Hashimoto's Encephalopathy: Case Series and Literature Review.

PURPOSE OF REVIEW: To describe the clinical manifestations of Hashimoto's encephalopathy (HE) and discuss its pathogenesis in light of recent research. RECENT FINDINGS: The pathogenesis of HE is uncertain. Available evidences point towards an autoimmune etiology due to vasculitis or other inflammatory process. Detection of thyroid antibodies - antithyroid peroxidase and anti-thyroglobulin are essential for diagnosis. Autoimmune encephalitis including Anti-IgLON5 disease needs to be excluded in suspected cases with appropriate tests for neuronal surface antibodies. Detection of thyroid autoantibodies is nonspecific, as these can be detected in some normal individuals and in other autoimmune diseases. In recent years, attention has turned to an aggressive form of Hashimoto's thyroiditis accompanied by elevated serum IgG4 levels in younger males with very high levels of thyroid antibodies. The role of the thyroid autoantibodies in the central nervous system (CNS) tissue damage remains unclear and these can act only as markers for diagnosis. Conversely, they have a role to play in determining the thyroid pathology - more glandular fibrosis associated with thyro-peroxidase antibody than with the thyroglobulin antibody. HE is a syndrome characterized by altered mental status, confusion, hallucinations, delusions, and sometimes seizures, in association with high serum anti-thyroid antibody concentration that is usually responsive to glucocorticoid therapy. Diagnosis requires the exclusion of other causes of encephalopathies and encephalitis including autoimmune encephalitis associated with neuronal surface antibodies and paraneoplastic ones. Diagnosis also is dependent on the demonstration of thyroid autoantibodies in serum. Since there is no direct pathophysiologic link between antithyroid antibodies, Hashimoto thyroiditis and the cerebral syndrome, the nomenclature HE could be misleading. The response to steroids led to a renaming of the syndrome to steroid responsive encephalopathy associated with autoimmune thyroiditis (SREAT), though some cases do not respond to steroids. In recent years, attention has turned to an aggressive form of Hashimoto's thyroiditis accompanied by elevated serum IgG4 levels (IgG4-related disease). This is characterized by a higher incidence in men (5:1) than in women, onset at a younger age, more intense thyroid inflammation and higher antithyroid antibody titters. Such patients have excessive production of IgG4 + plasmacytes, which infiltrate various organs leading to their fibrosis and sclerosis, sometimes resulting in inflammatory tumors. HE is treated with corticosteroids along with treatment of the dysthyroid condition, if any. There are yet no guidelines regarding steroid dose and/or duration.

MRI and steroid-responsive encephalopathy associated with autoimmune thyroiditis: first report of conus medullaris involvement and literature review of the known neuroimaging profiles.

BACKGROUND: Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT) is a rare but potentially reversible autoimmune encephalopathy. The most frequent neuroimaging correlates are normal brain MRI or non-specific white matter hyperintensities. METHODS: We present the first description of conus medullaris involvement, also providing an extensive review of MRI patterns described so far. RESULTS: Our results show that in less than 30% of cases, it is possible to find focal SREAT neuroanatomical correlates. Among these, T2w/FLAIR temporal hyperintensities are the most frequent, followed by basal ganglia/thalamic and brainstem involvement, respectively. CONCLUSIONS: Unfortunately, spinal cord investigation is an uncommon practice in the diagnostic approach of encephalopathies, thus neglecting potential pathological lesions of the medulla spinalis. In our opinion, the extension of the MRI study to the cervical, thoracic, and lumbosacral regions may allow finding new, and hopefully specific, anatomical correlates.

Steroid-responsive encephalopathy in autoimmune thyroiditis (SREAT) as a differential diagnosis of Creutzfeldt-Jakob disease.

