Dizziness and other sensations of imbalance are, along with headache, back pain, and fatigue, among the most frequent complaints in medicine (Kroenke and Mangelsdorff). The significance of these complaints varies greatly. For the most part they are benign, but there is always the possibility that they signal an important neurologic disorder. Diagnosis of the underlying disease demands that the complaint of dizziness be analyzed correctly—the nature of the disturbance of function being determined first and then its anatomic localization. This approach to neurologic diagnosis is invaluable in the patient whose main complaint is dizziness.
The term dizziness is applied by the patient to a number of different sensory and psychic experiences—a feeling of rotation or whirling as well as nonrotatory swaying, weakness, faintness, light-headedness, or unsteadiness. Blurring of vision, feelings of unreality, syncope, and even petit mal or other seizure phenomena may be called "dizzy spells." These experiences fall into four categories: (1) vertigo, a physical sensation of motion of self or the environment; (2) near syncope, a sensation of faintness; (3) disequilibrium, a disorder of imbalance of stance or gait; and (4) ill-defined light-headedness, or "giddiness," a symptom that often accompanies anxiety. Hence, close questioning of the patient as to how he is using the term dizziness is a necessary first step in clinical work.
Several mechanisms are responsible for the maintenance of a balanced posture and for awareness of the position of the body in relation to its surroundings and to gravity. Continuous afferent impulses from the eyes, labyrinths, muscles, and joints inform us of the position of different parts of the body. In response to these impulses, the adaptive movements necessary to maintain equilibrium are carried out. Normally, we are unaware of these adjustments because they operate largely at a reflex level. The most important of the afferent impulses are the following.
Visual information from the retinae and possibly proprioceptive impulses from the ocular muscles, enable us to judge the distance of objects from the body. This information is coordinated with sensory information from the labyrinths and neck (see below) to stabilize gaze during movements of the head and body.
Impulses from the labyrinths, which function as highly specialized spatial proprioceptors and register changes in the velocity of motion (either acceleration or deceleration) and position of the body in relation to the gravitational vertical. The cristae of the three semicircular canals sense angular acceleration of the head in the three planes of roll, pitch and yaw, and the maculae of the saccule and utricle sense linear acceleration and gravitational pull. In each of these structures, displacement of sensory hair cells is the effective stimulus. In the semicircular ducts, this is accomplished by movement of the endolymphatic fluid, which, in turn, is induced by rotation of the head. In the utricle and saccule, the hairs are displaced by the movement of the otoliths in response to gravity, thus generating a force that displaces the otoliths. This end organ is a force transducer that converts the generated force into neural impulses that are conducted down the vestibular nerve to the vestibular nuclei. In either case (angular and linear acceleration), the force causes depolarization of the nerve terminals and initiation of impulses in the vestibular nerve, with the production of two main reflex responses: the vestibuloocular, which stabilizes the eyes, and the vestibulospinal, which stabilizes the position of the head and body.
Impulses from the proprioceptors of the joints and muscles are essential to all reflex, postural, and volitional movements. Those from the neck are of special importance in relating the position of the head to the rest of the body. The sense organs listed above are connected with the cerebellum and pathways in the brainstem, particularly the vestibular nuclei and, via the medial longitudinal fasciculi, with the ocular motor nuclei. These cerebellar and brainstem structures are the important coordinators of the sensory data and provide for postural adjustments and the maintenance of equilibrium. They are the basis of the mechanisms whereby the perceptions of one's self (the body schema) and one's surroundings (the environmental schema) are matched. Accordingly, any disease that disrupts these neural mechanisms may give rise to vertigo and disequilibrium. The interdependence of the two schemata (self and environment) is ascribed to the fact that the various sense organs—retinal, labyrinthine, and proprioceptive—are usually activated simultaneously by any body movement.
One element of the sense of stable equilibrium derives from the ability to match visual and positional information during motion. Through reflex mechanisms, we come to see objects as stationary, while we are moving (mainly the ocular fixation reflex) and moving objects as having motion when we are either moving or stationary (vestibuloocular reflex). At times, especially when our own sensory information is incomplete, we mistake movement of our surroundings for movements of our own body. A well-known example is the feeling of movement that one experiences in a stationary train when a neighboring train is moving.
A factor that influences equilibrium is the effect of aging on all the afferent structures that subserve stability. The elderly may lose their balance on extending the neck, and their peripheral sensory afferents are often impaired, as are the protective postural mechanisms, making falls more frequent. A destructive lesion of one or both labyrinths may leave an elderly person permanently unbalanced, whereas a younger person largely compensates for the loss.
Clinical Characteristics of Vertigo
A careful history and physical examination usually afford the basis for separating true vertigo from the dizziness caused by near syncope, gait disorder, and anxiety. Any illusion or hallucination of motion in any plane qualifies as vertigo. The recognition of vertigo is usually not difficult when the patient states that objects in the environment have spun around or moved rhythmically in one direction or that a sensation of whirling of the head and body was experienced. A distinction is sometimes drawn between subjective vertigo, meaning a sense of turning of one's body, and objective vertigo, an illusion of movement of the environment, but its significance is limited.
Often, however, the patient is not so explicit and a number of related experiences may be described. The feeling may be described as to-and-fro or up-and-down movement of the body, usually of the head, or the patient may compare the feeling to that imparted by the pitch and roll of a ship. Or the floor or walls may seem to tilt or to sink or rise up. In walking, the patient may have felt unsteady and veered to one side, or may have had a sensation of leaning or being pulled to the ground or to one side or another (pulsion or static tilt), as though being drawn by a strong magnet. This feeling is particularly characteristic of vertigo. Oscillopsia, a rhythmic, jerking, illusory movement of the environment, is another effect of vestibular disorder, especially if induced by movement of the head. Observant patients may actually note this rhythmic movement of the environment due to nystagmus.
