Facial nerve paralysis

Under a facial paralysis or Bell's palsy ( facial paralysis ) refers to a disorder of the facial nerve ( VII cranial nerve) with paralysis especially of mimic facial muscles and other muscles supplied by this nerve and gland. Not affected by the paralysis of the muscles of mastication, as it is supplied by the trigeminal nerve. A facial palsy usually occurs on one side.

Conventionally, the facial paralysis of the peripheral type ( "peripheral facial palsy " ) of the facial paralysis of central type is discriminated ( " central facial paresis ").

The facial paralysis was by Nicolaus Anton Friedreich (1761-1836) first studied in detail.

Facial paralysis of the peripheral type

In the peripheral facial paralysis it comes to damage to the facial nerve in its course from its heartland in the brain stem to its ramifications in the area of the parotid gland.

Causes

In about 75% of cases the cause is unknown ( idiopathic facial paralysis therefore also called, also Bell's palsy). Idiopathic facial palsy, with about 25 new cases of disease per 100 000 people in the most common cranial nerve disease. The local reactivation of infection with the herpes simplex virus type 1 is responsible probably for most cases of idiopathic facial palsy. By inflammatory processes in the context of such an infection there is a swelling of the nerve in the bony Fazialiskanal, whereby the function of the nerve is disturbed. The extent and duration of the injury determine the degree of weakness of the facial muscles. About 80% of patients develop over the course of 3-8 weeks, to a complete restoration of the function of the nerve. Idiopathic facial palsy is also described in domestic dogs.

In about 25% of cases of Bell's palsy is a known cause is based. These include infections, where a successful pathogen detection, as well as injuries, tumors, autoimmune diseases and congenital malformations. Generally, in these cases, the prognosis of the paralysis usually poor and the recovery of function usually takes longer.

Many pathogens, both viruses and bacteria can cause a facial paralysis. A facial palsy may, under a reactivation of the chickenpox virus ( varicella zoster virus ) arise in the course of zoster oticus and is then known as Ramsay Hunt syndrome. Also, the causative agent of mononucleosis ( Epstein -Barr virus ) and the HIV virus can cause a facial paralysis. You may also arise in the context of bacterial infections such as tuberculosis, neuroborreliosis, or neurosyphilis ( a neurological manifestation of syphilis ). Infection and inflammation in the ears such as acute otitis media or mastoiditis and labyrinthitis ( bony structures in the ears ) can also be the cause.

A bilateral facial palsy ( facial diplegia ) is common in the Guillain -Barre syndrome, an autoimmune disease of the nervous system, and in the tick-borne neuroborreliosis. The Heerfordt syndrome is associated with the autoimmune disease sarcoidosis and can lead to bilateral recurrent facial paralysis. Another presumably mediated by the immune system disease is the Melkersson -Rosenthal syndrome. Again, it may repeatedly come to two-sided facial paralysis.

Regarding injuries that can lead to damage of the Fazialisnervs, longitudinal and transverse fractures of the temporal bone and cuts come in the lateral facial region in question. Also in the scope of medical interventions ( for example, during surgery ) can cause facial paralysis come ( iatrogenic causes).

Tumors can cause harm by their growth the facial nerve. In question, the acoustic neuroma, tumors of the parotid gland and the cholesteatoma come. A scattering of tumor cells in the meninges ( meningitis, neoplastic ) can also lead to facial palsy and is associated with a poor prognosis.

As Moebius syndrome is called with additional disorders of eye movements ( sixth nerve palsy ) a congenital bilateral facial paralysis.

Symptoms

Consequence of a peripheral facial palsy is the weakness or complete paralysis of the facial muscles a page. The patients or their family members notice a drooping mouth corners and a weak or incomplete mouth closure. This can run down while drinking fluid from the affected mouth. Patients can not wrinkle the affected side of the face. If the orbicularis oculi muscle is affected, the lid closure is not or only partially possible ( lagophthalmos ). When patients try to close your eyes, in the absence of eyelid closure, the normal upward movement of the eyeball can be observed (so-called Bell 's phenomenon ). As signe of the cils ( Zilienzeichen ) visualizing Stay eyelashes is called incomplete or weak eyelid closure. In incomplete eyelid closure is a risk of damage to the cornea of the eye. Furthermore, it can lead to paralysis of the platysma. In animals, a drooping of the ear can be observed.

