J Korean Ophthalmol Soc.  2014 Mar;55(3):325-332. 10.3341/jkos.2014.55.3.325.

The Clinical Features of Ocular Myasthenia Gravis in Thyroid-Associated Ophthalmopathy

• Sohn EJ
• Hur MC
• Ahn HB

• KMID: 2218257
• DOI: http://doi.org/10.3341/jkos.2014.55.3.325

Abstract

PURPOSE
There are some challenges to accurate diagnosis of ocular myasthenia gravis (MG) in thyroid-associated ophthalmopathy (TAO) patients because the clinical features of these diseases are similar. The aim of this study was to discuss the clinical features and treatment options that may help differentiate these 2 diseases.
METHODS
We performed a retrospective analysis using the medical records of patients who visited our clinic and were diagnosed with ocular MG and TAO, from January 2002 to December 2012. The diagnosis of Ocular MG was made on the basis of clinical symptoms and signs with laboratory evaluation, including assays for antithyroid and antiacetylcholine receptor (AchRAb) antibodies, and the Ice, neostigmine, and electromyography tests.
RESULTS
Of the 9 ocular MG patients with associated ophthalmopathy, 5 were male and 4 were female. The mean age was 36 +/- 16.0 years and the follow-up period was 45.6 +/- 36.6 months. Graves' disease (8 patients) was predominant and all patients showed abnormal thyroid function. Atypical symptoms and/or mild clinical features were predominant in ocular MG patients with TAO. Positive test results were obtained as follows: Neostigmine test 33.3%, electromyography 44.4%, ice test 77.8% and anti-AchR titer test 77.8%. Thyroid function test results were abnormal in all patients. In 3 patients who were first diagnosed with TAO, symptoms remained persistent despite steroid therapy then improved dramatically by administration of an anti-acetylcholinesterase agent. These patients were diagnosed with ocular MG in conjunction with TAO.
CONCLUSIONS
Patients with thyroid disease who show atypical features, symptomatic changes with fatigue, odd appearing ptosis, and who, do not exhibit good response to treatment of TAO need to be examined for ocular MG with additional tests and treatment.

Keyword

Clinical features; Ocular myasthenia gravis; Thyroid associated ophthalmopathy

MeSH Terms

Antibodies
Diagnosis
Electromyography
Fatigue
Female
Follow-Up Studies
Graves Disease
Graves Ophthalmopathy*
Humans
Ice
Male
Medical Records
Myasthenia Gravis*
Neostigmine
Retrospective Studies
Thyroid Diseases
Thyroid Function Tests
Thyroid Gland
Troleandomycin
Antibodies
Ice
Neostigmine
Troleandomycin

Figure

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  Figure 1. (A) The patient showed exophthalmos without ptosis in the both eyes. (B) The patient showed lid retraction without ptosis in the left eye.

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  Figure 2. (A, B) The patient showed unilateral ptosis and hypotropia without exophthalmos in the right eye.

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  Figure 3. (A, yellow arrow) In patients (case 4) with limited eye movement, orbital computed tomography showed a thickening of the right medial rectus muscle. (B) In patients (case 7) with limited eye movement, orbital computed tomography showed normal thickness of all rectus muscles.

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  Figure 4. (A) The patient (case 5) showed ptosis in the both eyes after steroid pulse therapy. (B) The ptosis improved after treatment with Anticholineaseterase.

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  Figure 5. (A) The patient (case 6) showed ptosis in the right eye after steroid pulse therapy. (B) The ptosis improved after treatment with Anticholineaseterase.

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  Figure 6. (A) The patient (case 9) showed ptosis and hypotropia in the right eye. (B) Pseudoptosis in right eye, the ptosis disappeared when the hypotropic eye assumes fixation on covering the normal eye.

Reference

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