Lower motor neuron facial palsy unmasking a rare brainstem stroke: a case report of medial Pontomedullary junction infarction

Medial Pontomedullary Junction (MPMJ) infarction is an uncommon cerebrovascular event with distinctive clinical presentations that often mimic benign conditions, such as Bell's palsy, complicating early diagnosis. This case report describes a 43-year-old female presenting with acute facial droop, dysarthria, dysphagia, and sensory deficits suggestive of Bell's palsy. Despite an unremarkable initial CT scan, advanced imaging with MRI revealed a left MPMJ infarction, highlighting the critical role of diffusion-weighted imaging (DWI) in detecting brainstem lesions. The clinical features of lower motor neuron facial palsy, contralateral sensory deficits, and dysphagia distinguish MPMJ infarction from peripheral facial nerve disorders. Risk factors such as poorly controlled hypertension and diabetes likely contributed to arterial compromise in this patient. This report highlights the need for detailed neurological assessments and advanced imaging to accurately diagnose and manage atypical brainstem strokes, reducing severe morbidity risks.