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Bell's Palsy

Bell palsy

Facial nerve paralysis is a condition characterized by paralysis of one or all of the branches of the facial nerve. Bell’s palsy is unilateral weakness of the muscles of the face. It occurs when there is an injury to the seventh cranial nerve leading to drooping of one half of the face. It is also known as idiopathic facial paralysis.


The symptoms are usually acute appearing within 48 hours and they include lower facial paralysis on one side of the face, reduced secretion of tears, posterior auricular pain, increased sensitivity to sound (hyperacusis), disorders in taste, pain in the ear, inability to close the eye lids, facial muscle weakness, eye pain, blurred vision and epiphora [6].

  • At the onset, 136 patients presented postauricular pain, 114 were affected by dry eye, and 94 reported dysgeusia.[ncbi.nlm.nih.gov]
  • Incomplete sensory regeneration Dysgeusia or ageusia (impairment or loss of taste, respectively) may occur with incomplete regeneration of the chorda tympani.[emedicine.com]
Excessive Tearing
  • Upon observation, the left upper and lower eyelids were drooping and the left eye had excessive tearing. Motion palpation indicated multiple fixations in the cervical spine. Laboratory studies showed a microcytic anemia.[ncbi.nlm.nih.gov]
  • They can range from mild to severe and include Twitching Weakness Paralysis Drooping eyelid or corner of mouth Drooling Dry eye or mouth Excessive tearing in the eye Impaired ability to taste Scientists think that a viral infection makes the facial nerve[medlineplus.gov]
  • We address synkinesis, contractures of facial muscles, related facial pains, excessive tearing and dynamic facial asymmetry.[crystal-touch.nl]
  • This means that symptoms can also include drooling, excessive tearing, dryness of the eye or mouth, and ringing in the ear .[livescience.com]
  • We speculate that corneal irritation caused by lagophthalmos contributes to the induction of blepharospasm.[ncbi.nlm.nih.gov]
  • Also, a Bell’s palsy patient may need eye protection, as patients who are dealing with total facial paralysis sometimes struggle to close their eyes completely (lagophthalmos).[facialparalysisinstitute.com]
  • Lagophthalmos (pronounced lag-op-thal-mus): This is an inability to close the affected eye, which if prolonged may result in eye dryness and/or corneal ulceration.[facialpalsy.org.uk]
Eye Pain
  • pain, blurred vision and epiphora.[symptoma.com]
  • Changes in the ability to taste food Distorted facial expression due to weakness or paralysis Drooling Drooping of the eyelid and corner of the mouth Dry eyes or excessive tearing in one eye Pain on the affected side of face behind ear Sensitivity to[foundationforpn.org]
Posterior Auricular Pain
  • The symptoms are usually acute appearing within 48 hours and they include lower facial paralysis on one side of the face, reduced secretion of tears, posterior auricular pain, increased sensitivity to sound (hyperacusis), disorders in taste, pain in the[symptoma.com]
  • Signs and symptoms Signs and symptoms of Bell palsy include the following: Acute onset of unilateral upper and lower facial paralysis (over a 48-hr period) Posterior auricular pain Decreased tearing Hyperacusis Taste disturbances Otalgia Weakness of the[emedicine.com]
Facial Pain
  • On initial presentation in physical therapy the patient had unilateral facial paralysis, ipsilateral regional facial pain and numbness, and a history of a gradual, progressive onset of symptoms.[ncbi.nlm.nih.gov]
  • Dry mouth was present in 54 patients (19.7%), facial pain, hyperlacrimation, aural fullness, and hyperacusis represented a smaller percentage of the reported symptoms.[ncbi.nlm.nih.gov]
  • Patients often present with facial pain or paraesthesia, altered taste and intolerance to loud noise in addition to facial droop.[ncbi.nlm.nih.gov]
  • We address synkinesis, contractures of facial muscles, related facial pains, excessive tearing and dynamic facial asymmetry.[crystal-touch.nl]
  • Karen Johnson, deputy CEO of Facial Palsy UK, said that nearly 30 per cent of people with Bell’s palsy don't make a full recovery and are left with facial pain and spasms.[telegraph.co.uk]
Facial Spasm
  • The outcome measures were: incomplete recovery six months after randomisation, motor synkinesis, crocodile tears or facial spasm six months after onset, incomplete recovery after one year and adverse effects attributable to the intervention.[ncbi.nlm.nih.gov]
