Timothy C. Hain, MD, Chicago IL. Page last modified: April 13, 2014
Dizziness is a "sorting problem" for doctors, as it is a subjective symptom that can be caused or associated with many disorders.
General categories include:
Dizziness lacks diagnostic tests for many of these entities, and for this reason, many of which are assigned based on the consensus of a committee, rather than (for example), a blood test or X-ray finding.
Usually the situation is that a group of people meet periodically, and publish lists of symptoms, and suggest that individuals that endorse these particular symptoms, have a "disease". Nearly always, one can recognize these disorders, because the publication that describes the criteria, says that everything else must be excluded first. We call this a "wastebasket" diagnosis. It is not uncommon for several committees to "claim" the same symptom collection -- causing overlap and contention for a collection of symptoms.
The psychiatric community is of course very tolerant to committee diagnoses, and in fact, their entire field is built on recognition of collections of symptoms. The psychiatric "committee" is called the "DSM" -- diagnostic statistical manual. Thus, one major group of "committee" diagnoses are psychiatric disorders of nearly any type. A new psychiatric committee diagnosis relevant to dizziness is "Chronic Subjective Dizziness", or CSD. Somatization disorder is another broadly drawn psychiatric condition, defined by a committee.
The Neurological community's "big" committee diagnosis is Migraine. The migraine committee is called the IHS - -or international headache society. About 15% of the population has "migraine", and the description of headache symptoms now extends to 160 pages, and about 130 symptom patterns. The IHS meets frequently. Unsurprisingly, attempts to find the "migraine gene" always succeed, but nearly always find different genes (: In other words, Migraine seems to be a collection of many illnesses, with similar symptoms. Recently, another committee has been mobilized to assist the IHS with dizzines - -the Barany society has developed committees of it's own, that work with the IHS. Migraine has been growing more popular in recent years, and has taken over some of the territory of Sinus headache (Eros et al, 2007).
The inner ear doctors - -the otolaryngologists, or otologists, are evidently not as interested in purely subjective illnesses, and also have far less committee illnesses relating to dizziness. The American Academy of Otolaryngology (AAO) Meniere's committee met only twice, and has not met at all recently. Their decription document is small (about 5 pages total). Unsurprisingly then, far less people meet the Meniere's criteria than migraine - -roughly 1/2000 of the population rather than roughly 1/6 with migraine.
There are some "orphan" disorders that so far, have no committees to validate their existence. An example of this is "cervical vertigo", which has a good physiological underpinnings, but lacks a committee to define its symptoms.
To summarize -- Dizziness is largely subjective, and many medical committees have attempted to define illnesses that include dizziness. Committee illnesses are intrinsically vulnerable to the "lumping" error - -many distinct entities may be "lumped" into a single pseudo-illness.