Bell's Palsy is an ipsilateral Cranial Nerve VII (lower motor neurone) palsy. There is usually a sudden onset of facial weakness, that progressively worsens over 48 hours. The diagnosis itself, is one of exclusion.
CASE
A 60 yo male presents to the emergency department, with a 2 day history of progressive right facial weakness. It started suddenly on the right side of his face and over the last two days has progressed, so that he cannot raise his eyebrow and his mouth is drooping. He also complains of pain in the right ear. He is having difficulty closing the eyelid of his affected side and food is getting caught in his mouth, because he cannot chew properly.
He has a past medical history of diabetes and hypertension.
He has had a similar episode several years ago that was diagnosed as Bell’s Palsy and he was commenced on steroids and made a complete recovery.
He presents now as the symptoms are the same, however he is concerned, as he is not sure that he can have the same condition twice.
Your examination shows:
- His right eyebrow is drooped
- His right forehead is shiny ie., no creases compared to the left.
- The right side of his mouth is drooping
- He can’t close his right eye completely.
A stroke call is made from triage. However you believe that this is another episode of Bell’s Palsy.
The biggest challenge we face, is differentiating Bell’s Palsy from stroke.
Hard Facts
- It affects 1 in 5000 patients per year.
- Peak incidence is at 15-50 years of age.
- There is a recurrence rate of 12% however, multiple recurrences are rare.
- There is a family history in up to 8% of cases
- It can occur bilaterally, however this is rare and occurs in up to 1% of cases.
- 71% make a complete recovery, even without treatment. The rest will have varying degrees of disability.
- 17% will have contractions and 16% will have associated movements.
- Poor prognosis is more likely when patients:
- Are of older age
- Have complete facial weakness
- Have taste impairment
- Have pain other than just ear pain
- Have a past history of hypertension.
What Causes it?
Most cases are idiopathic.
- Infective Causes
- Viral infections can cause nerve sheath oedema
- Herpes Simplex Virus
- Herpes Zoster Virus
- HIV infection
- Systemic Diseases can increase the risk
- Hypertension
- Diabetes: It is more common in patients with diabetes
- Hypothyroidism
- Sarcoidosis
- Amyloidosis
- Sjogren’s Syndrome
- Pregnancy, increased further with eclampsia.
- Occur in third trimester and post partum
- Space occupying lesions
- Look especially for potential tumours including:
- Parotid gland tumours
- Posterior fossa tumours
- Lymphoma
- Nerve sheath tumours
- Other aetiologies
- Ramsay Hunt Syndrome
- Varicella Zoster Virus affects the geniculate ganglion
- The patient will have pain and vesicles in the affected ear.
- Bilateral Bell’s Palsy
- Usually associated with one of these diagnoses:
- Guillian-Barre Syndrome
- Sarcoidosis
- Lyme Disease
- Bell’s Palsy with hearing loss: In these patients beware of:
- Cholesteatoma
- Severe acute /chronic otitis media
- Haematological malignancies
- Beware leukaemia, especially in children
A Little Anatomy
The facial nerve originates from the facial nerve nucleus in the brainstem. It passes through the temporal bone and emerges at the stylomastoid foramen at the base of the skull.
It has Motor Fibres, which supply the muscles of facial expression.
It has Sensory Fibres which supply the anterior 2/3 of the tongue.
One of the most important clinical examination findings, to assist us in determining if the cause of the facial paralysis is central, or peripheral, is what happens to the patient’s forehead. The cells of the facial nucleus that innervate the upper face, receive corticobulbar fibres that originate in both cerebral hemispheres, whereas those cells in the facial nucleus that innervate the lower face, receive corticobulbar fibres primarily from the contralateral cerebral hemisphere. This means that the forehead receives a dual supply. Therefore, in a central lesion, the forehead should be spared.
In summary:
- A central lesion produces contralateral facial paralysis, with forehead sparing and contralateral hemiplegia, but does not affect salivary or lacrimal secretions, or taste.
- A peripheral facial palsy, where all the muscles of facial expression are affected, is a lesion of the ipsilateral facial nerve or facial nucleus.
Clinical Findings
In an ipsilateral facial droop in Bell’s Palsy, there will be:
- Forehead
- Loss of creases in the forehead and an inability to ‘furrow’ the forehead.
