How is facial nerve palsy with abnormal stapedial reflex managed?

Management of Facial Nerve Palsy with Abnormal Stapedial Reflex

In facial nerve palsy with abnormal stapedial reflex (ipsilateral present, contralateral absent), electrodiagnostic testing should be offered to determine prognosis and guide treatment decisions, followed by appropriate medical therapy including corticosteroids.

Diagnostic Evaluation

Initial Assessment

• Facial nerve palsy should be classified as complete (paralysis) or incomplete (paresis), as patients with complete paralysis have a higher risk of incomplete recovery compared to those with mere paresis 1
• Thorough cranial nerve examination should be performed to assess the extent of facial weakness using the House-Brackmann facial nerve grading scale 1
• Stapedial reflex testing provides important prognostic information, with presence of the reflex correlating with better outcomes 2, 3

Electrodiagnostic Testing

• For patients with complete facial paralysis, electrodiagnostic testing should be offered to quantify the extent of nerve damage and provide prognostic information 1
• Testing should be performed approximately 7 days after symptom onset, as results become stable and informative at this point 1
• Testing before 7 days may be misleading due to ongoing Wallerian degeneration, while testing beyond 14-21 days may be less reliable 1

Types of Electrodiagnostic Tests

• Electroneuronography (ENoG): Surface electrodes record electrical depolarization of facial muscles following electrical stimulation of the facial nerve 1

  • If response amplitude on the affected side exceeds 10% of the contralateral side, most patients recover normal or near-normal facial movement 1
  • If amplitude is less than 10% of the normal side, there is a higher risk of incomplete recovery 1

• Electromyography (EMG): Needle electrodes are inserted into facial muscles to record spontaneous depolarizations and responses to voluntary muscle contraction 1

  • Provides complementary information to ENoG, especially in patients with complete paralysis and ENoG showing less than 10% function 1

Imaging Studies

• MRI of the head, orbit, face, and neck with and without contrast is the preferred imaging modality for facial nerve palsy 1
• High-resolution CT of the temporal bone provides complementary information by characterizing the osseous integrity of the temporal bone 1
• Imaging is generally not necessary for typical Bell's palsy unless symptoms are atypical, recurrent, or persist for 2-4 months 1

Treatment Approach

Medical Management

• Corticosteroids: First-line treatment for Bell's palsy, which increases recovery rates from approximately 70% without treatment to 94% with steroids 1
• Local steroid injection: Consider local injection of steroids in the region of the stylomastoid foramen for cases with intratemporal branch injury (indicated by absent stapedial reflex) 4
• Eye protection: In cases of facial nerve palsy, corneal protection should be prioritized to avoid exposure keratitis or corneal abrasion 1

Monitoring and Follow-up

• Monitor stapedial reflex recovery, as return of a positive stapedial reflex is often the first sign of recovery, preceding other evidence of recovery by approximately 6 weeks 2
• The stapedial reflex test at 500 Hz for contralateral stimulation is particularly useful for evaluating the degree of facial paralysis and predicting prognosis 3
• Cases with positive reflex within 2 weeks typically show complete recovery within 12 weeks, while cases with positive reflex within 4 weeks show recovery within 24 weeks 3

Prognostic Considerations

• The presence of stapedial reflex is a strong positive prognostic indicator 2, 5
• Patients with present stapedial reflex have a full recovery rate of approximately 92%, compared to 73% in those with absent stapedial reflex 2
• The stapedial reflex test is more useful than electrogustometry for evaluating prognosis in patients with facial nerve palsy 5

Special Considerations

• Bilateral Bell's palsy is rare and may indicate an underlying systemic condition rather than idiopathic Bell's palsy 1
• Other conditions that may cause facial paralysis include stroke, brain tumors, parotid gland tumors, cancer involving the facial nerve, and systemic/infectious diseases such as herpes zoster, sarcoidosis, and Lyme disease 1
• The facial nerve carries impulses not only to facial muscles but also to lacrimal glands, salivary glands, stapedius muscle, taste fibers from the anterior tongue, and sensory fibers from the tympanic membrane and ear canal 1