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.

Difficulties in the Diagnostics and Treatment of Hashimoto's Encephalopathy-A Systematic and Critical Review.

Hashimoto's encephalopathy (HE) has been a poorly understood disease. It has been described in all age group, yet, there is no specific HE marker. Additionally, the treatment data in the available studies are frequently divergent and contradictory. Therefore, the aim of our systematic and critical review is to evaluate the diagnosis and treatment of HE in view of the latest findings. The databases browsed comprised PubMed, Scopus, and Google Scholar as well as Cochrane Library, and the search strategy included controlled vocabulary and keywords. A total of 2443 manuscripts were found, published since the beginning of HE research until February 2024. In order to determine validity of the data collected from studies, bias assessment was performed using RoB 2 tool. Ultimately, six studies were included in our study. HE should be considered in the differential diagnosis in patients with psychiatric and neurological symptoms. According to our findings, negative thyroid peroxidase antibodies (anti-TPOs) may represent a valuable parameter in ruling out HE. Nonetheless, this result cannot be used to confirm HE. Furthermore, the proposed anti NH2-terminal-α-enolase (anti-NAE) is non-specific for HE. The effectiveness of glucocorticoid therapy is 60.94%, although relapse occurs in 31.67% of patients following the treatment. Our review emphasizes the significance of conducting further large-scale research and the need to take into account the potential genetic factor.

Steroid-Responsive Encephalopathy Associated With Autoimmune Thyroiditis Presenting With Parkinsonism.

Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT) is a rare condition defined as encephalopathy with a positive antithyroid antibody. We report the case of a 52-year-old woman who presented with Parkinsonism associated with Hashimoto's thyroiditis. A few similar cases have been reported. Our patient responded well to corticosteroids with a significant reduction in symptoms. Diagnosis can pose a significant challenge in SREAT cases because of its variable clinical presentation. Therefore, we recommend evaluating thyroid function and thyroid autoantibodies in the context of acute and subacute encephalopathy. In the elderly population, SREAT, as a cause of Parkinsonism, should not be forgotten because of its simple treatment and significant improvements in neurological symptoms.

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: 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.

Cerebellar Ataxia in the Setting of Hashimoto's Thyroiditis: A Case Report.

Hashimoto's encephalopathy (HE) is a rare diagnosis with a heterogenous presentation. It may not be directly related to thyroid dysfunction as most patients are euthyroid when the symptoms start. There has been a lack of consensus building on the pathophysiology of HE, but most of the evidence points towards autoimmune vasculitis as the underlying process. HE can present as seizures, cognitive dysfunction, tremors, or stroke-like symptoms with focal neurological deficits. Cerebellar ataxia (motor incoordination due to dysfunction of the cerebellum) is seen in HE but is a rare occurrence. The objective of the article was to present a case of cerebellar ataxia in a patient with Hashimoto's thyroiditis. A 30-year-old previously healthy female presented with quickly progressive cerebellar ataxia, bilateral (B/L) limb weakness, and excessive tearing. She was found to have high titers of anti-TPO (anti-thyroid peroxidase) antibodies; a biopsy confirmed Hashimoto's thyroiditis and a battery of negative tests excluding other causes of encephalopathy. Hence, confirming a diagnosis of HE. The patient was given glucocorticoids which relieved her symptoms. After being symptom-free for a few months, she relapsed and was unsuccessfully treated by the steroids. Upon this, she was given IV immunoglobulins, which helped achieve complete resolution. HE can be treated with immunotherapy, and most patients have a good prognosis, but some can have persistent neurological defects if left untreated or treatment is delayed. Relapses are common and may require a more extended treatment regimen.

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.

Brain dysfunction and thyroid antibodies: autoimmune diagnosis and misdiagnosis.

