Chapter 7: Dizziness

Kevin A. Kerber, MD; Jennifer Castillo, MD

I. CASE HISTORIES

Case 7-1. A 65-year-old man presents complaining of dizziness. After looking up or turning over in bed, he experiences a sensation of spinning and nausea lasting less than a minute. Several years ago similar symptoms occurred but eventually resolved. He denies a change in hearing with these episodes or any other neurologic symptoms. His general medical and neurologic examinations are normal.

1. Where do you localize this lesion?
2. What is the diagnosis?
3. What would you do next?
4. Would your diagnosis change if downbeating nystagmus was seen after he was placed in the head-hanging position?

Case 7-2. A 65-year-old man presents with severe vertigo, which began this morning. The symptom became severe over one hour and has caused difficulty walking. His wife drove him to the appointment, and he required wheelchair transport from the car into the office. He is nauseous and has vomited several times. Hearing is unchanged, and he denies other neurologic symptoms. On examination, a spontaneous right-beating nystagmus is present and increases with right gaze, but decreases with left gaze. When trying to walk, he falls to the left side.

1. Where do you localize the lesion?
2. What is the diagnosis?

Case 7-3. A 35-year-old woman presents complaining of frequent dizzy spells. At times she experiences a spinning sensation, but usually lightheadedness is the most prominent symptom. Spells began two years ago and last anywhere from one hour to four days. At times, a tingling sensation of her face may accompany spells, but no other neurologic symptoms occur. She denies loss of hearing but occasionally experiences a high-pitched ringing in either ear. Her symptoms are much worse with movement, and some attacks have been triggered by turning her head quickly. Spells are also more likely to occur when she is under stress or after a poor night of sleep. She has a history of migraine headaches, but these do not generally occur with dizzy spells. Migraine headaches are common in her family, and her mother was also diagnosed with Ménière disease. Her examination is normal, including neurologic examination and positional testing.

1. Where do you localize the lesion?
2. What is the diagnosis?
3. How would you manage this patient?

II. DISORDERS

Dizziness is one of the most common principal complaints in the medical clinic. A very nonspecific term, dizziness generally refers to vertigo, imbalance, lightheadedness, or a presyncopal sensation. Since dizziness has different meanings to different patients, the initial step of the clinician is to define exactly what the patient is experiencing. Because some patients have difficulty with this, asking them to use one of the above descriptive terms may be helpful. The causes of dizziness are just as varied as the term itself. Thus, visual disturbances, inner ear dysfunction, peripheral neuropathy, lesions of central vestibular pathways or the cerebellum, cardiac arrhythmias, low blood pressure, medications, and metabolic disturbances can all cause dizziness. The evaluating physician must consider all these possibilities during the evaluation.

Vertigo refers to a spinning or tilting sensation of the environment and is due to an imbalance within the vestibular pathways, either centrally or peripherally. Normally, afferent vestibular signals are constant and symmetric from each inner ear organ. This results in a constant baseline tone, which keeps the eyes stationary at rest. An acute asymmetry in this tone results in a slow drift of the eyes. When the eyes drift too far off center the brain redirects the eyes back to midline with a quick movement (i.e., a fast phase). The appearance of these alternating slow and fast phases is called nystagmus.

Imbalance is a better label than dizziness when a patient describes feeling unsteady while standing or walking, unrelated to any head sensation. Lightheadedness refers to a "wooziheaded" or "swimyheaded" sensation, whereas presyncope includes the additional symptoms of faintness, tunneling of vision, loss of color (i.e., pallor), and diaphoresis. Hyperventilation syndrome causes perioral and extremity numbness and should be tested for in anyone with vague dizziness.

With knowledge of the clinical presentations of the most common causes of dizziness, usually a specific diagnosis is strongly suggested after a detailed history is taken. As in all neurologic disorders, the examination is used to localize the problem in the nervous system, and the time course is then used to narrow down the possible etiologies. Table 7-1 categorizes etiologies based on localization and time course.

