
'steroid-responsive encephalopathy associated with autoimmune
thyroiditis (SREAT)'. Plasma exchange and intravenous
immunoglobulin (IVIG) have been used in some patients. The
prognosis with treatment is generally good. Steroids are often
continued for many months.
Inheritance patterns and prenatal diagnosis
Is there support?
Information and support in the UK for Hashimoto's Encephalitis
is provided by the Encephalitis Society (see entry Encephalitis).
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