Facial paralysis is a condition characterised by the inability to move the muscles on one or both sides of the face due to damage or impairment of the facial nerve. The facial nerve, also known as cranial nerve VII, is responsible for controlling the muscles of facial expression, as well as playing a role in taste sensation and tear production.
When this nerve is affected, individuals may experience weakness, drooping, or complete loss of movement, which can have a profound impact on both physical appearance and daily function. Facial paralysis can occur suddenly or develop gradually and may be temporary or permanent. The severity and duration of symptoms largely depend on the underlying cause and the extent of nerve damage.
How does it occur?
Facial paralysis occurs when the facial nerve is damaged, disrupting the communication between the brain and the muscles of the face. This results in muscle weakness, asymmetry, and reduced mobility of facial structures. Paralysis can affect one side of the face (unilateral) or both sides (bilateral), with symptoms ranging from subtle weakness to complete immobility.
One of the most well-known causes of sudden facial paralysis is Bell’s palsy, which occurs without a clear reason. Bell’s palsy typically results in temporary weakness on one side of the face and often resolves within weeks to months, though recovery may vary.
Other forms of facial paralysis may develop gradually over time due to underlying conditions such as stroke, tumours, infections, or trauma. The condition may be partial, affecting only some facial muscles, or complete, involving the entire side of the face.
Causes of facial paralysis
Facial paralysis can be congenital, present at birth, or acquired later in life. Acquired facial paralysis generally arises from one of two primary mechanisms:
- Damage or inflammation of the facial nerve interrupts signals from the brain to the facial muscles.
- Damage to brain regions responsible for sending signals to the facial nerve, impairing communication and control.
The common causes of facial paralysis include:
- Stroke – Interruption of blood supply to the brain can damage regions that control facial muscles.
- Bell’s Palsy – A sudden, idiopathic form of facial nerve paralysis, often linked to viral infections.
- Ear infections – Middle ear infections can inflame or compress the facial nerve.
- Skull fractures – Trauma can directly injure the facial nerve.
- Autoimmune disorders – Conditions such as multiple sclerosis can damage nerve function.
- Tumours – Head, neck, or brain tumours, including facial nerve schwannomas, can compress nerves.
- Infections – Lyme disease and Ramsay Hunt syndrome can impair facial nerve function.
- Neurological disorders – Guillain-Barré syndrome affects peripheral nerves, including the facial nerve.
- Systemic conditions – Sarcoidosis can cause inflammation that affects cranial nerves.
Symptoms and signs of facial paralysis
- Inability to close the eye fully on the affected side
- Drooping of the mouth or difficulty smiling
- Difficulty making facial expressions such as frowning or raising eyebrows
- Altered taste sensation
- Increased sensitivity to sound (hyperacusis) in some cases
- Excessive tearing or dry eyes due to impaired eyelid function
- Depending on the cause, facial paralysis may appear suddenly or gradually worsen over time
