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

Eun Jung Sohn; Mun Chong Hur; Hee Bae Ahn

doi:10.3341/jkos.2014.55.3.325

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Sohn, Hur, and Ahn: The Clinical Features of Ocular Myasthenia Gravis in Thyroid-Associated Ophthalmopathy

Original Article

J Korean Ophthalmol Soc 2014;55(3):325-332.

Published online: 7 September 2014

DOI: https://doi.org/10.3341/jkos.2014.55.3.325

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

Eun Jung Sohn, MD, Mun Chong Hur, MD, Hee Bae Ahn, MD, PhD

Department of Ophthalmology, Dong-A University College of Medicine, Busan, Korea

Address reprint requests to Hee Bae Ahn, MD, PhD Department of Ophthalmology, Dong-A University Medical Center, #26 Daesingongwon-ro, Seo-gu, Busan 602-715, Korea, Tel: 82-51-240-5227, Fax: 82-51-254-1987, E-mail: hbahn@dau.ac.kr

Received 8 June 201318 September 2013 Accepted 29 January 2014

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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 dis-cuss 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 ba-sis of clinical symptoms and signs with laboratory evaluation, including assays for antithyroid and antiacetylcholine re-ceptor (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.

Keywords: Clinical features, Ocular myasthenia gravis, Thyroid associated ophthalmopathy

References

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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.

Figure 2.

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

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.

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.

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.

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.

Table 1.

Data from 9 cases of ocular MG with thyroid associated ophthalmopathy

No.	Age	Sex	Diagnostic discordance (month)	Sign				AchR Ab titer	ICE test	Orbital CT	Tx.	F/U period (month)
No.	Age	Sex	Diagnostic discordance (month)	LOM	Ptosis	Exo	Othres	AchR Ab titer	ICE test	Orbital CT	Tx.	F/U period (month)
1	51	F	3	15-30°	Unilat.	+	Hypo	5.22	-	-	M,S	108
2	22	M	0	<15°	Bilat.	-	-	<0.01	+	-	M	36
3	49	M	2	15-30°	None	-	-	0.73	-	-	S	96
4	67	F	0	30-45°	None	-	-	-	+	+	S	24
5	29	M	8	30-45°	Bilat.	+	-	2.01	+	+	M,S	48
6	19	M	12	15-30°	Unilat.	-	Hypo	1.1	+	-	M,S	16
7	39	F	1	15-30°	Unilat.	-	Retraction	<0.01	+	+	M	51
8	32	F	0	15-30°	Unilat.	-	-	-	-	-	-	Loss
9	16	M	1	30-45°	Unilat.	+	Hypo	0.04	+	-	M,S	7

Tx. = treatment; LOM = limitation of ocular movement; Exo = exophthalmox; Hypo = hypotropia; M = mestinon (Anti - acetylchoinerase); S = steroid; Unilat. = unilateral ptosis; Bilat. = bilateral ptosis.

Table 2.

Baseline characteristics of ocular MG with thyroid associated ophthalmopathy

Characteristics	Value
Number of patients	9 patients
Sex (M : F)	5 : 4
Age (years)	36.00 ± 16.03 (16-67)
Follow up lengths (month)	45.60 ± 36.6
Diagnostic discordance (month)	3.00 ± 4.21
Type of Thyroid disease
Graves’ disease	8 patients
Hashimoto thyroiditis	1 patient

Values are presented as mean ± SD.

Table 3.

Clinical features of ocular MG with thyroid associated ophthalmopathy (VISA group)⁷

Variable	Frequency (n)	Proportion (%)
Ptosis (n = 9)
Unilateral	5	56
Bilateral	2	22
None	2	22
Exophthalmos (>15 mm) (n = 9)
Present	3	33
Absent	6	67
Limitation of ocular movement (n = 9)
<15°	1	11
15-30°	5	56
30-45°	3	33
>45°	0	0

Table 4.

Diagnostic test for ocular MG in thyroid associated ophthalmopathy patients (n = 9)^*

	ICE test	Neostigmine test	Jolly test	Anti-Ach Ab
Positive rate (%)	77.8	33.3	44.4	77.8

^* Ocular myasthenia gravis (MG) is suspected in thyroid associated ophthalmopathy patients, the test was performed.

Table 5.

Result of thyroid function tests

Case		TSH^*	Free T4^†	TSH R Ab^‡	TPO Ab^§
1	Graves’ disease	0.06	2.51	53.23	23.59
2	Graves’ disease	0.04	2.43	59.71	23.68
3	Graves’ disease	0.005	1.42	23.16	233.71
4	Graves’ disease	0.129	1.32	14.14	8.43
5	Graves’ disease	0.002	1.47	405	157.34
6	Graves’ disease	0.77	2.08	99.42	10.42
7	Graves’ disease	0.001	>6.00	3.28	15.54
8	Hashimoto thyroiditis	4.59	1.29	0.8	126.12
9	Graves’ disease	>80	0.28	52.02	>3000

^* 0.35-4.94 uIU/mL

^† 0.78-1.48 ng/dL

^‡ 0-14 U/l

^§ Mic-Ab, 0-60 IU/ml.

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