OverviewFacial paralysis is a debilitating condition in which the nerve responsible for facial movement is damaged. It is usually limited to one side of the face. The most obvious functional defect is loss of the ability to communicate emotions, such as happiness or anger. The effects are far greater, however.
Loss of nerve control in the forehead causes the eyebrows to drop. This interferes with expression and can lead to blockage of the visual field. Paralysis of the upper eyelid results in an inability to close the eye or blink. As a result, the cornea is at great risk for injury by dehydration or contact with foreign bodies. The conjunctiva is also damaged by excessive exposure, leading to redness and swelling.
The combination of damage to the trigeminal nerve, which leads to loss of sensation to the cornea and facial paralysis, should be considered an emergency and warrants referral to an ophthalmologist for evaluation and long-term care.
Paralysis of the lower eyelid tends to exacerbate the effects of losing upper eyelid function by increasing exposure damage. The drain tract for tears runs through the lower eyelid, and when the muscle of the lower eyelid is not functioning, the tear duct no longer functions as an active drain. Excess tearing, or epiphora, may result. Some patients, particularly the elderly, also suffer from loss of tone that allows the lower eyelid to drop forward and away from the eye, called ectropion.
In this case, the opening of the tear duct is no longer in contact with the main tear reservoir, and severe epiphora may occur. Epiphora, combined with the effects of drying of the eye and drooping of the eyebrow, may lead to significant visual impairment.
When the central branches of the facial nerve are damaged, paralysis of the nose and midfacial, or cheek, regions occur. Paralysis of the nose leads to nasal obstruction because the nostril is no longer able to flare out to the side, but instead collapses against the central portion of the nose. Weakness in the cheek region can lead to collection of food between the cheek and gum when eating and problems with oral hygiene.
Paralysis of the mouth leads to severe facial asymmetry when smiling. The patient also has difficulty drinking with a straw and may suffer from significant drooling.
Weakness in the lower face causes drooping of the muscles and skin over the jaw, or jowling. This is predominantly a cosmetic issue, though it may worsen the drooling.
The effects of facial paralysis are worsened by the normal-functioning side of the face. Through a condition that we refer to as compensatory contra lateral contraction, a patient’s desire to move the paralyzed side of the face results in excessive muscular contraction on the functional side.
This causes unopposed pull of the facial features toward the normal side of the face. Examples include hyper-contraction of the forehead, elevating the eyebrow above its normal position and contraction of the corner of the mouth, causing a grimacing expression.
These effects are significantly age dependent. A young patient with good overall tone of the facial muscles and skin will have fewer functional and cosmetic concerns, while an elderly patient will have rapid onset of significant symptoms.
SymptomsThe onset of symptoms with facial paralysis depends on the etiology of the problem. With infectious or inflammatory paralysis, the symptoms may progress for several days to peak at five to seven days.
Paralysis caused by tumors may worsen gradually for weeks or months. Traumatic paralysis usually has an immediate onset, though it may not be recognized until later if trauma to the central nervous system or other organs prevents full assessment of the patient’s injuries.
Symptoms can be very severe once paralysis has reached its full effects. The symptoms are far-ranging and interfere with communication, expression of emotion, eating, speaking and vision. Blindness may result if proper care is not taken.
CausesThere are more than 100 known causes of facial paralysis, but all are one of two main types: infectious/inflammatory and traumatic.
The most common cause of facial paralysis is Bell’s Palsy. The condition is caused by an infection of the facial nerve by the herpes simplex virus. This occurs in approximately 30 people per 100,000 annually. It develops rapidly during 24 to 48 hours, and reaches its maximal effect in about five days. Eighty-five percent of those affected have complete or near-complete recovery of facial function within six months.
Trauma is the second most common cause of facial paralysis. This kind of paralysis can be caused by injuries, such as motor vehicle accidents or gunshot wounds, or nerve injury during surgery for tumors of the facial nerve or nearby structures.
Tumors in the cerebello-pontine angle, parotid gland or skin may cause paralysis of the facial nerve. Tumors can also grow in the facial nerve. Central nervous system disorders, such as acute idiopathic polyneuritis and multiple sclerosis, can at times present with facial paralysis. Other infectious causes, such as Herpes Zoster virus or Ramsay-Hunt syndrome, Cocksackie virus, Lyme disease, otitis media, polio, tuberculosis, mononucleosis, mumps and influenza, have also been reported.
Risk FactorsThe risk factors for facial paralysis depend on the underlying condition. In Bell’s Palsy, there does not appear to be a predilection for gender, though the incidence is increased with pregnancy.
DiagnosisEvaluation of facial paralysis requires a full head and neck exam, including otologic examination. It is essential to search for an underlying cause.
For patients with Bell’s Palsy, no further studies are generally required, though close follow up is necessary to be certain that the condition resolves as expected.
If a mass is found in the parotid gland or elsewhere, imaging (usually a CT scan) is required. For patients who have hearing loss, vertigo or significant involvement of other cranial nerves, evaluation of the temporal bone with a CT scan and MRI is needed.
ComplicationsThe possible complications from facial paralysis depend on the underlying cause of the disorder.
If a patient has Bell’s Palsy, failure of facial function to return would be considered a complication.
Blindness is the most severe complication that may occur with facial paralysis. This is caused when the eyelids do not close enough to protect the eye, and the cornea dries and becomes opaque. Some degree of visual impairment may be expected with full facial paralysis. This is caused, at least in part, by the need to place moisturizing ointment and drops in the eye.
RecoveryProtecting the eye is the most critical therapy for patients with facial paralysis. This can be done with moisturizing ointment and drops.
If this is insufficient or impractical, a plastic moisturizing “bubble” can be placed over the eye. Temporary external adhesive weights can be placed on the upper eyelid to improve closure.
More specific care, such as self-administered physical therapy, may be prescribed. The type of rehabilitation depends on the underlying diagnosis and whether any surgical procedures were performed.