Facial 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 innervation of 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 inability to close the eye. This places the cornea 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) with 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 loss of upper eyelid function, namely increased exposure damage. However 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, and excess tearing (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 (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 (cheek) region occurs. 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 most importantly to severe facial asymmetry when smiling. In addition to this, the patient 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.

Ironically, 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”, patients’ 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 of this effect 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.

Treatments

The treatment for facial paralysis depends on the underlying cause. For Bell’s Palsy (idiopathic facial paralysis), treatment with both steroids and an anti-viral medication such as famcyclovir is required. If the paralysis is caused by trauma, the nerve should be repaired if possible. For a nerve that has been transected, primary suture repair should be undertaken. If a small section of the nerve is missing, the nerve can sometimes be mobilized and the ends brought together for repair. If a larger segment of nerve is missing, an interposition nerve graft should be placed.

Repair of the nerve is not always possible. This includes instances where the segment coming out of the brain is not accessible, or if the segment entering the target muscle is involved. In these cases, other methods to restore facial form and function are required. These may include nerve or muscle transfer, and plastic surgery of the facial soft tissue. Placement of a weight (hinged-titanium or gold) in the upper eyelid will help the eye to close in a more normal fashion, and this is the most common surgical procedure performed for patients with facial paralysis.

There are more than 100 known causes of facial paralysis, which can be broken down into two main types: infectious/inflammatory, and traumatic. The most common cause of facial paralysis is Bell’s Palsy, which appears to be caused by infection of the facial nerve by the herpes simplex virus. This occurs in approximately 30 people per 100,000 annually. It develops rapidly over 24-48 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 next most common cause of facial paralysis. This can be from injuries such as motor vehicle accidents or gunshot wounds, or it can be due to injury to the nerve sustained during the surgical treatment of tumors of the facial nerve or nearby structures.

Tumors of numerous types in several areas may cause paralysis of the facial nerve. Among these are tumors in the cerebello-pontine angle, parotid gland, or skin. Tumors can also arise in the facial nerve itself. 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 (Ramsay-Hunt syndrome), Cocksackie virus, Lyme disease, otitis media, polio, tuberculosis, mononucleosis, mumps, and influenza have also been reported.

The 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.

Evaluation of facial paralysis requires a full head and neck exam, including otologic examination. It is essential to search for an underlying cause. For patients whose history and examination are consistent 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 should be undertaken.

The 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.

The most severe complication that may occur with facial paralysis is blindness. This is caused when the eyelids do not close enough to protect the eye, and the cornea dries and becomes opacified. With full facial paralysis, some degree of visual impairment may be expected, and caused at least in part by the need to place moisturizing ointment and drops in the eye.

The most critical therapy for patients with facial paralysis is protection of the eye. This can be done with moisturizing ointment and drops. For the patient for whom this is insufficient or impractical, a plastic moisturizing “bubble” can be placed over the eye, or temporary external adhesive weights and be placed on the upper eyelid to improve closure.

More specific care such as self-administered physical therapy may sometimes be prescribed, but the exact type of rehabilitation depends on the underlying diagnosis and whether or not any surgical procedures were performed.