Differences Between Central and Peripheral Facial Paralysis: A Comprehensive Guide

Facial paralysis can be broadly categorized into two primary types: central (supranuclear) and peripheral (infranuclear). The key distinction between the two lies in whether the upper portion of the face—particularly the forehead and eye muscles—is affected. This crucial difference helps clinicians make an accurate diagnosis and determine the underlying cause, which may range from stroke to nerve damage or infection.

Understanding Central Facial Paralysis

Central facial paralysis occurs due to a lesion above the facial nerve nucleus, typically in the cerebral cortex or internal capsule. Because the upper facial muscles receive bilateral input from both brain hemispheres, damage to one side of the brain does not completely disrupt motor control of the forehead and eyes.

This means that patients with central facial palsy usually retain the ability to raise their eyebrows and close their eyes tightly. The most noticeable symptoms appear in the lower part of the face. When asked to smile or show their teeth, individuals often exhibit drooping of the mouth corner, shallow nasolabial folds, and asymmetry limited to the lower face.

Associated Neurological Signs

Another hallmark of central facial paralysis is its frequent association with other neurological deficits. Most commonly, it coexists with central tongue paralysis, where the tongue deviates toward the side opposite the brain lesion when protruded. This combination strongly suggests a central nervous system origin, such as ischemic stroke, brain tumor, or multiple sclerosis.

Recognizing Peripheral Facial Paralysis

In contrast, peripheral facial paralysis results from damage to the facial nerve itself—anywhere from the nucleus in the brainstem to its distal branches in the face. Since this involves the lower motor neuron pathway, there is no compensatory input from the opposite hemisphere, leading to complete paralysis on the affected side.

Patients with peripheral palsy experience total facial weakness, including the forehead. They are unable to lift their eyebrows, frown, or create forehead wrinkles. The orbicularis oculi muscle, responsible for eye closure, is also impaired, resulting in difficulty closing the eye—a condition known as lagophthalmos.

Key Clinical Features

When smiling or showing teeth, the face pulls dramatically toward the unaffected (healthy) side, highlighting the full extent of muscle involvement. Additional symptoms may include dry eye, increased sensitivity to sound (hyperacusis), and even loss of taste over the anterior two-thirds of the tongue if the chorda tympani branch is involved.

Common causes of peripheral facial paralysis include Bell's palsy (idiopathic), Ramsay Hunt syndrome, Lyme disease, trauma, or tumors compressing the facial nerve. Early diagnosis and treatment—often involving corticosteroids and antivirals—are critical for optimal recovery.

Why Accurate Differentiation Matters

Distinguishing between central and peripheral facial paralysis is essential for proper medical management. Misdiagnosis can delay life-saving interventions, especially when the cause is a stroke or a growing brain lesion. A thorough clinical examination focusing on forehead movement remains the cornerstone of differentiation.

Advanced imaging techniques like MRI and neurophysiological tests such as electromyography (EMG) may be used to confirm the diagnosis and assess nerve function. Prompt referral to a neurologist or ENT specialist ensures timely care and improves long-term outcomes.