Surgical treatment of permanent damage of facial nerve is now the only available efficient method for restoration of mimic muscle movement, or atrophy of facial muscles.
Treatment of facial neuropathy requires complex approach to treatment – it needs surgical invasion, revision of the middle ear including intropethrosal part of facial nerve, in order to restore nerve conduction and movement of mimic muscles. Sometimes doctor perform anamostosis of facial nerve with some other donor nerve as soon as possible after paresis occurs. Doctors may particular attention to special medical gymnastics before and after surgery that’s combined with medication treatment.
Doctors distinguish different types of facial nerve damage including the following:
- idiopathic neuropathy (Bell palsy) — the most widespread (75%)form of paralysis, when it’s impossible to understand an etiologic factor. This form tends to be seasonal disease that outrages after getting cold and other similar conditions;
- otogenic neuropathy contributes to about 15% cases of facial nerve damage. Most often, trunk of facial nerve is damaged by chronic inflammatory diseases of the middle ear and during surgical invasion (sanitation operations, mastoidotomy, and so on);
- particular attention is paid to facial nerve damage caused by and brain traumas when the base of skull is broken, after wounds and closed damage of neck and face;
- infectious neuropathy — the rarest (10%) form of facial nerve damage that develops when a person gets affected by Herpes zoster virus (Hunt syndrome), poliomyelitis, parotitis, flu, etc.
Typically, pathogenesis of facial nerve neuropathy includes swelling and ischemia. Different etiological factors described above can lead to disorders in vessel tonus, tendency to spasms (most often, arterial veins), that can be followed by their widening and stasis of perineurium capillars that worsens their penetrance. Swelling can lead to pressure on veins and lymph node walls, which, in its turn, results into ischemia of nerve trunk, swelling and hemorrhage, destruction of ischemized nerve area. It’s especially pronounced in vertical (distal) part where the channel is anatomically narrowed.
Clinical performance of facial nerve damage depend on the volume of damage and degree to which penetrance has been disturbed. There are symptoms of damage of facial and intermediate nerves. When the facial nerve is damaged, a person experiences paralysis or paresis of mimic muscles – facial palsy. The eye on the affected side is opened, and a person cannot close it (lagophthalmos), or eyelids won’t close up.
Since eyelids cannot close normally, a person has tears, and if damage affected the level of separation of superficial petrous nerve and well as its root (in cerebellopontine corner), there can also be dryness in eyes. A person cannot contract the brow, or knit eyebrows on the affected face side. Nasolabial fold is evened on the side of paralysis, mouth is pulled to the healthy side and it doesn’t move, which makes foods and liquids leak from this part of mouth. When cheeks are puffed, sail symptom appears (the cheek starts trembling from the air passing out). A patient cannot blow a candle or whistle. Bell symptom is also pronounced: when eye is squinted, the eyeball on the affected side turns aside and slightly out. In non-squinted eye corner, sclera can be observed.
Early symptoms of developing facial palsy or slight nerve damage include the symptom of rare eye blinking – asynchronous blinking of eyes, or rare blinking on the damaged side. When a person narrows eyes, eyelashes extrude more, and a patient cannot narrow the eye on the damaged side separately.
Together with above-mentioned symptoms of facial palsy, the following conditions may also appear:
- vegetovascular disorders (eye dryness or tearing);
- unilateral taste perversion on 2/3 front part of the tongue (it always occurs, if the damage is located higher than separation of chorda tympani);
- hearing disorders (acoustic hyperesthesia, especially for low tones).
If there are symptoms of facial palsy (paresis) combined with permanent taste perversion in the from 2/3 of the tongue on affected side, the process is localized in fallopian chanel and is caused by a disease of the middle ear. Combination of pacial palsy together with pronounced symptoms of hyperesthesia means that there was damage to the nerve to stapedius muscle. If facial nerve in the inner hearing channel higher than discharge of greater petrosal nerve was damaged, a person will experince dryness of eyes, taste perversion on 2/3 front part of the tongue and hearing loss in one ear. It’s typical of tumors of VIII skull nerve.
