Despite being relatively rare in toddlers, juvenile myasthenia gravis should be considered in the differential diagnosis of children showing different types of eye-related symptoms, a case report says.
The case report study, “Mummy, my eyelids are heavy”: A case series of juvenile myasthenia gravis,” was published recently in the European Journal of Ophthalmology.
Myasthenia gravis (MG) is an autoimmune disease caused by the abnormal production of antibodies against proteins essential for muscle contraction. It often is associated with a series of debilitating symptoms, including muscle weakness, extreme fatigue, and sleep and mood disturbances.
Juvenile myasthenia gravis (JMG) is an early-onset form of the disorder that may affect toddlers, children and teenagers up to the age of 16. The disorder is relatively rare in children, accounting for only 10–15% of all MG cases, and even more rare in toddlers, who are frequently misdiagnosed.
In this case report study, researchers from the University Of Malaya in Malaysia described the clinical cases of three female toddlers who were 18–24 months old when they showed the first signs of JMG that included a series of ocular abnormalities.
All children were followed at a tertiary medical center in Malaysia. Two of the three children were twin sisters who experienced the first signs of the disorder at roughly the same age.
One of the twins started having droopiness in her right eyelid by the age of 18 months. This quickly progressed to affect both eyelids.
On physical examination she showed no signs of visual impairments. However, by the time she was examined, she already had eyelid droopiness (ptosis) in both eyes: the right eye was completely covered by her eyelid, while the left eye was partially covered.
Blood tests revealed she had high levels of anti-acetylcholine receptor (AchRs) antibodies, confirming the diagnosis of generalized MG. She was started on oral prednisolone (a steroid) and her ptosis gradually improved. Now she is on maintenance therapy with oral pyridostigmine (20 mg, every six hours), sold under the brand name Mestinon by Bausch Health, and her symptoms are well-controlled.
Like her sister, the second twin started showing signs of droopiness in her left eyelid by the age of 22 months. Eventually this also progressed to affect both eyelids, following the same clinical presentation her sister had experienced four months earlier.
On physical examination her visual acuity was normal and she had asymmetrical ptosis, which was more severe on her left eye. Like her sister, blood tests confirmed the presence of AchRs, indicating she also had generalized MG.
She was started on oral pyridostigmine and oral prednisolone and her ptosis rapidly improved. Currently she has no symptoms of the disorder and is slowly tapering off prednisolone and maintenance therapy with oral pyridostigmine (20 mg, every six hours).
The third girl was 24 months old when she started showing signs of ptosis in both upper eyelids. Later her mother noticed her right eye was slightly deviated from the center pointing upward. As in the previous two cases, her visual acuity was considered normal for her age.
However, unlike the twin sisters, blood tests found no signs of abnormal antibodies targeting proteins necessary for muscle contraction, and she was diagnosed with ocular MG, a milder form of MG that affects only the muscles surrounding the eyes and eyelids. She was started on pyridostigmine and her symptoms rapidly improved. Currently she is on maintenance therapy with oral pyridostigmine (10 mg, every six hours).
“The possibility of a purely ocular MG at presentation should be borne in mind, progressing to develop myasthenic crisis even while on treatment, as it is seen in our second case,” the authors wrote.
“Juvenile myasthenia gravis is relatively rare in toddlers. Early diagnosis and commencement of treatment is important to slow the progression of the disease and avoiding life-threatening events,” they concluded.