Table 7-1 Common Causes of Dizziness

AICA = anterior inferior cerebellar artery.

III. HISTORY

In addition to determining the key historical information of the symptom, review of systems should address the information contained in Table 7-2. 

Table 7-2 Important Historical Points

IV: EXAMINATION

Previously a source of frustration due to a lack of localizing features, recently described bedside examination tests enhance the ability of the clinician to identify specific disorders causing dizziness.

General Medical
The examination first begins with a general medical examination to ensure that orthostatic drops in blood pressure or heart arrhythmias are not missed. The external auditory canal should also be examined, though a visualized abnormality causing dizziness is very unusual. Fluid build-up or infection of the middle ear generally only causes localized pain and muffled hearing. Erosion into the inner ear structures, rare since the advent of antibiotics, is required for such patients to develop vertigo. Viral inner ear disorders are not usually associated with middle ear findings. The outer ear should be inspected for vesicles, which occur as part of the Ramsey-Hunt syndrome, a disorder caused by the herpes zoster virus.

General Neurologic

A focused neurologic examination is necessary to ensure that obvious focal deficits are not missed. Particular attention should be directed to the evaluation of facial and palatal strength since a close anatomical relationship exists with vestibular structures. Subtle hemiparesis is best evaluated using the test for pronator drift. A normal sensory examination (including pinprick, proprioception, and vibration), along with normal deep tendon reflexes, excludes a peripheral neuropathy (see chapter 10). Coordination should be closely examined to ensure ataxia is not present (see chapter 8).

Nystagmus. Nystagmus consists of alternating slow and fast eye movements, giving the appearance of "beating" of the eyes toward one side. It can be spontaneous (i.e., present in primary gaze), gaze evoked (i.e., only present after looking in one direction), or positional (i.e., present in only certain positions). The examiner should first observe for nystagmus while the patient's eyes are in primary position (i.e., straight ahead) (Video 7-1). If present in this position, the patient is noted to have spontaneous nystagmus and the direction of the fast phase should be recorded. Spontaneous nystagmus caused by an acute vestibular lesion beats to the direction opposite to the affected ear, increases with gaze in the direction of the fast phase of nystagmus, and decreases with gaze in the direction opposite of the fast phase. Next, search for gaze-evoked nystagmus by having the patient look about 30 degrees in each direction (Video 7-2). Normally, the eyes remain stable in each position. A few beats of nystagmus can occur in normal patients with extremes of gaze (i.e., more than 30 degrees) and is referred to as end-gaze nystagmus.

Audio-vestibular. Hearing should be tested at the bedside in patients complaining of dizziness; however, a formal audiogram is generally necessary in any patient with auditory complaints. Using finger rub, whisper, or a tuning fork, the examiner first compares hearing between the two sides (Video 7-3). If an asymmetry is noted, the Weber and Rinne tests can be used to differentiate a sensorineural from a conductive loss.

Gait evaluation. Gait evaluation is important when examining dizzy patients as well (see chapter 8) (Video 7-4, Video 7-5). As mentioned previously, often patients are referring to imbalance when using the term dizziness. Therefore, patients with neurodegenerative disorders such as Parkinson disease or ataxia may present with dizziness. The patient's casual gait should be examined for heel strike, stride length, and base width. Patients should be observed when walking in tandem and standing in the Romberg position as well. A decreased heel strike, stride length, flexed posture, and decreased arm swing, suggests Parkinson disease. A wide-based gait with inability to tandem walk is characteristic of truncal ataxia. 

V. CLUES TO DIAGNOSIS

Patients complaining mainly of light-headedness or presyncope should have their evaluation directed toward identifying causes of decreases in cerebral perfusion. The most common causes are orthostatic hypotension or vasodepressor syncope. Overtreatment with antihypertensive or other medications, particularly among older people, is another common cause. Transient arrhythmias are suspected when symptoms are episodic and without clear triggers.

