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Título

Purely bulbar myasthenia gravis: a case report

RESUMO

Case presentation: A 69-year-old female, previously hypertensive, was evaluated for sudden dysphagia with mild dysarthria and dysphonia. Neurological examination also showed hypoesthesia of the right hemiface. She spontaneously recovered 24 hours before admission to hospital. There was no alcohol or drug use history. Laboratory tests and cranial CT were normal, but electrocardiogram showed an atrial fibrillation rhythm. Within 48 hours of admission, the symptoms returned, with sudden severe dysphagia, which worsened throughout the day, requiring the use of a nasoenteral tube. She was urgently submitted to a new cranial CT with intracranial and cervical CT angiography, but both were normal. Brain MRI was then performed, but was also normal. We ended up ruling out a vascular cause and pursued a therapeutic test with pyridostigmine 60 mg and oral corticosteroid. A positive response was rapidly seen during the first hours after administration, evolving with progressive dysphagia improvement. She tested negative for muscle-specific thyrokinase and acetylcholine receptor binding antibodies. Electroneuromyography with repetitive stimulation and chest tomography came out normal. Discussion: Myasthenia gravis is an autoimmune disease of the postsynaptic neuromuscular junction characterized by fluctuating weakness involving ocular, bulbar, limb and/or respiratory muscles. The disease occurs at any age, with an early peak in the 2nd and 3rd decades and a late peak between the 6th and 8th decades. Diagnosis is based on investigation of the clinical history and typical examination findings. More than 50% of patients have isolated ocular symptoms of ptosis and/or diplopia and only about 15% of patients have bulbar symptoms. Final comments: This is a case report of a 69-year-old hypertensive woman who suddenly started the condition with isolated bulbar symptoms, without involvement of other muscle groups, mimicking a posterior circulation stroke/transient ischemic attack. Although the initial hypothesis was a vascular condition, the fatigability presented led to the suspicion of myasthenia. The case highlights the importance of differential diagnosis of sudden neurological events, particularly involving bulbar symptoms, which should raise suspicion for myasthenia gravis.