An 82-year-old man with facial diplegia and bulbar involvement : case report

Introduction Acute or subacute bilateral facial diplegia with bulbar involvement is an uncommon neurological presentation that encompasses a broad spectrum of potentially life-threatening disorders requiring prompt diagnosis and treatment. In cases with an acute or subacute course, the differential diagnosis can often be limited to two entities: Guillain–Barré syndrome (GBS) and myasthenia gravis (MG). Distinguishing between these conditions may be challenging, particularly when MG presents with atypical features such as predominant bulbar involvement, bilateral facial weakness, or an absence of obvious symptom fluctuation. Case presentation An 80-year-old man with a history of malignancies presented with rapidly progressive bilateral facial diplegia, tongue paresis, dysarthria, dysphagia, and ptosis. Hyporeflexia and a recent diarrheal episode initially suggested a GBS variant. Despite intravenous immunoglobulin therapy, the patient developed respiratory failure requiring mechanical ventilation. Plasma exchange resulted in rapid and dramatic improvement. Subsequent testing revealed strongly positive acetylcholine receptor and anti-titin antibodies, confirming seropositive MG. Conclusion Myasthenia gravis may initially present as a myasthenic crisis without clear diurnal fluctuation and with atypical manifestations, including bilateral facial weakness, isolated dropped head syndrome, isolated ocular symptoms without ptosis, distal limb weakness such as foot or hand drop, or limb-girdle weakness. In such atypical presentations, distinguishing myasthenia gravis from Guillain–Barré syndrome can be challenging. The temporal evolution of symptoms, electrophysiological findings, and response to treatment may therefore be crucial in establishing the correct diagnosis.