The background of the study. Hashimoto’s encephalopathy is defined as the presence of confusion or impaired consciousness (encephalopathy) in a patient who has a high serum concentration of antithyroid antibodies. This study was done to determine the frequency of high concentrations of the antibodies in cerebrospinal fluid (CSF) in patients with neurologic disorders.
How the study was done. From January 2000 to October 2002, 1978 patients with confusion, cognitive impairment, stroke, or seizures were evaluated at a single hospital. Serum samples were obtained from patients with unexplained encephalopathy for measurements of antithyroid peroxidase and antithyroglobulin antibodies. In patients with high serum concentrations of one or both antibodies, the antibodies were measured in CSF. The antibodies were also measured in the serum and CSF of patients with other neurologic disorders. The diagnosis of Hashimoto’s encephalopathy was based on the presence of neurologic abnormalities and a high CSF concentration of one or both antithyroid antibodies.
The results of the study. Among the 1978 patients, 143 had findings that warranted measurements of serum antithyroid antibodies. Twelve of the 143 patients (8 percent) had a high serum concentration of one or both of the antithyroid antibodies. Nine of these 12 patients had a high CSF concentration of one or both antithyroid antibodies, and therefore were considered to have Hashimoto’s encephalopathy. Six had Hashimoto’s thyroiditis; all had normal thyroid function. The symptoms in these nine patients were: confusion, 5; impaired consciousness, 3; paresthesias, 3; memory loss, 2; ataxia, 2; sensory deficit, 2; paraparesis, 1; and hemiparesis, 1.
The conclusions of the study. A diagnosis of Hashimoto’s encephalopathy should be based on the presence of high CSF concentrations of antithyroid antibodies.
The original article. Ferracci F, Bertiato G, Moretto G. Hashimoto’s encephalopathy: epidemiologic data and pathogenetic considerations. J Neurol Sci 2004;217:165-8.