A 33-year-old woman presents to a walk-in clinic with a severe right-sided facial paralysis that...

This patient presents with acute unilateral facial paralysis, most consistent with Bell palsy , a peripheral (lower motor neuron) facial nerve palsy. MCCQE objectives emphasize distinguishing peripheral facial palsy from central (upper motor neuron) causes , such as stroke.

In a peripheral lesion (e.g., Bell palsy), the entire ipsilateral face is affected, including the forehead, because the facial nucleus receives ipsilateral input. Therefore, patients cannot wrinkle their forehead, close their eye, or smile on the affected side. Associated findings may include hyperacusis and loss of corneal reflex. A recent viral illness supports Bell palsy and is not concerning.

In contrast, a central lesion (e.g., stroke) spares the forehead due to bilateral cortical innervation of the upper facial muscles. Thus, ability to wrinkle the forehead on the affected side suggests a central cause, which is more concerning and requires urgent evaluation for cerebrovascular disease. Recognizing forehead sparing is critical in differentiating stroke from Bell palsy in acute facial paralysis.