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Bell Palsy: Diagnosis and Management
Author: Selim R. Benbadis, MD; Contributor: Elhaam Iranmanesh, MD | January 17, 2023
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Images from Cirpaciu D, Goanta CM, Cirpaciu MD. J Med Life. 2014;7 spec no. 3:68-77. [Open access.] PMID: 25870699, PMCID: PMC4391412.
Bell Palsy: Diagnosis and Management
Author: Selim R. Benbadis, MD; Contributor: Elhaam Iranmanesh, MD | January 17, 2023 | Contributor Information
Bell palsy is the most common cause of facial paralysis; more specifically, it the most common cause of lower motor neuron (LMN) facial palsy.[1-3] The muscles on one side of the face suddenly weaken or become paralyzed. Determining the etiology can be difficult, but the mechanism is often an inflammatory process. Damage or trauma to the facial nerve (cranial nerve [CN] VII) from infectious, immunologic, ischemic, and traumatic mechanisms and causes may be involved.[1-6] This condition is often temporary, usually resolving without treatment within a few months (70%-80%).[1-3]
The annual incidence of Bell palsy in the United States is 25-35 per 100,000 persons, with an estimated 40,000 individuals affected each year.[3] Males and females are affected equally. Individuals of any age can suffer from Bell palsy, but it is more likely to affect older people.[3] The incidence peaks after age 40 years.[4]
The left image shows a female patient with right facial palsy and dynamic asymmetry. The right image in the same patient reveals the absence of wrinkles on the right side of the forehead.
Images from Worme M, Chada R, Lavallee L. BMC Res Notes. 2013;6:337. PMID: 23985267, PMCID: PMC3847606. [Creative Commons Attribution 2.0 Generic (CC BY 2.0).]
Bell Palsy: Diagnosis and Management
Author: Selim R. Benbadis, MD; Contributor: Elhaam Iranmanesh, MD | January 17, 2023 | Contributor Information
Pathophysiology
As noted earlier, the precise cause of idiopathic Bell palsy is not known. One theory proposes that nonspecific inflammation of the nerve leads to focal edema, demyelination, and ischemia.[4] There is also some evidence that infection with herpes virus simplex type 1 (HSV-1) may play a role.[1,3,4,6]
Several other viruses have been implicated in Bell palsy. In the setting of the COVID-19 pandemic, multiple case reports have been published linking the virus to Bell palsy.[15,16]
Bell palsy is also more common in patients with conditions that compromise the immune system, such as infection with human immunodeficiency virus (HIV). Other risk factors include pregnancy, diabetes, hypertension, sarcoidosis, tumors, and Lyme disease.[1-4]
The illustrations show the signs of Ramsay-Hunt syndrome (discussed in slide 5). Vesicular lesions appear in the ear but are not exclusive to Bell palsy (top left image); facial drooping, widened palpebral fissure, and decreased smile are evident (right side of face) (right image). The photograph (bottom left image) demonstrates a sharp midline delineation of a rash in a middle-aged patient with Ramsay-Hunt syndrome.
Images from Kumarihamy KW, Ralapanawa DM, Jayalath WA. BMC Res Notes. 2015;8:26. PMID: 25648561, PMCID: PMC4322451. [Creative Commons Attribution 4.0 International (CC BY 4.0).]
Bell Palsy: Diagnosis and Management
Author: Selim R. Benbadis, MD; Contributor: Elhaam Iranmanesh, MD | January 17, 2023 | Contributor Information
Signs/Symptoms
Signs/symptoms of Bell palsy often have a sudden onset and then peak within 48-72 hours.[1,6] They can vary among individuals and range in severity from mild weakness to complete paralysis, and include the following features[1,4,6]:
Unilateral (common) or bilateral (rare; eg, Guillain-Barré syndrome) facial twitching, weakness, or paralysis
Drooping of the eyelid and corner of the mouth
Drooling and/or excessive tearing in an eye
Dry eye and/or dry mouth
Taste impairment
Pain/discomfort around the jaw and behind the ear
Unilateral or bilateral tinnitus
Headache
Hyperacusis on the affected side(s)
Impaired speech
Dizziness
Difficulty chewing or drinking
The photographs show a patient who was diagnosed with probable leptospirosis and concurrent myocarditis and severe Bell palsy. Involvement of the left frontalis muscle and mouth deviation to the right side are present (ie, left facial paralysis) (left image). The right image is the same patient after 6 months; total improvement of the left-sided facial nerve palsy can be seen.
Images from Aditya V. Case Rep Obstet Gynecol. 2014;2014:626871. [Open access.] PMID: 24772359, PMCID: PMC3977111.