Some patients may be able to identify their symptoms only when asked to compare them with the feeling of movement they experience when they come to a halt after rapid rotation. If the patient is unobservant or imprecise in descriptions, a helpful tactic is to provoke a number of dissimilar sensations by rapid rotation, or by asking the patient to stoop for a minute and straighten up; having him stand relaxed for 3 min and checking his blood pressure for orthostatic effect; and, particularly, having him hyperventilate for 3 min. Should the patient be unable to distinguish among these several types of induced dizziness or to ascertain the similarity of one of the types to his own condition, the history is probably too inaccurate for purposes of diagnosis.
When the patient's symptoms are mild or poorly described, small items of the history—a desire to keep still and a disinclination to stoop or walk during an attack, a tendency to list to one side, an aggravation of symptoms by turning over in bed or closing his eyes, a sense of imbalance when making a quick turn on foot or in a car, and a preference for one position of the body or head—help to identify them as vertigo. At the other end of the scale are attacks of such abruptness and severity as to virtually throw the patient to the ground. Independently occurring vertiginous attacks of the usual variety mark these falling episodes as part of Ménière disease (see further on). On the other hand, a dizzy sensation that is not made worse markedly by vigorous shaking of the head is unlikely to relate to vertigo, particularly that type due to peripheral vestibular disease.
All but the mildest forms of vertigo are accompanied by some degree of nausea, vomiting, pallor, perspiration, and some difficulty with walking. The patient may simply be disinclined to walk or may walk unsteadily and veer to one side, or he may be unable to walk at all if the vertigo is intense. Forced to lie down, the patient realizes that one position, usually on one side with eyes closed, reduces the vertigo and nausea, and that the slightest motion of the head aggravates them. One common form of vertigo, benign positional vertigo (see further on), occurs with the repositioning that accompanies lying down, sitting up, turning, or looking upwards. The source of the gait ataxia associated with vertigo (vertiginous ataxia) is recognized by the patient as being "in the head," not in the control of the legs and trunk. It is noteworthy that the coordination of individual movements of the limbs is not impaired in these circumstances—a point of difference from most instances of cerebellar disease. Loss of consciousness as part of a vertiginous attack nearly always signifies another type of disorder (seizure or faint).
Nonvertiginous Types of Dizziness
It is important to distinguish vertigo from the more common complaints for which the term dizziness is used by patients. These include the feeling of impending fainting (near syncope), a disorder of gait (disequilibrium), and an ill-defined feeling of lightheadedness. Many patients in the last category who initially complain of dizziness will, on closer questioning, describe his symptoms as a "distant feeling," "walking on air," "inability to focus," or some other unnatural sensation in the head. These sensory experiences are particularly common in states characterized by anxiety or panic attacks—often, but not always, with depression.
This constellation of nonvertiginous symptoms has been loosely referred to as "phobic," "functional," and "psychogenic" vertigo. Every clinician encounters numerous such patients. In Brandt's (1996) extensive experience, phobic vertigo (his term) was second only to benign positional vertigo (described below) as a cause of consultation in his dizziness clinic. He relates the disorder to anxiety and panic spells, but finds that it exists more often as an independent entity that is subject to improvement after careful explanation and reassurance. We agree with Furman and Jacobs that the term psychiatric dizziness, if used at all, should be restricted to dizziness that occurs as part of a recognized psychiatric syndrome, notably extreme anxiety disorder. Often, there is a component of avoidance of crowds, open spaces and tight circumstances. There seems to be little point in signifying the nonvertiginous symptoms with separate designations based on the settings in which they commonly occur ("supermarket syndrome," "motorist disorientation syndrome," "phobic postural vertigo," "street neurosis") but they do emphasize the psychogenic nature and may facilitate recognition of the syndrome. Furman and Jacobs have related anxiety-type dizziness to minor degrees of vestibular dysfunction, but we have not found it possible to determine whether there is a genuine labyrinthine disorder in all of these patients.
Oculomotor disorders, such as ophthalmoplegia with diplopia, may be a source of spatial disorientation and brief sensations of vertigo, mild nausea, and staggering. These symptoms are maximal when the patient looks in the direction of action of the paralyzed muscle; it is attributable to the receipt of two conflicting visual images. Some normal persons may experience such symptoms for brief periods when first adjusting to bifocal glasses.
In a peculiar symptom called the Tullio phenomenon, a loud sound, or yawning, produces a brief sensation of vertigo or tilting of the environment. Some patients with this symptom are found to have an absence or thinning of the bony roof of the superior semicircular canal, which can be detected by thin (1 mm) slice CT. This disorder, which is a form of perilymphatic fistula, is caused by a spontaneous or traumatic dehiscence of the bone of the superior canal. Occasionally, patients with Ménière disease report this symptom.
Other causes of dizziness are more difficult for the physician and patient to define. In severe anemic states, particularly pernicious anemia, and in aortic stenosis, easy fatigability and languor may be attended by light-headedness, related particularly to postural change and exertion. In the emphysematous patient, physical effort may be associated with weakness and peculiar cephalic sensations, and violent paroxysms of coughing may lead to giddiness and even fainting (tussive syncope) because of impaired venous return to the heart. The dizziness that often accompanies acute hypertension is difficult to evaluate; sometimes it is an expression of anxiety, or it may conceivably be the result of an unstable adjustment of cerebral blood flow. It is doubtful that chronic hypertension causes dizziness, although many of the medications for its treatment certainly can cause the symptom.
