Thyroid associated orbitopathy with ocular myasthenia in primary hypothyroidism: Keep those eyes open

Challenges in diagnosing coexisting ocular myasthenia gravis and thyroid eye disease

Ocular myasthenia gravis (OMG) and thyroid eye disease are two autoimmune conditions that have several overlapping clinical features, and these coexist with a small but not insignificant frequency. Segregating these diagnoses is typically straightforward, but, when the two diseases co-occur in the same individual, making a diagnosis of OMG can be very challenging. In this review we address what is known about the coexistence of OMG and thyroid eye disease and we highlight the clinical features that are suggestive of overlapping conditions. We also describe the major testing approaches used in the diagnosis of these two entities, with special emphasis on the potential shortcomings of individual tests in patients with overlapping disease. In patients with thyroid eye disease, securing a diagnosis of OMG may not be possible on the basis of a single positive test. A multimodal approach using clinical, serologic, imaging, and electrodiagnostic data, is typically required.

Rare Co-occurrence of Ocular Myasthenia Gravis and Thyroid-Associated Orbitopathy (Ophthalmopathy) in an Individual With Hypothyroidism

Ocular myasthenia gravis (Ocular MG, OMG) shares many clinical features with thyroid-associated orbitopathy or thyroid-associated ophthalmopathy (TAO). In the rare instance of their coexistence, clinicians may fail to diagnose ocular MG when TAO is also present. Here we report the case of a patient with both TAO and ocular MG, whose "hyperthyroidism"-most likely the hashitoxicosis variant of Hashimoto's thyroiditis-rapidly transformed to hypothyroidism after radioactive iodine therapy. This is reminiscent of a previous case of a patient with MG, in whom disease onset coincided with the methimazole-induced transformation from hyper- to hypothyroidism. It is possible that the same transformation from "hyper-" to hypothyroidism, which occurred after radioactive iodine therapy and was accompanied by hypothyroidism-associated orbitopathy (ophthalmopathy), may have induced the development of myasthenia gravis in our patient. The hypothyroidism may have been caused by the radioactive iodine therapy and/or it may simply reflect the natural course of the hashitoxicosis variant of Hashimoto's thyroiditis. The co-occurrence of hypothyroidism, hypothyroidism-associated orbitopathy (ophthalmopathy) and ocular MG has never been reported. Our case highlights the need for clinicians to focus on overlapping symptoms of hyperthyroidism and the hashitoxicosis variant of Hashimoto's thyroiditis, and to carefully differentiate between them, especially when deciding on radioactive iodine therapy. In addition, our case highlights that the possible co-occurrence of TAO should be considered when a patient with thyroid disease displays both ptosis and eye movement dysfunction, and when only the ptosis is dramatically resolved after treatment with pyridostigmine bromide.

Prevalence, Phenotype, and Psychosocial Well-Being in Euthyroid/Hypothyroid Thyroid-Associated Orbitopathy

BACKGROUND

At the onset of thyroid-associated orbitopathy (TAO), most patients are hyperthyroid, while scarce data are available on euthyroid/hypothyroid TAO. The aim of this study was to assess the prevalence, phenotype, and psychosocial burden of patients with initially euthyroid/hypothyroid TAO.

METHODS

The medical records of 461 consecutive and unselected patients with TAO followed at a specialized joint thyroid-eye clinic were analyzed within this retrospective cross-sectional study. Main outcome measures were the prevalence of initially eu- or hypothyroid TAO as well as ophthalmic signs and symptoms, disease-specific quality of life (QoL), work impairment, and rate of psychotherapy in initially eu-/hypothyroid versus hyperthyroid TAO.

RESULTS

The prevalences of eu-/hypothyroid and hyperthyroid TAO were 4.3% (n=20; [confidence interval, CI, 2.6-6.3]) and 95.7% (n=441; [9.37-9.74]), respectively. In 12 patients (2.6% [CI 1.3-4.3]), Hashimoto's thyroiditis was present and in 8 (1.7% [CI 0.7-3.0]) no thyroid disease was noted at the time of inclusion. One (0.05%) patient with eu-/hypothyroid TAO and 172 (39%) with hyperthyroid TAO had clinically active TAO (p=0.001). In eu-/hypothyroid versus hyperthyroid patients, 14 (70%) versus 135 (30.6%) had a mild TAO, 6 (30%) versus 183 (64.2%) a moderate-to-severe TAO, and 0 versus 23 (5.4%) had a sight-threatening TAO (p<0.001). TAO was asymmetric in 4 (20%) eu-/hypothyroid and in 27 (6.1%) hyperthyroid patients (p=0.038). Only 5.3% versus 30.2% and 10.5% versus 44.1% of patients with eu-/hypothyroid and hyperthyroid TAO, respectively, were on sick leave (p=0.003) or work disabled (p=0.018). QoL was less impaired in eu-/hypothyroid versus hyperthyroid TAO (median visual functioning and appearance scores: 100 versus 75; p<0.001 and 81.25 versus 75; p=0.315). Of patients with eu-/hypothyroid and hyperthyroid TAO, 15% and 20.2% had psychotherapy respectively (p=0.409). Eu-/hypothyroid TAO was positively (odds ratio 7.05, p=0.060) and negatively (odds ratio: 0.09, p=0.026) associated with a unilateral involvement and thyrotropin-receptor autoantibodies respectively.

CONCLUSIONS

Compared with hyperthyroid TAO, QoL and working ability are less impaired in eu-/hypothyroid TAO with an often asymmetric and less severe clinical phenotype.