How to determine facial nerve damage

Although our face only accounts for a small area of ​​our entire body, there are actually many nerves distributed on the face that control many of our physiological functions. Once facial nerve damage occurs, it is likely to affect our normal life. Therefore, everyone must correctly and promptly judge whether there is a problem with their facial nerves, correctly determine the cause of the disease and deal with it in a targeted manner.

1. Causes

Common causes of facial nerve injury are fractures of the petrous and mastoid parts of the middle cranial fossa. About 50% of longitudinal fractures and 25% of transverse fractures in this area are accompanied by injury to the VIIth cranial nerve. Especially in longitudinal fractures parallel to the long axis of the petrous cone, the facial nerve is most likely to be involved, bruised or compressed by fracture fragments, resulting in early or delayed facial nerve paralysis.

2. Clinical manifestations

⒈ Regional paralysis symptoms

The main clinical manifestations of facial nerve injury can be divided into local symptoms in four areas: frontal, periorbital, midface and perioral. It can also manifest as paralysis of all facial muscles on the same side. Frontalis muscle paralysis can cause the inability to frown, the eyebrows are lower than the healthy side, the palpebral fissure becomes larger, and the forehead wrinkles become lighter or disappear. Paralysis of the orbicularis oculi muscle can cause the eyelids to be unable to close. When you close your eyes forcefully, the eyeballs will roll outward and upward, exposing the sclera. Paralysis of the buccinator muscle causes the corners of the mouth to droop when the mouth is closed, the cheeks to puff out and air to leak, the nasolabial groove to become shallow, the person cannot whistle, and food to remain between the cheek and gums when eating. During the recovery period of facial paralysis, associated movements or excessive movements of the affected side may occur.

⒉ Classification of facial paralysis

According to the degree of facial nerve damage, it can be divided into complete facial paralysis and incomplete facial paralysis; according to the recoverability after injury, it can be divided into temporary facial paralysis and permanent facial paralysis; according to the course of the disease, it can be divided into early facial paralysis and late facial paralysis. The clinical manifestations of different types of facial paralysis vary in location and degree.

⒊ Characteristics of facial nerve injury at different times

(1) Early facial paralysis after injury indicates contusion or laceration of the facial nerve, which is usually complete facial paralysis.

(2) Delayed facial paralysis occurs 5 to 7 days after injury and is often caused by compression of the facial nerve or surrounding edema. The prognosis is relatively good.

4. Characteristics of facial nerve injury in different parts

(1) Extracranial injuries mainly present with ipsilateral facial muscle paralysis and loss of corneal reflex.

(2) Patients with tympanic nerve involvement above the stylomastoid foramen may experience taste disturbance in the anterior 2/3 of the tongue and decreased saliva secretion on the affected side.

(3) Damage to the higher vertical segment of the facial nerve canal and the onset of hyperacusis.

(4) Previous damage to the geniculate ganglion may result in reduced or stopped tear secretion and dry conjunctiva on the same side.

(5) Damage to the internal auditory canal or the cerebellopontine angle can cause symptoms such as deafness and vertigo.

(6) Injury to the internal segment of the brainstem is often accompanied by abducens nerve palsy and contralateral limb hemiplegia, which is called Millard-Gubler syndrome.

5. Others

Facial nerve injury may also be accompanied by external auditory canal bleeding and cerebrospinal fluid otorrhea.