Hashimoto encephalopathy, also known as steroid-responsive encephalopathy associated with autoimmune thyroiditis, has been defined by sub-acute onset encephalopathy, with elevated thyroid antibodies, and immunotherapy responsiveness, in the absence of specific neural autoantibodies. We aimed to retrospectively review 144 cases referred with suspected Hashimoto encephalopathy over a 13-year period, and to determine the clinical utility of thyroid antibodies in the course of evaluation of those patients. One hundred and forty-four patients (all thyroid antibody positive) were included; 72% were women. Median age of symptom onset was 44.5 years (range, 10-87). After evaluation of Mayo Clinic, 39 patients (27%) were diagnosed with an autoimmune CNS disorder [autoimmune encephalopathy (36), dementia (2) or epilepsy (1)]. Three of those 39 patients had neural-IgGs detected (high glutamic acid decarboxylase-65, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor-receptor and neural-restricted unclassified antibody), and 36 were seronegative. Diagnoses among the remaining 105 patients (73%) were functional neurological disorder (n = 20), neurodegenerative disorder (n = 18), subjective cognitive complaints (n = 14), chronic pain syndrome (n = 12), primary psychiatric (n = 11), sleep disorder (n = 10), genetic/developmental (n = 8), non-autoimmune seizure disorders (n = 2) and other (n = 10). More patients with autoimmune CNS disorders presented with sub-acute symptom onset (P < 0.001), seizures (P = 0.008), stroke-like episodes (P = 0.007), aphasia (P = 0.04) and ataxia (P = 0.02), and had a prior autoimmune history (P = 0.04). Abnormal brain MRI (P = 0.003), abnormal EEG (P = 0.007) and CSF inflammatory findings (P = 0.002) were also more frequent in the autoimmune CNS patients. Patients with an alternative diagnosis had more depressive symptoms (P = 0.008), anxiety (P = 0.003) and chronic pain (P = 0.002). Thyoperoxidase antibody titre was not different between the groups (median, 312.7 versus 259.4 IU/ml; P = 0.44; normal range, <9 IU/ml). None of the non-autoimmune group and all but three of the CNS autoimmune group (two with insidious dementia presentation, one with seizures only) fulfilled the autoimmune encephalopathy criteria proposed by Graus et al. (A clinical approach to diagnosis of autoimmune encephalitis. Lancet Neurol 2016; 15: 391-404.) (sensitivity, 92%; specificity, 100%). Among patients who received an immunotherapy trial at our institution and had objective post-treatment evaluations, the 16 responders with autoimmune CNS disorders more frequently had inflammatory CSF, compared to 12 non-responders, all eventually given an alternative diagnosis (P = 0.02). In total, 73% of the patients referred with suspected Hashimoto encephalopathy had an alternative non-immune-mediated diagnosis, and more than half had no evidence of a primary neurological disorder. Thyroid antibody prevalence is high in the general population, and does not support a diagnosis of autoimmune encephalopathy in the absence of objective neurological and CNS-specific immunological abnormalities. Thyroid antibody testing is of little value in the contemporary evaluation and diagnosis of autoimmune encephalopathies.

Anti-Thyroid Peroxidase/Anti-Thyroglobulin Antibody-Related Neurologic Disorder Responsive to Steroids Presenting with Pure Acute Onset Chorea.

Background: Pure acute onset chorea without encephalopathy has rarely been reported in anti-thyroid peroxidase (anti-TPO)/anti-thyroglobulin (anti-TG) antibody-related neurologic disorders responsive to steroids (ATANDS). Case report: We report a 16-year-old female who presented with acute chorea without encephalopathy. Anti-TPO antibodies were found to be strongly positive (>1200 IU/ml) along with anti-thyroglobulin and anti-thyroid stimulating hormone receptor antibodies. After pulse intravenous methylprednisolone therapy (1 g/day for five consecutive days), all the movements seized, and she was discharged with oral prednisolone 30 mg/day with gradual tapering over next three months. After one year of follow-up, she is stable, drug-free, and never had any other problems. Discussion: Anti-thyroid antibodies testing should be included in routine/conventional panel that is done for elucidating causes of chorea as ATANDS can be easily missed and is treatable with widely available, relatively low-cost drugs like steroids with a promising outcome.