INTRODUCTION: Steroid-responsive encephalopathy in autoimmune thyroiditis (SREAT) is characterised by a wide range of neuropsychiatric symptoms and elevated thyroid antibodies. SREAT can mimic sporadic Creutzfeldt-Jakob disease (sCJD) and distinguishing between both entities is important because SREAT responds to corticosteroids. MATERIAL AND METHODS: Data of patients reported to the National Reference Centre for the Surveillance of CJD in Göttingen, Germany between August 1994 and October 2008 was retrospectively reviewed. In the case and control groups, 49 patients had SREAT and 48 had sCJD with elevated thyroid antibodies. RESULTS: Antibodies against thyroid peroxidase were the most common antibodies in both SREAT (86%) and sCJD (88%), followed by antibodies against thyroglobulin (SREAT, 63.3%; sCJD, 39.6%; p = 0.020) and TSH-receptor-antibodies (SREAT, 14.3%; sCJD, 2.1%; p = 0.059). Epileptic seizures were observed more frequently in the SREAT group (SREAT, 44.9%; sCJD, 12.5%; p < 0.001). Dementia (SREAT, 61.2%; sCJD, 100%; p < 0.001), ataxia (SREAT, 44.9%; sCJD, 89.6%; p < 0.001), visual impairment (SREAT, 22.4%; sCJD, 50%; p = 0.005), extrapyramidal disorder (SREAT, 32.7%; sCJD, 60.4%; p = 0.006), myoclonus (SREAT, 38.8%; sCJD, 81.3%; p < 0.001) and akinetic mutism (SREAT, 6.1%; sCJD, 37.5%; p < 0.001) were observed more frequently in sCJD. Cerebrospinal fluid (CSF) pleocytosis was observed more frequently in SREAT patients (SREAT, 33.3%; sCJD, 6.4%; p = 0.001), as was a pathological increase in protein concentration (SREAT, 68.8%; sCJD, 36.2%; p = 0.001). CONCLUSIONS: In a case of encephalopathy, the diagnosis of SREAT should also be considered in suspected cases of CJD so as to be able to start corticosteroid treatment quickly.

Steroid responsive encephalopathy associated with autoimmune thyroiditis as a cause of acuteencephalopathy.

Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT), known as Hashimoto's encephalopathy (HE), represents a heterogeneous group of neurological and neuropsychiatric symptoms associated with a presence of antithyroid antibodies in case of other causes of encephalopathy were excluded. Clinical symptoms most commonly includes acute onset of encephalopathy, behaviour changes and cognitive dysfunction, epileptic seizures as well as cerebellar and extrapyramidal symptoms. Corticoids provides rapid and sustained therapeutic benefit in most patients and only a few patients require other immunosuppressive therapy such as plasmapheresis, intravenous immunoglobulins, or others. We present the cases of two patients with acute onset of encephalopathy, status epilepticus based on SREAT, with rapid improvement after steroid treatment.

Patients with a relapsing course of steroid-responsive encephalopathy associated with autoimmune thyroiditis exhibit persistent intrathecal CD4+ T-cell activation.

BACKGROUND AND PURPOSE: Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT) is a rare condition defined by encephalopathy with acute or subacute onset, the presence of serum anti-thyroid antibodies, and reasonable exclusion of alternative causes. Despite having strong response towards corticosteroid treatment, some patients exhibit a chronic-relapsing course and require long-term immunosuppression. Markers for early identification of those patients are still absent. Thus, we aimed to characterise clinical as well as laboratory parameters of our local SREAT cohort. METHODS: We retrospectively evaluated a cohort of 22 SREAT patients treated in our hospital from January 2014. RESULTS: A total of 14 patients with a monophasic disease course and eight patients with multiple relapses were identified. Neither baseline characteristics nor routine cerebrospinal fluid (CSF) parameters were able to distinguish between those patient groups. Flow cytometry following initial relapse therapy showed treatment-resistant sequestration of activated CD4+ T cells in patients with a relapsing disease course, whereas other lymphocyte subsets showed uniform changes. Such changes were also present in long-term follow-up CSF examination. CONCLUSION: Our findings indicate a potential biomarker for risk stratification in patients with SREAT. Currently, it remains unclear whether the observed two phenotypes are different spectra of SREAT or represent separate diseases in terms of pathophysiology.

