History and exam
Key diagnostic factors
common
single episode
Ipsilateral or contralateral recurrence is unusual (has been reported to occur in only approximately 6.8% of people with Bell's palsy).[3]
Recurrence should prompt further investigations to rule out an alternative diagnosis.
unilateral
Bell's palsy is rarely bilateral. Presentation with bilateral facial palsy should prompt immediate work-up for an alternate diagnosis, such as Lyme disease, ascending inflammatory demyelinating polyneuropathy (Guillain-Barré syndrome), sarcoidosis, or haematogenous malignancy (e.g., leukaemia).
absence of constitutional symptoms
Fever, general malaise, myalgia, arthralgia, headache, or rash (erythema migrans or other) suggests an alternative diagnosis, such as Lyme disease, autoimmune disorder, or granulomatous disease.
involvement of all nerve branches
Facial nerve conduction blockade in Bell's palsy originates proximal to the geniculate ganglion, prior to any branching; hence, all branches are affected in equal fashion. Unequal distribution of facial weakness across the facial zones on examination in the acute setting rules out Bell's palsy.
keratoconjunctivitis sicca
Keratoconjunctivitis sicca (dry eye) is common in Bell's palsy and occurs acutely because of the loss of adequate blink function, with parasympathetic dysfunction to the lacrimal gland also a contributing factor. It may lead to ulcerative keratitis (corneal ulcer) and subsequent blindness.
Keratoconjunctivitis sicca may later progress to epiphora and gustatory hyperlacrimation (Bogorad's syndrome or crocodile tears) as a late sequela of Bell's palsy, secondary to aberrant regeneration of pre-ganglionic parasympathetic fibres carried within the facial nerve.
pain
Post-auricular pain and mild-to-moderate otalgia often occurs, as the facial nerve carries general somatic sensory axons that relay cutaneous sensation from the posterior external auditory canal, concha, and post-auricular region (the cell bodies of which are located in the geniculate ganglion).
Sensory disturbances range from absent, to a dull ache or feeling of heaviness, to mild-to-moderate pain.
Severe pain suggests zoster sine herpete of the facial nerve.[38]
synkinesis
Facial synkinesis is the involuntary and abnormal synchronous movement of a facial region concomitant with reflex or voluntary movement in another facial region and may occur only as a late sequela of Bell's palsy (first observed 3-6 months following onset) in up to 30% of patients.[3] The presence of synkinesis concurrent with facial weakness (a mixed picture) in the acute phase is highly suggestive of an alternative diagnosis such as a neoplastic process.
Other diagnostic factors
common
presence of risk factors
Possible risk factors include black or Hispanic ancestry, arid/cold climate, hypertension, diabetes, pregnancy, intranasal influenza vaccination, and a positive family history.
any age
Bell's palsy can occur at any age from 2 years to death but is more prevalent between ages 15 and 45 years.[3]
uncommon
hyperacusis
Hyperacusis (unusual sensitivity to sound on the same side as the facial palsy) occurs because of an insult to branchial efferents to the stapedius muscle, resulting in impairment of the stapedius reflex.
dysgeusia
Dysgeusia (taste disturbance) of the ipsilateral tongue occurs because of an insult to special visceral afferents of the facial nerve, which relay gustatory sensation from the ipsilateral anterior two-thirds of the tongue.
Risk factors
strong
intranasal influenza vaccination
A clinical trial of an intranasal application of inactivated influenza vaccine resulted in a marked increase of Bell's palsy, and as a result, was stopped at interim analysis.[33] This vaccine is no longer in clinical use.
pregnancy
Bell's palsy is three times more common in pregnancy, particularly in the third trimester and first week post-partum.[16]
weak
upper respiratory tract infection
Symptoms of recent upper respiratory tract infection may be reported.[34]
arid/cold climate
One epidemiological study of US military personnel in a variety of locations around the world suggested an increased incidence of Bell's palsy in arid or cold climates.[35]
hypertension
family history of Bell's palsy
Having a family member with Bell's palsy may increase the probability that other family members will develop it; 4% of patients with Bell's palsy report having had family members with facial palsy.[3]
diabetes
Bell's palsy is more common in patients with concomitant diabetes.[37]
Use of this content is subject to our disclaimer