The diagnosis of Bell palsy is largely one of exclusion and depends on a thorough neurologic examination. It is based on the clinical recognition of symptoms, such as ipsilateral sagging of the eyebrow, which is key in recognizing the peripheral facial palsy of Bell palsy. This is opposed to central facial palsy, which spares the upper third of the contralateral face. With the weakness of all facial muscles seen in Bell palsy, one may also observe ptosis, flattening of the nasolabial fold, and inability to control the lips and mouth. The upward movement of the eye while attempting to close the eye, which is due to weakness of the orbicularis oculi, is a pathognomonic sign termed "Bell phenomenon."[19]These facial motor symptoms develop acutely within hours to 1-2 days and are maximal within 3 weeks or less from symptom onset. Patients may also present with associated hyperacusis due to disruption of fibers to the stapedius muscle; pain around the neck or ear; facial paresthesia; dry eyes and dry mouth; or dysgeusia, especially on the anterior two thirds of the tongue.
Once a clinical diagnosis has been established, patients should receive reassurance and counseling that the prognosis is usually favorable. Patients should be educated about the risk for corneal exposure and should use lubricating drops during waking hours, as well as a patch to close the eyelid at night. Evidence-based guidelines from the American Academy of Neurology (AAN) provide a level A recommendation that oral steroids should be offered to patients with acute-onset Bell palsy within 1-3 days of symptom onset.[20] Prednisone (60-80 mg/d) for 1 week is a common regimen. The AAN also provides a level C recommendation that antivirals can be offered in addition to steroids to increase the probability of recovery of facial function; however, the benefit of antivirals has not yet been established.[20] Nevertheless, early combined therapy with prednisone (60-80 mg/d) and valacyclovir (1000 mg three times daily) for 1 week can be offered, especially to those with severe facial palsy.
To assess facial function, physician-graded scales, such as the House-Brackmann scale and the Sunnybrook Facial Grading System (FGS), are commonly used. The House-Brackmann scale was intended only to describe recovery after vestibular schwannoma surgery and is thought to lack sensitivity compared with the Sunnybrook FGS.[21] The Sunnybrook FGS was proposed in 1996 by Ross and colleagues[22] and rates the following three categories: (1) resting or static symmetry of the affected side compared with the normal side; (2) dynamic symmetry of voluntary movement of the affected side, as measured by the degree of muscle excursion compared with the normal side; and (3) rate of degree of involuntary muscle contraction (synkinesis) of the affected side. The Sunnybrook FGS ranges from 0 to 100 and has been robustly validated, with reliable reproducibility between observers.[23] Because patients with Bell palsy typically recover within 3 weeks, one randomized trial found the use of Sunnybrook FGS at 1 month to most accurately predict nonrecovery at 12 months.[24]
Severe or complete facial paralysis, bilateral paralysis, involvement of other nerves, or nonrecovery within 4 weeks should prompt referral to a specialist; additional evaluation; and consideration of differential diagnosis, such as neoplasms, HIV infection, Lyme disease, Guillain-Barré syndrome, multiple sclerosis, sarcoidosis, Sjögren syndrome, and even rare conditions like Melkersson-Rosenthal syndrome. In these cases, electrodiagnostic and imaging studies may be useful.
Electrodiagnostic tests, such as EMG and nerve conduction studies, can provide information on the viability of the nerve, especially in patients with a clinically complete lesion. These tests are most useful when performed within 2 weeks to help guide treatment decisions on surgical management.[25] Within 1-3 months of symptom onset, needle EMG can yield prognostic information on the degree of muscle denervation and axonal damage and can also confirm any subclinical signs of re-innervation and recovery.[26]
Imaging studies, such as CT with contrast or gadolinium-enhanced MRI, should be focused on the brain, temporal bone, and parotid glands. High-resolution CT can demonstrate bony erosions, and MRI can evaluate for inflammation, edema, or neoplasm. Imaging can be used if a patient fails to improve within 4 months of symptom onset and then again at 7 months. Pathologic investigation, such as parotid gland biopsy, may be used if symptoms persist and imaging remains negative.[27]
Medscape © 2019 WebMD, LLC
Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.
Cite this: James Lee, Stephanie Oh, Gaurav Gupta. A 44-Year-Old With a Headache, Photophobia, and Phonophobia - Medscape - Nov 13, 2019.
Comments