Teaching NeuroImages: Isolated peripheral facial palsy due to ipsilateral pontine infarction.

A 72-year-old woman presented left peripheral facial palsy for 1 day. Neurologic examination revealed isolated left peripheral facial palsy (figure 1). She did not have additional pontomedullary symptoms or signs, such as diplopia, abduction weakness, facial sensory loss, vertigo, nystagmus, or dysarthria. A brain diffusion-weighted MRI scan showed a hyperintense signal in the left dorsal pons (figure 2) in the region of the seventh nerve nucleus. Infranuclear facial palsy with isolated facial weakness has been reported rarely, and may be misdiagnosed as Bell palsy.