  • "For the minority of patients that have incomplete recovery of facial strength or have other residual deficits including facial spasm, treatments may include botulinum toxin injections and various surgical procedures to restore facial symmetry," Simpson[cbsnews.com]
  • A third study found a better prognosis for young patients, aged below 10 years old, while the patients over 61 years old presented a worse prognosis.Major possible complications of the condition are chronic loss of taste (ageusia), chronic facial spasm[en.wikipedia.org]
  • Secondary outcomes The presence of motor synkinesis, contracture, hyperkinesia, facial spasm or crocodile tears preferably six months after onset. Incomplete recovery after one year.[doi.org]
  • spasms Normal symmetry and tone at rest Slight to moderate forehead movement Complete eye closure with effort Slight asymmetry of the mouth with maximum effort Grade IV Moderately severe dysfunction Obvious and disfiguring weakness Normal symmetry and[racgp.org.au]
  • A stroke will usually cause a few additional symptoms, such as numbness or weakness in the arms and legs. And unlike Bell's palsy, a stroke will usually let patients control the upper part of their faces.[web.archive.org]
  • The disorder, which is not related to stroke, is the most common cause of facial paralysis.[web.archive.org]
  • And unlike Bell's palsy, a stroke will usually let patients control the upper part of their faces.[en.wikipedia.org]
  • Another complication is increased risk of stroke. Stroke prevention and follow-up is recommended. Some people don't recover completely.[bodyandhealth.canada.com]
Guillain-Barré Syndrome
  • The weakness or symptoms seen in Bell's palsy is sometimes associated with the following: Diabetes High blood pressure Trauma Toxins Lyme disease Guillain-Barré syndrome Sarcoidosis Myasthenia gravis Infection, especially following a viral infection with[columbianeurology.org]
  • Bell's palsy must be differentiated from Lyme disease, Guillain-Barré syndrome, sarcoidosis, parotid tumor, and stroke. Lymphoma can also in rare instances be a cause of facial paralysis.[bodyandhealth.canada.com]
Unilateral Facial Weakness
  • Bell palsy is largely a diagnosis of exclusion, but certain features in the history and physical examination help distinguish it from facial paralysis due to other conditions: eg, abrupt onset with complete, unilateral facial weakness at 24 to 72 hours[ncbi.nlm.nih.gov]
  • Its most alarming symptom is unilateral facial weakness, which can result in the inability to close the eyelids, smile, or whistle.[ncbi.nlm.nih.gov]
  • Abstract Bell's palsy is a kind of peripheral neural disease that cause abrupt onset of unilateral facial weakness.[ncbi.nlm.nih.gov]
  • Introduction Bell's Palsy, defined as unilateral facial weakness, is a relatively common pediatric problem affecting children from infancy to adolescence (Illustration Shown on the Right).[pedclerk.bsd.uchicago.edu]
  • Bell's palsy is an idiopathic, acute unilateral facial weakness that evolves rapidly and is maximal within two days. Moderate ear discomfort, sensitivity to sound and reduced tearing may occur.[ncbi.nlm.nih.gov]
Trigeminal Neuralgia
  • neuralgia G50.1 Atypical facial pain G50.8 Other disorders of trigeminal nerve G50.9 Disorder of trigeminal nerve, unspecified G51 Facial nerve disorders G51.0 Bell's palsy G51.1 Geniculate ganglionitis G51.2 Melkersson's syndrome G51.3 Clonic hemifacial[icd10data.com]
  • Inheritance in such cases may be autosomal dominant with low penetration; however, which predisposing factors are inherited is unclear. [25] The family history may also be positive for other nerve, nerve root, or plexus disorders (eg, trigeminal neuralgia[emedicine.com]
Cranial Nerve Involvement
  • MRI should be considered for the following patients: decompressive surgery is being contemplated atypical signs and symptoms suggest another diagnosis may be possible: slow progressive palsy spasm preceding palsy multiple cranial nerves involved recurrent[radiopaedia.org]
  • nerve involvement other than the facial nerve.[emdocs.net]


The diagnosis of Bell’s palsy is usually made based on history and physical examination. However, investigations may be needed to exclude other conditions.

