Sarah aljamaan Ghadir jwaid Facial nerve Sarah aljamaan Ghadir jwaid

Objective: Anatomy of facial nerve. BRANCHES OF FACIAL NERVE

Anatomy of facial nerve Facial nerve runs from pons to parotid. There are many branches It is a mixed nerve having motor and a sensory root.

BRANCHES OF FACIAL NERVE 1- Greater superficial petrosal nerve: It arises from geniculate ganglion . 2. Nerve to stapedius: It arises at the level of second genu and supplies the stapedius muscle. 3. Chorda tympani: It arises from the middle of vertical segment, passes between the incus and neck of malleus, and brings taste from anterior two- thirds of tongue. 4. Muscular branches: to stylohyoid and posterior belly of digastric. 5. Peripheral branches: there is temporal, zygomatic, mandibular, and cervical And together form pes anserinus (goose-foot)

They supply all the muscle of facial expression

CAUSES OF FACIAL PARALYSIS The cause may be central or peripheral. The peripheral lesion may involve the nerve in its intracranial, intratemporal or extratemporal parts. Peripheral lesions are more common and about two- thirds of them are of the idiopathic variety

Idiopathic ”Bell palsy” 60 -75% of facial paralysis is due to Bell palsy It is defined as idiopathic, peripheral facial paralysis or paresis of acute onset. Both sexes are affected with equal frequency. Any age group may be affected with increasing age. Risk of Bell palsy is more in diabetics (angiopathy) and pregnant women (retention of fluid).

Etiology 1- Viral infection: Most of the evidence supports the viral etiology due to herpes simplex, herpes zoster or the Epstein–Barr virus 2- Vascular ischemia: It may be primary or secondary. Primary ischemia is: induced by: cold or emotional stress. Secondary ischemia is: the result of primary ischemia which causes increased capillary permeability leading to exudation of fluid, edema and compression of microcirculation of the nerve. 3. Hereditary: The fallopian canal is narrow 10% of the cases of Bell palsy have a positive family history. 4. Autoimmune disorder: T-lymphocyte changes have been observed.

Clinical Features Onset is sudden. Patient is unable to close his eye. On attempting to close the eye, eyeball turns up and out (Bell phenomenon). Saliva dribbles from the angle of mouth. Face becomes asymmetrical. Tears flow down from the eye (epiphora ). Pain in the ear may precede or accompany the nerve paralysis. Some complain of noise intolerance (stapedial paralysis) or loss of taste (involvement of chorda tympani). Paralysis may be complete or incomplete. Bell palsy is recurrent in 3–10% of patients.

Diagnosis Diagnosis is always by exclusion. 1- careful history: complete otological and head and neck examination, X-ray studies, blood tests such as total count, peripheral smear, sedimentation rate, blood sugar and serology. 2- Nerve excitability tests: are done daily or on alternate days and compared with the normal side to monitor nerve degeneration. 3- Localizing the site of lesion (topo diagnosis): helps in establishing the etiology and also the site of surgical decompression of nerve, if that becomes necessary.

Treatment General: Reassurance. Relief of ear pain by analgesics. Care of the eye Eye must be protected against exposure keratitis. Physiotherapy: massage of the facial muscles gives psychological support to the patient. It has not been shown to influence recovery. Active facial movements are encouraged when there is return of some movement to the facial muscles.

Medical: Steroids Prednisolone is the drug of choice, If patient reports within 1 week, the adult dose is 1 mg/kg/day divided into morning and evening doses for 5 days and the Patient is seen on the fifth day. If paralysis is incomplete or is recovering, dose is tapered during the next 5 days. If it remains complete, the same dose is continued for another 10 days and thereafter tapered in next 5 days (total of 20 days). Contraindications: pregnancy, diabetes, hypertension, peptic ulcer, pulmonary tuberculosis and glaucoma. Steroids are useful to prevent incidence of synkinesis, crocodile tears and to shorten the recovery time they can be combined with acyclovir for Herpes zoster oticus or Bell palsy. 2. Other drugs: Vasodilators, vitamins, mast cell inhibitors and antihistaminics have not been found useful.

Surgical: Nerve decompression : Vertical and tympanic segments of nerve are decompressed. Some workers have suggested total decompression including labyrinthine segment by postaural and middle fossa approach.

Prognosis 85-90% of the patients recover fully. 10-15% recover incompletely and may be left with some stigmata of degeneration. Recurrent facial palsy may not recover fully. Prognosis is good in incomplete Bell palsy (95% complete recovery) and in those where clinical recovery starts within 3 weeks of onset (75% complete recovery).

Electrodiagnostic Tests These tests are useful to differentiate between neurapraxia and degeneration of the nerve. They also help to predictprognosis and indicate time for surgical decompression of the nerve. 1- Nerve excitability test (NET) 2-Maximal stimulation test (MST) 3-Electromyography (EMG) 4-Electroneuronography (evoked electromyography) (ENoG)