Light-headedness and paresthesias can be caused by hyperventilation. Patients should be tested with at least two minutes of hyperventilation to see if their symptoms are reproduced by this activity.

Imbalance can be caused by a peripheral neuropathy, so an adequate sensory examination is required to exclude a stocking-glove loss of sensation and absent reflexes. Early neurodegenerative disorders can also present with complaints of imbalance, so the examiner should search for other features of Parkinson disease. Ataxia is associated with abnormal eye movements such as gaze-evoked nystagmus. Unilateral vestibular loss is generally only associated with transient imbalance since compensation occurs generally after several weeks.

If vertigo is the complaint, then patients should be placed in one of three categories:

(1) Prolonged spontaneous attack of vertigo
(2) Recurrent spontaneous attacks of vertigo
(3) Recurrent episodes of positional vertigo

Prolonged spontaneous attacks of vertigo. This refers to a single severe attack of vertigo. The main differential diagnosis is vestibular neuritis versus a brainstem or cerebellar stroke. Patients with vestibular neuritis mainly complain of vertigo, although nausea and imbalance are common accompaniments. Symptoms are usually rather sudden in onset but peak over hours. Spontaneous unilateral nystagmus is seen (i.e., the nystagmus never changes direction). Stroke symptoms are acute in onset and generally peak within seconds. Other symptoms such as slurred speech, double vision, trouble swallowing, numbness and weakness are usually present with lesions of the brainstem. Wallenberg syndrome is a classic stroke disorder caused by infarction of the lateral medulla. Findings include gaze-evoked and spontaneous nystagmus, slurred speech, difficulty swallowing, ipsilateral Horner syndrome, ipsilateral facial numbness, and contralateral body numbness. With cerebellar infarctions, however, dizziness may be the only complaint, so a careful examination searching for central eye movement abnormalities and/or ataxia is required. Nystagmus is direction changing (fast component to right on right gaze and fast component to left on left gaze) and often vertical. Ataxia may be demonstrated on finger-nose-finger or gait testing.

Recurrent spontaneous episodes of vertigo. As the label implies, the key to this category is the occurrence of many episodes over months to years. The most common diagnoses are Ménière syndrome, migraine-associated vertigo, transient ischemic attacks, and posterior fossa malformations. Ménière syndrome causes fluctuating hearing loss and episodes of vertigo lasting longer than 20 minutes. Over time, fixed hearing loss is present on the audiogram. Migraine-associated vertigo is a diagnosis of exclusion since no radiologic or biological marker exists. Migraine headaches usually occur in these patients although most do not have headaches with vertigo attacks. The diagnosis is suggested by ruling out other causes, the presence of typical migraine triggers, and a positive family history. Transient ischemic attacks (TIAs) are characterized by minutes-long duration of vertigo, usually accompanied by other neurologic symptoms. Occasionally, transient ischemia of the cerebellum or brainstem can present with isolated dizziness, but inevitably over time other symptoms develop. Therefore, this is an important diagnosis to make because patients with TIA are at high risk for stroke. Chiari malformation is characterized by downbeating nystagmus.

Recurrent positional vertigo. Benign paroxysmal positional vertigo (BPPV) is the most common cause of positional vertigo. Symptoms are triggered by head movements and last less than one minute. The typical triggers are reaching up for objects (top-shelf vertigo) or rolling over in bed. The diagnosis is made with observing the characteristic nystagmus on hanging-head testing (Dix-Hallpike maneuver, Epley maneuver with the patient sitting on the exam table turn the head to the right 45 degrees, quickly lay the patient back with their head in about 20 degrees extension, ask the patient if they experience vertigo and observe for nystagmus then repeat the maneuver to the left; a positive test consists of a combination of rotary and jerk nystagmus that fatigues with repeated testing). The vertigo tends to fatigue with repeated testing. Other causes of positional vertigo include posterior fossa mass lesions and cerebellar degeneration. Often abnormalities of eye movements or coordination are seen during the general neurologic examination in patients with central positional nystagmus.

