Dizziness is a general term that includes four syndromes: A) vertigo—the illusion of motion, B) pre-syncope—the feeling that one is about to faint, C) disequilibrium—the feeling of unsteady gait, and D) light-headedness—the feeling of a vague imbalance inside one’s head.  To follow are pertinent examples from each of these four syndromes.

      A. Vertigo is the false sensation of motion when nothing is actually moving.  One may feel that the room is spinning or that one is tumbling.  Moreover, one or both ears may feel plugged, have diminished hearing, or emit a ringing sound.  The four commonest causes of such illusion of motion are:
1. Vestibular Neuritis—inflammation of the balance nerve of the inner ear—is usually caused by viral infections or migraines.  The episodes come on suddenly, last several days, and then slowly resolve without treatment.  When such episodes prove recurrent, the usual cause is a dormant herpes virus that reactivates periodically, causing the same syndrome to recur.  Treatment with anti-viral medicines may shorten the course if given early, and anti-viral medicines when taken daily may prevent or lighten the vertigo attacks. 
2.  Meniere’s Disease—high ear canal fluid pressure—is caused by build up of fluid in the balance canals of the inner ear.  Menire’s recurrent and prolonged episodes of vertigo may result in diminished hearing and ear ringing.  The vertigo responds to diuretics, which reduce the fluid overload and decrease the ear canal pressure.
3.  Benign Positional Vertigo—sudden, brief attacks of vertigo provoked by head turning even when the patient is in bed—is caused by floating crystals inside the balance canals of the inner ear and is the commonest cause of episodic vertigo.  Regardless of posture, when the head is moved from one position to another, the floating crystals tumble in the ear canal fluid, agitate the balance nerve, and cause brief vertigo spells.  The vertigo resolves in less than a minute but leaves the head feeling slightly fuzzy for a while.  The treatment is to maneuver the floating crystals out of the inner ear canals and down into the ear canal sinks.  This Epley maneuver can be done in the office setting and can provide dramatic relief.  Otherwise, the condition may last several months before it spontaneously resolves.
4.  Hyperlipidemic,Transient Ischemic Inner Ear Attacks—sudden, prolonged spells of vertigo caused by a sudden drop in inner ear blood supply—is seen in older persons who have high cholesterol.  Once the cholesterol is lowered, the vertigo resolves.  Other factors such as high blood pressure, diabetes, and smoking may amplify the bad effects of high cholesterol on the inner ear circulation.

      B.  Pre-Syncope—faint-headedness as if one is about to collapse and lose consciousness—is caused by insufficient blood supply to the brain, which in turn causes the person to sweat, become nauseous, and turn pale.  The two commonest causes of such pre-faints are:
1.  Postural Hypotension—the dropping of one’s blood pressure upon rising from a sitting or lying-down position—is usually caused by overactive blood pressure medications or by dehydration from any cause such as diarrhea, sweating, and prolonged exercise.  It usually resolves momentarily as one begins to move and can be avoided by getting up slowly while holding the arms above one’s head for a few seconds.
2.  Cardiac Arrhythmias—abnormal heartbeats that reduce brain blood supply—cause a faint feeling that may be followed by syncope.  It is not position dependant and is always serious.  When an older person feels suddenly faint or faints for no reason, a cardiologist should be consulted.

      C.  Ataxia—a disequilibrium that results in gait unsteadiness—is caused by diseases of the brain balance centers or of the peripheral nerves.  The diseases are numerous but can be diagnosed with a careful neurological examination and some special tests.  Common causes are brain tumors, brain and nerve degenerations, strokes, high brain water, and pernicious anemia, which is a vitamin B12 deficiency. 

      D.  Light-headedness—a vague feeling of dizziness or imbalance inside the head—is usually pervasive, chronic, tends to fade in and out without reason, and is not influenced by head position, body posture, or blood pressure.  Gait is unaffected, function is preserved, the physical and neurological examinations are intact, and all tests and investigations are normal.  The commonest causes of this syndrome are anxiety disorders, with or without panic.  Once the anxiety is treated, the dizziness disappears.  Heightened brain sensitivity, increased brain alarm, excessive brain adrenaline, and unconscious hyperventilation are the suspected causes.  This dizziness can be reproduced or magnified with forced hyperventilation in the office setting.  The condition is very common and is often misdiagnosed and mistreated.