Hashimoto Encephalopathy
Hashimoto encephalopathy is an uncommon syndrome associated with Hashimoto thyroiditis that is most often characterized by subacute onset of confusion with altered level of consciousness, hallucinations or somnolence, focal neurologic deficits, and focal or generalized tonic-clonic seizures. Hashimoto encephalopathy is believed to be an immune-mediated disorder rather than a direct effect of abnormal thyroid function.The mechanism of Hashimoto encephalopathy is unknown. The bulk of evidence points to an autoimmune vasculitis or other inflammatory process, perhaps due to immune complex deposition.
A diagnosis of Hashimoto encephalopathy is supported by the findings of elevated anti-thyroid peroxidase (TPO) or antithyroglobulin (Tg) antibody, exclusion of other causes of encephalopathy and response to corticosteroids. Antithyroid antibodies are probably not pathogenic, because the central nervous system does not express antigens recognized by these antibodies. No relationship exists between severity of neurologic symptoms and anti-TPO or Tg antibody concentration. Changes in antithyroid autoantibody levels do not consistently correspond with response to treatment.
Hashimoto encephalopathy is usually treated with corticosteroids and treatment of a dysthyroid state. Patients who are unresponsive to corticosteroids have been treated with immunosuppressive medications such as azathioprine and cyclophosphamide. Clinical improvement with intravenous immune globulin and plasmapheresis has been reported in individual cases. Most patients have a good outcome, but a few have persistent cognitive deficits.
