Supranuclear infarction mimicking Bell's palsy: a case report of splenial infarction

The classic distinguishing feature between peripheral and central facial palsy is the preservation of forehead wrinkles; however, in rare instances, supranuclear lesions can present as peripheral-type facial palsy involving both the upper and lower face, and cases caused by splenial infarction are particularly uncommon among them.

We report a 61-year-old woman who presented with isolated left-sided peripheral-type facial palsy. No predominance of lower facial involvement or dissociation between emotional and volitional facial movements was observed. Magnetic resonance imaging (MRI) on the day after symptom onset revealed an acute infarction in the right splenium of the corpus callosum, with no evidence of brainstem or peripheral responsible lesions. Bilateral facial nerve conduction studies and needle electromyography showed no abnormalities. The splenial lesion was considered the most likely cause of her facial palsy. Following treatment with antiplatelet agents, lipid-lowering therapy, and neurotrophic support, her facial palsy began to improve on day 3 of hospitalization and had markedly improved by discharge on day 6. At six-month follow-up, she had recovered well without recurrence.

This case further expands the spectrum of supranuclear lesions that can present as peripheral-type facial palsy and provides preliminary evidence that splenial infarction may be associated with isolated peripheral-type facial palsy. However, further accumulation of cases is needed to validate this association.