Facial Nerve Palsy

Facial Nerve

Anatomy
· Facial nerve arises at junction of pons and medulla
· Traverses the following structures
o Posterior cranial fossa
o Internal auditory meatus
o Temporal bone in the facial canal
o Stylomastoid foramen
o Parotid gland
· The terminal motor branches are:
o Temporal
o Zygomatic
o Buccal
o Marginal mandibular
o Cervical

Function
· Motor to the muscles of facial expression

· Parasympathetic secretomotor to the lacrimal gland
o via the greater petrosal nerve

· Parasympathetic secretomotor to the submandibular and sublingual salivary glands
o via the Chorda tympani

· Taste to the anterior two-thirds of the tongue
o via the Chorda tympani and lingual nerve

· Somatic sensory to an area of skin around the external auditory meatus
o via fibres from the geniculate ganglion

Facial nerve palsy
· Lower motor neurone affects whole of one side of face
· Upper motor neurone spares the forehead
· Bell's palsy accounts for 40% of facial nerve palsies
· Idiopathic and usually self-limiting
· May result from viral infection

Causes (Intracranial, Intratemporal, Infratemporal)

· Intracranial
o Brainstem lesions
o Cerebrovascular accident
o Multiple sclerosis
o Acoustic neuroma
o Cholesteatoma

· Intratemporal
o Otitis media
o Ramsay Hunt syndrome - herpes zoster oticus
o Trauma - temporal bone fracture
o Iatrogenic

· Infratemporal
o Parotid tumours
o Trauma
o Surgery

Management
· Protection of eye
· Tarsorrhaphy may be required if palsy persists
· Surgery
· Bell's palsy - steroids may be beneficial
· Ramsey Hunt syndrome - acyclovir