Encephalopathy associated with Hashimoto thyroiditis: pediatric perspective.

In recent years, neuropsychiatric symptoms associated with Hashimoto thyroiditis have been increasingly recognized in both adult and pediatric patients. This neurologic complication has been termed "Hashimoto encephalopathy," and it can begin abruptly, in the form of seizures or agitation, with or without other neurologic complaints, or it can develop gradually, in a relapsing-remiting manner, including, among others, cognitive deterioration and psychiatric illness. The occurrence of Hashimoto encephalopathy is unrelated to the patient's thyroid function status. Although the pathogenesis of this encephalopathy is not fully understood, evidence for both autoimmune and vasculitic mechanisms exists. Owing to a low index of suspicion, this encephalopathy is very likely underdiagnosed in children. The diagnosis of Hashimoto encephalopathy is based on detecting antithyroid antibodies in these patients, although there is no correlation between antibody levels and the severity of the illness. Cerebrospinal fluid analysis, electroencephalography, and neuroimaging studies do not show consistent findings to support the diagnosis. Physicians' awareness of this complication is of great importance because most patients respond dramatically to corticosteroid therapy. Moreover, early recognition might also avoid an expensive diagnostic work-up in patients with unexplained encephalopathy (J Child Neurol 2006;21:1-5).