Probably the commonest syndrome associated with diving occurs during descent, when problems related to middle ear equilibration are noticed. The middle ear is an air-filled bony cavity communicating with the external environment via the eustachian tube. It is via the eustachian tube that air enters and exits the middle ear to maintain an equal pressure as ambient pressure changes. As the diver descends, increasing pressure is exerted against the tympanic membrane; this is countered as the diver voluntarily forces air through the eustachian tube into the middle ear resulting in equalization of pressures. Failure to achieve equilibration results in a “squeeze” manifest as pain in the affected ear; this is usually reversible by a small ascent and additional efforts to reequilibrate. If descent is uncontrolled and equilibration does not occur, pressure differences result in closure or collapse of the proximal eustachian, subsequent to which air flow through the eustachian tube ceases. Rupture of the tympanic membrane occurs with further descent, allowing water into the middle ear, which typically produces nausea and vertigo; this occurs in relatively shallow depths (5-15 ft) if equilibration has not occurred. Diagnosis is based on history (failure of the diver to notice “clicks” or “pops” associated with equilibration during descent, sharp pain in the ear, or a sound reported with tympanic membrane rupture, followed by
vertigo) and physical examination (the tympanic membrane may demonstrate capillary engorgement, edema, or hemorrhage, or rupture may be noted). In some patients, signs of a seventh nerve palsy are noted; this is usually self-limited. Treatment includes avoidance of diving for several weeks until complete healing of the tympanic membrane occurs, oral and topical (spray) decongestants, and exercises to force fluid from the middle ear through the eustachian tube (Frenzel maneuvers); this is performed by repeated swallowing with a closed glottis, pursed lips, and pinched nose. Oral antibiotics should be prescribed if tympanic membrane rupture has occurred, and oral steroids may hasten improvement in seventh nerve palsy. Prevention includes avoidance of diving when upper airway congestion is present and recognizing early in descent that signs of middle ear equilibration are failing to occur; the prophylactic use of pseudoephedrine, typically 60 mg taken 30 minutes to 1 hour before diving, is sometimes recommended, although controversial.

Barotrauma may also involve the external auditory canal (external ear squeeze) and the inner ear; these injuries are far less common than middle ear barotrauma. External ear squeeze occurs during descent when the external ear canal is occluded, thereby preventing equilibration of pressure during descent. Obstruction can occur if obstructing cerumen or earplugs are present. Pain is noted, often with blood reported in the canal. On examination, the canal is typically hemorrhagic; tympanic membrane rupture may also be noted. Inner ear barotrauma results when significant differences in pressure between the middle and inner ear develop suddenly (with very rapid or uncontrolled descents); patients report severe nausea, diaphoresis, lightheadedness, confusion, and disorientation. The “classic” symptoms of inner ear barotrauma are tinnitus, vertigo, and hearing loss. Symptoms may be delayed. Treatment includes bed rest with the head elevated, avoidance of diving until full resolution occurs, and otherwise supportive measures.