Initial serum thyroid peroxidase antibodies and long-term outcomes in SREAT.

OBJECTIVE: To quantify clinical outcome in patients with steroid-responsive encephalopathy and associated autoimmune thyroiditis (SREAT) after the acute phase and explore potential associations of initial serum thyroid peroxidase antibody titers (TPO-Abs) with outcome. MATERIALS AND METHODS: Retrospective chart review of patients diagnosed with SREAT between 01/2005 and 05/2014 in a tertiary care center and followed in an affiliated autoimmune outpatient clinic. Outcome was quantified using the extended Glasgow Outcome Scale (GOS-E). We calculated Pearson's correlation coefficients to quantify associations with clinical outcome at follow-up. RESULTS: Among 134 patients with encephalopathy of unknown etiology, we identified 13 patients diagnosed with SREAT. In two patients, the diagnosis was revised at subsequent hospitalization (NMDA-R encephalitis and adult-onset Still's disease). The median follow-up time was 11 months, and the median GOS-E was 6 (range 3-8). Higher serum TPO-Ab-titers correlated with more favorable outcomes (Pearson coefficient 0.65, P = 0.03). CONCLUSION: A correlation between TPO-Ab-titers and outcome has not been reported previously and challenges the notion of a mere bystander role of TPO-Abs in SREAT.

Steroid responsive encephalopathy associated with autoimmune thyroiditis (SREAT) presenting as major depression.

BACKGROUND: Hashimoto's encephalopathy is a neuropsychiatric disease with symptoms of cognitive impairment, stroke-like episodes, seizures, and psychotic or affective symptoms associated with autoimmune thyroiditis and excellent steroid responsiveness; therefore, it is also called "steroid responsive encephalopathy associated with autoimmune thyroiditis" (SREAT). CASE PRESENTATION: We present the case of a 50-year-old woman who developed a first-onset depressive syndrome with predominant cognitive impairment and inability to work. Antidepressive treatment and cognitive behavioral therapy over two years were unsuccessful. Neurological examination was unremarkable. Serum analysis showed increased thyroid peroxidase and thyroglobulin antibodies. Cerebrospinal fluid protein and albumin quotient were increased. Magnetic resonance imaging depicted unspecific, supratentorial white matter lesions and frontal accentuated brain atrophy. Electroencephalography was normal. Neuropsychological testing for attentional performance was below average. High-dose intravenous treatment with methylprednisolone over 5 days and oral dose reduction over 3 weeks led to the sustained improvement of clinical symptoms. Following discharge from the hospital, the patient returned to work, and 6.5 months after the start of therapy, no neuropsychological deficit remained. CONCLUSION: This case report illustrates that SREAT might present with purely depressive symptoms, thus mimicking classical major depression. In such cases, corticosteroid therapy may be an effective treatment option.

Characterization of neurological morbidity associated with thyroid antibodies: Hashimoto's encephalopathy and beyond.

BACKGROUND: Hashimoto's Encephalopathy (HE) manifests with various neurologic symptoms associated with elevated thyroglobulin (TG) and/or thyroperoxidase (TPO) antibodies. Some patients with thyroid antibodies exhibit neurological presentations not consistent with HE. This study aims to characterize the spectrum of neurological morbidity in patients with thyroid antibodies. METHODS: We reviewed all patients tested for TG or TPO antibodies from 2010 to 2019. Patients tested for thyroid antibodies as part of a neurological workup for new symptoms were classified into the following categories: patients meeting full criteria for HE, patients with other neuroimmunological disorders, patients with unexplained neurological symptoms not fully meeting HE criteria, and patients with incidental non neuroimmunological disorders. RESULTS: There were 2717 patients with positive thyroid antibodies in the dataset including 227 patients (78% female, age 54 ± 19 years) who met inclusion criteria. Twelve patients (5%) met HE criteria, 30 (13%) had other neuroimmunological disorders, 32 (14%) had unexplained neurological symptoms, and 153 (67.4%) had incidental disorders. In addition to cognitive dysfunction, seizures, movement disorders, motor weakness, and psychosis, HE patients were also more likely to have cerebellar dysfunction, language impairment, and sensory deficits. They were more likely to carry a Hashimoto's thyroiditis diagnosis and had higher titers of thyroid antibodies. They all had a robust response to steroids. CONCLUSION: The neurological spectrum of HE may be wider than previously reported, including frequent cerebellar, sensory, and language dysfunction. A subgroup of thyroid antibody positive patients with unexplained neurological symptoms may represent further expansion of thyroid antibody-related neurological disorders.

