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Hashimoto's Encephalopathy
A Neuroendocrine Disorder

By Beverly Seminara, Patient Advocate

Beverly Seminara is a patient advocate who herself has Hashimoto's Encephalopathy. Recognizing that there is not much information disseminated about this rare condition, Beverly has researched and developed information and resources for H.E. patients. Please see Beverly's informational website, Hashimoto's Encephalopathy - A Complete List of Published Case Studies, and other information and articles online.
* * *

Hashimoto's Encephalopathy is a very rare and potentially deadly autoimmune disease with symptoms that can mimic many different neurological disorders. It is a treatable disorder -- if doctors figure out what it is in time and begin treating it. It is critical for the patient that doctors, neurologists and endocrinologists recognize this disease as soon as possible. When properly diagnosed and treated, patients begin positively responding within two weeks from the horrifying and most frightening symptoms.

Hashimoto's Encephalopathy is a disease that may have a connection to Hashimoto's Thyroiditis. However, many patients were euthyroid (normal thyroid range) or hypothyroid upon onset. It must be made absolutely clear that just because someone is has Hashimoto's Thyroiditis or another thyroid problem, that does not mean that the individual is destined to develop Hashimoto's Encephalopathy - this condition is quite rare.

Hashimoto's Thyroiditis was named after the Japanese physician Dr. Hakaru Hashimoto, who first described this condition in 1912. Hashimoto's Thyroiditis is the most common cause of hypothyroidism in the U.S., and is an autoimmune or chronic lymphocytic type of thyroiditis.

Hashimoto's Thyroiditis is not uncommon. The thyroid gland typically becomes and the antibodies the body normally produces to protect the body and fight foreign substances such as bacteria, are found to 'attack' their own thyroid tissue. Thyroid antibodies are present in 95% of Hashimoto's Thyroiditis patients and the thyroid autoimmune antibody test serves as a marker for Hashimoto's Thyroiditis. Treatment is basically the treatment for hypothyroidisim - thyroid hormone replacement drugs. Hashimoto's Encephalopathy is quite a different situation. There are some conflicting views by researchers as to Hashimoto's Encephalopathy being a type of autoimmune cerebral vasculitis, a neuroimmunological syndrome, a neurological encephalopathy, a condition that develops due to Hashimoto's Thyroiditis, or perhaps a disorder that should be classified separately. What is known is that it is a neuroendocrine disorder - meaning it affects both the endocrine system, and the neurological (nervous) system.

Hashimoto's Encephalopathy is underdiagnosed - it is likely that more cases exist than are actually properly diagnosed. It is also a treatable condition, but not curable, however, long term prognosis is good with proper treatment. It is also a relapsing condition, and a steroid responsive disorder, treatable with pral corticosteroids (Prednisone or its derivatives.) Hashimoto's Encephalopathy typically have high antithyroid antibody titers as do patients with Hashimoto's Thyroiditis, and all patients with Hashimoto's Encephalopathy eventually are diagnosed with Hashimoto's Thyroiditis as well.

As with Hashimoto's Thyroiditis, antibodies attack the thyroid gland, but with Hashimoto's Encephalopathy, antibodies also attack neurons in the brain. The neurological symptoms frequently lead to mistaken neurological diagnoses.

Many symptoms can occur. Some patients experience many of these symptoms, others may show some but not all of the symptoms listed here. Symptoms include:

  • Confusion
  • Disorientation
  • Psychosis
  • Coma
  • Tremors
  • Convulsions
  • Concentration Problems
  • Attention Span Problems
  • Difficulty Retaining Information
  • Short Term Memory Problems
  • Seizure Activity
  • Monoclonal Jerks - Involuntary Muscle Jerks
  • Dementia
  • Fatigue
  • Coordination Difficulties
  • Headaches
  • Episodes of Stroke
  • Episodes of Stroke-Like Deterioration
  • Right Sided Hemiparesis - Right Sided Partial Paralysis
  • Aphasia - Speech Difficulties
  • Articulation Difficulties
  • Word Finding Difficulties
  • Fine Motor Movement Problems - Coordination of arms, hands, fingers.
It's easy to see how, with these types of symptoms, a patient could easily be misdiagnosed with many other neurological disorders, such as stroke, early dementia, Alzheimers, psychosis, Wilson's Disease, Pick's Disease, brain cancer, primary progressive aphasia, and others. [Those are just a few of the misdiagnoses I personally had. Can you imagine being told you have one of these and to: "Get your affairs in order, you will be in a nursing home in six months or six years." ]

If Hashimoto's Encephalopathy is misdiagnosed, the lack of proper treatment can result in irreversible dementia, coma or even death. Remember it is treatable, and with proper treatment, long term prognosis is good.

