Hashimoto's associated ataxia

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.

Elevated titers of anti-thyroperoxidase antibodies in patients with multiple system atrophy: a pilot study

OBJECTIVES

Multiple system atrophy (MSA) is a neurodegenerative disease characterized by progressive neuronal loss and alpha-synuclein deposition in oligodendroglial cells in the central nervous system. The cause of MSA remains essentially unknown. A cerebellar syndrome was associated with autoimmune thyroid disease in some cases, apparently not related to MSA and was partially responsive to immunomodulatory therapy.

PATIENTS AND METHODS

28 euthyroid patients who fulfilled the diagnostic criteria for probable MSA, 11 with MSA-cerebellar type (MSA-C), 17 with MSA-parkinsonian type (MSA-P), 28 patients with Parkinson's disease (PD) and 26 normal euthyroid controls were tested the for serum levels of anti-thyroperoxidase antibodies (anti-TPO) and anti-thyroglobulin (Anti-TG) antibodies (Ab).

RESULTS

The laboratory results were statistically similar in all three groups, but 3 MSA-C patients had highly elevated anti-TPO Ab titers.

CONCLUSION

We identified the presence of elevated anti-TPO levels in a small subgroup of MSA-C patients but neither in MSA-P or PD patients nor in healthy controls. These findings may suggest an autoimmune etiology in some cases of MSA-C.

Hashimoto's encephalopathy: myth or reality? An endocrinologist's perspective

Since the first description of a case of episodic encephalopathy associated with Hashimoto's thyroiditis in 1966, many cases of corticosteroid-responsive encephalopathy associated with positive antithyroid antibodies, clinical Hashimoto's thyroiditis, or spontaneous autoimmune thyroid failure have been reported. These patients have neurologic manifestations of encephalopathy unrelated to other known causes. The condition has thus been termed 'Hashimoto's encephalopathy'. The literature shows no proven association between thyroid disease and the neurologic process. Although the association of a common endocrinologic condition and a rare neurologic disease may occur by chance, this type of encephalopathy probably has an autoimmune nature and thus is more likely to occur in the background of another autoimmune condition such as autoimmune thyroid disease. Until the pathogenesis of these coincident conditions is better defined, the term 'corticosteroid-responsive encephalopathy associated with autoimmune thyroiditis' is more accurate and descriptive than Hashimoto's encephalopathy. Advances in the field may clarify this seemingly inconsistent terminology.

A case report of plasma exchange therapy in non-paraneoplastic cerebellar ataxia associated with anti-Yo antibody

A 71-year-old-woman was admitted to the S. Eugenio Hospital for a history of progressively impaired standing and gait. Anamnesis revealed systemic hypertension, gastric polyposis and juvenile pulmonary tuberculosis. Neurological examination showed a severe truncal and gait ataxia, without any sensory-motor impairment. Motor and somato-sensory evoked potentials were normal. Brain Magnetic Resonance Imaging (MRI) showed minimal signs of chronic ischemia only at a supratentorial level. Cerebral Single Photon Emission Computed Tomography, spinal MRI, total body computed tomography, Esophagogastroduodenoscopy, and finally total body Positron Emission Tomography resulted negative for neoplasms. Oncological serum markers were negative. Serum antibody against Purkinje's cells (Anti-Yo) was detected and titer was 1:80, while normally it should be undetectable. Other autoantibodies (Anti-Hu, Anti-Ri) were undetectable. Two sessions of plasma exchange (PE) were thus performed, leading to a rapid, marked and durable improvement of standing and gait and to a reduction of the autoantibody, which became undetectable. No serious adverse effect was noted. Although no definite therapy for autoimmune cerebellar ataxia has been established, PE should be considered as one of the main therapeutic choices.