Bell Palsy: Diagnosis and Management
Author: Selim R. Benbadis, MD; Contributor: Elhaam Iranmanesh, MD | January 17, 2023 | Contributor Information
These photographs are from a pregnant patient with lower motor neuron facial palsy and syndrome of hemolysis, elevated liver enzyme levels, and low platelet levels [HELLP].
Top left image: The nasolabial fold is flat on the right side of the face. At the same time, the patient was also unable to wrinkle her forehead on the same side (not shown).
Top right image: She was unable to show all her teeth on the right side.
Bottom left image: The patient could not purse her lips on the right side.
Bottom right image: She exhibited Bell phenomenon (upward rolling of the eye on the affected side with partial closure of the eyelid when asked to close both eyes).
Image of Herpes zoster oticus on day 6 in a patient with Ramsay-Hunt syndrome courtesy of Manolette Roque, MD, ROQUE Eye Clinic.
Bell Palsy: Diagnosis and Management
Author: Selim R. Benbadis, MD; Contributor: Elhaam Iranmanesh, MD | January 17, 2023 | Contributor Information
Ramsay-Hunt syndrome
Ramsay-Hunt syndrome is a rare condition that consists of a typical Bell palsy following varicella zoster virus (VZV) reactivation.[7] It includes additional features such as the following[7]:
An erythematous, painful, vesicular rash on the pinna and, often, the external ear canal due to the sensory distribution of CN VII; the rash and blisters may also affect the mouth, soft palate, and top portion of the esophagus
Tinnitus as well as otalgia that may be severe and refer to the neck
Sensorineural hearing loss that is usually transient but may become permanent in rare cases
Hyperacusis
Vertigo or dizziness that is more severe than in idiopathic Bell palsy
(Rarely) Loss of taste, dry mouth, and/or dry eyes
The annual incidence of Ramsay-Hunt syndrome in the United States is 5 per 100,000 persons, primarily in those older than 60 years.[7] It is the second most common cause of atraumatic peripheral facial paralysis, and both sexes are equally affected.[7]
Images of a patient with bilateral Ramsay-Hunt syndrome and diabetes at presentation (left) and at 8 weeks of follow-up (right) from Syal R, Tyagi I, Goyal A. BMC Ear Nose Throat Disord. 2004;4(1):3. PMID: 15575957, PMCID: PMC535933. (CC BY 2.0).
Bell Palsy: Diagnosis and Management
Author: Selim R. Benbadis, MD; Contributor: Elhaam Iranmanesh, MD | January 17, 2023 | Contributor Information
Bilateral peripheral facial palsy with Bell phenomenon occurs in about 1% of patients.[4,6,8] When affected patients attempt to close their eyes, the eyes do not fully close and the eyeballs rotate upward (left image).
Although the causes for unilateral facial palsy can also cause the bilateral condition, bilateral facial palsy is far less likely to be idiopathic Bell palsy. Therefore, an etiology should be sought, including Guillain-Barré syndrome, Lyme disease, carcinomatosis, and lymphoma.[4,6,8]
Simplified illustration of the pathway corticobulbar fibers travel from the cerebral cortex to the motor nucleus of the facial nerve courtesy of Ushtar W. Amin, MD, and Selim R. Benbadis, MD. MM = muscles.
Bell Palsy: Diagnosis and Management
Author: Selim R. Benbadis, MD; Contributor: Elhaam Iranmanesh, MD | January 17, 2023 | Contributor Information
Diagnosis
The diagnosis of Bell palsy is usually made on a clinical basis and after excluding other potential causes of facial paralysis.[1,3-6,8,12-14] Thus, routine laboratory studies are generally not indicated.
One initial consideration is identifying whether the facial paralysis is from a central or peripheral lesion.
Any lesion that affects the motor corticopontine pathway above the nucleus of CN VII can cause central facial weakness, resulting in lower facial paralysis.[9,10] Stroke (most common[11]), tumor(s), and demyelination can produce central facial palsy.
Lesions that occur at the level of the pons or distal along the course of CN VII can cause peripheral facial palsy, in which ipsilateral total facial paralysis occurs.[9,10] Causes of peripheral facial palsy include facial fractures, HSV, Ramsay-Hunt syndrome, diabetes, sarcoidosis, Lyme disease, middle ear or mastoid infections, carcinomatosis, lymphoma, chronic meningitis, and cerebellopontine angle or glomus jugulare tumors.
Image courtesy of Medscape.
Bell Palsy: Diagnosis and Management
Author: Selim R. Benbadis, MD; Contributor: Elhaam Iranmanesh, MD | January 17, 2023 | Contributor Information
Forehead wrinkling
A simple test to differentiate between central and peripheral facial palsies is to ask the patient to wrinkle their forehead.[9,10] The lesion is central if the entire forehead wrinkles; it is peripheral if only one side of the forehead wrinkles.