Laboratory tests

  • Complete blood count
  • Erythrocyte sedimentation rate
  • VDRL test
  • HIV screening
  • Fasting blood glucose
  • Thyroid function test
  • CSF analysis


  • CT scan
  • MRI

Other investigations that can be carried out include EMG, nerve conduction tests, blepharokymography and histology.


Most patients who suffer from this condition often recover spontaneously without treatment. However, treatment might be needed in some patients and also to accelerate recovery. Medical treatments include the use of corticosteroids, antiviral agents and a combination of the two.

The eye should also be protected with the use of artificial tears and ointments. They should be applied to make up for the lack of lacrimation. The use of external eyelid weights have also proven to be beneficial.

There is a place for physical therapy like facial exercises, neuromuscular retraining, and acupuncture in the treatment of Bell’s palsy [7]. Surgeries to manage this condition, though not commonly advocated, include facial nerve decompression and eyelid implants.


Close to 90% of patients recover in 3 months or less without any apparent disfigurement. There are three groups that the patients fall into based on their prognosis. The first group are those who recover completely from the lesion without any long-term complications and this is the group most patients fall into. The second group does not recover completely but they appear completely recovered to the inexperienced eye, most people in this group have had axonotmesis with interruption of the axons. The last group are those with permanent neurological damage, visible even to the inexperienced eye, and this group is made up mostly by the elderly [5].

Factors associated with poor prognosis include advanced age, complete paralysis and reduced taste or salivation on the affected side. Other factors are pain in the posterior auricular area and decreased lacrimation.


The cause of Bell’s palsy has not been fully understood, however, some factors have been associated with increased likelihood of developing the disease. The most implicated factor is exposure to cold like in chilly weathers and air-conditioned environments. Others include infection with herpes simplex virus, herpes zoster, Lyme disease, HIV, Epstein-Barr virus, cytomegalovirus, syphilis and mycoplasma. It could also result from microvascular disease like diabetes and hypertension and from other inflammatory causes, viral diseases and autoimmune diseases [2].


Bell’s palsy has an annual incidence of between 0.015% and 0.03%. It is most commonly seen during the winter months. It is the commonest cause of unilateral facial paralysis and it occurs more on the right side of the face. Bell’s palsy affecting both sides of the face is rare. It also has a higher incidence in people who have underlying medical conditions like diabetes, HIV and preeclampsia.

The incidence of Bell’s palsy increases with advancing age with the highest incidence seen in patients 65 years and over. It affects both male and female sexes equally, and there is no clear difference in the incidence for different races [3].

Sex distribution
Age distribution


The exact way by which this condition occurs is still unclear. However, it is mostly agreed that due to ischemia and edema, there is compression of the facial nerve within the facial canal. Thee facial canal is a small hole in the temporal bone which the facial nerve goes through during its course. The exact way by which this edema or inflammation comes about is unclear.

The commonest site of compression of the facial nerve is at the meatal foramen which has a diameter that is less than 0.7mm. The labyrinthine segment, the first portion of the facial nerve goes through this foramen. Due to its constricted limits, it is rational that processes such as inflammation, compression, ischemia and demyelination will weaken nerve conduction at this site [4].

Facial nerve injury in Bell’s palsy usually occurs near or at the geniculate ganglion, peripheral to the nerve’s nucleus. There is associated autonomic and gustatory abnormalities accompanying the motor paralysis if the injury occurs proximal to the geniculate ganglion. The same effects are seen if they occur between the geniculate ganglion and the origin of the corda tympani, but the lacrimal glands are spared. If it occurs at the stylomastoid foramen, there is only facial paralysis.