Localization of the lesion

Since the facial nerve gives off several nerve branches in its course in Fazialiskanal, the location of a lesion (injury, failure) can be determined rather well. So, in addition the following symptoms, depending central the lesion is localized:

If the lesion

• Before the departure of the chorda tympani, it comes to the same side taste disturbance in the anterior two thirds of the tongue and diminished salivary secretion at rest ( sublingual and submandibular gland ).
• Before the departure of the stapedius nerve produced an increased sensitivity to sound ( hyperacusis ) on the affected side (missing Stapediusreflex ).
• Before the departure of the greater petrosal nerve, the lacrimal secretion is reduced ( diagnosis with Schirmer test).

Facial paralysis of central type

The term commonly used " central facial palsy " is misleading, since in a centrally induced paralysis of the facial muscles no damage to the Fazialisnervs is. The neurologically preferred name of a facial paralysis of central type is " central facial paresis. "

Cause of a central facial palsy is an injury to the nerve cells that run in the brainstem of the motor cortex ( precentral gyrus ) to the core area of the Fazialisnervs. These neurons are also referred to as the first motor neurons. They convey the information for voluntary movements of the facial muscles to the lower motor neurons that make up the facial nerve in its entirety. The cell bodies of motor neurons form the second core (Latin for nucleus ) of the Fazialisnervs in the brainstem. Therefore, a central facial paresis is sometimes referred to as " supranuclear " paresis. The first motor neurons cross on their way to the brain stem, the sides, so that the core of the left Fazialisnervs receives and vice versa Information of the right cerebral cortex. Deviating get the lower motor neurons that supply the muscles of facial expression of the upper parts of the face, information from both hemispheres of the brain.

Because of this neuronal circuitry it comes, for example, if damage occurs to the left motor cortex ( precentral gyrus ) to a weakness of the facial muscles of the right side of the face with a cut forehead muscles and Lidschlusses.

Rarely, it can lead to dissociation of voluntary motor and automatic or emotional motor with a central facial paresis. Patients may exhibit arbitrarily or on the request, the teeth in these cases, for example, does not. However, this is possible if the patient laugh or smile spontaneously.

Causes of a central facial paresis, for example, stroke ( cerebral infarction or hemorrhage ), tumors of the brain or brain inflammatory diseases such as multiple sclerosis.

Therapy

The treatment depends on the cause of the disease. Conservative treatment of idiopathic peripheral facial paralysis consists of a so-called steroid pulse therapy, which is usually the ten days a glucocorticoid, usually prednisolone is administered. The affected facial muscles are trained with occupational therapy, physical therapy or speech therapy. Specific causes such as Lyme disease or VZV are treated with appropriate antibiotics or antivirals. Is not it possible the closing of the eyelids, tear replacement is prescribed with film forming eye drops and eye ointment, also a moisture chamber is then applied to prevent drying of the cornea of the eye overnight.

For a permanent complete or nearly complete facial paralysis is a possibility of surgery ( anastomosis between the hypoglossal nerve and Fazialisstumpf, face surgery, nerve suture, nerve transplantation).

Forecast

The prognosis is variable depending on the cause. In idiopathic facial palsy occurs in a large proportion of cases of spontaneous healing. But even in cases of idiopathic facial paralysis can occur despite optimal treatment residual symptoms. This includes the occurring of taste buds in unilateral irritation watering (crocodile tears phenomenon ), the Fazialiskontraktur and pathological associated movements.

Fazialisblock in surgery

In particular, in ophthalmic surgery an artificial paralysis of the orbicularis oculi muscle is brought about by means of a so-called Fazialisblocks in intraocular surgery in combination with a peri- or retrobulbar anesthesia, an injective, local anesthetic procedure with different techniques and anesthetics. The aim here is to prevent the unintentional closing of the eyelids during the operation.