Bell's palsy

LMN Facial nerve palsy - abrupt, isolated, unilateral, peripheral facial paralysis without detectable cause.
Etiology We often don't know, but possibly:
- viral
- microvascular e.g. diabetic
- inflammatory
Clinical presentation Rapid onset (within 72h), unilateral facial paralysis over upper AND lower half
Dry eye, change in taste, hyperacusis, drooling
Pathogenesis
Diagnostic investigations Bell's palsy is a clinical diagnosis of exclusion.
Management Prednisolone if pt presents within 72h - e.g. 50 mg daily for 10 days
Advise eye care - tear substitutes, tape eye shut, safety netting for corneal injury
Complications: corneal drying

red flags - should prompt investigation into ddx

copied shamelessly from CKS:

  • Sparing of brow function (ability to raise the eyebrow on the affected side) — may indicate an upper motor neurone lesion (such as stroke).
  • Insidious onset, pain within facial nerve distribution, persistent facial paralysis for over 6 months, or ipsilateral hearing loss — may indicate head or neck cancer.
  • Paralysis of individual branches of the facial nerve or other cranial nerve involvement. 
  • Parotid mass
  • Uneven distribution of weakness across facial zones — if this occurs in the acute phase it is highly suggestive of a neoplasm in the parotid, or along the course of the facial nerve.
  • Bilateral signs! - Lyme disease, sarcoidosis
  • Vesicular or ulcerating skin lesions