Vertigo Key Points

• The most common cause of persistent vertigo is a peripheral vestibular disorder (38% to 56%).

• Central vestibular causes of vertigo represent less than 10% of all causes.

• Head movement always worsens the feeling of true vertigo.

• Benign paroxysmal positional vertigo is the most common cause of peripheral vestibular vertigo and is twice as common in women as men.

• Pneumatic otoscopy can cause nystagmus and vertigo in the presence of a perilymph fistula.

• Tinnitus is primarily caused by sensorineural hearing loss but occasionally can be the symptom of a vascular abnormality, hypermetabolic state, medication, or intracranial mass.

The sense of balance or equilibrium occurs when there is normal and harmonious function of several systems and organs in the body. These include the musculoskeletal system, the cardiovascular system, the central nervous system, the eyes, and the ears. Abnormal function of any of these can result in the sensation of dizziness or disequilibrium. The term vertigo is reserved to describe a perceived sensation of motion, usually spinning, of the person relative to the environment, or vice versa. Causes of disequilibrium can be categorized into one of three groups: peripheral (inner ear or labyrinthine), central nervous system (CNS), or systemic (e.g., cardiovascular, metabolic). Although not pathognomonic of a labyrinthine disorder, true vertigo most often indicates aberrant function of the inner ear.

Because patients use "dizzy" to describe many sensations, the actual sensation is best clarified by a detailed history (Box 19-1). The major studies on the causes of persistent dizziness, from Drachman and Hart (1972) to Davis (1994), all describe four diagnostic categories: lightheadedness, presyn-cope, disequilibrium, and vertigo. The investigators all conclude that the most common cause of persistent dizziness is a peripheral vestibular disorder (38%-56% of cases) followed closely by a psychogenic disorder (6%-33%). In about 25% of patients, the complaint is the result of the combined

Box 19-1 History for "Dizziness"

Description of the sensation (including associated symptoms) Onset (acute, gradual)

Duration (date sensation was first noted, length of time it lasts) Intensity (how troubling is it?)

Exacerbations (activities, positions, circumstances that worsen the situation)

Remissions (activities, positions, circumstances that make sensation better)

Medications (prescription, herbal, over the counter)

Other medical problems (e.g., diabetes, hypertension, heart disease)

Psychosocial (any stressors?)

effects of multiple sensory deficits, medications, or orthosta-sis, leading to complaints of presyncope, lightheadedness, or disequilibrium. Finally, central vestibular etiologies are unusual and represent less than 10% of all causes.

A thorough medical history allows the physician to distinguish between true vertigo (a sensation of spinning) and other sensations, such as presyncope, lightheadedness, and unsteadiness. The physical examination and laboratory evaluation are guided by the accuracy of the history. A sensation of vertigo originates from within the vestibular system but can be either peripheral (vestibular nerve and inner ear) or central (cerebellum, brainstem, thalamus, and cortex).

Questions regarding hearing and neurologic deficits can help elicit which part of the vestibular system is involved (Wiet et al., 1999) (see eTable 19-1 online). Peripheral vertigo tends to be episodic, whereas central vertigo is constant. Neurologic symptoms or loss of consciousness do not occur with peripheral vertigo but are possible with central vertigo. Nystagmus, which is labeled by the direction of the fast component, can be present in both types of vertigo and can be horizontal or rotary; vertical nystagmus occurs only in central vertigo.

The physical examination should include assessment of orthostatic blood pressure changes, a complete ocular examination, tuning fork tests (Weber's and Rinne's), pneumatic otoscopy (elicits vertigo in patients with perilymphatic fistula), balance tests (Romberg's), gait (including tandem walking), and cranial nerve evaluation. The Dix-Hallpike maneuver (see eFig. 19-3 online) is especially helpful in diagnosing benign paroxysmal positional vertigo (BPPV). Head movement always worsens the feeling of true vertigo. If it does not, the dizziness can be attributed to a cause other than vestibular dysfunction.

Laboratory testing can include an audiogram if no specific cause of vertigo can be found after the medical history and physical examination. Electronystagmography (ENG) is an objective study of the vestibular system and can help localize a vestibular lesion. Electrodes placed about the eye sense the movements of nystagmus as either spontaneous or initiated by maneuvers such as caloric testing, positioning, opto-kinetics, and pendulum tracing. A brain MRI scan is indicated in patients with unilateral otologic symptoms and in those unresponsive to treatment. Blood tests, when necessary, can include CBC, rapid plasma reagin (RPR), vitamin B12 level, folate level, drug screens, and heavy metal testing when indicated.

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