Diagnostic and Therapeutic Challenges of Steroid-Responsive Encephalopathy Associated With Thyroiditis: A Case Report.

Steroid-responsive encephalopathy associated with thyroiditis (SREAT) is a rare autoimmune disorder characterized by cognitive dysfunction. SREAT is frequently overlooked despite its profound impact on patients and the healthcare system. This case report details a male patient who experienced a series of neuropsychiatric symptoms over several months, ultimately attributed to SREAT, emphasizing the critical impact of delayed recognition. The case underscores the diverse and often complicated presentations of SREAT, advocating for the timely consideration of autoimmune encephalopathy in patients with unexplained neuropsychiatric symptoms and abnormal thyroid function. Furthermore, it illustrates the effectiveness of steroids in managing SREAT and the challenges posed by long-term steroid use. Comprehensive diagnostic criteria and tailored treatment strategies are crucial for improving patient outcomes in this rare but impactful disorder.

Hashimoto encephalopathy: a literature review and case report with comprehensive neuropsychological evaluation.

Objective: Hashimoto's encephalopathy (HE), a rare immune-mediated disorder, manifests as altered mental state, cognitive and psychological dysfunction, seizures, and myoclonus. Little is known, however, about the neuropsychological profiles of individuals with HE due to the sparse amount of research. This report overviews HE, summarizes findings from available published neuropsychological evaluations, and details neuropsychological examinations of a 57-year-old White woman with a confirmed HE diagnosis evidencing persistent neuropsychological impairment at two discrete timepoints. Method: An extensive literature search was conducted on PubMed and Google Scholar for studies including neuropsychological evaluations of HE cases. Our neuropsychological evaluation included chart review, diagnostic clinical interview, performance-based neurocognitive assessment, and measures of personality and psychopathology. Results: Our assessment revealed a largely subcortical pattern of neurocognitive impairment and impactful neuropsychiatric symptoms that, together, significantly impacted the patient's quality of life and functional status. The patient's performance improved during a six-month re-evaluation within the domains of cognition, psychological functioning, and functional independence. Conclusions: This article highlights the complexity and possible long-term sequela of HE. Complex medical history (including autoimmune disorders) and psychiatric presentation at onset may be factors related to longer-term cognitive dysfunction. Neuropsychology and psychology can serve important and unique roles in assessing long-term functioning and response to treatment in such cases.

Steroid-responsive encephalopathy associated with autoimmune thyroiditis presenting as cortisone sensible psychosis with reversible leukoencephalopathy.

INTRODUCTION: Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT) is a frequently discussed neuropsychiatric syndrome with elevated thyroid antibodies in the context of various clinical neuropsychiatric phenotypes. MRI abnormalities are usually nonspecific and treatment can be complex. CASE STUDY: We present a case of a woman in her sixties with SREAT whose psychosis kept worsening under cortisone tapering. After three years with cortisone side effects, therapy was changed to plasmapheresis and rituximab treatment with an excellent initial response, subacute unexplained deterioration with extensive leukoencephalopathy on MRI shortly after, and full recovery with regression of leukoencephalopathy afterwards. DISCUSSION: SREAT varies in clinical and diagnostic presentation. Its precise pathophysiology is unknown, as are the best treatment protocols. The case illustrates that some patients with SREAT syndrome might end up in constellations, in which it proves difficult to wean off steroid treatment and illustrates treatment alternatives such as plasmapheresis and/or rituximab. In addition, it highlights leukoencephalopathy as possible MRI finding in the context of SREAT. Further research is necessary to fully comprehend the (potentially different) pathomechanisms and courses of SREAT.