Postural nonvertiginous dizziness is another state in which inadequate vasomotor reflexes prevent a constant cerebral circulation; it is notably frequent in persons with orthostatic hypotension of any cause, for example, in those taking antihypertensive drugs, as well as in patients with a polyneuropathy that has an autonomic component. Such persons, on rising abruptly from a recumbent or sitting position, experience a swaying type of dizziness, dimming of vision, and spots before the eyes that last for several seconds. The patient is forced to stand still and steady himself by holding onto a nearby object. Occasionally, a syncopal attack may occur at this time (see Chap. 18). Hypoglycemia gives rise to yet another form of dizziness, marked by a sense of hunger and attended by trembling, sweating, and other autonomic symptoms. Drug intoxication—particularly with alcohol, sedatives, and antiepileptic drugs—may induce a nonspecific dizziness and, at advanced stages of intoxication, true vertigo.
In practice, it may nonetheless be difficult to separate these types of dizziness from vertigo, for there may, or may not be, feelings of rotation, impulsion, up-and-down movement, oscillopsia, or other disturbance of motion. The ancillary symptoms of true vertigo—namely, nausea, vomiting, tinnitus and deafness, staggering, and the relief obtained by sitting or lying still—are also absent. Furthermore, it is not an uncommon circumstance to find more than one type of dizziness in an individual who is carefully tested.
The Neurologic and Otologic Causes of Vertigo
The fact that vertigo may constitute the aura of an epileptic seizure supports the view that this symptom may have a cerebrocortical origin. Indeed, electrical stimulation of the cerebral cortex in an unanesthetized patient, either of the posterolateral aspects of the temporal lobe or the inferior parietal lobule adjacent to the sylvian fissure, may evoke intense vertigo. The occurrence of vertigo as the initial symptom of a seizure is, however, infrequent. In such cases, a sensation of movement—either of the body away from the side of the lesion or of the environment in the opposite direction—lasts for a few seconds before being submerged in other seizure activity. Vertiginous epilepsy of this type should be differentiated from vestibulogenic seizures, in which an excessive vestibular discharge serves as the stimulus for a seizure. The latter is a rare form of reflex epilepsy, in which tests that induce vertigo may provoke the seizure (see Chap. 16).
The issue of migraine as a cause of vertigo has occasioned much discussion. Several authoritative clinicians attribute many instances of otherwise unexplained dizziness and vertigo to migraine with aura, but it is not entirely clear whether they are referring to an attack of basilar migraine, usually in children (migrainous vertigo), or to episodes of vague disequilibrium or vertigo at various times in migraineurs, which has been more typical in our experience. A survey by Neuhauser and colleagues found that 7 to 9 percent of patients had conventional migrainous symptoms during or before a vertiginous attack, and in half of those the vertigo was regularly associated with migraine. This number is certainly higher than in most practices, but it does support the idea that migraine can cause vertigo as discussed further on.
Lesions of the cerebellum produce vertigo depending on which part of this structure is involved. Large, destructive processes in the cerebellar hemispheres and vermis, such as cerebellar hemorrhage may, or at times may not, cause vertigo. However, strokes in the territory of the medial branch of the posterior inferior cerebellar artery (which arises distal to the branches to the medulla, and therefore does not involve the lateral medulla) causes intense vertigo and vomiting that is indistinguishable from that caused by labyrinthine disorder. In two such pathologically studied cases, a large zone of infarction extended to the midline and involved the flocculonodular lobe (Duncan et al). Falling in these cases was toward the side of the lesion; nystagmus was present on gaze to each side but was more prominent on gaze to the side of the infarct. These findings have been confirmed by CT and MRI (Amarenco et al). Early in the course of an acute attack of vertigo, when it may be difficult to assess the gait and the quality of nystagmus, it may be necessary to exclude a cerebellar infarct or hemorrhage by use of imaging procedures.
Labyrinthine disease, on the other hand, causes predominantly unidirectional nystagmus to the side opposite the impaired labyrinth and swaying or falling toward the involved side—i.e., the direction of the nystagmus is opposite to that of the falling and past pointing (the latter referring to overshooting a target by the patient's finger with eyes closed, as originally described by Bárány ). Ataxia and dysarthria are, of course, typical of many forms of cerebellar disease but may be minimal or absent in cerebellar hemorrhage and some infarctions as well as being lacking in all forms of vestibular disease.
The topic of vertigo with fluctuating ischemia in the territory of the basilar and vertebral arteries (transient ischemic attack [TIA]) and the problem of subclavian steal syndrome are discussed further on under "Vertigo of Brainstem Origin" and in Chap. 34. Also common in practice is vertigo caused by the demyelinating lesions of multiple sclerosis, as noted in the later section.
Biemond and DeJong described a kind of nystagmus and vertigo originating in the upper cervical roots and the muscles and ligaments that they innervate (so-called cervical vertigo). Spasm of the cervical muscles, trauma to the neck, and irritation of the upper cervical sensory roots were said to produce asymmetrical spinovestibular stimulation and thus to evoke nystagmus, prolonged vertigo, and disequilibrium. Toole and Tucker demonstrated a reduced flow through these vessels (in cadavers) when the head was rotated or hyperextended. In our view, the existence of "cervical vertigo," or at least these interpretations of it, is open to question. However, we acknowledge having encountered patients with cervical dystonia who describe something akin to vertigo, and this may speak to a relationship between cervical proprioceptors and vertigo.
Causes of vertigo other than Ménière disease that originate in the vestibular nerve are discussed further on.
In summary, for all practical purposes, vertigo indicates a disorder of the vestibular end organs, the vestibular division of the eighth nerve, or the vestibular nuclei in the brainstem and their immediate connections, including the inferior cerebellum. Although lesions of the cerebral cortex, eyes, and perhaps the cervical muscles may give rise to vertigo, they are not common sources of the symptom, and vertigo is rarely the dominant manifestation of disease in these structures. The clinical problem resolves by deciding which portion of the labyrinthine–vestibular apparatus is involved. Usually this determination can be made on the basis of the form of the vertiginous attack, the nature of the ancillary symptoms and signs, and tests of labyrinthine function. These tests are described below, followed by a description of the common labyrinthine–vestibular syndromes.
