Hashimoto’s encephalopathy presenting periodic synchronous discharge, as a differential diagnosis for Creutzfeldt-Jakob disease

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.

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.

[A case of genetic Creutzfeldt-Jakob disease that required differential diagnosis of acute encephalopathy associated with Sjogren's syndrome]

An 86-year-old female was admitted to our hospital with acute progressive gait disturbance and cognitive impairment. Brain MR diffusion weighted imaging revealed abnormal high signal intensities in the bilateral hemispheres, dominantly in the frontal lobe. We first suspected acute encephalopathy due to Creutzfeldt-Jakob disease (CJD) from her clinical information. At the same time, we could not negate the possibility of Sjögren's syndrome (SjS) -related encephalopathy based on the abnormal findings on brain MRI and positive anti-SS-A antibody in the serum. After consulting with an otorhinolaryngologist and a pathologist, biopsy of the salivary gland was performed with a strict precaution against infection of prion virus. Pathological examination of the biopsy specimen showed accumulation of many lymphocytes around the gland, which satisfied grade 4 in the Greenspan classification. A definite diagnosis of SjS was made based on the pathological findings, and intravenous high dose methylprednisolone followed by oral prednisolone were administered for suspected SjS-related encephalopathy. However, the neurological symptoms did not improve and we judged that SjS-related encephalopathy was unlikely. The poor response to steroid therapy and the presence of tau protein, strongly positive 14-3-3 protein and a codon 180: Val/Ile mutation in the cerebrospinal fluid finally led to a clinical diagnosis of genetic CJD. In-hospital cooperation in terms of infection prevention is important when performing invasive procedure in the case of suspected CJD to distinguish treatable encephalopathy.

Case Report: Paraneoplastic Hashimoto's Encephalopathy Associated With Lymphomatosis Cerebri With Periodic Synchronous Discharges Resembling Creutzfeldt-Jakob Disease

Hashimoto's encephalopathy (HE) is an autoimmune encephalopathy that presents with various clinical symptoms, including cognitive deterioration, convulsive seizures, and personality changes. HE is associated with thyroid autoimmunity; however, few cases have been reported to develop as paraneoplastic syndrome. Herein, we report the case of a 73-year-old woman with onset of rapidly progressive dementia. Brain magnetic resonance imaging showed diffuse T2 hyperintensity areas involving the bilateral cerebral white matter, right midbrain tegmental area, left cerebral peduncle, and right middle cerebellar peduncle without clear diffusion hyperintensities and gadolinium enhancement. Her neurological symptoms worsened rapidly, and she presented with the apallic syndrome. Electroencephalogram showed periodic synchronous discharge, suggestive of Creutzfeldt–Jakob disease. However, a brain biopsy revealed infiltration of atypical lymphoid cells expressing CD20, and the anti-NH2 terminal of the α-enolase antibody was detected, diagnosing the complication with lymphomatosis cerebri and HE. High-dose intravenous methylprednisolone therapy and oral prednisolone with whole cranial irradiation enabled her to have simple conversations and consume food orally; however, severe cognitive impairment persisted. Although HE is a rare complication of malignant lymphoma, clinicians should be aware that it could be strongly suspected if the clinical symptoms worsen in the absence of imaging changes.

Clinical findings of a probable case of MM2-cortical-type sporadic Creutzfeldt-Jakob disease with antibodies to anti-N-terminus of α-enolase

We report the case of a 76-year-old woman presenting with 47-month history of progressive dementia and cortical blindness with no family history. Antibodies against thyroid glands and the N-terminus of α-enolase (NAE) were detected in her serum. Neurological examination revealed progressive dementia, frontal signs, visual disturbance, and exaggerated bilateral tendon reflexes in both legs. Diffusion MRI showed cortical hyper-intensities in the bilateral occipital and parietal, and the left frontal and temporal cortices. ^99mTc-ethyl cysteinate dimer-single photon emission computed tomography indicated decreased regional cerebral blood flow throughout the bilateral parietal lobes and partially in the left frontal and temporal lobes. PRNP gene analysis showed no mutations with methionine homozygosity at codon 129 in peripheral blood. Cerebrospinal fluid examination, including 14-3-3 and total tau protein detection, revealed normal levels; however, prion proteins were amplified by the real-time quaking-induced conversion method. Hashimoto's encephalopathy was excluded on the basis of unresponsiveness to corticosteroids. The symptoms progressed slowly. Periodic sharp-wave complexes were observed on electroencephalogram 36 months after the onset of symptoms; the patient reached a state of akinetic mutism at 47 months. This was a probable case of MM2-cortical-type sCJD with anti-NAE antibodies based on the World Health Organization (WHO) diagnostic criteria for sCJD, genetic information, and the slowly progressive course. However, this case did not meet with the probable WHO diagnostic criteria until 3 years after symptom onset, highlighting the difficulty of diagnosing a living case of the MM2-type of sCJD. Therefore, establishment of clinical diagnostic criteria for MM2-type of sCJD is required.

Epilepsy in systemic autoimmune disorders

Autoimmunity and inflammation have been implicated as causative factors of seizures and epilepsy. Autoimmune disorders can affect the central nervous system as an isolated syndrome or be part of a systemic disease. Examples of systemic autoimmune disorders include systemic lupus erythematosus, antiphospholipid syndrome, rheumatic arthritis, and Sjögren syndrome. Overall, there is a 5-fold increased risk of seizures and epilepsy in children with systemic autoimmune disorders. Various etiologic factors have been implicated in causing the seizures in these patients, including direct inflammation, effect on blood vessels (vasculitis), and production of autoantibodies. Potential treatments for this autoimmune injury include steroids, immunoglobulins, and other immune-modulatory therapies. A better understanding of the mechanisms of epileptogenesis in patients with systemic autoimmune diseases could lead to targeted treatments and better outcomes.