- Bell’s palsy is the most common cause of acute facial nerve paresis/paralysis, and the most common acute mononeuropathy.
- Patients may have impaired eye closure which may lead to eye injury.
- Not all patients with facial paresis/paralysis have Bell’s palsy. Alternative underlying etiologies must be considered.
When evaluating a patient with facial paresis/paralysis for Bell’s palsy, the following should be considered:
- Bell’s palsy is rapid in onset (<72 hours).
- Bell’s palsy is diagnosed when no other medical etiology is identified as a cause of the facial paresis/paralysis.
- Bilateral Bell’s palsy is rare.
- Currently, no cause for Bell’s palsy has been identified.
- Other conditions may cause facial paresis/paralysis, including stroke, brain tumors, tumors of the parotid gland or infratemporal fossa, cancer involving the facial nerve, and systemic and infectious diseases, including varicella zoster, sarcoidosis, and Lyme disease.
- Bell’s palsy is typically self-limited. Most patients with Bell’s palsy show some recovery without intervention within 2-3 weeks after onset of symptoms and completely recover within 3-4 months.
- Bell’s palsy may occur in men, women, and children but is more common in persons 15-45 years old; individuals with diabetes, upper respiratory ailments, or compromised immune systems; and during pregnancy.
Table 1. Abbreviations and Definitions of Common Terms
|Acute||Occurring in <72 h|
|Bell’s palsy||Acute unilateral facial nerve paresis/paralysis with onset in <72 h|
and without identifiable cause
|EMG testing||A test in which a needle electrode is inserted into affected muscles to record both spontaneous depolarizations and the responses to voluntary muscle contraction|
|ENoG testing (neurophysiologic studies)||A test used to examine the integrity of the facial nerve, in which surface electrodes record the electrical depolarization of facial muscles following electrical stimulation of the facial nerve|
|Facial paralysis||Inability to move the facial muscles|
|Facial paresis||Impaired ability to move the facial muscles|
Table 2. House-Brackmann Facial Nerve Grading System
|4||Moderately severe dysfunction|
Table 3. Etiologies and Clinical Features of Facial Paralysis
|Type||Condition||Etiologic Agent||Distinguishing Factors|
|Autoimmune||Guillain-Barré||Autoimmune/ infectious||Acute polyneuropathy; ascending paresis/paralysis; paresis/paralysis of hands, feet progressing to the trunk|
|Melkersson-Rosenthal syndrome||Unknown||Recurrent facial paresis/paralysis; swelling of face/lips; fissures or folds in tongue|
|Multiple sclerosis||Unknown||Abnormal neurologic exam with intermittent symptoms|
|Sarcoidosis||Unknown||May be bilateral; abnormal laboratory test results including ACE level|
|Congenital||Mobius syndrome||Possibly viral||Young age, bilateral in nature, unable to move face or eyes laterally|
|Endocrine||Diabetes||Microvascular disease||Other signs and symptoms of diabetes, laboratory testing|
|Idiopathic||Acute facial nerve paresis/paralysis||Unknown||Classic Bell’s palsy with other etiologies excluded|
|Infectious||Encephalitis/ meningitis||Fungal, viral, or bacterial||Headache, stiff neck, cerebrospinal fluid abnormalities|
|Herpes simplex||Herpes simplex virus along axons of nerve residing in the geniculate ganglion||Fever, malaise|
|HIV||HIV||Fever, malaise, CD4 count|
|Lyme disease||Spirochete Borrelia burgdorferi||May be bilateral, rash, arthralgias|
|Mononucleosis||Epstein-Barr virus||Malaise, difficult to distinguish|
|Otitis media||Bacterial pathogens||Gradual onset, ear pain, fever, hearing loss|
|Ramsay Hunt syndrome||Varicella zoster virus||Pronounced prodrome of pain, vesicular eruption in ear canal or pharynx|
|Syphilis||Treponema pallidum||Other neurologic and cutaneous manifestations|
|Inherited||Heritable disorders||Autosomal dominant inheritance||Family history as high as 4%; may have other neurologic disorders|
|Neoplastic||Facial nerve tumor, skin cancer, parotid tumors||Multiple carcinomas of the head and neck||May involve only select branches of the facial nerve or other cranial nerves and present as multiple cranial neuropathies|
|Neurovascular||Stroke||Ischemia, hemorrhage||Forehead sparing most often, extremities often involved|
|Traumatic||Injury to facial nerve||Trauma, including forceps delivery||Timing of injury coincides with trauma|