Relapsing encephalopathy with dancing eyes and jerky limbs.

We report a case of relapsing-remitting opsoclonus-myoclonus-ataxia syndrome (OMAS) in a patient with Hashimoto's encephalopathy, diagnosed after comprehensive evaluation. OMAS as a manifestation of Hashimoto's encephalopathy has been reported once previously. It is hoped that recognition of this entity and early initiation of immunotherapy will improve clinical outcomes for patients.

Hashimoto's encephalopathy: Follow-up data from neuropsychology, lumbar puncture, and FDG-PET.

Hashimoto's encephalopathy is a rare disease with nonspecific symptoms, associated with elevated levels of anti-TPO and/or anti-TG. It can be potentially fatal. However, it is responsive to steroid and treated in due time, it can be fully reversible.

SREAT presenting as decades of intractable seizures and isolated delusional episodes with clinical, laboratory, and EEG confirmation of treatment response.

We report a case of a 60-year-old woman with a history of intractable seizures and isolated delusional psychosis who was later diagnosed with steroid-responsive encephalopathy associated with autoimmune thyroiditis. The patient underwent right temporal lobectomy (epilepsy surgery) 15 years before coming to this clinic, but continued to have focal seizures, resulting in frequent emergency room visits thereafter. After admission for intensive inpatient video electroencephalogram monitoring and subsequent 7 months of close follow-up, both the electroencephalogram abnormalities and isolated delusional psychosis were found to be responsive to immunotherapy. This suggests that her epilepsy may be autoimmune in nature. Steroid-responsive encephalopathy associated with autoimmune thyroiditis was diagnosed after 26 years since the onset of seizures. Performing invasive epilepsy surgery in patients with autoimmune epilepsy cannot reverse the inflammatory process; therefore, it is reasonable to test for autoimmune etiologies before excision surgery on patients with medically intractable epilepsy. This case demonstrates the clinical use of quantitative electroencephalogram in assisting with the diagnosis of steroid-responsive encephalopathy associated with autoimmune thyroiditis and supports that it is a spectrum disorder with protean manifestations.

Psychotic Symptoms of Hashimoto's Encephalopathy: A Diagnostic Challenge.

Hashimoto's encephalopathy (HE) is a rare and underdiagnosed neuropsychiatric illness. We present the case of a 17-year-old girl who was admitted to a tertiary-care psychiatric center with acute onset psychosis and fever. Her psychotic symptoms were characterized by persecutory and referential delusions, as well as tactile and visual hallucinations. Her acute behavioral disturbance warranted admission and treatment in a psychiatric setting (risperidone tablets, 3 mg/day). She had experienced an episode of fever with a unilateral visual acuity defect approximately 3 years before admission, which was resolved with treatment. Focused clinical examination revealed an enlarged thyroid, and baseline blood investigations, including thyroid function test results were normal. Abnormal laboratory investigations revealed elevated anti-thyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-TG) levels (anti-TPO of 480 IU/mL; anti-TG of 287 IU/mL). Results of other investigations for infection, including cerebrospinal fluid examination, electroencephalography, and brain magnetic resonance imaging were normal. She was diagnosed with HE and was treated with intravenous corticosteroids (methylprednisolone up to 1 g/day; tapered and discontinued after a month). The patient achieved complete remission of psychotic symptoms and normalization of the anti-thyroid antibody titers. Currently, at the seventh month of follow-up, the patient is doing well. This case highlights the fact that in the absence of well-defined clinical diagnostic criteria, a high index of suspicion is required for early diagnosis of HE. Psychiatrists need to explore for organic etiologies when dealing with acute psychiatric symptoms in a younger age group.

Current knowledge on Hashimoto's encephalopathy: a literature review. / Conocimientos actuales en encefalopatía de Hashimoto: revisión de la literatura.

