In an acute cortical (supranuclear) stroke, is the ability to raise the eyebrows typically preserved?

Does Stroke Spare the Eyebrow?

Yes, in acute cortical (supranuclear) stroke, the ability to raise the eyebrows is typically preserved due to bilateral cortical innervation of the upper facial muscles. 1

Anatomical Basis for Eyebrow Sparing

The fundamental distinction lies in the pattern of cortical innervation:

• Upper facial muscles (including the frontalis muscle that raises the eyebrow) receive bilateral cortical input from both cerebral hemispheres, which explains why unilateral supranuclear lesions spare forehead function 1
• Lower facial muscles receive predominantly contralateral cortical innervation, making them vulnerable to unilateral cortical lesions 1
• This bilateral representation means that even when one hemisphere is damaged by stroke, the intact contralateral hemisphere can still activate the upper facial muscles 2

Clinical Presentation in Cortical Stroke

The key clinical distinction is forehead involvement: preserved forehead function indicates supranuclear pathology, while complete forehead paralysis indicates nuclear or infranuclear (peripheral) pathology. 1

In middle cerebral artery (MCA) territory strokes specifically:

• Weakness predominantly affects lip opening and lower facial movements 2
• Eyelid closure and eyebrow elevation are typically spared because the upper face motor representation exists in both MCA and anterior cerebral artery (ACA) territories 2
• Quantitative studies confirm that lower facial muscles show significantly greater impairment than upper facial muscles in hemispheric stroke 3

Important Caveats and Exceptions

While eyebrow sparing is the rule, there are notable exceptions:

• Anterior cerebral artery (ACA) strokes can cause weakness in eyelid closure 2, though this is less common than lower facial weakness in MCA strokes
• Bilateral supranuclear lesions (acute pseudobulbar palsy) can cause complete facial weakness including the forehead, though this requires interruption of corticonuclear pathways in both hemispheres 4
• Approximately 19.4% of cortical stroke patients may lack obvious cortical deficits on initial examination, making clinical assessment challenging 5

Practical Clinical Application

When evaluating facial weakness:

1. Test forehead function specifically: Ask the patient to raise their eyebrows and wrinkle their forehead 1
2. If forehead movement is preserved with lower facial weakness, this indicates a supranuclear (cortical) lesion 1
3. If the entire ipsilateral face is paralyzed including inability to close the eye or wrinkle the forehead, this indicates a peripheral (nuclear or infranuclear) facial nerve lesion 1
4. Consider imaging with MRI with contrast when clinical examination suggests central pathology to localize the lesion 1

Common Pitfall to Avoid

Do not assume all facial weakness in stroke patients represents supranuclear pathology. Peripheral facial nerve lesions result in complete ipsilateral facial paralysis including forehead involvement, which can occur coincidentally or as part of skull base pathology 1. The presence or absence of forehead sparing is the critical distinguishing feature that guides further diagnostic workup and localization.