There is no documented way to prevent Bell’s palsy. However, lifestyle changes that reduce the risk of acquiring risk factors like HIV, diabetes and hypertension could be beneficial.


Bell’s palsy is named after Sir Charles Bell, a Scottish anatomist who first described the disease. It results from an injury to the motor neuron of the facial nerve and is self-limiting in over 80% of cases. Symptoms usually subside over a period of three months [1].

Patient Information


Bell’s palsy is a condition that leads to weakness of one side of the face and it is caused by injury to the facial nerve.


The cause of Bell’s palsy is unclear but the following factors have been known to contribute to development of the condition. They are exposure to cold, herpes simplex virus, herpes zoster, HIV, cytomegalovirus, sarcoidosis, Lyme disease and Epstein–Barr virus.

Signs and symptoms

Symptoms of Bell’s palsy mainly affect one half of the face and they include drooping of the face, drooping of the eyelid, altered taste sensation, lack of tears in the eye, increased sensitivity to sound, drooling, inability to make facial expressions like smiling [8].


Diagnosis of Bell’s palsy is mainly made one the bases of the presenting symptoms, although some tests might be needed to exclude other conditions. Such tests include blood tests for infection, glucose, HIV and syphilis. Imaging tests like CT scan and MRI may also be required. Some nerve conduction tests may also be carried out.


Treatment involves the use of corticosteroids, antivirals, artificial tears and ointments. Physical therapies to train the muscles of the face are also beneficial. In some cases, surgery on the facial nerve or the eyelids would be beneficial [9] [10].



  1. Anderson P. New AAN guideline on Bell's palsy. Medscape Medical News. November 7, 2012. Accessed November 12, 2012.
  2. Holland NJ, Weiner GM. Recent developments in Bell's palsy. BMJ. Sep 4 2004;329(7465):553-7.
  3. Mutsch M, Zhou W, Rhodes P, Bopp M, Chen RT, Linder T, et al. Use of the inactivated intranasal influenza vaccine and the risk of Bell's palsy in Switzerland. N Engl J Med. Feb 26 2004;350(9):896-903.
  4. Murakami S, Mizobuchi M, Nakashiro Y, Doi T, Hato N, Yanagihara N. Bell palsy and herpes simplex virus: identification of viral DNA in endoneurial fluid and muscle. Ann Intern Med. Jan 1 1996;124(1 Pt 1):27-30.
  5. Unlu Z, Aslan A, Ozbakkaloglu B, Tunger O, Surucuoglu S. Serologic examinations of hepatitis, cytomegalovirus, and rubella in patients with Bell's palsy. Am J Phys Med Rehabil. Jan 2003;82(1):28-32.
  6. Kim YH, Choi IJ, Kim HM, Ban JH, Cho CH, Ahn JH. Bilateral simultaneous facial nerve palsy: clinical analysis in seven cases. Otol Neurotol. Apr 2008;29(3):397-400.
  7. Cardoso JR, Teixeira EC, Moreira MD, Fávero FM, Fontes SV, Bulle de Oliveira AS. Effects of exercises on Bell's palsy: systematic review of randomized controlled trials. Otol Neurotol. Jun 2008;29(4):557-60.
  8. Baugh R, Basura G, Ishii L, Schwartz S, Drumheller C, Burkholder R, et al. Clinical Practice Guideline: Bell's Palsy. Otolaryngol Head Neck Surg November 2013 vol. 149 no. 3 suppl S1-S27. 
  9. Hato N, Yamada H, Kohno H, Matsumoto S, Honda N, Gyo K, et al. Valacyclovir and prednisolone treatment for Bell's palsy: a multicenter, randomized, placebo-controlled study. Otol Neurotol. Apr 2007;28(3):408-13.
  10. 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. Sep 2 2009;302(9):985-93.

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Last updated: 2019-07-11 22:31