How to Differentiate the Affected and Healthy Sides in Facial Paralysis

Facial nerve inflammation, commonly known as peripheral facial paralysis, is a condition that affects many individuals. One of the most confusing aspects for patients and even some caregivers is identifying which side of the face is affected. The facial nerve controls the muscles responsible for facial expressions. When this nerve is damaged or inflamed, the muscles it controls on the same side of the face become weak or paralyzed.

Key Signs to Identify the Affected Side

One of the most noticeable symptoms is the disappearance of forehead wrinkles on the affected side. When a person tries to look upward, the wrinkles on the affected side fail to form. Similarly, when attempting to frown, the eyebrow on the affected side remains motionless. Another clear indicator is difficulty closing the eye on the affected side—this often results in incomplete eye closure, with the eyeball appearing pale or exposed.

Changes in Facial Expressions and Mouth Movement

Facial asymmetry becomes more apparent during expressions. For example, when a person smiles or bares their teeth, the corner of the mouth on the healthy side pulls upward, while the affected side remains slack, causing the mouth to tilt toward the healthy side. Additionally, the corner of the mouth on the affected side tends to droop, giving the face a lopsided appearance.

Functional Differences Between the Sides

When attempting to puff out the cheeks or blow air out, individuals with facial paralysis often struggle to maintain pressure on the affected side. This leads to air leakage, making such actions difficult. Chewing can also be problematic, as food may fall out of the mouth on the affected side due to reduced muscle control.

Understanding Facial Nerve Control

All these symptoms—loss of forehead wrinkles, inability to frown, drooping mouth corners, impaired eye closure, and diminished nasolabial folds—are localized to the same side of the face. This is because the facial nerve innervates the muscles on the corresponding side, and any damage disrupts this control. Recognizing these signs early can help in seeking timely medical evaluation and treatment, which is crucial for recovery.