I know. It's a terrifying disease. I have had Hashimoto's Encephalopathy since the summer of 1995. I went untreated for three years. My condition continued to deteriorate. I went from neurologist to neurologist even with a case study in hand on Hashimoto's Encephalopathy, with the recommended treatment, and still I did not receive the treatment specified by the case study -- oral corticosteroids - commonly known as Prednisone. It wasn't until I finally found an endocrinologist who acknowledged its existence, even though he had never heard of it. He seriously considered the case study and welcomed the challenge of something new, something not in the textbooks. We worked as a team and began treatment with Medrol, a form of Prednisone. It took us one year, beginning in October 1998, starting off at extremely high doses and suffering all the horrible side effects that come with it, to find my "Magic Number" - the perfect number of milligrams that treats my condition. We found that number in the spring of 1998, only after I had to suffer a relapse to know for sure that 6 mgs. was too high, and 2 mgs. was too low, that 4 mgs. a day is what I needed.

In the beginning of this disease and experiencing some or many of the symptoms mentioned, many patients undergo extensive neurological testing' as a course of process of elimination. Finally, if they are lucky, they receive the correct diagnosis. The endless neurological tests performed may often be normal, or may show an irregular EEG, or in some cases MRI testing show some atrophy within the brain. If an endocrinologist is called in, tests may show that the euthyroid patient is now hypothyroid and all patients now have Hashimoto's Thyroiditis. The Thyroid Autoimmune Antibody Test will show high titers of antithyroid antibodies.

The good news for patients who are lucky enough to receive the correct diagnosis and proper treatment, is that long term prognosis is good with this often underdiagnosed disease. I can only speak from my own experience with Hashimoto's Encephalopathy, even with the knowledge that a relapse can happen at no given internal, or that it could be triggered by stress or just being overtired, or perhaps someday maybe I may be one of the few fortunate patients that actually goes into total remission, or maybe not.

Having Hashimoto's Encephalopathy changes you, yes. Perhaps you are not exactly how you were before, but you're alive, functioning, able to perform daily routine activities, be independent. The relapse that may occur is correctable. I may have a relapse next week, maybe not for months, years. It is unpredictable. But when/if it does happen, correcting it for me, is just upping my milligrams from 4 mgs. a day to 6 mgs. for two or three days. No side effects from the medication and most important the relapse is gone and I am as I was before.

Interestingly, 34 case studies on Hashimoto's Encephalopathy have been published since 1966, and still this disease is underdiagnosed and misdiagnosed. The majority of cases are women. But it is imperative to note that this disease knows no gender or age. Case studies show ages 12 to 82 afflicted and just recently, titles indicating Pediatric Hashimoto's Encephalopathy. Studies are from all over the world and include multiple patients in each study. India, Italy, Greece, Scotland, Norway, The Netherlands, Spain, Japan, Germany, Great Britain, France, etc. So far only 10 people have been published in case studies within the United States. But they haven't added me or one other young woman I know who was recently diagnosed. That makes 12 of us in the United States, plus how many more in the other countries? We were diagnosed and treated. The question is: How many more are there? Misdiagnosed? Suffering needlessly? Hospitalized, or institutionalized needlessly? In psychiatric institutions needlessly? In nursing homes needlessly? Dying needlessly? Makes you wonder.

For many patients, the neurological symptoms will appear first. Specialists are often will be unable to make a clear diagnosis. Many may receive a neurological diagnosis often ending with - 'of unknown etiology,' meaning of unknown cause. I did. Too many are being misdiagnosed.

If I had not challenged the doctors, educated myself on every medical term and test, asked question after question, been so determined and tenacious to pursue my "Final Diagnosis of Primary Progressive Aphasia of Unknown Etiology," I would not be here today. I am passionate about this underdiagnosed disease, desperately want to let people know, especially neurologists and endocrinologists, that when they have that one patient exhibiting such symptoms and medical testing is so inconclusive for any disease they already know : Think, could this be Hashimoto's Encephalopathy? Then they will again save another life.


For a comprehensive listing of all published case studies on Hashimoto's Encephalopathy, visit Beverly Seminara's website, Hashimoto's Encephalopathy - A Complete List of Published Case Studies.

