Bell's Palsy Flashcards
Define Bell’s Palsy
Bell palsy is an acute unilateral peripheral facial nerve palsy
Explain the aetiology/risk factors for Bell’s palsy
- This is an IDIOPATHIC lesion of the peripheral facial nerve (LMN)
RISK FACTORS:
- Pregnancy
- FHx of Bell’s Palsy
- Diabetes
- URTI
- Hypertension
List some differentials for Facial nerve Palsy (9)
- Stroke
- Brain tumour
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Ramsey-Hunt syndrome:
- HSV-1 within the geniculate ganglion (cell bodies of facial nerve as it enters IAM) causes inflammation of the facial nerve and/or myelin sheath
- Due to close proximity of CN 8, can get tinitus, hearing loss, nystagmus, vertigo
- Temporal bone fracture
- Lyme disease by Borrelia burgdorferi (travel to endemic area)
- Parotid tumour (CN7 runs behind it) or enlargment due to mumps
- Cerebello-Pontine angle tumour (acoustic neuroma) affecting CN 5, 7 & 8
- Myasthena Gravis
- Multiple Sclerosis
Recognise the presenting symptoms of Bell’s palsy (7)
If the symptoms do not match the description below it is NOT Bell’s Palsy and other differentials must be considered
- Acute onset UNILATERAL facial weakness/paralysis involving both upper and lower facial muscles
- Keratoconjunctivitis sicca (dry eye) occurs acutely due to loss of adequate blink function & lack of innervation to lacrimal gland.
- Drooling
- Otalgia ± post-auricular pain as CN7 carries cutaneous sensation from ear canal and outer ear
- Hyperacusis: Sensitivity to loud sounds ipsilaterally due to loss of innervation to stapedius so auditory reflex to loud noise is diminished
- Taste disturbance (dysguesia) due to loss of innervation from tongue
Recognise the signs of Bell’s palsy on physical examination (1)
-
Acute onset, unilateral weakness/paralysis of all facial muscles equally on the background of an otherwise NORMAL PHYSICAL EXAMINATION
- Loss of naso-labial fold
- eyebrow ptosis
- Anything else suggests a different diagnosis
Identify appropriate investigations for Bell’s palsy and interpret the results
Routine laboratory or imaging studies are not necessary for most cases, but sometimes they can help to confirm the diagnosis or rule out other diseases that can cause facial weakness.
-
Electromyography (EMG) can confirm the presence of nerve damage and determine the severity and extent
- Uses very thin wire electrodes that are inserted into a muscle to assess changes in electrical activity that occur during movement and at rest
- Blood tests can sometimes help in diagnosing other concurrent problems such as diabetes and Lyme Disease.
- Diagnostic imaging using MRI or CT scan can rule out other structural causes of pressure on the facial nerve (such as an artery compressing the nerve) and also check the other nerves.
Generate a management plan for Bell’s palsy (3)
- Corticosteroids (within 72 hrs)
-
Eye protection
- glasses
- eye lubricant
- artificial tears
- tape eyes shut when sleeping
If severe palsy:
- Surgical decompression
Complications of Bell’s Palsy (3)
- Ulcerative keratitis (corneal ulcer) and subsequent blindness.
-
Gustatory lacrimation (Crocodile tears):
- Faulty regeneration of pre-ganglionic parasympathetic fibres to the salivatory glands but instead of innervating salivatory glands they innervate the lacrimal glands so lacrimation is seen when eating/tasting
-
Synkinesis on affected side
- voluntary muscle movement causes the simultaneous involuntary contraction of other muscles. An example might be closing one eyelid causing mouth twitchting
Outline the prognosis of Bell’s Palsy
- The nerve/myelin regenerates and there is recovery WITHOUT RECURRENCE in up to 6 months - if it recurs or has not fully resolved by 6 months consider a different diagnosis
- Bell’s palsy has a good prognosis
- 94% of peole presenting with incomplete paralysis fully recover
- 61% of people presenting with complete paralysis fully recover
- Poor prognostic factors:
- Pregnancy
- EMG showing >95% difference between both sides
- Diabetes
- Loss of taste on presentation