VI. RED FLAGS AND WHEN TO REFER

When symptoms are sudden in onset and associated with other neurologic symptoms, patients should be sent directly to the emergency department, where treatment with IV tissue plasminogen activator may be indicated if the patient is seen within a three-hour time window for a stroke (Table 7-3).

A referral to an otolaryngologist is indicated for patients with recurrent dizzy episodes associated with hearing loss (i.e., Ménière syndrome) since a low salt diet or future surgical treatment may be required.  Patients with a single severe episode of vertigo fitting the clinical picture of vestibular neuritis can be treated for nausea and encouraged to resume activities as soon as possible. Patients with asymmetric motor, sensory or cranial nerve findings should be evaluated by a neurologist.

Table 7-3 Referral Evaluation Timeframe for Patients Presenting With Dizziness

VII. CASE DISCUSSIONS:

Case 7-1. This is a classic presentation of BPPV. The patient has typical triggers, symptoms lasting less than one minute, and characteristic nystagmus on examination. In this case, the lesion is localized to the right posterior semicircular canal and the diagnosis is BPPV. If nystagmus had been downbeating, the lesion would localize to the cerebellum and a work-up for central causes should ensue.

Case 7-2. The sudden onset of symptoms, which developed over an hour, and the lack of other neurologic signs and symptoms strongly suggests an acute vestibular neuronitis. The examination localizes to the vestibular nerve because of unilateral nystagmus. If nystagmus changed direction, the findings would instead localize to the cerebellum and stroke would be the leading concern. One should consider the possibility of ischemia to the vestibular nerve in patients with a strong history of cardiovascular disease.

Case 7-3. The patient's symptoms are chronic and variable, and her examination is normal. In addition, a personal and family history of migraine headaches and typical migraine triggers are present, so migraine-associated vertigo is the most likely diagnosis. Her examination is nonlocalizing.

VIII. CME QUESTIONS

1. A 50-year-old woman has experienced brief episodes of vertigo brought on by looking up or turning over in bed for the last month. What is the most likely cause of her symptoms?

a. Benign paroxysmal positional vertigo
b. Central positional vertigo
c. Ménière syndrome
d. Vestibular neuritis

2. A 50-year-old woman has experienced brief episodes of vertigo for the last month. During the examination, persistent downbeating nystagmus is seen. What is the most likely cause of her symptoms?

a. Benign paroxysmal positional vertigo
b. Chiari malformation
c. Ménière syndrome
d. Vestibular neuritis

3. A 50-year-old man experiences sudden-onset vertigo. His symptoms are constant but are worse with movement. What examination findings would indicate a diagnosis of vestibular neuritis?

a. Left-beating nystagmus in primary gaze, left-beating nystagmus in left gaze, no nystagmus in right gaze
b. Right-beating nystagmus in primary gaze, left-beating nystagmus in left gaze, no nystagmus in right gaze
c. Left-beating nystagmus in primary gaze, left-beating nystagmus in left gaze, right-beating nystagmus in right gaze
d. Left-beating nystagmus in primary gaze, left-beating nystagmus in left gaze, downbeating nystagmus in right gaze.

4. What is NOT required for a diagnosis of Ménière disease?

a. Episodes of vertigo last more than 20 minutes
b. Hearing loss
c. Positional vertigo
d. Recurrent episodes of vertigo

5. What is characteristic of Wallenberg syndrome?

a. Gaze-evoked nystagmus
b. Horner syndrome
c. Slurred speech
d. All of the above

CME ANSWERS

1. a. Benign paroxysmal positional vertigo

2. b. Chiari malformation

3. a. Left-beating nystagmus in primary gaze, left-beating nystagmus in left gaze, no nystagmus in right gaze

4. c. Positional vertigo

5. d. All of the above