Applied Evidence

“I feel dizzy, Doctor”

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Diagnosing the underlying cause of this common complaint can be challenging because many conditions present with dizziness. This review—and accompanying algorithm—can guide your evaluation.


 

References

PRACTICE RECOMMENDATIONS

› Refer a patient who reports that his dizziness is accompanied by hearing loss to an otolaryngologist for evaluation. C
› Use the HINTS (Head Impulse, Nystagmus, and Test of Skew) procedure to differentiate central from peripheral vertigo. A
› Use the Dix-Hallpike procedure to diagnose benign paroxysmal positional vertigo. B

Strength of recommendation (SOR)

A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series

With an estimated lifetime prevalence of 17% to 30%,1 dizziness is a relatively common clinical symptom, but the underlying cause can be difficult to diagnose. That’s because patients’ descriptions of dizziness are often imprecise, and this symptom is associated with a wide range of conditions. A careful history and physical examination are key to diagnosis, as is an understanding of the mechanisms of dizziness.

This article covers the range of diagnoses that should be considered when a patient presents with dizziness, and provides insight regarding features of the patient’s history that can better elucidate the specific etiology.

What do patients mean when they say, “I feel dizzy”?

“Dizziness” is a vague term, and patients who report dizziness should be asked to further describe the sensation. Patients may use the word dizziness in an attempt to describe many sensations, including faintness, giddiness, light-headedness, or unsteadiness.2 In 1972, Drachman and Hart proposed a classification system for dizziness that describes 4 categories—presyncope, vertigo, disequilibrium, and atypical (TABLE 1).3 These classifications are still commonly used today, and the discussion that follows describes potential causes of dizziness in each of these 4 categories. A stepwise approach for evaluating a patient who reports dizziness can be found in the ALGORITHM.3-6

Syncopal-related dizziness can have a cardiovascular cause

Presyncope is a feeling of impending loss of consciousness that’s sometimes accompanied by generalized muscle weakness and/or partial vision loss. Taking a careful history regarding the events surrounding the episode should distinguish this type of dizziness, and doing so is essential because most of the underlying pathogenesis involves the cardiovascular system and requires specific interventions.

Dysrhythmias can cause syncope and may or may not be accompanied by a feeling of palpitations. Diagnosis is made by electrocardiogram (EKG) followed by the use of a Holter monitor.

Vasovagal syncope is caused by a sudden slowing of the pulse that’s the result of stimulation of the vagal nerve. It can occur from direct stimulation of the nerve from palpation (or strangulation), or from an intense autonomic discharge, as when people are frightened or confronted with something upsetting (eg, the sight of blood.)

Orthostatic hypotension results from a change in body position in which either autonomic mechanisms cannot maintain venous tone, causing a sudden drop in blood pressure, or in which the heart cannot compensate by speeding up, as when a patient is taking a beta-adrenergic antagonist or has first-degree heart block. It can also result from hypovolemia.

Measuring the patient’s blood pressure in the recumbent, seated, and standing positions can verify the diagnosis if an episode occurred soon before the examination. This kind of dizziness can be treated by instructing the patient to rise slowly, or by making appropriate medication adjustments. If conservative measures fail, medications such as midodrine or droxidopa can be tried.7

Hypoglycemia, hypoxia, or hyperventilation can also precipitate syncopal symptoms. Taking a careful history to assess for the presence of seizure-related features such as tonic/clonic movements or loss of bowel and bladder control can be helpful in distinguishing this form of dizziness.

Vertigo can have a central or peripheral cause

Vertigo is dizziness that is characterized by the sensation of spinning. The presence of vertigo implies disease of the inner ear or central nervous system. The “wiring diagram” of the vestibulo-ocular reflex is fairly straightforward, but sorting out the symptoms that arise from lesions within the system can be a diagnostic challenge. Vertigo has classically been divided into causes that are central (originating in the central nervous system) or peripheral (originating in the peripheral nervous system).

The HINTS (Head Impulse, Nystagmus, and Test of Skew) protocol is a group of 3 tests that can be used to differentiate central from peripheral vertigo (TABLE 2).8,9 To perform the head impulse test, the examiner asks the patient to focus his gaze on a target and then rapidly turns the patient’s head to the side, watching the eyes for any corrective movements.10 When the eyes make a corrective saccade, the test is considered to be positive for a peripheral lesion.

Horizontal nystagmus is assessed by having the patient look in the direction of the fast phase of the nystagmus. If the nystagmus increases in intensity, then the test is considered positive for a peripheral lesion.

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