Bell's Palsy

Question 1

Definition

Answer 1

Acute neurological condition that presents with rapid onset of unilateral facial paralysis (usually less than 72 hours).

Question 2

Epidemiology and Risk factors

Answer 2

• Age 15-45 years: usually occurs in early-middle age and has much lower incidence in children and the elderly population
• Pregnancy
• Diabetes mellitus
• Recent upper respiratory tract infection

Question 3

Pathophysiology

Answer 3

Aetiology unknown
Lower motor neuron lesion that affects the facial nerve (7th). Its role:
- Motor fibres innervate the muscles of facial expression
- Sensory fibres which provide taste to the anterior tongue
- Parasympathetic fibres to the lacrimal and salivary glands
By affecting these comonents of the facial nerve, Bell’s palsy causes:
- UNILATERAL FACIAL WEAKNESS
- ALTERED TASTE
- DRY MOUTH

Question 4

Signs

Answer 4

• Facial paralysis:
  = Inability to move facial expression on the affected side
  = The forehead is affected
  = Inability to raise eyebrows
• Change in taste in anterior tongue
• Unable to fully close eye

Question 5

Symptoms

Answer 5

• Unilateral facial weakness
• Altered taste
• Hyperacusis (noise sensitivity) = due to the paralysis of the stapedius muscle, which is innervated by VII
• Dry mouth and dry eyes
• Ear pain (seen in up to 50% of patients)

Question 6

Differential diagnosis

Answer 6

Stoke (DOESN’T AFFECT FOREHEAD - In Bell’s Px can’t raise eyebrows) = because it receives innervation from both hemispheres of brain

Question 7

Diagnosis

Answer 7

Clinical diagnosis
Consider:
- CT/MRI
- Infectious disease screen
- Angiotensin convertin enzyme (ACE) = sarcoidosis

Question 8

Treatment

Answer 8

FIRST LINE =
- Prednisolone = For Px who present < 72 hours
- Antivirals: e.g Aciclovir = not recommended as monotherapy but can be given as adjuvent therapy with corticosteroids
- Eye protection: artificial tears and lubricants should be considered

Question 9

Complications

Answer 9

• Eye injury
• Facial pain
• Psychological disturbance: Associated with depression