Dizziness, lightheadedness, or giddiness can result from many different diseases and is not limited to problems in the inner ears. In general, these symptoms can be broken into two broad categories: presyncopal lightheadedness, and vestibular dizziness.
Syncope is the medical term for a faint. When you feel as if you are passing out or about to faint, you are experiencing presyncopal lightheadedness. During fainting loss of consciousness occurs, and you will usually slump or fall to the floor. Just prior to fainting there is a sensation that vision is dimming, the world is fading far away, and thoughts are hard to keep focused. There may be a rushing or ringing sound in the ears and a feeling of weakness or nausea. A faint typically occurs when the blood flow to the head is abruptly reduced, either because the blood pressure or volume is too low, or the heart rhythm is disturbed. There are many different disorders that can cause faints or lightheadedness. For example, dehydration, medications, and palpitations can all result in a faint.
The vestibular system combines the inner ear and brain balance pathways, so vestibular dizziness can be due to either of these. It is typically a sensation of movement inside the head. If you experience an inner feeling of motion when no movement of your head has occurred, then you are having an episode of vestibular dizziness. The sensation is often a spinning feeling, but it can also be a tilting, rocking, falling or accelerating sensation. Often people report a fear of fainting during the spells, but it is rare to actually become unconscious during a vertigo spell due to inner ear disease. While having a spell of vestibular dizziness you may see the environment appear to tilt or to whirl, but you will not usually experience a graying-out or dimming of vision as occurs during fainting. Vestibular dizziness accompanies many different diseases of the inner ear and brain balance system.
The classic sensation caused by inner ear disease is vertigo. Sensations of spinning can be brought on by diseases of the inner ear or the brain. When the feeling of spinning is slow, you may be able to keep your eyes focused so the room does not appear to move. If the spinning is fast, it is common to see the world appear to turn about you. The world can spin in a horizontal or vertical plane (like being on a merry-go-round or doing flips) or can spin around in front of you, like the drum of a clothes dryer. The speed of the spinning sensation is often affected by vision. If the sensation is strongest with the eyes open, it can often be slowed by focusing your eyes at one point in the room. In other cases, it may be more comfortable to keep your eyes closed. Reading or looking in certain directions can increase the speed of the spinning sensation.
Vertigo that is brought on by a specific movement, or that is associated with hearing loss or ringing in one ear, is usually due to inner ear disease. Vertigo that occurs without warning and that is not associated with other ear symptoms can be due to either brain or inner ear disorders. Specialized testing and the presence of other symptoms can help differentiate these.
In my next post, I’ll discuss other sensations of dizziness that indicate vestibular disease.