Dizziness

Dizziness is a nonspecific term for an unpleasant sensation of imbalance or altered orientation in space. It describes an unpleasant sensation of imbalance or altered orientation in space. Because the word is used by patients for many different experiences, it is a symptom rather than a diagnosis. It can arise from disorders of the inner ear, the brain, the heart and blood vessels, the endocrine and blood systems, medication effects, and psychological factors. It is one of the most frequent complaints in general practice. Primary care physicians care for more than one half of all patients who present with dizziness.

Classification

Clinicians commonly sort dizziness into a small number of types, each with different causes and different approaches to evaluation. Dizziness can be classified into four main types: vertigo, disequilibrium, presyncope, or lightheadedness. A fifth group, dizziness of psychological origin, is sometimes listed separately.

Vertigo

Vertigo is an illusion of movement, most often experienced as spinning. It is usually rotatory, but sensations of body tilt or impulsion may also occur. It is typically accompanied by nystagmus, oscillopsia, postural imbalance, and autonomic symptoms (eg, sweating, pallor, nausea, vomiting). Vertigo points to a problem somewhere in the vestibular system, which is the network that senses head motion and helps maintain balance. Vertigo indicates dysfunction or imbalance within the central or peripheral vestibular pathways.

Disequilibrium

Disequilibrium is unsteadiness that is not experienced as spinning. It is a state of nonvertiginous altered static (eg, standing) or dynamic (eg, walking) postural balance. Sufferers often report that they feel off-balance when walking and may fall. The distinction between sensory and motor causes matters in practice: patients with sensory disequilibrium generally do worse in the dark and frequently have a Romberg sign on examination, whereas motor disequilibrium is generally not exacerbated in the dark or by closing the eyes.

Presyncope

Presyncope is the sensation of impending loss of consciousness without actually fainting. It is commonly associated with generalized weakness, diaphoresis, nausea, and epigastric distress. It is a warning that the brain is receiving insufficient blood flow, so its causes overlap with those of syncope.

Lightheadedness

Lightheadedness is a vague feeling of being faint, floaty or woozy, without true vertigo or imminent fainting. It is the least specific category and often requires the exclusion of the other three types before a cause can be considered.

Time course

Beyond the type of symptom, clinicians also classify episodes by duration and pattern. One widely used scheme distinguishes acute vestibular syndrome, episodic vestibular syndrome, and chronic vestibular syndrome. Examples of acute syndromes include stroke or acute unilateral vestibulopathy, episodic syndromes include benign paroxysmal positional vertigo, Menière's disease, vestibular migraine and vestibular paroxysmia, and chronic syndromes include bilateral vestibulopathy and persistent postural perceptual dizziness.

Causes

Published estimates of cause distribution vary between studies and settings. It has been estimated that approximately 40% of dizziness is caused by a dysfunction of the balance organs of the inner ear. Central causes are less common but more dangerous. Central abnormalities cause approximately 25% of dizziness experienced by patients. Another series reported that approximately 10 percent of patients with dizziness have a central brainstem vestibular lesion; 15% have a psychiatric disorder; and 25 percent have other problems, such as presyncope and disequilibrium.

Peripheral vestibular disorders

Disorders of the inner ear are the largest group. The three most frequent forms of peripheral vestibular disorders are, in order of frequency, benign paroxysmal positional vertigo (BPPV), Menière's disease, and vestibular neuritis.

Benign paroxysmal positional vertigo (BPPV) is caused by displaced calcium carbonate particles in the semicircular canals. It involves dislodgement of otoconia (calcium carbonate crystals) which translocates into one of the semicircular canals, preferentially posterior canal in 60-90% of cases. It is brief and triggered by head position changes, and it can affect people of all ages but is most common in people over the age of 60. Its lifetime prevalence is estimated at 2.4%.
Menière's disease involves episodic attacks. Its crises are spontaneous and recurring vertigo events, usually accompanied by nausea and/or vomiting, with spontaneous nystagmus, hearing loss, fullness of the ear and tinnitus on the affected side.
Vestibular neuritis is an inflammation of the vestibular nerve, often following a viral illness. The vertigo resolves slowly over a few days, but a sensation of disequilibrium may persist for months because of unilateral impairment of vestibular function.
Vestibular migraine produces episodic vertigo together with migraine features. It is generally considered a diagnosis of exclusion.
Persistent postural-perceptual dizziness (PPPD) is a chronic condition in which symptoms of unsteadiness persist for months and are worsened by upright posture and visually busy environments.

Central causes

Central causes arise in the brainstem, cerebellum or related pathways. Common central etiologies include vestibular migraine and vertebrobasilar ischemia. Posterior-circulation stroke is the most important of these, because it can be life-threatening and easily overlooked when symptoms resemble a benign inner-ear problem.

Cardiovascular causes and presyncope

Presyncope is most often linked to blood pressure regulation. Orthostatic hypotension is the most common cause, but arrhythmias, orthostatic intolerance (eg, postural orthostatic tachycardia syndrome) and other conditions may also cause it. Causes include both cardiac (dysrhythmias, aortic stenosis, coronary artery disease) and non-cardiac causes, such as orthostatic hypotension, postural orthostatic tachycardia syndrome, postprandial hypotension, vasovagal episodes, and medications. Cardiac causes such as atrial fibrillation and other cardiovascular disease are particularly important in older patients.