Depending on duration of disease, there are the following stages distinguished: acute stage — up to 2 weeks, subacute period — up to 4 weeks, chronic stage — more than 4 weeks. Development and prognosis of disease depend on the seriousness of facial nerve damage, its etiology, how body reacts, and how timely and appropriate treatment was.
Most cases of facial nerve damage of idiopathic origin usually have positive prognosis, while otogenic and traumatic damage can cause neuropathy that cannot be cured at all.
Therefore, otolaryngologist has to evaluate all etiologic factors normally, development of neuropathy and, most important – find new approaches to treatment. Treatment should be complex: it must include measures to influence the causes of disease (if these can be found) and non-pathogenic mechanisms (swelling, ischemia).
If traumatic damages are being treated, doctors usually apply advanced surgical treatment. OPerations are made to restore integration of facial nerve (decompression of intrapethrosal part of facial nerve, moving and stiching of nerve trunk with anamostosis of facial nerve together with another donor nerve). The main indication for facial nerve treatment is disease of nerve (inflammation or tumor), or damage caused by traumas (break of the base of the skill, iatrogenic injury), and tumor processes in adjacent structures.
There’s also inborn facial muscle paralysis, so-called Moebius syndrome. In case of this condition, person’s face reminds of a masc: mimic is disrupted, mouth and eyes cannot close completely, tongue and eyeball movements are slow, there are speech disorders and excessive salivation. This is a very rare disease that’s caused by pathologies of the nervous system. However, sometimes facial paralysis is caused by traumas, operations, inflammatory processes and so on.
This is a very complicated and labor-intensive operation. When a doctor diagnoses loss of arousal, it’s the first sign of facial nerve degeneration – surgery is prescribed, if conservative treatment gives no positive results.
The operation is made on the nerve itself, and it’s sophisticated, because facial nerve is shorter than 1 cm when it goes out of stylomastoid foramen. The doctor leads the end of phrenic, hypoglossal or eleventh cranial nerve to the trunk of facial nerve. They are located deep in the neck, which is why accessing them is very challenging for a surgeon.
Unfortunately, function of facial nerve is not always restored after stitching of the above mentioned nerves. Other method of facial nerve restoration is stitching of masseter muscle flaps with mimic muscles. Alternatively, doctors can hang paralyzed muscles in case of facial nerve paralysis.
A surgeon pulls the group of paralyzed muscles up leading the caproic nerve through the fiber and puts the fixing end of nerve on the cheek bone or arc.
All of these operations are aimed at restoring the function of the facial nerve. There are also cosmetic operations – they’re performed to restore patient’s appearance.
All operations for facial nerve paralysis are divided into the following groups:
- Restoration of facial nerve function (decompression, neurolisys, stitching of damaged facial nerve and plastics with a free implant).
- “Regeneration” of mimic muscles with the help of operations on sympathetic nervous system.
- reinnervation of mimic muscles by stitching the facial nerve with other movement nerves (phrenic, hypoglossal or eleventh cranial nerves).
- Dynamic suspension of paralyzed face parts.
- Static suspension of paralyzed face parts.
- Remedial surgical procedures.
- Combined operation methods.
In case of facial nerve paralysis lasting for more than 1 year, a person experiences atroph of facial muscles on the affected side, which is why tendon plastics does not give effects.
Unilateral facial paralysis can be treated with autotransplantation of a part of gracilis (inner part of the hip) that’s injected under skin between mouth corner and cheekbone arc on the paralyzed face part with single-moment reinnervation and revascularization. In this case, the whole hypoglossal nerve is used for muscle reinnervation, and its lower branch is connected with peripheral end of hypoglossal. Additionally, neurotization of donor muscle is performed with the help of a transplant of sural nerve connected with cheek nerve of healthy face part. This method is done with microsurgical techniques.