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.