03/08/2025
Bells or stroke?
When differentiating facial weakness caused by a stroke from Bell’s palsy, one of the most important clues is whether the forehead is involved.
In stroke, it’s an upper motor neuron lesion so the forehead is usually spared. They can still raise their eyebrows and wrinkle their forehead on the affected side.
That’s because the upper facial muscles receive signals from both sides of the brain, so even if one hemisphere is knocked out, the other side can still control the forehead.
Bell’s palsy is a lower motor neuron lesion of the facial nerve. In this case, the entire side of the face is flaccid. They will be unable to raise the eyebrow, wrinkle the forehead, or close the eyelid fully.
The corner of the mouth also droops, and they may struggle to smile on that side.
Looking at the onset and associated features, a stroke typically has a sudden onset and often comes with other signs—like limb weakness, slurred speech, visual changes, or gait disturbances.
Bell’s palsy usually comes on more gradually over several hours, often noticed upon waking. It tends to be isolated to the face. There are no arm or leg symptoms, and patients might report pain around the ear or a change in taste on the front of the tongue. Some also describe sounds being uncomfortably loud on the affected side due to paralysis of the stapedius muscle.
When examining the eyes, stroke patients can usually close their eye on the affected side, although the movement may be slightly weak. In Bell’s palsy, they may be unable to close the eye completely, which risks corneal drying and damage. Their eye may appear wide and unblinking.
Bell’s palsy the entire half of the face is paralysed.
To test this clinically, ask the patient to raise their eyebrows, close their eyes tightly, and smile. If the forehead moves well and the eye closes, but the smile is uneven, this suggests stroke. If the forehead doesn’t move and the eye can’t close, with a droopy mouth as well, this is consistent with Bell’s palsy.
We cover this in our Aged Care Acute Nursing assessment course .
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This post is for awareness only
