Family Practice Issues in Neurology

Fall 1999
Volume 10, Number 2

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Dizziness is a very common complaint and is often difficult to evaluate. By using a systemic history, the dizziness can be classified into vertigo, presyncope, dysequilibrium, or lightheadedness. This classification significantly narrows the differential diagnosis, helps target the affected organ system, and can help define the appropriate specialist referral for persistent cases. In some patients, the etiology cannot be determined, but it is important to rule out significant pathology.

Introduction. Dizziness is one of the most common complaints in ambulatory care, accounting for nearly 8 million outpatient visits annually in the United States.1 It is also often a perplexing problem for physicians in primary care office practice, resulting in frequent referrals to specialists. Because of its complexity, patients with dizziness frequently see numerous physicians before an accurate diagnosis can be made and a treatment plan instituted.

Spatial orientation depends on the proper function and central integration of information from several organ systems. These include the eyes, the vestibular system (vestibular labyrinth, eighth nerve, and vestibular nuclei in the brain stem), central pathways from the vestibular nuclei to the cerebral cortex, cerebellum, and proprioceptive system. Because each system may be affected by many different disease states, the number of diagnostic possibilities in a patient complaining of dizziness is great.

To accurately diagnose a patient with dizziness, the clinician must use a systemic approach, eliminating some diagnoses by a thorough history, a careful neurologic examination, and still others with the use of special diagnostic tests. The first and most important diagnostic step in evaluating a patient with the broad complaint of dizziness is a thorough history. Various sensations may be described by patients as “dizziness.” These include vertigo, presyncope, dysequilibrium, and lightheadedness. By accurately classifying the dizziness into one of these categories, the differential diagnosis can be limited. This classification will be used in this article to summarize the diagnostic features and medical management of common disorders that cause dizziness.

Vertigo. Vertigo is the true sensation of movement, and refers to a spinning or rotating sensation. True vertigo generally reflects disease of the vestibular system. In a study of patients presenting with dizziness to an ambulatory care clinic, 54% complained of vertigo.2 In patients with true vertigo, it is helpful to ask, “What is the nature and length of attacks? Does head motion incite or aggravate the vertigo? Are there associated cochlear symptoms, such as hearing loss, tinnitus, or a sensation of aural fullness? Are these exaggerated when the dizziness is worse? Was there antecedent head injury, pressure change, or symptoms of a viral syndrome?”

Benign Paroxysmal Positional Vertigo (BPPV). The vertigo caused by BPPV, which was first described by Barany in 1921,3 occurs only in certain positions, and the true vertigo lasts only seconds. The spinning typically occurs when the affected ear is in the dependent position, or when the head is turned sharply to the right, the left, or by looking upward. Schuknecht attributed this condition to inorganic deposits on the cupula of the posterior semicircular canal, the sensitivity of their mass to gravitational force being the proposed mechanism of stimulation. He designated the condition cupulolithiasis.4

The diagnosis is confirmed by the Hallpike maneuver during which the head is turned to the involved side and extended over the edge of the table. The observer looks for nystagmus and patient subjectively reports vertigo. The word nystagmus stems from the Greek nystazein, which means to nod, especially in sleep. Clinically, it refers to an involuntary rapid alternating movement of  the eyes. In BPPV, the nystagmus is horizontal, vertical or rotary, delayed in onset, and fatigues when the head position is assumed repeatedly.

During acute events, treatment is primarily symptomatic. Medications are usually ineffective, and the most obvious treatment is to avoid the offending position. In the majority of cases, BPPV is a self- limited disease with resolution of symptoms in 90% of patients receiving no treatment within 3 months. The goal of treatment, however, is to habituate the vestibular system rather than suppress it. Head positioning exercises, patient specific habituation training, and the canolith repositioning maneuver have been shown to be very effective in quickly controlling vertigo in the majority of patients with BPPV.

Vestibular Neuronitis. As the name implies, vestibular neuronitis is caused by an inflammatory reaction of the vestibular division of the eighth cranial nerve. The majority of cases referred to as acute labyrinthitis, inner ear infection, epidemic vertigo and toxic labyrinthitis are examples of vestibular neuronitis. Numerous causes for this inflammatory reaction have been proposed including vascular insufficiency; viral, diabetic neuropathy, toxic and allergic etiologies.

The diagnosis is based on a single, severe, prolonged episode of vertigo of sudden onset, often with vomiting and complete debilitation. Unlike Meniere’s disease, there is usually no involvement of the auditory system. After the acute episode, which usually lasts 3 or 4 days, the patient may experience residual unsteadiness or postural dizziness for a prolonged period, but usually recovers completely within 6 months. Caloric testing during electronystagmography (ENG) demonstrates a unilateral reduced vestibular response. Because of the paretic vestibular nerve, it is important to rule out a vestibular neuroma by brain stem-evoked response audiometry or a magnetic resonance imaging study with gadolinium enhancement.

Since the course is usually one of gradual improvement, treatment is supportive during the acute phase. Bed rest, sedation, and intravenous fluids are supplemented with vestibular suppressing drugs, such as diazepam or dimenhydrinate. Short term use of steroids has also been effective.5 If positional dizziness persists after the acute attack, positional compensating exercises may be helpful to hasten resolution.