Tests of Labyrinthine Function
The most rudimentary test of labyrinthine function is simply to have the patient shake his head from side-to-side in an attempt to elicit symptoms that simulate the dizziness that has been described and to observe the degree of postural instability during this maneuver. Falling and marked intensification of the dizziness is almost always an indication of labyrinthine disease. Also, nystagmus may be evoked, indicating a vestibular instability. More informative in identifying a diseased labyrinth is the "rapid head impulse" test, which is conducted by asking the patient to fixate on a target and then for the examiner to rotate the patient's head quickly by 10 degrees (an explanation must be given to encourage the patient to relax the neck muscles and remain focused on the fixation point). The eyes are observed for a slippage from the target; this is most evident by a quick saccadic return to the point of focus. Ocular instability is observed when the patient turns his head toward the side of the affected labyrinth. This use of the vestibuloocular reflex is said by Halmagyi and Crener to be among the most dependable bedside tests of labyrinthine function.
Maneuvers designed to elicit positional vertigo by rapidly changing from a seated to a supine position with the head turned to one side bring about vertigo in a number of conditions but are specifically intended to detect benign positional vertigo and are described further on.
A number of other interesting but less validated tests that bring out instabilities in station and gait may be used to supplement the conventional tests for vestibular dysfunction. The Unterberger maneuver requires the patient to march in place with eyes closed and arms outstretched. Normally, less than 15 degrees or so of rotation is displayed; asymmetry of labyrinthine function is manifest as excessive rotation away from the diseased side. A related test involves having the patient walk around a chair with eyes closed; an increasing or decreasing radius is indicative of an imbalance between the two sides of the labyrinthine apparatus. Both of these tests, however, often show abnormalities with cerebellar disease as well, in which the patient veers to the affected side. The sensitivity of maneuvers such as these has been questioned. We can only comment that they seem in our experience to demonstrate vestibulocerebellar lesions.
Vestibular (labyrinthine) stimulation can also be produced by rotating the patient in a Bárány chair or any type of swivel chair. The patient is asked not to fixate or is defocused with Frenzel lenses during rotation to avoid the effects of optokinetic nystagmus. The normal response is nystagmus in the direction opposite to rotation. In contrast, if the patient is asked to focus on his own thumb in an outstretched arm, there should be no nystagmus if the rotational velocity is slow; the ability to suppress this vestibuloocular response reflects the integrity of the vestibular organ and nerve on the side toward the direction of rotation. Electronystagmography (ENG) provides a more refined method of detecting disordered labyrinthine function because it permits the accurate recording of eye movements without visual fixation. ENG is usually coupled with caloric stimulation or with modern devices for rotational testing that allow precise control of the velocity, acceleration, and extent of rotation beyond what can be done with a traditional chair.
Irrigation of the ear canal alternately with cold and warm water (caloric testing) may be used to disclose a reduction in labyrinthine function in the form of an impairment or loss of thermally induced nystagmus on the involved side. Caloric testing is accomplished by having the patient lay supine on the examining table with the head tilted forward 30 degrees to bring the horizontal semicircular canal into a vertical plane, the position of maximal sensitivity of this canal to thermal stimuli. Each external auditory canal is irrigated for 30 s, first with water at 30°C (86°F) and then at 44°C (111.2°F), with a pause of at least 5 min between each irrigation. In normal persons, cold water induces a slight tonic deviation of the eyes to the side being irrigated, followed, after a latent period of about 20 s, by nystagmus to the opposite side (direction of the fast phase). Warm water induces nystagmus to the irrigated side. (As noted in Chap. 14, this is the basis for the mnemonic COWS: cold opposite, warm same, referring to the direction of fast phase of the nystagmus.) In normal subjects, the nystagmus usually persists for 90 to 120 s, although the range is considerably larger. Nausea and symptoms of excessive reflex vagal activity may occur in sensitive individuals.
Simultaneous irrigation of both canals with cold water causes a tonic downward deviation of the eyes with nystagmus (quick component) upward. Bilateral irrigation with warm water yields a tonic upward movement and nystagmus in the opposite direction ("cold upward, warm down, referring again to the fast phase of nystagmus; "CUWD"). Caloric testing will reliably answer whether the vestibular end organs react, and comparison of the responses from the two ears will indicate which one is paretic. Recording of eye movements during the test allows quantification of these responses. Galvanic stimulation of the labyrinths is effective but offers no particular advantage over caloric stimulation.
Ménière Disease and Other Forms of Labyrinthine Vertigo
Labyrinthine disorders are the most common causes of true vertigo. Ménière disease is characterized by paroxysmal attacks of vertigo associated with fluctuating tinnitus and deafness. One or the other of the latter two symptoms may be absent during the initial attacks of vertigo, but invariably they assert themselves as the disease progresses and increase in severity during acute attacks. Ménière disease affects the sexes about equally and has its onset most frequently in the fifth decade of life, although it may begin earlier or later. Cases of Ménière disease usually occurs as a sporadic trait, but hereditary forms, both autosomal dominant and recessive, have been described (see reviews by Konigsmark). The main pathologic changes consist of an increase in the volume of endolymph and distention of the endolymphatic system (endolymphatic hydrops). It had been speculated several decades ago that the paroxysmal attacks of vertigo are related to ruptures of the membranous labyrinth and release of potassium-containing endolymph into the perilymph, changes that have a paralyzing effect on vestibular nerve fibers and lead to degeneration of the delicate cochlear hair cells (Friedmann). An immune pathogenesis has also been proposed, based tentatively on the presence of circulating antibodies putatively against heat shock protein in some patients.
