In some people, the canal of facial nerve misses the bony wall and is separated from the middle-ear cavity by only a thin membrane. If such a person experiences an overpressure in the middle ear equal or greater to the capillary pressure, circulation to the facial nerve stops, the facial nerve loses its functionality and facial muscle is paralyzed (facial baroparesis). This can happen while flying or diving. Fortunately, the pressure in the middle ear returns to normal soon after the exposure, restoring the circulation to the nerve and enabling its functionality. Facial baroparesis tends to recur with flying or repeated diving.
ManifestationsSymptoms include numbness, paresthesia, weakness or even paralysis of the face. Decreased sensation and a facial droop can be seen, generally on one side of the face.
ManagementFacial baroparesis usually is discovered postdive. Even when its duration is brief and it resolves spontaneously, the patient should be evaluated by a physician to exclude other possible causes such as stroke, infection, trauma or decompression sickness.
In rare instances of protracted facial baroparesis, treatment may be necessary. There is experimental evidence that overpressure lasting more than 3.5 hours may cause permanent damage. Divers who continue to experience facial numbness and drooping should see a physician within three hours.