Test battery of cranial nerves VII and VIII for assessing herpes zoster oticus

Objective: This study adopted a test battery of cranial nerves (CNs) VII and VIII comprising a facial nerve function test, audiometry, a caloric test, and ocular and cervical vestibular-evoked myogenic potential (oVEMP and cVEMP, respectively) tests to assess the function of CNs VII and VIII comprehensively so as to predict facial nerve recovery in patients with herpes zoster oticus (HZO).

Study design: Case series with chart review.

Setting: University hospital.

Methods: A total of 20 patients with HZO underwent a test battery of CNs VII and VIII. Registering the unaffected nerve bundles in the internal auditory canal was based on the number of normal results in the test battery of CNs VII and VIII. Fair facial nerve recovery is defined as the improvement of facial paresis to facial nerve grades I to II/VI.

Results: In 20 patients with HZO, 6, 7, 3, and 4 patients had 0, 1, 2, and 3 unaffected nerve bundles, respectively. A significantly positive correlation was identified between the number of unaffected nerve bundles and fair facial nerve recovery. Similarly, a statistically significant predictor of fair facial nerve recovery was noted for unaffected nerve bundles (odds ratio, 15.42) but not for grading of the facial nerve (odds ratio, 0.49).

Conclusion: Grading of the facial nerve alone fails to predict the outcome of facial paresis in patients with HZO mainly because it overlooks the involvement of CN VIII. Alternatively, a combined test battery of CNs VII and VIII may serve as a strong predictor for facial nerve recovery.