In typical Ménière disease, the attacks of vertigo are abrupt and last for several minutes to an hour or longer. The vertigo is unmistakably whirling or rotational and usually so severe that the patient cannot stand or walk. Varying degrees of nausea and vomiting, low-pitched tinnitus, a feeling of fullness in one ear and a diminution in hearing are practically always associated. Nystagmus is present during the acute attack; it is horizontal in type, usually with a rotary component and with the slow phase to the side of the affected ear. On attempting to touch a target with the eyes closed, there is past pointing as well as a tendency to fall toward the affected ear when standing or walking. The patient prefers to lie with the faulty ear uppermost and is disinclined to look toward the normal side, which exaggerates the nystagmus and dizziness. As the attack subsides, hearing improves, as does the sensation of fullness in the ear; with further attacks, however, there is a progressive increase in deafness.
The attacks vary considerably in frequency and severity. They may recur several times weekly for many weeks on end, or there may be remissions of several years' duration. Frequently recurring attacks may give rise to a mild chronic state of disequilibrium and a reluctance to move the head or to turn quickly. With milder forms of the disease, the patient may complain more of head discomfort and of difficulty in concentrating than of vertigo and then may be considered to signify anxiety. Symptoms of anxiety are common in patients with Ménière disease, particularly in those with frequent severe attacks.
A small proportion of patients with Ménière disease experience sudden, violent falling attacks. These episodes have been referred to by the quaint name "otolithic catastrophe of Tumarkin" who attributed them to deformation of the otolithic membrane of the utricle and saccule. Patients characteristically describe a sensation of being pushed or knocked to the ground without warning, or there may be a sudden movement or tilt of the environment just before the fall. Consciousness is not lost, and vertigo of the usual type and its accompaniments are not part of the falling attack, although some patients become aware of these symptoms after falling. The attacks may occur early or late in the course of the disease. Typically, several attacks occur over a period of a year or less and remit spontaneously (Baloh et al). An initial attack must be distinguished from other types of drop attacks, but the occurrence of the more typical vertiginous attacks of Ménière disease, with deafness and tinnitus, clarifies the diagnosis.
The hearing loss in Ménière disease usually precedes the first attack of vertigo but it may appear later. Episodic deafness without vertigo has been called cochlear Ménière syndrome. As already mentioned, with recurrent attacks, there is a saltatory progressive unilateral hearing loss (in most series only 10 percent of cases involve both ears, but Baloh places the figure closer to 30 percent). Early in the disease, deafness affects mainly the low tones and fluctuates in severity; actually, tones below 500 Hz are affected early on, and this loss is not evident to the patient. Without measurable fluctuations in pure-tone audiometric thresholds, the diagnosis is left uncertain. Later the fluctuations cease and high tones are affected. Speech discrimination is relatively preserved. The attacks of vertigo usually cease when the hearing loss is complete but there may be an interval of months or longer before this occurs. Audiometry reveals a sensorineural type of deafness, with air and bone conduction equally depressed. Provided that deafness is not complete, loudness recruitment can be demonstrated in the involved ear (see earlier).
During an acute attack of Ménière disease, rest in bed is effective treatment, as the patient can usually find a position in which vertigo is minimal. The antihistaminic agents—cyclizine, meclizine, or transdermal scopolamine—are useful in the more protracted cases. Promethazine is an effective vestibular suppressant, as is trimethobenzamide (given in 200-mg suppositories), which also suppresses nausea and vomiting. For many years, a low-salt diet in combination with ammonium chloride or potassium and diuretics has been used in the treatment of Ménière disease, but the value of this regimen has never been established. The same is true for dehydrating agents such as oral glycerol and more recently introduced calcium channel blockers. Mild sedative drugs may help the anxious patient between attacks. The administration of corticosteroids was at one time popular but they have never been proven effective; transtympanic irrigation with dexamethasone is still practiced by some otologists but neither of these approaches is currently popular.
If the attacks are very frequent and disabling, permanent relief can be obtained by surgical means. Destruction of the labyrinth should be considered only in patients with strictly unilateral disease and who have reached the point of complete or nearly complete loss of hearing. In patients with bilateral disease or significant retention of hearing, the vestibular portion of the eighth nerve can be sectioned. Currently, an endolymphatic–subarachnoid shunt is the operation favored by some surgeons, and selective destruction of the vestibule by a cryogenic probe or transtympanic injection of gentamicin is favored by others. Decompression of the eighth cranial nerve, by separating it from an adjacent vessel, as suggested by Janetta, is still a controversial measure and probably better suited to the treatment of sustained and disabling but unexplained vertigo, rather than the treatment of Ménière disease. The decision to undertake any surgical procedure must be tempered by the fact that a majority of the patients, who are middle-aged, stabilize spontaneously in a few years.
Benign Paroxysmal Positional Vertigo (BPPV)
This disorder of labyrinthine function is more frequent than Ménière disease and—while it does not have the same implications in the long-term, an acute attack can be quite disabling. It is characterized by paroxysmal vertigo and nystagmus that occur only with the assumption of certain positions of the head, particularly lying down or rolling over in bed, bending over and straightening up, or tilting the head backward. It is common for the patient to report that the paroxysm of vertigo began in the middle of the night or early morning, presumably while shifting position during sleep and rapidly making one ear dependent, on rolling over to get out of bed, or to turn off an alarm. Brandt (1994) prefers the descriptive adjective positioning vertigo to positional vertigo, insofar as the symptoms are induced not by a particular head position but only by rapid changes in head position. This disorder was first described by Bárány (1921) but Dix and Hallpike emphasized its benign nature and were responsible for its further characterization, particularly the discrete positional movements that provoke it. Individual episodes last for less than a minute, but these may recur periodically for several days or for many months—rarely for years. As a rule, examination discloses no abnormalities of hearing or other identifiable lesions in the ear or elsewhere. A thorough summary of the condition has been given by Furman and Cass.
