What Is Hashimoto's Encephalopathy?

Hashimoto's encephalopathy is a rare brain disorder that can produce a range of symptoms in patients that may include seizures, tremor, or even coma. This disorder is associated with Hashimoto's thyroiditis, an autoimmune illness in which patients have an abundance of antibodies against thyroid proteins in their serum. Most patients with Hashimoto's encephalopathy improve after treatment with corticosteroids and/or thyroid medication.

The thyroid gland is located in the neck, and it produces hormones that regulate metabolism. Molecules of iodide that are ingested in the diet collect in the thyroid gland and are converted to iodine by the enzyme thyroid peroxidase. Iodine is incorporated into the molecule thyroglobulin and forms two different thyroid hormones. These hormones act on many different cell types and serve to increase the metabolic rate and maintain body temperature.

Hashimoto's thyroiditis develops when white blood cells of the body begin to attack the thyroid gland. This autoimmune disorder leaves patients feeling tired and unable to tolerate cold temperatures. Diagnosis is based on the presence of antibodies in the serum against the enzyme thyroid peroxidase (TPO) as well as the hormone thyroglobulin (TG). Patients may also have low levels of thyroid hormones, a condition known as hypothyroidism that requires treatment with thyroid hormones.

Encephalopathy is a term used to describe any disorder of the brain. Symptoms of Hashimoto's encephalopathy vary but may include seizures, memory loss, and disruption of language skills. Patients may also experience mood and behavioral changes as well as a reduced attention span. Since these symptoms can be generated by other neurological disorders, a firm diagnosis of Hashimoto's encephalopathy would require a complete patient history along with blood work.

Blood tests would give the physician an indication of levels of thyroid hormones as well as the presence of antibodies against the thyroid proteins TPO and TG. The physician may also order testing of the cerebrospinal fluid (CSF). Patients with Hashimoto's encephalopathy usually have elevated levels of protein in the CSF. Electroencephalography (EEG), which measures brain activity, may also be useful in ruling out other sources of any seizures.

Once the diagnosis of Hashimoto's encephalopathy has been confirmed, the medical professional will develop a treatment plan. Corticosteroids typically reduce the immune response and slow the production of anti-thyroid antibodies. If the patient also has hypothyroidism, treatment with thyroid hormones may be necessary for the remainder of the patient's life. Many patients see a reduction in neurological symptoms after treatment.