Encephalopathy of Autoimmune Origin: Steroid-Responsive Encephalopathy With Associated Thyroiditis.

Background/Objective: Our objective is to highlight the importance of identifying symptoms of steroid-responsive encephalopathy with associated thyroiditis (SREAT), especially in the setting of intermittent cognitive dysfunction, and to inform that SREAT can develop even in patients with a history of partial thyroidectomies. Case Report: We present a case of a 51-year-old woman with a long-standing history of hypothyroidism presenting with acute onset myoclonus, involuntary tremors, fatigue, malaise, and palpitations for two weeks, with intermittent lapses in cognitive function. The patient's workup is completely within normal limits, including her cognition, except for elevated thyroid stimulating hormone levels and markedly elevated levels of antithyroid peroxidase antibodies, despite the fact that she previously had a partial thyroidectomy. Discussion: SREAT is an autoimmune condition characterized by cognitive dysfunction, elevated thyroid autoantibodies, and therapeutic response to corticosteroids. SREAT is primarily considered a diagnosis of exclusion. A crucial feature is the hallmark of significant improvement in symptoms when glucocorticoids are administered. There is a significant correlation between patients with elevated antithyroid peroxidase antibodies and new-onset SREAT. Although total thyroidectomy has been reported as a definitive treatment of SREAT, response to corticosteroids is the "sine qua non" in diagnosing this condition. Conclusion: Hashimoto's thyroiditis can lead to a rare complication called SREAT, presenting with various neurologic symptoms. Prompt glucocorticoid treatment is vital, and a positive response confirms the diagnosis. Total thyroidectomy may be necessary for definitive SREAT treatment. More research is needed for alternate treatments and an understanding of the pathophysiology of SREAT.

Thyroid Disorders and Movement Disorders-A Systematic Review.

Background: There is overlap between movement disorders and neuroendocrine abnormalities. Objectives and methods: To provide a systematic review on the association of thyroid dysfunction and movement disorders. Thyroid physiological function and classical thyroid disorders highlighting typical and atypical manifestations including movement disorders, as well as diagnostic procedures, and treatments are discussed. Results: Hypothyroidism may be associated with hypokinetic and hyperkinetic disorders. There is debate whether their concomitance reflects a causal link, is coincidence, or the result of one unmasking the other. Hypothyroidism-associated parkinsonism may resemble idiopathic Parkinson's disease. Hypothyroidism-associated hyperkinetic disorders mainly occur in the context of steroid-responsive encephalopathy with autoimmune thyroiditis, that is, Hashimoto disease, mostly manifesting with tremor, myoclonus, and ataxia present in 28-80%, 42-65% and 33-65% in larger series. Congenital hypothyroidism manifesting with movement disorders, mostly chorea and dystonia, due to Mendelian genetic disease are rare.Hyperthyroidism on the other hand mostly manifests with hyperkinetic movement disorders, typically tremor (present in three quarters of patients). Chorea (present in about 2% of hyperthyroid patients), dystonia, myoclonus, ataxia and paroxysmal movement disorders, as well as parkinsonism have also been reported, with correlation between movement intensity and thyroid hormone levels.On a group level, studies on the role of thyroid dysfunction as a risk factor for the development of PD remain non-conclusive. Conclusions: In view of the treatability of movement disorders associated with thyroid disease, accurate diagnosis is important. The pathophysiology remains poorly understood. More detailed case documentation and systematic studies, along with experimental studies are needed.

[Hashimoto's encephalopathy-An underdiagnosed disease in psychiatry?] / Hashimoto Enzephalopathie ­ Eine unterdiagnostizierte Erkrankung in der Psychiatrie?

