eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > Reconstructive Surgery
Bell Palsy: Differential Diagnoses & Workup
Updated: Oct 26, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
- Multimedia
Differential Diagnoses
Other Problems to Be Considered
Traumatic
Birth traumaTemporal bone fracture
Barotrauma
Facial traumaNeurologic Cranial nerve syndromesSystemic Diabetes mellitus
Alcoholic neuropathy
Hyperthyroidism
PregnancyInfectious Acute otitis media
Chronic otitis media
Herpes zoster oticus
Necrotizing otitis media
Cholesteatoma
Mumps
Mononucleosis
Lyme disease
Viral syndromes
TuberculosisVascular Benign intracranial hypertension
Intratemporal aneurysmToxic Thalidomide
Tetanus
Carbon monoxideNeoplastic Acoustic neuroma
Glomus tumors
Facial nerve neuroma
Metastatic disease
Fibrous dysplasiaIatrogenic Surgical
Embolization
Anesthesia nerve blocksIdiopathic Melkersson-Rosenthal syndrome
Autoimmune syndrome
Multiple sclerosis
Myasthenia gravis
Sarcoidosis
Amyloidosis
Wegener granulomatosis
Kawasaki disease
Workup
Laboratory Studies
- For endemic areas, Lyme titers may be appropriate in patients presenting for the first time.
- For recurrent episodes of IFP, further workup should include diagnostic evaluation based on the differential diagnosis.
- Antineutrophil cytoplasmic antibody (cANCA) levels are indicated if applicable to exclude Wegener granulomatosis.
Imaging Studies
- MRI with gadolinium enhancement is indicated at initial examination when the history and physical examination findings are consistent with the diagnosis of acute IFP.
- MRI with gadolinium may demonstrate enhancement of the nerve within the facial canal at the labyrinthine and geniculate segments or the internal auditory canal.
- Little correlation between the enhancement of the facial nerve and the clinical outcome has been noted. However, a recent analysis of early MRIs with gadolinium of the intratemporal facial nerve demonstrated the ability to predict the long-term outcome of the facial paralysis; these findings (increased signal intensity in the internal auditory canal after administration of gadolinium) correlated favorably with those of electrodiagnostic testing.
- Thus, MRI is useful as a means of excluding other pathologies as the cause of paralysis.
- Radiological evaluation by CT scanning and other methods is indicated if other associated physical findings indicate or if the paresis is progressive and unremitting. CT scanning demonstrates the architecture of the temporal bone and may be used if some other pathology is suspected.
Other Tests
- Audiometry
- All patients should undergo audiography and early latency auditory evoked potentials (AEP).
- Typically, the hearing threshold is not affected by IFP.
- Impedance testing may reveal an absent or diminished stapedial reflex because of paresis of the stapedial branch of the facial nerve.
- Electrodiagnostic testing
- This may be an important adjunct in determining the prognosis of IFP.
- It is reserved for patients with complete paralysis or for those demonstrating progression from partial to complete paralysis.
- Electroneuronography
- This is a physiological test that uses electromyography to objectively measure the difference between potentials generated by the facial musculature on both sides of the face in response to a supramaximal electrical stimulation of the facial nerve.
- Because all electrodiagnostic testing is performed on the nerve distal to the proposed site of injury, sufficient time is needed for Wallerian degeneration to occur, usually 48-72 hours. Testing should begin 3 days from the onset of complete paralysis.
- Electrodiagnostic testing measures the facial nerve degeneration indirectly. If a patient does not reach 90% degeneration within the first 3 weeks of onset of paralysis, some studies suggest the prognosis is excellent, with over 80-100% of the patients recovering with excellent function. The patients who reach over 90% degeneration within the first 3 weeks of onset of paralysis have a much more guarded prognosis, with only 50% having good recovery of facial motion.
- The rate of degeneration also predicts the prognosis. Those who have 90% degeneration by 5 days have a worse prognosis than those with 90% degeneration at 14 days.
- Electromyography
- This is an electrodiagnostic test that measures electrical activity of the striated muscle via electrode placement within the muscle, and findings reflect the health of the facial nerve.
- Early voluntary contraction within 2 weeks of paralysis indicates a good prognosis. Short waves signify denervation.
- Blepharokymographic analysis
- Blepharokymographic analysis, a high-speed eyelid motion-analysis system, has been recently used to evaluate movement of the eyelids. Computerized based analysis may prove helpful in diagnosing Bell palsy, predicting prognosis, and evaluating response to therapeutic measures such as a gold weight placement.
More on Bell Palsy |
| Overview: Bell Palsy |
 Differential Diagnoses & Workup: Bell Palsy |
| Treatment & Medication: Bell Palsy |
| Follow-up: Bell Palsy |
| Multimedia: Bell Palsy |
| References |
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References
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Further Reading
Keywords
Bell palsy, Bell's palsy, BP, acute facial paralysis, idiopathic facial paralysis, IFP, facial palsy, lower motor neuron facial paresis, lower motor neuron facial paralysis, cranial nerve VII, CN VII