Meniere’s Disease. Patients with classic Meniere’s disease complain of intermittent spells of spinning vertigo associated with fluctuating hearing impairment, tinnitus, and a sensation of pressure or fullness in the involved ear. It is a capricious disease with variations in this classic constellation of symptoms being the rule rather than the exception.

The severe vertigo usually lasts for hours, following which the patient may have the auditory symptoms for several days. After the initial attacks, the hearing usually returns to normal, but on subsequent occasions, there is a progressive permanent hearing loss. Occasionally, the patient will present with only the vertigo (vestibular Meniere’s syndrome) or only the auditory symptoms (cochlear Meniere’s syndrome).

Histologically, Meniere’s disease is characterized by distention of the membranous labyrinth (endolymphatic hydrops). The cause for this is unknown despite many decades of study. Theories include electrolyte imbalance, autoimmune disease, allergies, vasomotor reactions, trauma, metabolic disorders, infectious processes (eg, viral, syphilitic), and hereditary factors. While there is no definitive test for this disorder, ENG, electrocochleography (ECOG), dehydration testing, and screening blood profiles can be helpful.

There are a myriad of medications employed in the management of Meniere’s disease, and in vestibular disorders in general. The mainstay of therapy is diuretics, with concurrent restriction of dietary sodium, caffeine, and alcohol. In certain cases, vasodilators, steroids, and other anti-inflammatory drugs may be helpful. Recently, there is some evidence that perfusion of the labyrinth with steroids given transtympanically may be of some benefit. Surgical procedures for patients who fail medical management include endolymphatic sac procedures, use of ototoxic antibiotics, such as gentamycin to ablate the affected vestibular system, labyrinthectomy, and vestibular nerve section.

Other Causes Of Vertigo. Discussion of all causes of vertigo is beyond the scope of this article. However, it should be emphasized that the clinician should not direct attention too strongly to the inner ear, even if the dizziness is vertiginous in nature because other central portions of the vestibular system may produce identical symptoms. Examples of central causes of vertigo include multiple sclerosis, vestibular migraines6, brain stem and cerebellar tumors, impaired circulation to the vestibular nuclei as occurs in atherosclerosis and vertebrobasilar insufficiency, vestibular epilepsy, cervical vertigo, and vascular compression syndromes.

Presyncope. Presyncope can be defined as a sensation of impending loss of consciousness or faintness. This symptom accounted for 16% of patients presenting to an ambulatory care clinic with the complaint of dizziness.2

Orthostatic Hypotension. One common cause of presyncope is orthostatic hypotension. These patients present with symptoms occurring only at the assumption of a more upright posture, that is, lying to sitting, or sitting to standing. Upon standing, documentation of a 10mm Hg drop in systolic blood pressure or any drop in diastolic blood pressure is diagnostic. In a large study of patients presenting to a neurotology practice, 18.67% had abnormal blood pressures (hypotension, hypertension, and orthostatic hypertension).7

Arrhythmias. Cardiac arrhythmias commonly present with symptoms of presyncope. Diagnosis is by electrocardiogram or rhythm monitoring documenting tachycardia (other than sinus), bradycardia (rate <50), or sinus pauses (>3 seconds).

Dysequilibrium. The sensation of dysequilibrium is defined as a sensation of imbalance, often with a feeling of falling, when standing or walking, usually without cephalic sensation. This sensation is usually continuous without an episodic nature. In the ambulatory care setting, dysequilibrium accounted for 2% of patient’s primary complaint of dizziness, but it was a contributing factor in 17% of patients presenting with the complaint of dizziness.2

Vestibular Nerve Injury. The most common cause of dysequilibrium is vestibular nerve injury with a reduced vestibular response to caloric stimulation seen on ENG testing. This may be the end result from vestibular neuronitis, Meniere’s disease, vascular occlusion, peripheral neuropathy, multiple sclerosis, or acoustic tumor.

Other Causes. Other causes for dysequilibrium include noncorrectable visual impairment, metabolic disorders, peripheral neuropathy, cervical spondylosis, orthopedic disorders interfering with ambulation, or gait disturbances related to neurological or musculoskeletal disease (eg, hemiparesis or arthritis). Often, the cause of the dysequilibrium is multifactorial. In these cases, a customized program of vestibular rehabilitation is often extremely effective to force compensation of other organ systems and increase the patient’s independence and safety.

Lightheadedness. One of the most challenging groups of patients is that presenting with non-specific symptoms of lightheadedness. These patients often present a vague history of dizziness, which makes diagnosis difficult. In a large percentage of these patients, psychiatric problems are either the primary cause of the complaint, or a significant contributing factor. In the ambulatory care study, psychiatric factors contributed to the dizziness in at least 40% of patients, and was felt to be the primary cause in 16%.2 Whether primary or contributory, psychiatric disorders should be recognized as potentially treatable comorbid conditions.

Conclusion. In summary, dizziness is often self-limited, but when it does persist, a directed history and physical examination can establish a presumptive cause in most patients.Vestibular function testing, radiographic imaging, and psychiatric evaluation are the most useful supplemental measures. The etiology of dizziness is often multifactorial, and in some patients, no etiology can be identified. It is important in these patients to exclude serious conditions, but fortunately, serious treatable causes of dizziness are rare.
 

Address comments and questions to:

David C. Kelsall, MD
799 East Hampden Avenue, Suite 510
Englewood, CO 80113

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