If you have a persistent feeling of tilting, swaying, whirling or spinning motion of oneself or of the surrounding world when nothing is moving, you are experiencing vertigo.
In other words, it’s not a nice feeling whether it happens under the water or on the surface. But why does it happen and is there anything we can do to avoid it, and importantly, what are some strategies for handling it if it occurs underwater?
Vertigo that occurs during or after diving is a common symptom of middle-ear or inner-ear injury. It is often associated with nausea and in severe cases vomiting.
If vertigo happens underwater, the diver may not be able to tell which way is up; panic and vomiting may cause choking and drowning. On land, the patient may not be able to sit or stand.
There are various causes of vertigo. In diving, it is most often caused by inner-ear barotrauma. (A ‘barotrauma’ refers to injuries caused by increased air or water pressure (‘baro’), such as during airplane flights or scuba diving, when the pressure on one side of a membrane is not balanced by an equal pressure on the other leading to a ‘trauma’.)
It can also occur from stimulation of one side and not the other, such as when the pressure difference in only one ear equalises (alternobaric vertigo) or when cold water enters one ear but not the other (caloric vertigo). This type of vertigo disappears as the condition equalises and leaves no lasting effects except that the associated disorientation, nausea and vomiting while underwater may contribute to diving accidents.
If you experience vertigo underwater, stop ascending or descending and try to hold onto something solid if possible. It will usually pass once the pressures in the middle ears equalise (alternobaric), or the colder water in the affected ear warms. Gentle equalisation can sometimes be helpful but forceful equalisation must be avoided in order to avoid or minimise damage to the ears.
If vertigo persists after the dive, you should avoid straining (including valsava) and consult a diving doctor soon as possible. The worst-case scenario is damage to the inner ear which needs to be addressed promptly and appropriately.
Damage to vestibular organs by DCS, barotrauma or acoustic shock may be permanent. (The vestibular organs provide the brain with all the sensory information about motion, equilibrium, and spatial orientation – in a sense they are our internal gyroscope which tells us which way is up, and whether and in what direction we’re moving). In case of single-ear injury, vertigo may go away in two to six weeks, because the brain learns to compensate and ignores the side that is damaged, but the canal will not heal. The diver will have difficulties maintaining balance in the dark when deprived of visual clues. Damage to both vestibular organs is debilitating and may make certain life activities (such as driving a car) challenging or impossible.
Return to diving after inner-ear barotrauma or DCS should be evaluated on an individual basis depending on the extent of permanent injury of inner-ear organs.