The diagnosis of this disorder is settled at the bedside by moving the patient from the sitting position to recumbency, with the head tilted 30 to 40 degrees over the end of the table and 30 to 45 degrees to one side, as originally described by Dix and Hallpike (Fig. 15-5). This need not be done abruptly but should occur in one smooth motion over a few seconds or less. After a latency of a few seconds, this maneuver provokes a paroxysm of vertigo; the patient may become frightened and grasp the examiner or the table or struggle to sit up. The dysfunctional ear is the one that is downward when vertigo is elicited. We cannot refute the contention made by von Brevern and colleagues that the right labyrinth is more often responsible. The vertigo is accompanied by oscillopsia and nystagmus with the rapid components away from the affected (dependent) ear. The nystagmus is predominantly torsional with an additional vertical component in the eye opposite the affected ear according to Baloh and colleagues. The induced vertigo and nystagmus last no more than 30 to 40 s and usually less than 15 s. Changing from a recumbent to a sitting position reverses the direction of vertigo and nystagmus (position-changing nystagmus), and this is perhaps the most certain sign that the disorder originates in the labyrinth. With repetition of the maneuver, vertigo and nystagmus become less apparent, and after three or four trials, they can no longer be elicited (referred to as "fatigue"); they can be reproduced in their original severity only after a protracted period of rest. The head-hanging maneuver does not always evoke vertigo and nystagmus in patients whose histories are otherwise consistent with the diagnosis of benign paroxysmal vertigo; therefore Froehling and coworkers do not insist on it for diagnosis if the history is compatible but without the sign, we are uncertain how to confirm the diagnosis. It may still be appropriate to prescribe the corrective exercises as a trial.
Dix-Hallpike maneuver to elicit benign positional vertigo (originating in the right ear). A. The maneuver begins with the patient seated and the head turned to one side at 45 degrees, which aligns the right posterior semicircular canal with the sagittal plane of the head. B. The patient is then helped to recline rapidly so that the head hangs over the edge of the table, still turned 45 degrees from the midline. Within several seconds, this elicits vertigo and nystagmus that is right beating with a rotary (counterclockwise) component. An important feature of this type of "peripheral" vertigo is a change in the direction of nystagmus when the patient sits up again with his head still rotated. If no nystagmus is elicited, the maneuver is repeated after a pause of 30 s, with the head turned to the left. Treatment with the canalith repositioning maneuver is shown in Fig. 15-6.
Such attacks of vertigo may come and go for years, particularly in the elderly, and require no treatment. At the other end of the scale is the rare patient with positional vertigo of such persistence and severity as to require surgical intervention.
Baloh and colleagues, in their study of 240 cases of benign positional vertigo, found that 17 percent had their onset within several days or weeks after cerebral trauma and 15 percent after presumed viral neurolabyrinthitis. The significance of these preceding events is unclear, insofar as they did not appear to influence the clinical symptoms or course of the disorder. The provocative suggestion has been made on the basis of small epidemiologic studies such as the one by Jeong and colleagues that osteoporosis is associated with an increased frequency of the disorder.
Sudden changes in position, particularly of the head, may induce vertigo and nystagmus or cause a worsening of these symptoms in patients with all types of vestibular–labyrinthine disease, including Ménière disease and the types associated with vertebrobasilar stroke, trauma, and posterior fossa tumors. However, only if the paroxysm has the special characteristics noted above—namely, elicitation by change in head position, latency of onset, brevity, reversal of direction of nystagmus on sitting up, fatigability with repetition of the test, and the presence of distressing subjective symptoms of vertigo or its recurrence for months or years without other symptoms—can it be regarded as "benign paroxysmal" in type.
Schuknecht is credited with demonstrating that benign positional vertigo was caused by cupulolithiasis, in which otolithic crystals become detached and attach themselves to the cupula of the posterior semicircular canal. It is now generally believed that the debris, probably detached from the otolith, forms a free-floating clot in the endolymph of the canal (canalolithiasis) and gravitates to the most dependent part of the canal during changes in the position of the head (see Brandt et al).
In 90 percent of cases, the posterior semicircular canal is implicated; the remaining 10 percent are caused by cupulolithiasis in the lateral canal. As mentioned, the conventional maneuver to elicit BPPV may not only fail to induce symptoms in cases of lateral canal cupulolithiasis but the corrective maneuver may even inadvertently produce it. The disorder of the lateral canal is nicely summarized by De la Meilleure and coworkers.
The debris is thought to act by inducing currents on the cupula and triggering an attack of vertigo. Based on this presumed mechanism, several canalith repositioning maneuvers have been devised (Semont et al; Epley), allowing the debris to gravitate out of the semicircular canal and into the vestibule, where it will not induce a current during angular acceleration.
The first part of the Epley canalith repositioning maneuver (Fig. 15-6) is similar to the diagnostic Hallpike maneuver, the only difference being that the patient is positioned without extending the head into the hanging position of the Dix-Hallpike diagnostic maneuver, first with one ear down and the head turned, then the other ear, in order to establish the side responsible for symptoms. Next, with the patient in the position that causes symptoms, the head is turned in a series of three steps, each separated by about 20 s: first the head is turned 45 to 60 degrees toward the opposite ear; the patient is then turned onto his side and the head turned an additional 45 degrees, until the head is parallel to the ground; then the head is turned once more until it more nearly faces the floor. We have become aware that this last step, which is a necessary part of the maneuver, is sometimes omitted by neurologists. After about 20 s, the patient is returned to the upright position. It was formerly believed that the patient should be instructed to avoid the head-down position for 24 hours, but recent studies have demonstrated that this is probably not necessary. Often a single treatment sequence suffices to terminate a period of positional vertigo (approximately 80 percent respond), but a second sequence carried out immediately after the first probably gains another small group who derive benefit. Additional treatments carried out in the same session are said to add no further benefit. In recalcitrant cases, our otolaryngology colleagues have applied a large vibrator to the temporal bone while the Epley maneuver was being performed, after which the episodes ceased; presumably this mobilizes the crystals and aids in moving them out of the canal. An incompletely implemented Epley maneuver risks converting the usual posterior semicircular canal cupulolithiasis to one involving the lateral canal, which may be more difficult to treat.