Hashimoto's encephalopathy is a rare disease, with a reported prevalence of 2.1 per 100 000. Clinical manifestations include confusion, decreased state of consciousness, cognitive deficit, seizures, myoclonus, ataxia, and focal neurological deficits. Due to the wide variety of signs and symptoms, clinical diagnostic suspicion is essential. Diagnosis is based on three pillars: the presence of neurological clinical manifestations after ruling out other causes of encephalopathy. 2) Presence of increased antithyroid antibodies. 3) Significant clinical improvement after the administration of immunomodulation. The treatment of Hashimoto's encephalopathy pursues two objectives: to control the autoimmune process and to control the complications of the disease. Although in most cases recovery is complete with treatment, the risk of relapse can range from 12.5 to 40% in follow-ups to 2 years.

La encefalopatía de Hashimoto es una enfermedad rara. Se reporta una prevalencia de 2,1 por cada 100 000 habitantes. Entre las manifestaciones clínicas se describen confusión, disminución del estado de consciencia, déficit cognitivo, convulsiones, mioclonus, ataxia y/o déficits neurológicos focales. Debido a la amplia variedad de signos y síntomas, la sospecha clínica diagnóstica es fundamental. El diagnóstico se basa en tres pilares: la presencia de manifestaciones clínicas neurológicas, con la exclusión de otras causas de encefalopatía; presencia de anticuerpos antitiroideos aumentados; una mejoría clínica notable luego de la administración de inmunomoduladores. El tratamiento de la encefalopatía de Hashimoto tiene dos objetivos: controlar el proceso autoinmune y controlar las complicaciones de la enfermedad. Aunque en la mayoría de los casos la recuperación es completa con el tratamiento, el riesgo de recaídas puede oscilar entre 12,5 a 40% en seguimientos a dos años.

Steroid-responsive Encephalopathy Associated with Autoimmune Thyroiditis (SREAT) Presenting with Pure Cerebellar Ataxia.

Background: Myoclonus and tremor are common movement disorder phenomenologies in steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT). Pure ataxia without encephalopathy has rarely been reported. Case report: We report 21- and 40-year-old females who presented with subacute pure ataxia without encephalopathy. After immunotherapies, both exhibited initial improvement of ataxia, and subsequently remained in plateau phase. Discussion: This treatable disorder should be added to the differential diagnoses of progressive cerebellar ataxia, and anti-thyroid peroxidase and anti-thyroglobulin should be considered as part of the workup. It is crucial not to misdiagnose SREAT presenting with pure cerebellar ataxia as degenerative or spinocerebellar ataxia.

Hashimoto encephalopathy in pediatric patients: Homogeneity in clinical presentation and heterogeneity in antibody titers.

OBJECTIVE: Hashimoto encephalopathy is an autoimmune encephalopathy characterized by elevated antithyroid antibodies and a favorable response to corticosteroid. This study delineated the clinical characteristics of pediatric Hashimoto encephalopathy and the significance of low antithyroid antibody titers in diagnosis and treatment. SUBJECTS AND METHODS: Clinical manifestations, antibody titers, and treatment responses were retrospectively reviewed in six consecutive children diagnosed with Hashimoto encephalopathy between August 2008 and July 2016. RESULTS: Age at diagnosis was 10-17years. Presenting symptoms were seizures, altered consciousness, behavioral changes, psychosis, tremor, and dystonia. Thyroid function was normal in five patients, and one had hypothyroidism prior to the encephalopathy. Antithyroid antibody titer was increased at presentation in five patients and one week later in the other. Antibody levels were extremely varied (anti-thyroglobulin, 20.5-2318.0U/ml; anti-thyroid peroxidase, 12.5-2231.0U/ml; reference range, <60U/ml) and <180U/ml in two patients. Electroencephalogram was abnormal in five patients. Brain magnetic resonance imaging was unremarkable. Four patients responded to high-dose corticosteroid and one improved with additional intravenous immunoglobulin. The remaining patient did not respond to both treatments and normalized after plasmapheresis. Autoantibody titers decreased with treatment response in the acute stage. Two patients with low antibody titers showed similar clinical presentations and responses. CONCLUSIONS: The clinical presentations and treatment responses in Hashimoto encephalopathy were similar, irrespective of antithyroid antibody titer. Because the initial antithyroid antibody titers can be normal or mildly-elevated, follow-up testing of antithyroid antibodies is required in patients who are clinically suspect for Hashimoto encephalopathy.

