Dizziness

By Richard H. Hurd


I. Background
Dizziness is a rather imprecise term often used by patients to describe any of a number of peculiar subjective symptoms. These symptoms may include faintness, giddiness, light-headedness, or unsteadiness. True vertigo, a sensation of irregular or whirling motion, is also included in a patient's complaint of dizziness. Dizziness represents a disturbance in a patient's subjective sensation of relationship to space (1).

II. Pathophysiology

A. Etiology
The causes of dizziness are numerous. It is helpful for the diagnostician to think in general categories of causes when searching for an etiology (see Table 2.2.1).

B. Epidemiology
Dizziness is the complaint in an estimated 7 million clinic visits in the United States each year (2,3). It is one of the most frequent reasons for referral to neurologists and otolaryngologists. The reasons for frequent referral of this usually benign condition are many. Ruling out potentially serious causes, including those of cardiac and neurologic origin, can be difficult. In addition, the fact that there is no specific treatment for many of the causes of dizziness leads to frustration for both the patient and the physician.

III. Evaluation

A. History
It is extremely important, and can be very difficult, to get the patient to describe exactly what they mean when complaining of dizziness. A description of the attack, context, length, duration, and frequency is important. Any precipitating factors should be explored. Concurrent symptoms such as nausea, headache, chest fluttering, or tinnitus can help to direct the clinician to a cause. Any new or medication changes should be inquired about.

B. Physical examination
The physical examination, although thorough, is often focused on a specific system based on the history. It is seldom diagnostic in itself, but is more often confirmatory.
• Vital signs including orthostatic blood pressures begin the examination.
• A neurologic examination must be completed.
• A cardiovascular examination including the heart for murmur or arrhythmia and carotid arterial auscultation should be completed.
• An otoscopic examination to assess infection and nystagmus examination including gaze, Dix-Hallpike's maneuvers, and head shaking are important.
• An observation of gait to assess cerebellar function is also a part of the examination.

C. Testing
It is obvious that there is no laboratory or imaging study directly related to dizziness. Instead, these types of studies are dictated by the etiology that the clinician feels is most likely. They are more to confirm a diagnosis than to actually make it.
• Tests might include complete blood count, electrolytes, appropriate drug levels, and thyroid levels.
• Imaging studies such as magnetic resonance imaging might be indicated if the concern of tumor is high.
• A hearing test as well as maneuvers carried out in a tilt-chair to test labyrinth function may be of value.

D. Genetics
There does not appear to be any genetic predisposition to dizziness.

IV. Diagnosis
A. Differential diagnosis
• The differential diagnosis of dizziness includes all of those conditions mentioned in the preceding text that cause true dizziness (Table 2.2.1). It also includes many other conditions that cause patients to feel abnormal in some vague way, causing them to complain of dizziness. Psychologic conditions such as anxiety, depression, panic disorder, or somatization may all cause a patient to complain of dizziness. Cardiac arrhythmias, ischemic or valvular heart disease, vasovagal, anemia, or postural hypotension are some of the conditions leading to cerebral hypoperfusion, and therefore, Presyncope.
• Degenerative changes in the elderly may affect the vestibular apparatus, vision, or proprioception, all of which may be interpreted as dizziness. Finally, peripheral neuropathy or cerebellar disease may also be confused with dizziness.

B. Clinical manifestations
The clinical manifestations of dizziness are as varied as those entities included in both the etiologic and the differential diagnosis sections. The fact that dizziness is more often a symptom of some other condition than a separate diagnosis leads to a wide variety of manifestations that the clinician must decipher.


TABLE 2.2.1 Common Causes of Dizziness
Peripheral vestibulara Central vestibularb Psychiatricc Nonvestibular, nonpsychiatricd
Benign positional vertigo Cerebrovascular diseasee Hyperventilation Presyncope
Labrynthitis Tumorsf Disequilibrium
Meniere's disease Cerebellar atrophy Medications
Other Migraine Metabolic disturbances
Multiple sclerosis Infection
Epilepsy Trauma
Unknown causesh
aEncompasses 44% of patients.
bAccounts for 11% of dizziness cases.
cCauses make up 16% of the diagnosis.
dAccounts for 37% of the diagnosis.
eStroke or transient ischemic attack and dehydration comprise the largest part of this group.
fUsually acoustic neuroma.
gIncludes drug-induced, ototoxicity, and nonspecific vestibulopathy.
hA significant part of this subset and a significant part of all cases of dizziness.



References
1.M. Bajorek. Night sweats. In: Taylor R., ed. The 10-minute diagnosis manual. Philadelphia, PA: Lippincott Williams & Wilkins, 2000:31-33.
2.Kroenke K, Hoffman R, Einstadter D. How common are various causes of Dizziness? A critical review. South Med J 2000;93(2):160-168, Table 2, P7.
3.Sloane PD. Dizziness in primary care: results from the National Ambulatory Medical Care Survey. J Fam Pract 1989;29:33-38.


Source : Editors: Paulman, Paul M.; Paulman, Audrey A.; Harrison, Jeffrey D.
Title: Taylor's 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter, 2nd Edition. Copyright ©2007 Lippincott Williams & Wilkins