Patients who fail to respond to the Epley maneuver may respond to variations of repositioning such as the Semont maneuver (the patient begins in a sitting position with the head turned 45 degrees to one side, then drops laterally to a side lying position on the opposite ear, followed by a brisk swing of the body to drop the opposite side lying position) or the similar Brandt-Daroff exercises (sitting, to side lying, to sitting, performed repeatedly).
Positional vertigo caused by lateral canalolithiasis causes a purely horizontal nystagmus rather than the torsional and vertical type described above. In this case, another repositioning maneuver that involves rolling from one side to the other is used to liberate and reposition the otolithic debris.
It is important to reiterate that in some patients with positional vertigo, the disorder is neither benign nor paroxysmal. Jannetta and colleagues have described a group of patients in whom symptoms of vertigo and disequilibrium were almost constant (even in the upright position) and disabling and unresponsive to habituation and other medical therapy (disabling positional vertigo). They attributed this disorder to cross-compression of the root entry zone of the eighth cranial nerve by an adjacent blood vessel and have reported that decompression of the nerve provides lasting relief of symptoms.
Toxic and Idiopathic Bilateral Vestibulopathy
The common and serious ototoxic effects of the aminoglycoside antibiotics have already been mentioned—both on the cochlear hair cells, with loss of hearing and independently, on the vestibular labyrinths. Prolonged exposure to these agents produces a bilateral vestibulopathy without vertigo. Instead, there tends to be a disequilibrium associated with oscillopsia. The symptoms are especially troublesome when the patient moves. Often the disequilibrium is not discovered until a bedbound patient tries to walk.
Less-well appreciated is the occurrence of a slowly progressive vestibulopathy for which no cause can be discerned. The disorder affects men and women alike, with onset in middle or late adult life with the main abnormalities being unsteadiness of gait, which is worse in the dark or with eyes closed, and oscillopsia, which occurs with head movements and is particularly noticeable when walking. Vertigo and hearing loss are absent, as are other neurologic abnormalities. Bilateral vestibular loss can be documented with caloric and rotational testing. Baloh and colleagues, in a report of 22 patients with idiopathic vestibulopathy of this type, found that a significant proportion (9 of 22 cases) had a prior history of prolonged episodes of vertigo consistent with the diagnosis of bilateral sequential vestibular neuritis (see below).
Vestibular Neuritis (Neuronitis)
This was the term applied originally by Dix and Hallpike to a distinctive disturbance of vestibular function, characterized clinically by a paroxysmal and usually a prolonged single attack of vertigo and by a conspicuous absence of tinnitus and deafness. The entity is, however, more nebulous than most discussions indicate.
This disorder occurs mainly in young to middle-aged adults (children and older individuals also may be affected), without preference for either sex. The patient frequently gives a history of an antecedent upper respiratory infection of nonspecific type, but it is not clear whether this is requisite for the diagnosis. Usually, the onset of vertigo is fairly abrupt, although some patients describe a prodromal period of several hours or days in which they felt "top-heavy" or "off balance." Persistence of the symptoms for a day or more differentiates the process from Ménière disease. The vertigo is severe as a rule and is associated with nausea, vomiting, and the need to remain immobile.
Nystagmus (quick component) and a sense of body motion are to the opposite side, whereas falling and past pointing are to the side of the affected labyrinth. In some patients, the caloric responses are abnormal bilaterally, and in some, the vertigo may recur, affecting the same or the other ear. Auditory function is normal. Examination discloses vestibular paresis on one side, i.e., an absent or diminished response to caloric stimulation of the horizontal semicircular canal. If the patient will tolerate small head movements, the previously described rapid–head-impulse test of Halmagyi and Cremer is one of the best means of demonstrating absent function of one lateral semicircular canal.
Although the symptoms can be quite disabling for a short period, vestibular neuritis is an ostensibly benign disorder. The severe vertigo and associated symptoms subside in a matter of several days, but lesser degrees of these symptoms, made worse by rapid movements of the head, may persist for months. The caloric responses are gradually restored to normal as well. In some patients, there has been a recurrence months or years later, as already mentioned.
The portion of the vestibular pathway that is primarily affected in this disease is thought to be the superior part of the vestibular nerve trunk, which was observed to show degenerative changes by Schuknecht and Kitamura. Earlier, Dix and Hallpike had reasoned that the lesion was located central to the labyrinth, as hearing is spared and vestibular function usually returns to normal. They used the term vestibular neuritis because of the uncertainty of more precise localization within the peripheral vestibular pathway. The cause of vestibular neuritis is still uncertain, but many authorities have attributed it to a viral infection of the vestibular nerve, analogous to Bell's palsy, and from time to time, enhancement of the eighth nerve or the membranous labyrinth is seen after gadolinium administration on MRI. For want of more specific etiologic or pathologic data, many neurologists prefer the term vestibular neuropathy or neuritis or acute unilateral peripheral vestibulopathy. It is likely that the conditions described under the terms epidemic vertigo, epidemic labyrinthitis, and acute labyrinthitis or neurolabyrinthitis refer to the same process. Certainly, herpes zoster oticus causes this syndrome (as well as affecting the seventh nerve); this characterizes the Ramsay Hunt syndrome described in Chaps. 10 and 47.
