58. Diseases of the facial nerve: paresis and paralysis Flashcards
Difference between facial nerve paresis and facial nerve paralysis
- Facial nerve paresis=> partial dysfunction of facial muscles=>
- Weakness and impaired motor functions
- Facial nerve paralysis=>total inability of facial muscles to perform motor functions
Functional and aesthetic complications associated with paresis or paralysis of the facial muscles
- Difficulty drinking fluids and chewing food => Loss of motor control of the lips and cheeks
- Drooling of saliva outside the mouth
- Risk of corneal pain, infection, and reduced visual acuity=>loss of eyelid protection
- Asymmetric facial expression
Etiological factor classification for facial paralysis
- Intracranial (central cause):=>
- Vascular abnormalities
- CNS degenerative diseases
- Trauma to the brain
Intratemporal=> - Bacterial and viral infections
Extracranial=> - Malignant tumors of the parotid gland
- Trauma (lacerations, gunshot wounds)
- Iatrogenic causes
Extracranial iatrogenic causes where the facial nerve is at risk during oral and maxillofacial surgical procedures
- Facial trauma (lacerations, fractures)
- Orthognathic surgery
- Parotid gland surgery
Typical prognosis for motor dysfunction due to facial nerve injuries during surgical procedures
- Most injuries => temporary motor dysfunction
- Resolves within six months
- The overall risk of permanent motor deficit from facial nerve injuries during surgical procedures less than 1%
How facial paralysis occurs following the injection of a local anesthetic agent, and potential durations of paralysis
- Pterygomandibular block => needle is inserted too far back=>
- Local anesthetic into parotid gland
- Vascular reflex from the vasoconstrictor=>
- Ischemic paralysis near the stylomastoid foramen
- In the first instance, paralysis duration equal to anesthesia’s duration, while in the latter, may be longer, depending on degree of nerve damage.
Steps taken to manage facial paralysis following local anesthetic injection
- Reassuring patient explaining condition naturally
- Eye patch use=> prevent corneal ulceration
- Topical ointment and eye closure with a cotton pad
- Avoidance of contact lenses until paralysis dissapears
How facial nerve injuries classified according to Seddon or Sunderland
- Neuropraxia=>Resolves promptly w/ return of facial mobility within a few weeks
-
Axonotmesis=> Prolonged weakness w/ gradual return of function after several months
Neurotmesis=> Total and prolonged paralysis of the affected facial musculature w/ little or no return of function if untreated
House-Brackman classification for facial palsy
- Grade I=>Normal function w/out weakness
- Grade II=> Mild dysfunction w/ slight facial asymmetry and minor synkinesis
- Grade III=>Moderate dysfunction w/ obvious but not disfiguring asymmetry, contracture, and/or hemifacial spasm=>
- Residual forehead movement
- Grade IV=> Moderately severe dysfunction with obvious, disfiguring asymmetry, lack of forehead motion, and incomplete eye closure
- Grade V=> Severe dysfunction with asymmetry at rest and only slight facial movement
- Grade VI=> Total paralysis w/ complete absence of tone or motion
Bell’s Palsy
- Idiopathic paresis or paralysis of the facial nerve w/ a sudden onset
- Unilateral lower motor neuron paralysis that is not related to any other disease elsewhere in the body
- Idiopathic
- more common in women than men. It is 3.3 times more common in pregnant women, especially prevalent in the third trimester
Side of face usually affected by Bell’s Palsy
- Right or left side of the face equally=>
- Usually unilateral=>
- 1% of cases=> bilateral
Clinical features of Bell’s Palsy
- Sudden onset=> after awakening
- Unilateral involvement of the entire side of the face
- Abrupt loss of muscular control on one side
- Inability to smile, close the eye, wink, or raise the eyebrow on the affected side
- Whistling is impossible
- Bell’s sign=>Inability to close the eyelid, w/ upward rolling of the eyeball
Typical prognosis for Bell’s Palsy
- Maximum symptoms in about 2 weeks=>
- Remission within three weeks in 85% of cases
- Otherwise up to six months. Spontaneous
- Recovery common
How Bell’s Palsy managed
- Physiotherapy= maintain muscle tone through electrical stimuli
- gentle massage, and facial exercises
- Medication=>Prednisolone
- Surgical procedures
