Autoimmune Encephalopathy

From Steroid-Responsive Encephalopathy Associated with Autoimmune Thyroiditis
Arch Neurol. 2006;63:197-202.

“Neurologists are often consulted to evaluate patients with acute or subacute encephalopathy. The differential diagnosis for encephalopathy is wide, but the clinical features and findings on blood, cerebrospinal fluid (CSF), electroencephalography (EEG), and neuroimaging studies often (but not always) lead to an accurate diagnosis. Once infectious causes are excluded, an autoimmune or inflammatory process may be suspected on the basis of inflammatory and autoimmune markers in the serum and CSF and meningeal and parenchymal abnormalities on magnetic resonance imaging (MRI) of the brain.”

In 1966, the first case of “Hashimoto's Encephalopathy” was described. The report, Hashimoto's disease and encephalopathy, published in Brain, described an association of high titers of TPO (thyroperoxidase) antibody with encephalopathy. Because these antibodies typically cause Hashimoto's disease, the encephalopathy was termed “Hashimoto's Encephalopathy”.

Since then, over a hundred cases have been published, but the disease remains under-diagnosed, insufficiently studied and widely misunderstood. Part of this confusion is attributable to the fact that this extremely rare disease is known to different people by different names. While it was initially called “Hashimoto's Encephalopathy”, this is widely considered to be a misnomer. Researchers point out that this disease is not believed to be caused by anti-thyroid antibodies. On the contrary, they are considered to be highly correlated markers of this distinct condition. Preferred names for this disease include “Steroid Responsive Encephalopathy Associated with Hashimoto's Thyroiditis” or, more generally, “Autoimmune Encephalopathy".