How is Facial Paralysis Treated?

   

Injury to the nerve can be quite devastating, as it results in a visible deformity and difficulty with eye protection, speech and eating/drinking.  The treatment of facial nerve paralysis involves a number of considerations, including the cause of the nerve injury, the state of the neurons and nerve itself, and the functional impairment to the patient.

Motor Nerves Can Recover

One of the most important points to remember is that if the facial neurons are intact (in the brainstem), and the nerve is not severed, the nerve can regenerate.  The likelihood of this, and the degree to which it recovers, is inversely proportional to the distance the nerve has to regrow.  For example, if the nerve is damaged but not severed in the parotid gland, it has a better and more rapid chance of recovery than if it is injured just as it exits the brainstem. Because the nerve can regenerate, if there is a chance for nerve recovery, conservative (non-surgical) measures are often instituted for facial nerve paralysis patients.  In such situations, nerve recovery can take 12-18 months to occur.    

Diagnostic Tests

In the immediate days after a facial nerve injury due to trauma, several diagnostic tests are available that may determine whether or not decompression of the facial nerve or administration of anti-inflammatory medicines is warranted. 

In the months after an injury and when the nerve is presumed intact (not severed), electromyographic (emg) tests can be performed to search for evidence of a recovering nerve prior to any visible signs of recovery.  These tests can be a valuable aid in determining the likelihood of recovery.

Recovery after Facial Nerve Regeneration

Recovery of the facial nerve is dependent upon a conduit for the nerve to regrow.  This conduit is the 'shell' of the nerve that existed prior to injury.  Recovery is usually first noted by improvement of facial tone.  This is seen as the face, while not moving much, simply appears more 'lifted' or ''tighter' on the affected side.  Over time, twitches and finally voluntary movement may return. 

Sometimes, the regrowing nerves enter to wrong conduits, and end up at the wrong destinations.  When this happens, the nerve fibers the brain thinks are going to the eye may now actually go to the corner of the mouth.  When trying to close the eye, the corner of the mouth may lift.  This is called synkinesis.  When severe, the entire face contracts in one mass movement, and individual facial muscles cannot be moved independently.  This situation can gradually improve with time and practice.  Some physical therapists may be able to work with patients with synkinesis.  In some cases, botulinum toxin (botox®) can be injected reduce muscle movement.

Eye Protection

In the immediate aftermath of facial nerve injury, protection of the eye is paramount.  Eye blink can be affected by facial nerve paralysis. While we do not think much about this, blinking the eye provides vital moisture to the cornea. If this is disrupted, the corneal injury can lead to loss of vision. Thus, patients with facial paralysis need to constantly be aware of the necessity of eye lubrication. This can be achieved relatively easily during the day. However, while sleeping, patients must protect their eye. Taping the eyelid is often a relatively simple way to protect the eye during sleep.

Protection of the eye can be achieved by placement of a weight in the upper eyelid.  In this case, gravity pulls the eyelid down when the patient wants to close the eye (and voluntarily 'releases' the muscle that holds the eyelid up).  The weight is usually made of gold, but titanium is also sometimes used. The procedure is relatively easy, performed under local anesthesia in the office.  By measuring the correct weight to use beforehand, the surgeon can determine the optimal weight.  This is a non-destructive, easily reversed procedure, and is thus often performed in facial paralysis when eye closure is an issue and recovery may or may not occur.  If and when the eyelid function recovers, the weight can be easily removed in the office.  Infection or extrusion can occur in about 10 percent of these procedures, but fortunately is easily managed by prompt removal of the gold weight.

Brow Lifts

Facial paralysis results in descent of the eyebrow because the muscle that normally holds the brow in position no longer functions (frontalis muscle).  In some cases, this can result in impaired vision.  A relatively simple procedure to improve this is the browlift procedure.  In cases of facial paralysis, the most commonly used technique is the midforehead browlift, but it can sometimes be performed endoscopically.

Facial Slings

In some cases, the decision is made to perform a surgical procedure to restore/lift the midportion of the face to a more normal position.  This generally improves the area from the corner of the mouth to the nose, but can in some cases improve the lower lid as well.  This is termed a 'facial sling' and comes in two main varieties:  Static and dynamic.

Static facial slings lift the midfacial region to a more neutral position, but are immobile, or static.  In these cases, the face does not move, but does appear more natural as the corner of the mouth and nasolabial fold (the fold from the corner of the mouth to the nose) are restored.  Surgically, there are several variations, the essential idea is that a material (goretex ®, tissue from the leg, or donor tissue) is used to 'sling' the corner of the mouth and nasolabial fold into a more neutral position.

The dynamic sling supports the same tissues as the static sling.  Here, however, muscle tissue is 'transferred' from one position on the head to another, and is attached to the corner of mouth and nasolabial fold. The muscles used are innervated by a different nerve, and must be verified to be intact prior to transfer. 

The muscles used are:

Temporalis (temporalis transfer):  Most commonly transferred muscle. This muscle is large and sits above the ear on the skull.  It is used in jaw motion, but since there are several other muscles that can compensate for its absence, jaw function is usually unaffected.

Masseter (masseter transfer):  Less commonly used in modern facial reanimation surgery.  This is another muscle used in jaw motion.  As it sits lower on the face, it does not have the same desirable upward vector that the temporalis muscle does.

Anterior belly of digastric: This is a relatively rarely used procedure for reanimation of the corner of the lower lip in cases of lower lip palsy.

Another type of dynamic sling worth mention is the free tissue transfer. In this case, muscle from another portion of the body is moved to the face. Blood vessels and nerves must be reconnected.  The most commonly used muscle is the gracilis muscle. In this procedure, a muscle from the leg is transferred in a single- or multi-stage procedure to the face. In this case, a nerve from the masseter muscle or a grafted nerve from the opposite side of the face is used.

Nerve Repair

In some cases, the nerve is severed due to accidental trauma or surgical removal of tumor.  If the nerve ends are easily re-attached, a repair of the nerve can be performed.  This repair allows the severed nerve endings to regrow and 'find' their way back to the necessary targets.

If the nerve ends cannot be reattached,  a nerve graft is used. This is usually a sensory nerve in the neck or leg, whose absence does not create significant deficit. The nerve is harvested and a segment is used to reconnect the severed ends of the facial nerve. Once again, this acts as a conduit for facial nerve recovery.

In some cases, the hypoglossal nerve (twelfth cranial nerve, which gives movement to the tongue) can be connected to the facial nerve and used to give function to the face.  In this case, all or some of the movement of the tongue on this side is diminished.  The nerve fibers from the hypoglossal nerve grow into the facial nerve and innervate the muscles of the face.  With time, facial tone returns and some patients learn to control facial movement.  This procedure is called a hypoglossal-facial neve (12-7 nerve) transfer.

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