Endocrine Abstracts

JOINT2520

Introduction: Neuromyelitis optica (NMO) is a rare, inflammatory, autoimmune demyelinating disease of the central nervous system (CNS), primarily affecting the optic nerves and spinal cord. The presence of anti-aquaporin-4 (AQP4) antibodies plays a key role in its pathogenesis. Given the high expression of AQP4 in the hypothalamus and other endocrine-related regions, NMO is frequently associated with endocrine dysfunctions, particularly autoimmune thyroid disorders. This case highlights the intersection between NMO and endocrine comorbidities.

Observation: We report the case of a 50-year-old woman with a one-year history of NMO, initially presenting with ophthalmoplegia and progressive bilateral visual impairment. She was treated with plasmapheresis, high-dose corticosteroids, and azathioprine. Eleven months later, she was referred for the evaluation of an incidental thyroid nodule and signs suggestive of thyroid dysfunction. Laboratory investigations revealed positive anti-thyroid peroxidase (TPO) and anti-thyroglobulin (TG) antibodies, confirming Hashimoto’s thyroiditis. Clinical examination showed a palpable, heterogeneous thyroid gland, euthyroidism, and persistent asthenia. Further endocrine evaluation ruled out adrenal insufficiency and diabetes insipidus.

Discussion and Conclusion: Autoimmune thyroid disease, including Hashimoto’s thyroiditis and Graves' disease, is the most frequently reported endocrine comorbidity in NMO. The detection of AQP4 in thyroid follicular cells suggests a potential pathogenic link. Studies indicate that up to 40% of NMO patients may have concurrent autoimmune disorders. Moreover, recent research suggests that the presence of anti-TPO antibodies may correlate with increased severity of myelitis in NMO. Patients with elevated anti-TPO levels tend to have higher disability scores on the Expanded Disability Status Scale (EDSS), a greater number of spinal cord lesions, and more frequent longitudinally extensive transverse myelitis (LETM). This association could be explained by a more aggressive immune response or by the role of thyroid hormones in myelin repair. In addition, hypothalamic involvement in NMO, although rare (reported in 2.5%–3% of cases), can be highly specific and pathognomonic due to the strong expression of AQP4 in this region. Hypothalamic lesions may manifest as isolated clinical features, including dysautonomia, hypersomnia, metabolic disturbances, and endocrine dysfunctions such as central adrenal insufficiency and the syndrome of inappropriate antidiuretic hormone secretion (SIADH). SIADH results from impaired osmoregulation due to astrocytic damage in the hypothalamus, leading to hyponatremia and altered fluid balance. Given these associations, a systematic endocrine assessment is recommended in NMO patients to optimize management and improve long-term outcomes.