The image depicts the differences in appearance between central and peripheral facial palsies.
Images courtesy of Ushtar W. Amin, MD, and Selim R. Benbadis, MD.
Bell Palsy: Diagnosis and Management
Author: Selim R. Benbadis, MD; Contributor: Elhaam Iranmanesh, MD | January 17, 2023 | Contributor Information
Imaging studies
In general, imaging studies are not necessary. However, magnetic resonance imaging (MRI) may be used to exclude secondary causes of unilateral facial nerve paralysis.
In typical idiopathic Bell palsy, an MRI may show enhancement of the facial nerve. The MRI shown above (top image) reveals enhancement of the right CN VII in the distal internal auditory canal (arrow).
The second MRI (bottom image) reveals another secondary cause of unilateral peripheral facial nerve paralysis. A right parotid tumor with perineural invasion of the right facial nerve can be seen (arrow).
Image courtesy of Ushtar W. Amin, MD, and Selim R. Benbadis, MD.
Bell Palsy: Diagnosis and Management
Author: Selim R. Benbadis, MD; Contributor: Elhaam Iranmanesh, MD | January 17, 2023 | Contributor Information
Ischemic stroke is the most common cause of central facial weakness.[11]
The computed tomography (CT) scan reveals a right basal ganglia intraparenchymal hemorrhage caused by hypertension. This caused a hemiparesis on the ipsilateral side (ie, left side) as the facial paralysis.
Image courtesy of Ushtar W. Amin, MD, and Selim R. Benbadis, MD.
Bell Palsy: Diagnosis and Management
Author: Selim R. Benbadis, MD; Contributor: Elhaam Iranmanesh, MD | January 17, 2023 | Contributor Information
This diffusion-weighted (DWI) MRI demonstrates an acute left pontine infarction (arrow). A pontine lesion (eg, stroke) would cause a crossed syndrome (Millard-Gubler syndrome), a triad with CN VI palsy with peripheral facial weakness ipsilateral to the lesion (ie, left side) and hemiparesis on the contralateral side (ie, right side).
Therefore, although a unilateral peripheral facial nerve paralysis would likely occur, it would not be an isolated finding, would almost certainly affect other cranial nerves (eg, CN VI), and would be accompanied by long tract signs (eg, crossed hemiparesis).
Image from Volk GF, Pantel M, Guntinas-Lichius O. Head Face Med. 2010;6:25. PMID: 21040532, PMCID: PMC2984557. (CC BY 2.0).
Bell Palsy: Diagnosis and Management
Author: Selim R. Benbadis, MD; Contributor: Elhaam Iranmanesh, MD | January 17, 2023 | Contributor Information
Electroneuronography/Electromyography
Electroneuronography (ENoG) or electromyography (EMG) of the facial nerve is typically not necessary for making the diagnosis of Bell palsy.[1,3,4] In patients with severe paralysis, EMG may help to assess the degree and extent of the nerve injury and potentially predict the prognosis for recovery.[3,6] A 90% reduction in the compound muscle action potential (CMAP) (when compared to the unaffected side) in the first 10 days of onset predicts an incomplete recovery and the potential for surgical intervention.[1,4,12]
EMG studies should be performed at least 1 week (within 2 weeks) after symptomatic onset to avoid false-negative results.[12,13]
The EMG shown is from a child with left-sided facial palsy after brainstem surgery. The complete loss of voluntary activity in the left frontalis muscle (L) in comparison to the healthy right side (R) can be seen.
Image from Flickr | Erich Ferdinand [(CC BY 2.0).
Bell Palsy: Diagnosis and Management
Author: Selim R. Benbadis, MD; Contributor: Elhaam Iranmanesh, MD | January 17, 2023 | Contributor Information
Treatment
As noted earlier, the majority of patients with Bell palsy fully recover without treatment within a period of months.[1-3] However, synkinesis is a potential long-term sequela.
The following management strategies may provide some symptomatic relief[1,3-6,8,12-14]:
Prophylactic eye care is recommended. When a patient's eyes cannot fully close, there is an increased risk of physical damage to the cornea (exposure keratitis) as well as dry eye; therefore, an eye patch — particularly when sleeping — as well as lubrication with topical therapies such as artificial tears and lubricating ophthalmic ointment are recommended.
