Scope of the problem
Dizziness, a common complaint in patients presenting to the emergency department (ED), is a disorder of spatial orientation. It is the most common complaint in patients over the age of 75 years. Approximately 7% of ED patients present with dizziness, and dizzy patients account for 1.5% of admitted patients.
Evaluating the dizzy patient can be challenging, since it is a nonspecific symptom and is difficult to objectively measure. Although most cases are usually benign, emergency physicians need to be wary about life-threatening causes of dizziness, such as cardiac dysrhythmias and cerebrovascular events. In some cases, however, the patient can be cured at the bedside.
Two studies performed approximately 30 years apart have confirmed that there are four general subtypes of dizziness: vertigo, near-syncope, disequilibrium, and psychophysiologic dizziness. It is important to realize, however, that a person may describe more than one subtype, but rarely will describe elements of all four.
Pertinent anatomy that contributes to dizziness includes the vestibular, visual, proprioceptive, cardiac, and central nervous systems (CNS).
Vertigo is defined as an illusion of motion. The CNS coordinates and integrates sensory input from the visual, vestibular, and proprioceptive systems. Vertigo occurs when there is a mismatch of information from two or more of these systems. Vertigo is divided into central and peripheral causes (Table 18.1). Central vertigo indicates involvement of the cerebellum or the vestibular nuclei within the pons and medulla.