Facial nerve paralysis

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Facial nerve paralysis

attending physician	Dr. Yoshihisa Suzuki
Outpatient	Facial paralysis reconstruction outpatient clinic (2nd and 4th Thursdays)

The facial nerve is the nerve that controls the movement of the muscles that create facial expressions (facial muscles).
The facial nerve is divided into four branches: the temporal branch, the zygomatic branch, the buccal branch, and the marginal mandibular branch. When the nerve is paralyzed, various symptoms appear. Sometimes all the nerve branches are paralyzed, and sometimes only certain parts are paralyzed.

A) Paralysis of the temporal branch

Paralysis of the frontalis muscle causes the loss of wrinkles on the forehead, and the eyebrows and upper eyelids droop. The lowered position of the eyebrows and the overhanging upper eyelids make it difficult to see.
B) Paralysis of the zygomatic ramus

Paralysis of the orbicularis palpebrae muscle prevents the eyelids from closing, causing the cornea to dry out, which can lead to keratitis and corneal ulcers and potentially blindness. The lower eyelid becomes loose and everted, causing tears.
C) Paralysis of the buccinator branch

Because the corners of the mouth and upper lip cannot be lifted, the lip on the affected side droops, and the groove between the nose and mouth (nasolabial fold, or laugh line) disappears. Because the mouth cannot be closed properly, food and drink leak out and the left and right sides of the face become asymmetrical when smiling.
D) Paralysis of the marginal mandibular ramus

Since the corners of the mouth and lower lip cannot be pulled down, the lower lip is pulled toward the healthy side, resulting in an asymmetrical lip shape.
others

Pathological synkinesis: Contracture of facial muscles such as involuntary closing of the eyes in cases of partial paralysis: deepening of nasolabial folds, tightness of the cheeks

cause

Born
Viral infections (Hunt syndrome, Bell's palsy)
Neurological disorders
trauma
Surgery (intracranial tumor removal, parotid gland malignant tumor removal, etc.)

Timing of treatment

Regarding laughter reconstruction, if there is a possibility of natural recovery, reconstruction will be considered about one year after the paralysis. If there is a low possibility of natural recovery, aggressive surgery will be performed early, as the shorter the time since paralysis, the less likely the facial muscles will atrophy.
If keratoconjunctivitis is caused by lagophthalmos, there is a risk of blindness, so it is important to perform surgery as soon as possible. Our department is one of the few facilities nationwide that also performs corneal sensation reconstruction surgery in cases where lagophthalmos has caused conjunctival congestion or corneal ulcers. This surgery can weaken the movement of the eyelids closing in response to pathological synkinesis (involuntary eyelid closure).

treatment

fresh example(Cases where the onset of paralysis has not occurred long ago and degeneration or atrophy of the facial muscles is not significant)
- Neurosuturing
- nerve grafting: A portion of the sensory nerve (sural nerve) in the lower leg is harvested and transplanted. Although the harvested area will remain numb, the part that does not interfere with daily life will be used.
- Facial cross nerve grafting: The facial nerve on the affected side is anastomosed with some branches of the facial nerve on the healthy side.
- Nerve transfer surgery: Motor nerves other than the facial nerve are transplanted to move the facial muscles. The masseter nerve and hypoglossal nerve are used.
old example(If paralysis occurs more than 1-2 years ago): Nerve, muscle, or other tissue transplants will be required.

static reconstructive surgery

This surgery is performed to correct facial asymmetry in severely degenerated and atrophied tissue, although it cannot restore facial movement. Excess skin is removed, and the fascia lata and auricular cartilage are transplanted to lift the paralyzed side.
- Eyebrow lifting
  Paralysis of the temporal branch causes the eyebrow to droop lower than the healthy side. Excess skin on the side of the eyebrow is removed.
  However, the eyebrows do not move like they do on the healthy side, so there is a difference between the left and right sides when making expressions that involve raising the eyebrows or closing the eyes.
- Cheek lift
  Fascia lata is harvested and transplanted under the skin of the cheek to lift the nasolabial folds (laugh lines) and lips.
- eyelid
  The upper eyelid also droops due to ptosis of the eyebrows, so excess skin is removed.
  The lower eyelid also turns outward due to drooping of the cheek, so it is lifted by transplanting auricular cartilage or fascia lata.
  When the eyes cannot be closed (lagophthalmos) due to paralysis of the orbicularis oculi muscle that closes the eyelids, it may be necessary to adjust the upper eyelid as well as lifting the lower eyelid.
Dynamic reconstructive surgery: Reconstruction of facial muscles

If facial nerve paralysis occurs over a long period of time, the facial muscles will atrophy, and it may not be possible to restore movement with nerve reconstruction alone. In such cases, reconstruction using muscles will be necessary. By combining this with nerve grafting, it is also possible to restore laughter.
In order to lift drooping parts of the face due to paralysis or to create facial movement, masticatory muscles (temporalis and masseter) that are controlled by nerves other than the facial nerve, as well as some muscles from the thigh, back, abdomen, etc., are harvested along with their nerves and nutrient blood vessels and transplanted to the face under a surgical microscope.
- Eyelid function recovery
  Temporalis muscle transfer: In cases of lagophthalmos, this is a method in which part of the temporalis muscle is moved to the upper and lower eyelids to allow the eyelids to close.
- Cheek function recovery
  The nerves and blood vessels are attached and the gracilis and latissimus dorsi muscles are transplanted and sutured to the healthy facial nerve, hypoglossal nerve, trigeminal nerve, etc.

Function can only be restored once new nerves grow from the area where the nerve was sutured to the target tissue, so it may take more than a year to recover from surgery.
Furthermore, the facial nerve is a bundle of nerves that control the numerous muscles that create complex facial expressions, so it is impossible to connect them precisely one by one. Therefore, even if movement is successfully restored after surgery, it is often the case that the intended facial expression is not produced. Once movement has recovered, it is important to practice making facial expressions while looking in a mirror (rehabilitation).

Facial nerve paralysis

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