Facial baroparesis: a review.

If impaired eustachian tube function causes an overpressure to remain in the middle ear after ascent in diving or aviation in a subject with a defect in the wall of the facial canal, an ischemic neurapraxia of the seventh cranial nerve may occur. This type of facial palsy is designated facial baroparesis, baroparesis facialis, or alternobaric facial palsy. If the middle ear pressure is asymmetric the subject may also have alternobaric vertigo. A causative relationship between middle ear overpressure and facial palsy is supported by the palsy's rapid onset following a reduction in ambient pressure and by its quick disappearance after either an increase in ambient pressure or release of the middle ear overpressure. Transient compression-induced ischemic neurapraxia of the facial nerve is also demonstrated in animal experiments. A similar palsy, ischemic neurapraxia of the fifth cranial nerve due to compression in the maxillary sinus, has been reported in divers. Although it is under-reported, facial baroparesis occurs infrequently, with 23 subjects mentioned in the available literature. Nevertheless, it is important to be aware of its existence, because misdiagnosis as type II DCS or air embolism results in unnecessarily long recompression treatments and pointless delay of resumption of diving. In the worst case, a misdiagnosis might cause a diving license to be revoked.