"Hashimoto's Encephalopathy: A Steriod-Responsive Disorder Associated with High Anti-Thyroid Antibody Titers - Report of 5 Cases."
AUTHORS: P. J. Shaw, M. D.; T. J. Walls, M. D.; . K. Newman, M. B., ChB.; P. G. Cleland, M. B., BChir.; N. E. F. Cartlidge, M. B., B. S.
PUBLICATION: Neurology, 1998, February, 41 (2 Pt. 1) Pages 228-233.
FROM: The Department of Neurology (Drs. Shaw and Cartlidge), University of Newcastle Upon Tyne; The Regional Neurological Centre (Drs. Walls and Cleland), Newcastle General Hospital, Newcastle Upon Tyne; and the Department of Neurology (Dr. Newman), Middlesborough General Hospital, Middlesborough, UK. Address correspondence and Reprint requests to: Dr. Pamela J. Shaw, Department of Neurology, Ward 6, Royal Victoria Infirmary, Newcastle Upon Tyne, NE1 4L, United Kingdom.

Enter the number 91125591 in the search box at PubMed, or click here for a link to this abstract. LINK


We describe 5 patients with a relapsing encephalopathy in association with Hashimoto's disease and high titers of anti-thyroid antibodies. The presentation is usually with a subacute onset of confusion, alteration in conscious level, and focal or generalized seizures. The relapsing course, association with myoclonus or tremulousness, and episodes of stroke-like deterioration are characteristic features. The long-term prognosis is favorable with steroid therapy, though additional immunosuppressive therapy may be required. Neurologic investigation typically shows a diffusely abnormal EEG, high CSF protein level without pleocytosis, and normal brain CT and cerebral angiogram. Isotope brain scan may show patchy abnormal uptake. Hashimoto's encephalopathy should be recognized as a definite neurologic entity and added to the list of CNS complications of thyroid disease.

"Encephalopathy Associated with Hashimoto Thyroiditis: Diagnosis and Treatment."
AUTHORS: Drs. I. Kothbauer-Margreiter; M. Sturzenegger; J. Komor; R. Baumgartner; C. W. Hess.
PUBLICATION: Journal of Neurology, 1996, August; 243(8):585-593. Abstract available through: PubMed.

Enter the # 97018409 in the search box at PubMed, or click here for a link to this abstract. LINK


Six patients with Hashimoto thyroiditis (HT) and associated encephalopathy (HE) are described and compared with 14 well-documented cases retrieved from the literature. HE typically affects patients when they are euthyroid and, in an appropriate clinical situation, antithyroid autoantibodies are the main indicators of HE. Since clinical features of HE are unspecific, other aetiologies such as infectious, metabolic, toxic, vascular, neoplastic, and paraneoplastic causes have to be excluded. Our own six cases and those from the literature show that two types of initial clinical presentation can be differentiated: a vasculitic type with stroke-like episodes and mild cognitive impairment in nine patients, and a diffuse progressive type with dementia, seizures, psychotic episodes or altered consciousness in 11 patients. These types may overlap, particularly in the long-term course without treatment. Response to steroids was usually excellent with complete remission in 80%. Eighteen of the 20 patients were women. Characteristic, though unspecific, findings were abnormal EEG (90%) and CSF (80%). Together with quantitative neuropsychological testing, these proved sensitive for monitoring the efficacy of therapy. Conversely, antithyroid autoantibody titres did not correlate with the severity or type of clinical presentation. The link between HE and HT is not clear. A pathogenetic role for antithyroid autoantibodies in the central nervous system seems unlikely.

"Encephalopathy as the Presenting Symptom of Hashimoto's Thyroiditis."
AUTHORS: Drs. N. Watemberg; D. Willis; J. M. Pellock.
FROM: Child Neurology Division, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, USA.
PUBLICATION: Journal of Child Neurology, 2000 January; 15 (1) 66-9.

Enter the # 20104582 in the search box at PubMed, or click here for a link to this abstract. LINK.


In recent years, encephalopathy has increasingly been recognized as a complication of Hashimoto's thyroiditis. It can begin abruptly as a stroke-like event, acute seizures, or confusion, or as an insidious decline in cognitive function. Most reported cases have been on adult patients, although this encephalopathy does affect children as well. This form of encephalopathy should be considered in the differential diagnosis of children and adults with unexplained neurologic deterioration. We describe the case of a child in whom acute encephalopathy was the presenting symptom of Hashimoto's thyroiditis.

