What is the evidence of electrooculography (EOG) in the setting of facial paralysis after temporal bone trauma?

From the Guidelines

In cases of facial paralysis following temporal bone trauma, electrooculography (EOG) is not a recommended diagnostic tool, instead, electroneuronography (ENoG) should be performed within 3-14 days after injury to assess the integrity of the facial nerve. ENoG measures the compound muscle action potential of facial muscles in response to electrical stimulation, comparing the affected side to the normal side. A finding of greater than 90% degeneration on ENoG is a strong indication for surgical exploration and facial nerve decompression 1. The test works by stimulating the facial nerve at the stylomastoid foramen and recording the evoked muscle response, with results expressed as a percentage of function compared to the uninjured side. ENoG is particularly useful because it can predict prognosis and guide treatment decisions before clinical signs of recovery or degeneration become apparent. However, timing is critical - testing too early (before 72 hours) may miss degeneration that hasn't yet occurred, while testing too late may miss the window for surgical intervention. ENoG should be used alongside other assessments including clinical examination, House-Brackmann grading, and imaging studies (CT or MRI) to fully evaluate facial nerve status after temporal bone trauma.

The provided evidence does not support the use of EOG in the setting of facial paralysis after temporal bone trauma. The studies provided focus on Bell's palsy, which is a different condition, and do not mention EOG as a diagnostic tool 1. Therefore, the recommendation is based on the available knowledge of electroneuronography (ENoG) and its application in similar cases.

Key points to consider:

• ENoG is a valuable diagnostic tool for assessing facial nerve integrity after temporal bone trauma
• ENoG should be performed within 3-14 days after injury
• A finding of greater than 90% degeneration on ENoG is a strong indication for surgical exploration and facial nerve decompression
• ENoG should be used alongside other assessments, including clinical examination, House-Brackmann grading, and imaging studies (CT or MRI) to fully evaluate facial nerve status after temporal bone trauma.

From the Research

Electrooculography (EOG) in Facial Paralysis after Temporal Bone Trauma

There is limited direct evidence on the use of electrooculography (EOG) in the setting of facial paralysis after temporal bone trauma. However, the provided studies discuss the management and prognosis of facial paralysis in this context, with some mentioning electrophysiological testing.

Management and Prognosis

• The management of facial nerve trauma is based on the location and extent of the injury, with extratemporal trauma and transected nerve typically treated with surgical exploration and tension-free coaptation ideally within 72 hours 2.
• Surgical decompression compared to medical management is debated in the literature without consensus, and more large studies are needed 2.
• Electrophysiological testing, such as electroneuromyography, seems to be an accurate exploration for guiding treatment and can help determine the need for surgical intervention 3, 4.
• Good results (grades I to II on the House and Brackmann scale) were obtained in 63% of cases after medical management and in 39% of cases after surgical treatment 3.

Role of Electrophysiological Testing

• Electrophysiological testing, including evoked EMG, can help guide treatment decisions and predict outcomes 3.
• Serial electroneurography and electromyography can demonstrate the extent of nerve degeneration and inform the decision to perform surgery 4.
• While EOG is not specifically mentioned in the provided studies, electrophysiological testing in general plays a crucial role in the management of facial paralysis after temporal bone trauma.

Surgical Intervention

• The ideal timing for surgical intervention is at least within 1 month of injury, and the choice of surgical approach depends on the site of facial nerve injury 5.
• Late decompression may still have beneficial effects in patients who could not be operated on early, with some studies showing improved outcomes with delayed surgery 4.