Division of Endocrinology and Diabetes Medical School University of Minnesota Minneapolis, Minnesota 55455
To the editor:
The article titled "Triple H syndrome: a novel autoimmune endocrinopathy characterized by dysfunction of the hippocampus, hair follicle, and hypothalamic-pituitary-adrenal axis," published in JCEM (1) mentions Hashimotos encephalitis in its introductory paragraphs, which prompted us to write this letter. This is a vague term, describing an association between presence of thyroid antibodies and encephalitic features, published by Seipelt et al. (2) in their article in Journal of Neurology Neurosurgery and Psychiatry (2), which has not been corroborated by any other investigators, to date. This term has been loosely applied here and there and, over time, has become an established diagnosis, which is disturbing. We have been asked about this diagnosis in consultation, from neurologic wards. Extensive literature searches and peer discussions on this topic have failed to document conclusive evidence that this diagnosis exists.
Thyroid antibodies have been reported to be commonly prevalent in normal humans, in the range of 34% (3). As such, it would not be uncommon to find them in the context of rare diseases, but a cause and effect relationship should not be described without sufficient scientific evidence. There have been numerous reports, which link the elevated autoantibodies to several conditions like habitual abortions, myasthenia gravis, multiple sclerosis, and hepatitis C; etc. (4, 5, 6, 7). However, this only suggests underlying autoimmunity, not necessarily cause and effect. The patients described in the original and only article on Hashimotos encephalitis had neurological symptoms of myoclonus, dementia, cerebellar ataxia suggestive of a neurodegenerative disorder, but lacked Creutzfeld-Jakob disease markers (2). Three of seven patients had antithyroglobulin antibodies, while a different three of seven had microsomal antibodies. The authors reported that all of them responded dramatically to steroids, leading to full recovery, but later explain that their improvement was only temporary with residual symptoms and fluctuating courses. We do not feel compelled to believe that these patients had, indeed, developed an encephalitis from the thyroid autoantibodies, and the authors themselves have reported that they failed to demonstrate any thyroid autoantibody or antigen in the cerebrospinal fluid studies.
There are no published articles describing an increased incidence of encephalitis in established cases of autoimmune thyroid disease. There have been several reports of high prevalence of thyroid autoantibodies or thyroid dysfunction among patients with chronic conditions, like hepatitis C. However, a study from Sardinia, Italy, where hepatitis C is endemic, did not show an association between hepatitis C virus and thyroid autoimmunity (7). One should exercise reasonable judgment before making valid assumptions, and, so far, there is no evidence establishing a causative relationship between thyroid autoantibodies and encephalitis. We believe that the diagnosis "Hashimotos encephalitis" does not exist and henceforth be restricted from common usage until definite proof has been found that thyroid antibodies do cause encephalitis.
Received October 11, 2000.
References