Medications and metabolic causes

Drugs are a frequent and reversible cause. Many medications can cause presyncope, and regimens should be assessed in patients with this type of dizziness. Antihypertensives, sedatives and drugs affecting the central nervous system are common culprits. Metabolic and hematologic conditions such as hypoglycemia, anemia, dehydration and electrolyte disturbances can also produce lightheadedness.

Neurological and other causes of disequilibrium

Disequilibrium may arise from neurological disease. Parkinson disease and diabetic neuropathy should be considered with the diagnosis of disequilibrium. Lesions of the cerebellum and sensory loss from peripheral nerve damage are other important causes. Disequilibrium is also common with aging and can result from weakness or reduced vision.

Psychological causes

Anxiety, panic and hyperventilation are frequent contributors. Some patients with chronic dizziness have a psychiatric disorder, such as anxiety disorders or depression, and these conditions may amplify symptoms from any other cause.

Evaluation

Diagnosis depends mainly on careful history and examination, and laboratory tests are usually of limited value. A careful history that focuses on timing and triggers, in addition to a targeted physical exam, can help distinguish between benign versus more serious causes of dizziness.

History

Key questions concern onset, duration and triggers. Questions should focus on the timing of onset, duration, and evolution of symptoms, and on whether triggers such as movements or positioning provoke dizziness or whether symptoms occur spontaneously. Associated features such as hearing loss, tinnitus, headache, and neurological symptoms are also recorded. A very sudden onset is significant. Hyper-acute onset over a few seconds may suggest an acute cardiovascular cause.

Examination

Examination includes vital signs, otoscopy, cardiovascular and neurological assessment. Special physical examinations such as the Dix-Hallpike maneuver are used for acute episodic triggered vertigo to check for BPPV, the HINTS-plus test for spontaneous episodic vertigo to check for stroke, and the hyperventilation provocation test for patients suspected of anxiety. Eye movement, or nystagmus, is especially informative. Vertical, isolated torsional, or vertical-torsional nystagmus represent red flags for central causes.

Red flags

Red flags indicate a need for urgent investigation, usually for stroke or other central pathology. These include focal neurological deficits, sudden hearing loss, inability to stand or walk, new severe headache, downbeating or central nystagmus patterns, and failure to respond to appropriate vestibular treatments. Mnemonic lists such as the "five Ds" (diplopia, dysarthria, dysphagia, dysphonia, dysmetria) are used to prompt a neurological screen. A diagnosis of stroke should not be assumed solely on the basis of a normal exam, and the head-impulse, nystagmus and skew (HINTS) examination is used by trained clinicians for this purpose.

Laboratory and imaging tests

Routine testing is generally not recommended. Laboratory testing is not routinely recommended among patients with dizziness. Tests are ordered when a specific cause must be identified, guided by the history and examination. Imaging is reserved mainly for patients with red flags.

Diagnostic limits

Despite careful assessment, some patients remain without a clear diagnosis. Although appropriate history and physical examination usually leads to a diagnosis, the final cause of dizziness is not identified in up to one in five patients.

Management

Treatment depends on the underlying cause. Disequilibrium and lightheadedness can be alleviated by treating the underlying cause.

BPPV is typically treated with repositioning manoeuvres. The Epley maneuver is the best-known example. It involves a series of clinician-guided head and body movements to move the otoconia out of the semicircular canal and back into the utricle, with the assistance of gravity. It helps reduce BPPV symptoms in about 8 out of 10 people. A systematic review found scientific evidence showing good efficacy of Epley's maneuver in the treatment. Recurrence is common, and repeat repositioning treatments are often necessary.
Ménière's disease may be treated with intratympanic dexamethasone or gentamicin, along with dietary and diuretic measures used in clinical practice.
Vestibular neuritis is often treated with steroids, and vestibular rehabilitation is used to speed compensation.
Orthostatic presyncope may respond to alpha agonists, mineralocorticoids, or lifestyle changes.
Medication-related dizziness is managed by reviewing and adjusting the drug regimen.
Central causes require treatment of the underlying condition, such as stroke prevention or the management of vertebrobasilar disease.

Some controversy remains about the benefit of specific manoeuvres in particular subgroups. For example, the effects of Epley's manoeuvre in BPPV associated with Ménière's disease have been described as controversial in the literature.

Epidemiology

Dizziness is common across age groups. Dizziness is the chief presenting symptom in about 3 percent of primary care visits for patients 25 years and older. In emergency departments, the picture is different: approximately half of ED patients with dizziness have various medical conditions as its likely cause. Frequency rises with age, and balance disorders in older people are associated with falls and reduced quality of life.

Controversies and limitations

Several issues complicate both research and clinical practice. The term is broad, so studies that use "dizziness" can refer to very different symptoms. Classification schemes overlap, and some patients fit more than one category. Estimates of cause distribution vary by setting and by the diagnostic criteria used. Chronic dizziness is particularly difficult to treat, and psychological and physical contributors often coexist. Clinicians also debate how far vestibular treatments should be used in patients with uncertain or mixed diagnoses.

References

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A Meta-Analysis of the Epley Maneuver’s Effect on Dizziness Handicap Index (DHI) Scores in Patients with Posterior Canal Benign Paroxysmal Positional Vertigo (BPPV)medrxiv.org
Benign Paroxysmal Positional Vertigo (BPPV)hopkinsmedicine.org
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