Hashimoto's Encephalitis

Medical text was updated July 2010 by Dr Baba Aji, Specialist Registrar to Professor Tom Solomon, Consultant Neurologist, The Walton Centre for Neurology and Neurosurgery, Liverpool, UK.


Hashimoto’s Encephalopathy, Steroid responsive encephalopathy associated with autoimmune thyroiditis (SREAT), non - vasculitic autoimmune meningoencephalitis.

Background

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?

The clinical presentation is often a depression of brain function, drowsiness and sometimes coma. Two types have been described: (1) The relapsing and remitting type (symptoms at times worse and other times better) which manifests with encephalopathy and stroke – like episodes. (2) The diffuse progressive (widely dispersed) type which has a slow onset, progressive course with occasional fluctuations and manifest with psychiatric symptoms such as confusion, disorientation and psychosis. Either of these may present with tremors, jerks or epileptic seizures.

What are the causes?

Currently, the exact cause is unknown. The thyroid antibodies are a marker rather than the cause of the problem. Thyroid function is usually normal.

How is it diagnosed?

It is a diagnosis of exclusion and the differential is wide, ranging from stroke-like episodes, Alzheimer’s disease, Creutzfeldt-Jacob disease, to rare inborn errors of metabolism. Useful tests include Magnetic Resonance Imaging (MRI) of the brain, Electroencephalogram (EEG), Cerebrospinal Fluid (CSF) findings, endocrine and metabolic screens, and viral studies.

How is it treated?

Most patients with Hashimoto’s encephalitis improve with high dose steroids (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.


A useful reference is

www.ncbi.nlm.nih.gov

1: Neurology. 1991 Feb;41(2 ( Pt 1)):228-33. Related Articles, Links
Hashimoto's encephalopathy: a steroid-responsive disorder associated with high anti-thyroid antibody titers--report of 5 cases.

Shaw PJ, Walls TJ, Newman PK, Cleland PG, Cartlidge NE.

Department of Neurology, University of Newcastle upon Tyne, UK.

We describe 5 patients with a relapsing encephalopathy in association with Hashimoto's disease and high titers of anti-thyroid antibodies. The presentation is usually with a subacute onset of confusion, alteration in conscious level, and focal or generalized seizures. The relapsing course, association with myoclonus or tremulousness, and episodes of stroke-like deterioration are characteristic features. The long-term prognosis is favorable with steroid therapy, though additional immunosuppressive therapy may be required. Neurologic investigation typically shows a diffusely abnormal EEG, high CSF protein level without pleocytosis, and normal brain CT and cerebral angiogram. Isotope brain scan may show patchy abnormal uptake. Hashimoto's encephalopathy should be recognized as a definite neurologic entity and added to the list of CNS complications of thyroid disease.

Publication Types:
Case Reports
Review
Review of Reported Cases

PMID: 1992366 [PubMed - indexed for MEDLINE]


Last modified: August 2010