"Manifestation of Hashimoto's Encephalopathy Years Before Onset of Thyroid Disease."
AUTHORS: Drs. R. Peschen; M. Schabet; J. Dichgans.
FROM: Department of Neurology, Eberhard Karls University of Tubingen, Germany.
PUBLICATION: European Neurology, 1999; 41 (2) 79-84. May try Search: European Neurology.

Enter the # 99147991 in the search box at PubMed, or click here for a link to this abstract. LINK.


Patients with Hashimoto's encephalopathy (HE), a steroid-responsive disorder, associated with Hashimoto's disease and high levels of thyroid-related autoantibodies usually present with a subacute onset of confusion, focal or generalized seizures. Frequent EEG abnormalities include generalized, rhythmic bifrontal or temporal slowing. Elevated protein levels or an intrathecal IgG synthesis may be present in cerebrospinal fluid (CSF). A 39-year-old woman underwent a relapsing course of myocloni and generalized seizures. Initially, thyroid function, thyroid-related autoantibody screening and cerebral MRI were unrevealing. CSF showed oligoclonal bands. Short-term treatment with high doses of prednisolone resolved the myocloni. During the 5th episode of myocloni, signs of hyperthyroidism and elevation of thyroid microsomal antibody titer developed. Hashimoto's thyroiditis and HE were diagnosed. After subtotal thyroidectomy the patient remained asymptomatic.

"Hashimoto's Myoclonic Encephalopathy: An Underdiagnosed Treatable Condition?"
AUTHORS: Drs. F. Ghika-Schmid; J. Ghika; F. Regli; N. Dworak; J. Bogousslavsky; C. Stadler; L. Portmann; P.A. Despland.
PUBLICATION: Movement Disorders, 1996, September, 11 (5):555- 562. ADDITIONAL COMMENTS: Movement Disorders, 1997 May, 12; 12(3):471-2.

Enter the # 97020043 in the search box at PubMed, or click here for a link to this abstract. LINK


Hashimoto's encephalopathy is a steroid-responsive encephalopathy associated with elevated blood concentrations of antithyroid antibodies. The patients are usually euthyroid or mildly hypothyroid. The authors report two pediatric patients with Hashimoto's encephalopathy and review the literature. The clinical picture in adolescents, as with adults, is pleomorphic but frequently associated with seizures, confusion, and hallucinations. Alternatively, progressive cognitive decline manifested by a drop in school performance can be observed. The diagnosis of Hashimoto's thyroiditis is often overlooked at presentation and a high degree of suspicion is necessary for proper diagnosis.

"Pediatric Manifestations of Hashimoto's Encephalopathy."
AUTHORS: Elza Vasconcellos, M. D.; Jesus Eric Pina-Garza, M. D.; Toufic Fakhoury, M. D.; and Gerald M. Fenichel, M. D.
FROM: the Departrment of Neurology; Vanderbilt University Medical Center, Nashville, Tennessee, USA. Communications should be addressed to: Dr. Pina-Garza; Vanderbilt University, Medical Center, Department of Neurology, Suite 361, 2100 Pierce Avenue, Nashville, TN 37212.
PUBLICATION: Pediatric Neurology, 1999 May; 20 (5) 394-8. Vol. 20. No. 5, Pages 394-398.

Enter the # 99297799 in the search box at PubMed, or click here for a link to this abstract. LINK


National Institute of Health (NIH), Office of Rare Diseases.
"Hashimoto's Encephalopathy - Case Report , Response to Intravenous Immunoglobulin," by Elzbeth Wirkowski, M. D.
National Library of Medicine.
National Organization for Rare Disorders (NORD)
Archives of Neurology:
Journal of Stroke and Cerebrovascular Diseases

Definition of Hashimoto's Encephalopathy "Hashimoto's Encephalopathy. A relapsing encephalopathy occurring in association with Hashimoto Disease, with high titers of antithyroid antibodies. Clinically, the condition presents with altered consciousness, confusion, focal or generalized seizures, myoclonus and episodes of strokelike deterioration."

PUBLICATION: Companion to Clinical Neurology. William Pryse-Phillips, M. D. (Lond.) Professor of Medicine (Neurology) Memorial University of Newfoundland Faculty of Medicine, St. John's Newfoundland, Canada. 1991, Page 384.

For more information on Hashimoto's hypothyroidism, see Mary Shomon's Thyroid Site.

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