Oral corticosteroids within 72 hours of symptomatic onset may improve the likelihood of recovery of facial nerve function. The American Academy of Neurology (AAN) recommends either (1) 50 mg of prednisone for 10 days or (2) 60 mg for the first 5 days, followed by a 10-mg reduction each day for another 5 days.[14]
Oral antiviral therapy in conjunction with oral corticosteroids within 72 hours of symptomatic onset might provide a modest benefit for moderate to severe facial weakness if a viral cause is suspected (eg, HSV-1, VZV). The AAN notes that a proven benefit has not been established.[14] One antiviral regimen is valacyclovir 1 g three times daily for 7 days.[1,4]
Image from Volk GF, Pantel M, Guntinas-Lichius O. Head Face Med. 2010;6:25. PMID: 21040532, PMCID: PMC2984557. (CC BY 2.0).
Bell Palsy: Diagnosis and Management
Author: Selim R. Benbadis, MD; Contributor: Elhaam Iranmanesh, MD | January 17, 2023 | Contributor Information
Surgical intervention
Surgical decompression for Bell palsy remains controversial.[1,3,12] In rare cases (eg, ectropion), surgical measures may be necessary, particularly when structural interventions may improve eye closure.[1] Patients who have 90% axonal degeneration may be candidates for surgical intervention.[1,4,12,13]
Surgical decompression includes the following procedures[1]:
Selective myectomy
Selective neurectomy
Nerve-to-nerve transfer
Regional and free-tissue transfer
Complications of surgical decompression include CN VII injury, seizures, unilateral hearing loss, and cerebrospinal leak.[12]
The image shows an example of a summarizing schematic algorithm of the different possibilities of facial nerve reconstruction.
Images from Volk GF, Pantel M, Guntinas-Lichius O. Head Face Med. 2010;6:25. PMID: 21040532, PMCID: PMC2984557. (CC BY 2.0).
Bell Palsy: Diagnosis and Management
Author: Selim R. Benbadis, MD; Contributor: Elhaam Iranmanesh, MD | January 17, 2023 | Contributor Information
The intraoperative photographs are from a hypoglossal-facial jump nerve anastomosis procedure.
Image a: Harvest of the greater auricular nerve as an interpositional graft.
Image b: End-to-end nerve suture of the graft (g) to the peripheral facial nerve (f); p = parotid gland.
Image c: Incision (arrow) of the hypoglossal nerve (h).
Image d: End-to-side nerve suture between the hypoglossal nerve (h) and the graft (g).
Images from Socolovsky M, Paez MD, Masi GD, Molina G, Fernandez E. Surg Neurol Int. 2012;3:46. [Open access.] PMID: 22574255, PMCID: PMC3347494.
Bell Palsy: Diagnosis and Management
Author: Selim R. Benbadis, MD; Contributor: Elhaam Iranmanesh, MD | January 17, 2023 | Contributor Information
The top row of photographs are preoperative images of a middle-aged woman who had spontaneous left facial palsy. Note the complete facial palsy on the left side of her face.
The bottom row of photographs are postoperative images of the same woman following partial hypoglossal to facial nerve transfer. Note that the patient has good symmetry at rest, good active movement, and no tongue atrophy.
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Author
Selim R. Benbadis, MD
Director, Department of Neurology
University of South Florida
Tampa, Florida
Disclosure: Selim R. Benbadis, MD, has disclosed no relevant financial relationships.
Contributor
Elhaam Iranmanesh, MD
Resident (PGY4), Department of Neurology
University of South Florida
Tampa, Florida
Disclosure: Elhaam Iranmanesh, MD, has disclosed no relevant financial relationships.
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References
Eviston TJ, Croxson GR, Kennedy PG, Hadlock T, Krishnan AV. Bell's palsy: aetiology, clinical features and multidisciplinary care. J Neurol Neurosurg Psychiatry. 2015 Dec;86(12):1356-61. PMID: 25857657
Cirpaciu D, Goanta CM, Cirpaciu MD. Recurrences of Bell's palsy. J Med Life. 2014;7 spec no. 3:68-77. PMID: 25870699
Zandian A, Osiro S, Hudson R, et al. The neurologist's dilemma: a comprehensive clinical review of Bell's palsy, with emphasis on current management trends. Med Sci Monit. 2014 Jan 20;20:83-90. PMID: 24441932
Gronseth GS, Paduga R, for the American Academy of Neurology. Evidence-based guideline update: steroids and antivirals for Bell palsy: report of the Guideline Development Subcommittee of the American Academy of Neurology. Neurology. 2012 Nov 27;79(22):2209-13. PMID: 23136264.
Alrajhi F, Seraj H, Taher NO, Alnabihi AN. Bell's palsy in a patient after contracting COVID-19 with signs of aberrant nerve regeneration. Am J Ophthalmol Case Rep. 2022 Sep;27:101679. PMID: 35959246.
Amaki A, Cabrera CI, Li S, et al. Incidence of Bell Palsy in Patients With COVID-19. JAMA Otolaryngol Head Neck Surg. 2021 Aug 1;147(8):767–8. PMID: 34165518.
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