In recent years, research has increasingly focused on inflammatory processes as a trigger for psychiatric illnesses. Contrary to previous suggestions, clinical pictures with psychiatric features only also can occur, leading to erroneous diagnoses and treatments. We describe the case of a patient who was initially diagnosed paranoid schizophrenia on the basis of the clinical presentation. Antipsychotic treatment was frequently discontinued by the patient also due to inadequate response. After intensifying the diagnostic procedures autoimmune thyroiditis oft he Hashimoto type was detected in the patient. Excluding the other causes, Hashimoto's encephalopathy was considered as a differential diagnosis. The patient agreed to a therapeutic attempt with cortison leading to complete remission of psychotic symptoms thus confirming the diagnosis of steroid-responsive encephalopathy associated with autoimmune thyroiditis.

Autoimmune Encephalopathy Associated With Anti-thyroid Antibodies: A Case Report.

Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT), also known as Hashimoto encephalopathy (HE), is a rare condition. HE is characterized by abnormal brain function associated with elevated titers of anti-thyroid peroxidase (anti-TPO) and/or anti-thyroglobulin (anti-Tg) antibodies. We present a case of a 19-year-old female with rapidly progressing psychosis with mutism, catalepsy, echopraxia, and catatonia that developed over the course of three months. She was found to have high-level anti-thyroid antibodies raising suspicion of subclinical autoimmune thyroiditis and positive antinuclear antibodies. Imaging of the brain revealed generalized cerebral atrophy abnormal for her age. The patient was aggressively treated with corticosteroids and immunomodulators and her symptoms were greatly improved. This case emphasizes the significance of thyroid antibody measurement in patients presenting with psychiatric symptoms to evaluate patients for autoimmune encephalitis, since treatment with steroids and other immunosuppressive agents may be warranted.

Hashimoto Encephalopathy-Still More Questions than Answers.

The normal function of the nervous system is conditioned by the undisturbed function of the thyroid gland and its hormones. Comprehensive clinical manifestations, including neurological disorders in Hashimoto's thyroiditis, have long been understood and, in recent years, attention has been paid to neurological symptoms in euthyroid patients. Hashimoto encephalopathy is a controversial and poorly understood disease entity and the pathogenesis of the condition remains unclear. We still derive our understanding of this condition from case reports, but on the basis of these, a clear clinical picture of this entity can be proposed. Based on a review of the recent literature, the authors present the current view on the subject, discuss controversies and questions that still remain unanswered, as well as ongoing research in this area and the results of our own work in patients with Hashimoto's thyroiditis.

MRI Findings of Two Patients With Hashimoto Encephalopathy.

Hashimoto encephalopathy (HE), also known as steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT), is a rare type of autoimmune encephalitis that typically presents with cognitive and neuropsychiatric symptoms that resolve with steroids. Positive neuroimaging findings of HE are rarely reported in the literature. We present two cases of HE with abnormal MRI findings, including signal abnormalities in the claustrum, cerebral white matter, and mesial temporal lobes. HE and other forms of autoimmune encephalopathies can often be misdiagnosed as viral encephalopathies. As such detection of subtle neuroimaging findings in the context of suspicious clinical history should prompt further investigations to ensure accurate and timely diagnosis.

A Case of Euthyroid Steroid-Responsive Encephalopathy With Subacute Dementia.

Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT), frequently termed as Hashimoto's encephalopathy (HE), is characterized by reversible encephalopathy with the presence of elevated antithyroid antibodies. The condition was initially described due to its association with Hashimoto's thyroiditis. We report a case of euthyroid HE presenting as subacute dementia. A 50-year-old woman presented with progressive memory decline for six weeks. Thyroid function tests, thyroid ultrasound, and cerebrospinal fluid analysis were unremarkable. Electroencephalogram showed generalized slowing with triphasic waves. On magnetic resonance imaging, T1 weighted images revealed hyperintensity in bilateral basal ganglia. Antithyroglobulin and antithyroid peroxidase were markedly elevated. She improved remarkably on tablet prednisolone 60 mg once daily, confirming the suspicion of steroid-responsive encephalopathy. Thus, we conclude that patients with subacute cognitive decline could be screened for antithyroid antibodies in the dementia workup despite their euthyroid status.