Conocimientos actuales en encefalopatía de Hashimoto: revisión de la literatura / Current knowledge on Hashimoto's encephalopathy: a literature review

Resumen La encefalopatía de Hashimoto es una enfermedad rara. Se reporta una prevalencia de 2,1 por cada 100 000 habitantes. Entre las manifestaciones clínicas se describen confusión, disminución del estado de consciencia, déficit cognitivo, convulsiones, mioclonus, ataxia y/o déficits neurológicos focales. Debido a la amplia variedad de signos y síntomas, la sospecha clínica diagnóstica es fundamental. El diagnóstico se basa en tres pilares: la presencia de manifestaciones clínicas neurológicas, con la exclusión de otras causas de encefalopatía; presencia de anticuerpos antitiroideos aumentados; una mejoría clínica notable luego de la administración de inmunomoduladores. El tratamiento de la encefalopatía de Hashimoto tiene dos objetivos: controlar el proceso autoinmune y controlar las complicaciones de la enfermedad. Aunque en la mayoría de los casos la recuperación es completa con el tratamiento, el riesgo de recaídas puede oscilar entre 12,5 a 40% en seguimientos a dos años.

Abstract Hashimoto's encephalopathy is a rare disease, with a reported prevalence of 2.1 per 100 000. Clinical manifestations include confusion, decreased state of consciousness, cognitive deficit, seizures, myoclonus, ataxia, and focal neurological deficits. Due to the wide variety of signs and symptoms, clinical diagnostic suspicion is essential. Diagnosis is based on three pillars: the presence of neurological clinical manifestations after ruling out other causes of encephalopathy. 2) Presence of increased antithyroid antibodies. 3) Significant clinical improvement after the administration of immunomodulation. The treatment of Hashimoto's encephalopathy pursues two objectives: to control the autoimmune process and to control the complications of the disease. Although in most cases recovery is complete with treatment, the risk of relapse can range from 12.5 to 40% in follow-ups to 2 years.

Steroid-Responsive Chronic Schizophreniform Syndrome in the Context of Mildly Increased Antithyroid Peroxidase Antibodies.

BACKGROUND: Schizophreniform syndromes can be divided into primary forms from polygenic causes or secondary forms due to immunological, epileptiform, monogenic, or degenerative causes. Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT) is a secondary immunological form associated with increased thyroid antibodies, such as antithyroid peroxidase antibodies and shows a good response to corticosteroids. CASE PRESENTATION: We present the case of a 41-year-old woman suffering from a schizophreniform syndrome. Starting at the age of 35, she developed psychotic exacerbations with formal thought disorder, acoustic hallucinations, cenesthopathic experiences, and loss of ego boundaries. At the same time, she began to suffer from chronic sexual delusions and olfactory hallucinations, which did not respond to neuroleptic medication. Her levels of antithyroid peroxidase antibodies were slightly increased, and the blood-brain barrier was disturbed. An electroencephalogram (EEG) showed intermittent generalized slowing, and cerebral magnetic resonance imaging (cMRI) depicted mild temporolateral atrophy. High-dose corticosteroid treatment led to convincing improvement of attentional performance and the disappearance of delusions and olfactory hallucinations. CONCLUSION: SREAT can mimic typical symptoms of schizophreniform syndromes. The increased titer of antithyroid peroxidase antibodies in combination with the EEG slowing, blood-brain barrier dysfunction, and the cMRI alterations were the basis for suspecting an immunological cause in our patient. Chronic delusions, olfactory hallucinations, and cognitive deficits were successfully treated with corticosteroids. The occurrence of secondary immunological forms of schizophreniform syndromes demonstrates the need for innovative immunosuppressive treatment options.