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Neurology

Alternobaric Facial Paresis

Alternobaric facial paresis (AFP), also known as facial baroparesis, baroparesis facialis, or alternobaric facial nerve palsy, is a rare and usually transient neurapraxia affecting the seventh cranial nerve (CNVII, the facial nerve) due to pressure-related effects in the tympanic cavity. This condition arises when pressure in the middle ear compresses the facial nerve against the cochlear promontory, in the medial wall of the tympanic cavity, resulting in symptoms resembling Bell's palsy. AFP is

v1 · Reviewed Nov 7, 2026 by Automated Clinical Reviewer (Strict Verbatim v1)
  • Sparing of the forehead should suggest a central rather than peripheral cause, like stroke, and is inconsistent with AFP.
  • Misdiagnosis as neurologic decompression sickness or air embolism results in unnecessary recompression treatment and restriction of diving activities.
  • Until the AFP is resolved, the most significant risk is corneal damage due to keratitis from an inability to blink fully.
  • The diagnosis of AFP is based on history and findings consistent with peripheral facial nerve palsy in the setting of appropriate exposure to situations that can impede pressure equilibrium in the middle ear (usually diving or flying).
  • Examination shows unilateral lower motor neuron facial paralysis, sometimes accompanied by altered taste sensation.
  • Recall that peripheral facial nerve palsy should affect the entire ipsilateral side of the face with no "central sparing" of the forehead muscles.
  • MRI can be used to image the inner ear and to exclude stroke or underlying mass lesion.
  • High-resolution CT scanning of the temporal bone has poor (66%) sensitivity for finding the facial canal defect, which predisposes to AFP.
  • However, high-resolution CT is the study of choice for imaging the course of the nerve within the fallopian canal to the stylomastoid foramen.
  • In AFP, rapid management within 3 hours of symptom onset is essential to avoid permanent injury to the facial nerve.
  • Simple maneuvers should be tried to reduce pressure in the eardrum.
  • Yawning and swallowing may open the Eustachian tube.
  • The Toynbee (nose pinch followed by swallowing) and Valsalva (exhaling against a closed mouth and pinched nose) maneuvers work similarly.
  • Chewing gum or food can likewise open the Eustachian tube.
  • The use of local decongestants has the same goal: to reduce the edema of the Eustachian tube and its meatus in the nasopharynx to allow the air in the tympanic cavity to escape.
  • As a last resort, a simple myringotomy may be used.
  • Another therapeutic measure is to ensure sufficient local oxygenation.
  • Hyperbaric oxygen therapy, generally with a low-pressure setting of about 1.2 ATA (absolute technical atmosphere) with pure oxygen respiration, has been used to treat this type of barotrauma.
  • Recovery under hyperbaric oxygen therapy was observed in less than 2 minutes, and under normobaric oxygen therapy at high flow within 15 minutes.
  • Oral decongestants may be efficacious as well.
  • For example, a study of pseudoephedrine for middle ear discomfort during flight showed a statistically significant decrease in symptoms from 62% to 32%.
  • In the setting of recurrent AFP episodes related to flying, venting myringotomy tubes can prevent the pressure differential causing the problem.
  • However, this would present a contraindication for diving.
  • Until the AFP is resolved, the most significant risk is corneal damage due to keratitis from an inability to blink fully.
  • This can be alleviated with eye lubricant and eye patching.
  • Permanent facial nerve damage results if treatment is not initiated promptly.
  • AFP can be a recurrent issue for divers and flyers alike.
  • Misdiagnosis of central facial palsy (forehead sparing is the hallmark of this) as AFP could delay the diagnosis of stroke or another intracranial issue.
  • If AFP is mistaken in a diver as an air embolism, this will lead to unnecessary recompression treatment, restricted diving, and additional testing and treatment.
  • All patients with a history of AFP should be counseled to avoid air travel if they have an upper respiratory tract infection.
  • They should be warned about the risk of permanent facial nerve injury should prolonged ischemia occur in a future episode of AFP.
  • review
    Alternobaric Facial Paresis. StatPearls [Internet] — Jeffrey S. Cooper, Stephen Hendriksen, Eric J. Hexdall — StatPearls Publishing, 2024

Decision support only. Verify against local protocols and current labeling. Source: www.ncbi.nlm.nih.gov