[The detection of antithyroid antibodies in cerebrospinal fluid using fluorescent enzyme immuno assay (FEIA) is suitable for biological diagnosis of Hashimoto's encephalopathy]. / Détection des auto-anticorps antithyroïdiens dans le LCR par technique d'immunofluorométrie (FEIA) : application au diagnostic biologique de l'encéphalopathie d'Hashimoto.

Hashimoto encephalopathy (HE) is a rare condition often underdiagnosed. The clinical picture is heterogeneous with numerous neurological signs and is associated with the presence of high levels of anti-thyroperoxidase (TPO) and / or anti-thyroglobulin (TG) antibodies in the blood and cerebrospinal fluid (CSF). The determination of anti-TPO and anti-TG antibodies in CSF is performed in only few laboratories. The aim of our study was to adapt the EliATM fluoroenzymatic immuno assay (FEIA) to the detection of these autoantibodies in the CSF, and to compare the results with our previously published ELISA test (Blanchin S. 2007). For the FEIA technique, the detection threshold, and the quantification threshold have been determined for anti-TPO and anti-TG antibodies. FEIA results were concordant with ELISA at 75% and 100% for anti-TPO and anti-TG antibodies, respectively. Coefficients of variation (CV) of the intra-assay and inter-assay results were calculated as well as the uncertainties of measurement. The anti-TPO and anti-TG antibodies detection in CSF using FEIA technique correlate with the previously published ELISA and show good analytical performances. The availability of PhadiaTM 250 analyzer in a large number of laboratories will allow an easier biological detection. We hope that this test will respond to physician needs and help for HE diagnosis.

Amino acid sequence homology between thyroid autoantigens and central nervous system proteins: Implications for the steroid-responsive encephalopathy associated with autoimmune thyroiditis.

A few patients with Hashimoto's thyroiditis or Graves' disease develop a multiform syndrome of the central nervous system (CNS) termed Hashimoto's encephalopathy or steroid-responsive encephalopathy associated with autoimmune thyroid disease (HE/SREAT). They have high levels of thyroid autoantibodies (TgAb, TPOAb and/or TSH-R-Ab) in blood and cerebrospinal fluid. Autoantibodies against alpha-enolase, aldehyde reductase-I (AKRIA) and/or dimethylargininase-I (DDAHI), proteins expressed in the CNS among other tissues, were detected in the blood and, when searched, in the cerebrospinal fluid of HE/SREAT patients. Recently, we reported that alpha-enolase, AKRIA and DDAHI share local sequence homology with each of the three autoantigens (TgAb, TPOAb, TSH-R-Ab), often in epitope-containing segments of the thyroid autoantigens. We hypothesized that there might be additional CNS-expressed proteins homologous to thyroid autoantigens, possibly overlapping known epitopes of the thyroid autoantigens. We used bioinformatic methods to address this hypothesis. Six, 27 and 47 of 46,809 CNS-expressed proteins share homology with TSH-R, Tg and TPO, respectively. The homologous regions often contain epitopes, and some match regions of thyroid autoantigens which have homology with alpha-enolase, AKRIA and/or DDAHI. Several of the aforementioned proteins are present in CNS areas that show abnormalities at neuroimaging in HE/SREAT patients. Furthermore, autoantibodies against some of the said six, 27 and 47 proteins were reported to be associated with a number of autoimmune diseases. Not only we validated our hypothesis, but we think that such a variety of potential CNS targets for thyroid Ab against epitopes contained in regions that have local homology with CNS proteins may explain the polymorphic phenotypes of HE/SREAT. Only when elevated amounts of these Ab are synthesized and trespass the blood-brain barrier, HE/SREAT appears. This might explain why HE/SREAT is so relatively rare.