Imaging of Alternobaric Facial Palsy: An Etiologic Hypothesis.

Objective: To report a case of alternobaric facial palsy (AFP) with a hyperpneumatized temporal bone and to review the relevant literature in order to propose a new facet of AFP pathogenesis.

Methods: A patient with a hyperpneumatized temporal bone was found to have recurrent episodes of facial palsy associated with air travel. Systematic review of PubMed, Cochrane Library, and Embase characterized all articles related to transient facial palsy associated with altitude changes or diving with a focus on demographics and imaging findings.

Results: A 25 year-old male was referred for recurrent facial palsy associated with commercial air travel. Imaging demonstrated a hyperpneumatized and well-aerated temporal bone. Total air cell volume was calculated to be 8.59 cc on the affected side. A systematic review of the literature identified 49 cases of AFP. Mean age was 34 years old and 80% were male. Twelve cases had imaging of the temporal bone for evaluation, of which 85% demonstrated at least 1 area of hyperpneumatization. Hyperpneumatization was most frequently encountered in the mastoid, zygomatic root, and inferior petrous apex.

Conclusion: Hyperpneumatization of the temporal bone is critical to AFP etiology as it predicts higher middle ear pressure, if atmospheric pressure changes cannot be equilibrated, via reduced efficacy of normal tympanic membrane pressure buffering. This hypothesis helps to better account for the rarity of the condition and male preponderance.