CALORIC VERTIGO
This is a transient form of vertigo that is experienced mostly due to the unequal vestibular stimulation by cold water. On immersion, cold water usually enters both ears symmetrically. However, if cold water enters only one ear canal or if one eardrum is perforated causing more direct stimulation of that ear, it can bring about vertigo. One-sided ear canal obstructions can be caused by one of the following: poor-fitting asymmetric hoods, a lump of ear wax, swimmer’s ear, bony outgrowths in the ear canal, or even foreign bodies, such as ear plugs or an air bubble.
The perforation of the eardrum is a brief but dramatic cause of significant vertigo. Following a “pop” or a sharp, stabbing pain in the ear, cold water rushes into the ear and is immediately followed by vertigo. As soon as the water warms to body temperature, the stimulus is removed and the giddiness subsides. In the diving environment, the three major predisposing factors that cause tympanic membrane perforation that lead to vertigo are middle-ear barotrauma of descent, forceful auto-inflation of the middle ear and shock waves (such as falling onto the ear when entering the water from a boat or with the discharge of explosives in the water).