- The Eye:
- Drooping of the eyebrow and the eye
- The patient will not be able to raise the affected eyebrow
- Ask the patient to “Close your Eyes”
- There may be difficulty in completely closing the affected eyelid
- There may be tearing of the eye (epiphora)
- The Mouth:
- Ask the patient to “Show me your teeth”
- The corner of the mouth will droop
- Loss of the nasolabial fold
- Taste may be altered or lost
- There may be difficulty in eating food, as it gets trapped on the affected side
- The Ear
- There may be pain in the ear
- Hearing can be affected due to underlying otitis or cholesteatoma
- Hyperacusis may result- increased sensitivity to sound on the affected side
- Look for otitis or a choleasteatoma
- Look for vesicles in the ear, which assists with the diagnosis of Ramsay Hunt Syndrome
The severity of facial paralysis can be graded using the House-Brackmann Scale as follows:
| Grade
|
Impairment
|
| I
|
Normal
|
| II
|
Mild dysfunction (slight weakness, normal symmetry at rest)
|
| III
|
Moderate dysfunction (obvious but not disfiguring weakness with synkinesis, normal symmetry at rest) Complete eye closure w/ maximal effort, good forehead movement
|
| IV
|
Moderately severe dysfunction (obvious and disfiguring asymmetry, significant synkinesis) Incomplete eye closure, moderate forehead movement
|
| V
|
Severe dysfunction (barely perceptible motion)
|
| VI
|
Total paralysis (no movement)
|
If the patient has any other neurological symptoms other than the facial weakness, then a full neurological examination must be performed and a central cause pursued.
Investigations
Bell’s Palsy is a clinical diagnosis. If there is difficulty in making the diagnosis, an MRI may be of assistance.
In patients where the symptoms are not resolving within a few days, imaging may be indicated.
It is appropriate to perform some blood tests, such as a full blood count. This may be more relevant in children as one of the paediatric causes is leukaemia.
Management
Corticosteroids
Corticosteroids (usually Prednisolone) are the established treatment, as they not only assist recovery, but also reduce long term sequelae. They should be commenced within 72 hours of symptom onset for maximal benefit. Their benefit after 72 hours is uncertain. The number of patients needed to treat to avoid one incomplete recovery of facial function is 10.
Although the exact dose varies however, treatment regimes of 50-60mg of Prednisolone daily for 10 days have been commonly used.
Antivirals
Antivirals such as aciclovir (400mg five times daily for five days) and valaciclovir (1000mg per day for 5 days) have been used with corticosteroids. The combination has shown a small non-statistical increase in recovery rates. Antivirals alone, however are no better than placebo. There is low level evidence that combination therapy may improve the rates of incomplete recovery, compared with corticosteroids alone.
In conditions such as Ramsay Hunt Syndrome, antivirals must be included in the management strategy.
Eye Protection
An eye patch and lubricants are crucial to prevent drying of the eye. A lubricant may be needed during the day and an ointment at night. In severe cases they eye will need to be mechanically closed, by taping at night.
Surgical Treatment
At present surgical decompression is not practiced, although for those with permanent facial paralysis, facial reconstruction procedures can be considered.
Long term Sequelae
- Facial Synkinesis– This is the involuntary movement of some muscles occurring at the same time as deliberate movement of others ie., the mouth moves at the same time as the eye is closed. This is due to aberrant neural regeneration that results from motor neurons innervating the wrong muscle groups resulting in abnormal movements or facial synkinesis.
- Crocodile Tears– The patient produces tears whilst eating. This occurs as the regenerating fibres are misdirected and the fibres destined for the salivary glands become secretory fibres to the lacrimal gland.
- Incomplete recovery.
- Impairment of taste sensation.
- Facial muscle weakness and contracture.
References
- Peitersen E. Bell\u2019s palsy: the spontaneous course of 2,500 peripheral facial nerve palsies of different etiologies. Acta Otolaryngol Suppl 2002;549:4-30.
- Salinas R, Alvarez G, Daly F, Ferreira J, Cochrane Database of Systematic Reviews. 2010; (3)CD001942
- Adour K, Wingerd J, Doty HE. Prevalence of concurrent diabetes mellitus and idiopathic facial paralysis (Bell\u2019s palsy). Diabetes 1975;24:449-51.
- de Almeida JR, Al Khabori M, Guyatt GH, Witterick IJ, Lin VY, Nedzelski JM, et al. Combined corticosteroid and antiviral treatment for Bell palsy: a systematic review and meta-analysis. JAMA 2009;302:985-93.
- Lee HY, Byun JY, Park MS, Yeo SG. Steroid-antiviral treatment improves the recovery rate in patients with severe Bell\u2019s palsy. Am J Med 2013;126:336-41.
- Allen D, Dunn L. Aciclovir or valaciclovir for Bell\u2019s palsy (idiopathic facial paralysis). Cochrane Database Syst Rev 2004;3:CD001869.
- Risk of Leukemia in Children With Peripheral Facial Palsy. Ann Emerg Med. 2020 Aug 9:S0196-0644(20)30491-1. doi: 10.1016/j.annemergmed.2020.06.029.
- Somasundara D et al Managemant of Bell’s Palsy. Australian prescriber 2017;40:94-7
- Gilden D.H. Bell’s Palsy. NEJM September 23, 2004, 351;13: 1323-31
- Potterton B. Bell’s Palsy: A Review. British Journal of Family Medicine,3(3), May 2015
