Bell's Palsy

Question 1

What is Bell’s Palsy?

Answer 1

• A unilateral facial nerve palsy of unknown cause
• Typically an idiopathic facial nerve palsy
• Inflammation and Oedema of the facial nerve secondary to a viral infection or autoimmunity

Question 2

How many branches does the facial nerve have?

Answer 2

• 5 branches

Question 3

What is the route of the facial nerve?

Answer 3

• Nucleus is located in the pons which is part of the brainstem
• The nerve root passes through the internal acoustic canal within the temporal bone
• It then enters the facial canal
• It then exits the skull via the stylomastoid foramen
• It splits into 5 terminal motor branches within the parotid gland

Question 4

What extracranial branches are given off by the facial nerve?

Answer 4

• nerve to the stapedius
• Posterior auricular nerve
• Nerve to the posterior belly of the digastric muscle
• Nerve to the Stylohyoid muscle
• Chorda Tympani ( taste to the anterior 2/3 of the tongue)

Question 5

What are the 5 branches of the facial nerve?

Answer 5

• Temporal
• Zygomatic
• Buccal
• Mandibular
• Cervical

Question 6

What are the parasympathetic branches of the Facial Nerve?

Answer 6

• Greater Petrosal Nerve: Facial canal - Pterygopalatine ganglion - parasympathetic supply to the lacrimal gland
• Chorda Tympani: Facial canal - Submandibular ganglion - parasympathetic supply to the submandibular and sublingual glands

Question 7

What are the differential diagnosis for Bell’s Palsy?

Answer 7

• Otitis Media (inner ear disease)
• Parotid Disease (tumour)
• Sarcoidosis
• Guillain- Barre Syndrome
• Lyme disease
• Trauma
• Stroke
• Tumours
• Encephalitis
• Meningitis
• Multiple Sclerosis
• DM related neuropathy

Question 8

What is the typical onset of Bell’s Palsy?

Answer 8

• Rapid Onset <72 hours - unilateral facial weakness

Question 9

What are the symptoms of Bell’s Palsy?

Answer 9

• Unilateral facial weakness
• Post- Auricular/ Ear Pain
• Difficulty chewing
• Incomplete Eye Closure
• Drooling
• Tingling
• Hyperacusis ( heightened sensitivity to sound - Chorda tympani)

Question 10

What are the signs of Bell’s Palsy?

Answer 10

• Loss of nasolabial fold
• Drooping of the eyebrow
• Drooping of the corner of the mouth
• Asymmetrical smile
• Bell’s Sign (upward movement of the eye maintained on attempt to close the eye)

Question 11

Does Bell’s Palsy affect LMN or UMN?

Answer 11

• LMN

Question 12

How do you differentiate between LMN and UMN?

Answer 12

• UMN include a Stroke or Cerebral tumour
• UMN lesions there is forehead sparing due to the bilateral supply of the frontalis muscle
• LMN the frontalis is completely unilateral paralysis

Question 13

What disease would you suspect if there is Bilateral involvement?

Answer 13

• Lyme Disease
• Sarcoidosis
• Guillain- Barre Sundrome
• HIV

Question 14

What grading system is used for Facial Paralysis?

Answer 14

• House- Brackmann System

Question 15

What are the grades for House-Brackmann System?

Answer 15

• Grade 1: normal
• Grade 2 : mild
• Grade 3 : moderate
• Grade 4 : moderate- to - severe
• Grade 5 : severe
• Grade 6 : complete paralysis

Question 16

What Investigations are done for Bell’s Palsy?

Answer 16

• Blood tests
• Neuroimaging
• Specialist tests ( lumbar puncture, lyme serology)
• HIV screening

Question 17

What are features that may point to a differential diagnosis?

Answer 17

• Insidious onset
• Overt Pain
• Systemic illness
• Vestibular abnormalities
• Hearing abnormalities
• Forehead sparing
• Mass
• Recurrent palsy
• Bilateral involvement

Question 18

What is the managment for Bell’s Palsy?

Answer 18

• Prednisolone within 72 hours of onset (50mg for 10 days)
• Anti-viral treatment with corticosteroids (specialist decision)
• Eye care: lubricating drops and ointments, taping the eye when asleep, sunglasses outdoors
• Any patient with incomplete eye closure should be referred to ophthalmology

Question 19

What are the complications of Bell’s Palsy?

Answer 19

• Majority of patients will make a full recovery within 4 months
• Refer:
  1. develop eye symptoms (exposure keratopathy)
  2. no improvement after 3 weeks
  3. develop late problems with aberrant reinnervation (Marcus- Gunn Jaw-winking) - synkinesis

Question 20

What is Synkinesis?

Answer 20

• Voluntary muscle contraction leading to involuntary contraction of another muscle
• It is due to regenerating collateral nerves that have inadvertently supplied another muscle

Question 21

What is exposure keratopathy?

Answer 21

• Damage to the cornea that occurs primarily due to prolonged exposure of the ocular surface to the outside environment