Myasthenia gravis (MG) can mimic the symptoms of a stroke and should not be ruled out even in younger patients, a recent medical case report suggests.
The report, “Myasthenia gravis masquerading as acute stroke: a case report,” was published in the PanAfrican Medical Journal.
MG is an autoimmune disorder caused by the production of self-reactive antibodies that target and attack proteins needed for muscle contraction. This causes patients to experience fatigue and muscle weakness of varying degrees of severity that can be more widespread or restricted to a specific group of muscles in the body.
In some cases, the disease may manifest without the typical fatigue and muscle weakness that usually characterizes it, making diagnosis more difficult. In this case report, investigators describe a man in whom MG manifested with symptoms similar to those of a stroke, delaying his diagnosis.
The 48-year-old came to the neurology outpatient department at Sree Narayana Institute of Medical Sciences, in Kunnukara, India, complaining of difficulty swallowing, with food and fluids coming out of his nose when eating (nasal regurgitation), and slurred speech over two days.
He had no other known medical issues beyond high blood pressure, which he was not monitoring regularly.
An examination revealed weakness in his palatal muscles, which are found inside the mouth and used mainly for eating and speaking, impaired gag and cough reflexes, and a nasal speech quality. His eye movements and heart sounds were normal.
Given the patient’s high blood pressure and acute symptoms without daily fluctuations, MG was not considered and he was initially diagnosed with an acute ischemic stroke — a condition in which a blood clot blocks blood flow in a brain artery, causing damage.
A MRI scan did not, however, reveal any abnormalities, leading physicians to consider the patient had a diffusion-negative stroke, meaning a stroke that shows no obvious signs in a typical scan. The man was admitted to the hospital and treated for a stroke with a combination of anti-platelets and heparin to prevent blood clotting, and blood pressure medication.
Blood tests performed afterward found no signs of stroke and during his stay, the man continued to experience speech difficulty, high blood pressure, and nasal speech. On his third day at the hospital, he developed mild breathlessness that was managed with nebulized bronchodilators and corticosteroids, while doctors continued to optimize his blood pressure medication.
The patient was discharged after a week, despite persistent nasal voice and nasal regurgitation. To prevent food from possibly entering his airways, he was fed with a nasogastric (NG) tube, which goes through the nose directly to the stomach.
A week later, doctors noted some improvement, which, they wrote, “provided a false sense of assurance.”
A month later, the man still showed palatal muscle weakness with difficulty swallowing. A month after that, the man returned with worsening symptoms. These now included drooping eyelids, chewing difficulty that varied over the day, and increasing levels of fatigue.
Upon examination, physicians noticed his tongue had atrophied (its muscles had wasted) and taken on a furrowed/fissured appearance, similar to seeing crevices on a glacier.
With MG now a possibility, his medical team performed a repetitive nerve stimulation test — a conventional MG diagnostic test that measures nerves’ ability to stimulate muscle tissue. They also measured the levels of acetylcholine receptor antibodies circulating in his bloodstream, as these are one of the main types of self-reactive antibodies found in people with MG.
At the same time, the patient was started on a low dose of Mestinon (pyridostigmine), a standard medication used to treat MG.
When the results of the patient’s tests arrived and indicated the presence of MG, doctors began full treatment, consisting of a combination of neostigmine, Mestinon, and oral prednisolone.
Two weeks later, doctors saw his palatal muscle weakness and feelings of fatigue had eased, and found no evidence of a thymoma — a tumor of the thymus gland that is relatively common among MG patients.
He remained on his treatment regimen for two more months, leading to symptom improvement and the removal of his NG tube. The man became symptom-free after three months, with less furrowing of the tongue.
This particular symptom, the researchers wrote in the report, is rare but characteristic of MG and associated with tongue atrophy.
Given MG’s ability to mimic stroke symptoms and a trend toward increasingly frequent strokes among younger people, the investigators worry that misdiagnoses, such as that experienced by this patient, could become more common.
“While dealing with a case of a new onset of weakness,” they wrote, “especially in cranial musculature, myasthenia gravis must not be excluded from the list of differential diagnosis.”
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