Radiological Characteristics of Extraocular Muscles in Myasthenia Gravis Patients with Ocular Manifestations: A Case–Control Study

Figures & data

Figure 1 (A) Coronal contrast-enhanced T1-weighted orbital magnetic resonance imaging with fat suppression (CE-T1W/FS) in a patient with myasthenia gravis. (B) Coronal orbital computerized tomography scan in a patient with myasthenia gravis. The thickest part of bilateral inferior rectus muscles was measured (white line) in both cases.

Table 1 Mean Muscle Thickness of Each Muscle in the Myasthenia Gravis and Control Groups in All Participants

	Mean Muscle Thickness (mm) in the MG Group (SD)	Mean Muscle Thickness (mm) in the Control Group (SD)	P value
	n=20	n=20
Right MR	3.2 (0.8)	4.2 (0.6)	<0.001
Right LR	3.1 (1.0)	4.5 (0.6)	<0.001
Right SR	2.6 (0.7)	3.7 (0.7)	<0.001
Right IR	3.0 (0.9)	4.0 (0.6)	<0.001
Left MR	3.1 (0.7)	4.1 (0.7)	<0.001
Left LR	3.3 (0.9)	4.8 (0.6)	<0.001
Left SR	2.5 (0.6)	3.5 (0.7)	<0.001
Left IR	3.0 (0.9)	3.9 (0.7)	0.003

Abbreviations: SD, standard deviation; MR, medial rectus; LR, lateral rectus; SR, superior rectus; IR, inferior rectus.

Figure 2 Graph of the correlation between the sum of muscle thickness (mm) and disease duration (years) in the myasthenia gravis group.

Table 2 Mean Muscle Thickness of Each Muscle in the Myasthenia Gravis and Control Groups in Participants with MRI Scans

	Mean Muscle Thickness (mm) in the MG Group (SD)	Mean Muscle Thickness (in mm) in the Control Group (SD)	P value
	n=13	n=20
Right MR	3.3 (0.8)	4.2 (0.6)	0.001
Right LR	3.2 (1.0)	4.5 (0.6)	<0.001
Right SR	2.6 (0.8)	3.7 (0.7)	<0.001
Right IR	3.1 (0.9)	4.0 (0.6)	0.001
Left MR	3.2 (0.8)	4.1 (0.7)	0.002
Left LR	3.4 (0.9)	4.8 (0.6)	<0.001
Left SR	2.7 (0.5)	3.5 (0.7)	0.001
Left IR	2.9 (1.0)	3.8 (0.7)	0.005

Figure 3 (A) Coronal T2-weighted orbital magnetic resonance imaging with fat suppression (T2W/FS) and (B) coronal CE-T1W/FS in a 49-year-old woman with myasthenia gravis for 10 years, showing bilateral extraocular muscle (EOM) atrophy and isointensity with central hypointensity of bilateral inferior rectus muscles (arrow); (C) Coronal T2W/FS and (D) coronal CE-T1W/FS in a control participant, showing normal EOM size and isointense muscles.