During the acute stage, antihistamine drugs, promethazine, clonazepam, and scopolamine may be helpful in reducing the symptoms. Vestibular exercises are recommended by Baloh (2003) in his review of the subject. One clinical trial has demonstrated a more rapid recovery with the use of methylprednisolone, 100 mg orally, tapered over 3 weeks; valacyclovir did not have this effect (Strupp et al).
Other Causes of Vertigo of Vestibular Nerve Origin
Vertigo may occur with diseases that involve the eighth nerve in the petrous bone or at the cerebellopontine angle. Aside from vestibular neuritis, discussed above, the two most common causes of vertigo of eighth nerve origin are probably an acoustic or vestibular schwannoma and vascular irritation or compression by a small branch of the basilar artery. The frequency of the vascular compression syndrome as a cause of otherwise undifferentiated vertigo is not known (see earlier).
Regarding vestibular schwannoma, vertigo is rarely the initial symptom; the usual sequence is deafness affecting the high-frequency tones initially, followed some months or years later by mild chronic imbalance rather than vertigo and by impaired caloric responses, and then, if untreated, by additional cranial nerve palsies (the seventh, fifth, and tenth nerves), ipsilateral ataxia of limbs, and headache. Variations in the sequence of development of symptoms are frequent, and probably many vestibular schwannomas discovered in the process of an evaluation for vertigo are incidental; i.e., almost 1 percent of the general population harbors small tumors. In the diagnosis of vestibular and acoustic schwannoma, MRI and BAEP are the most important ancillary examinations. Bilateral vestibular/acoustic Schwannomas are almost always a manifestation of neurofibromatosis type 2.
Labyrinthine infarction can be a component of the stroke syndrome from occlusion of the anterior inferior cerebellar artery (AICA). In the complete syndrome there is hearing loss, cerebellar ataxia, and sometimes "screaming tinnitus" or lesser degrees of tonal tinnitus. Also reported is a clinical syndrome of unknown nature consisting of a single abrupt attack of severe vertigo, nausea, and vomiting without tinnitus or hearing loss but with permanent ablation of labyrinthine function on one side. It has been suggested that this syndrome is a result of occlusion of the labyrinthine division of the internal auditory artery, but so far, anatomic confirmation has not been obtained. Labyrinthine hemorrhage has been demonstrated by MRI in some of these patients; others are attributed, speculatively, to viral infection.
Basser described a particular form of paroxysmal vertigo that occurs in childhood. The attacks occur in a setting of good health and are of sudden onset and brief duration. Pallor, sweating, and immobility are prominent manifestations; occasionally, vomiting and nystagmus occur. No relation to posture or movement has been observed. The attacks are recurrent but tend to cease spontaneously after a period of several months or years. The outstanding abnormality is demonstrated by caloric testing, which shows impairment or loss of vestibular function, bilaterally or unilaterally, frequently persisting after the attacks have ceased. Cochlear function is unimpaired. The pathologic basis of this disorder has not been determined, and a suggested connection with migraine is tenuous. The special case of basilar artery migraine is discussed below.
Cogan has described an infrequent syndrome in young adults in which a nonsyphilitic interstitial keratitis is associated with vertigo, tinnitus, nystagmus, and rapidly progressive deafness. The prognosis for vision is good, but the deafness and loss of vestibular function are usually permanent. The cause and pathogenesis of this syndrome are unknown, although approximately half of the patients later develop aortic insufficiency or a systemic vasculitis that resembles polyarteritis nodosa. These vascular complications proved fatal in 7 of 78 cases reviewed by Vollertsen and colleagues.
There are many other causes of aural vertigo, such as purulent labyrinthitis complicating mastoiditis or meningitis; serous labyrinthitis caused by infection of the middle ear; "toxic labyrinthitis" caused by intoxication with alcohol, quinine, or salicylates; motion sickness; and hemorrhage into the inner ear. Bárány (1911) was the first to draw attention to the nystagmus and positional vertigo, worse on closing the eyes that occurs at a certain level of intoxication with alcohol and lasts a few hours. Such an episode of alcohol-induced vertigo tends to last longer than a vertiginous attack of Ménière disease, but in other respects, the symptoms (excepting tinnitus) are similar.
Vertigo with varying degrees of spontaneous or positional nystagmus and reduced vestibular responses is a frequent complication of cranial trauma. Vertigo, often of the nonrotatory, to-and-fro type, may follow cerebral concussion or whiplash injury, in which the head has not been impacted. Brandt has attributed this syndrome to a loosening or dislodgement of the otoconia in the otoliths. The vertigo in these circumstances usually improves in a few days or weeks and is rarely accompanied by impairment of hearing—in distinction to the vertigo that follows fractures of the temporal bones (as described earlier in this chapter in the discussion of deafness). Dizziness is also a prominent complaint as part of the syndrome of a postconcussion syndrome as described in Chap. 35, but usually this proves to be ill-defined giddiness rather than true vertigo.
There is, nonetheless, a type of vestibular concussion accompanying closed head trauma that may leave the patient with imbalance or positional vertigo. Otolaryngologists are familiar with a syndrome resulting from a perilymph fistula after traumatic injury. The trauma may be minor, even forceful coughing, sneezing, or lifting; some cases are a result of chronic ear infection or cholesteatoma. Disruption of the oval or round windows causes a leak of perilymph into the middle ear. Vertigo and nystagmus can be induced by pressure in the external ear canal (the fistula test). If enough perilymph migrates to the middle ear, a conductive hearing loss may also be detected. Superior canal dehiscence, in which loud sounds induce brief vertigo and nystagmus (Tullio phenomenon) is another result of perilymphatic fistula, as discussed earlier. A perilymph fistula may be pronounced enough to also cause low pressure of the spinal fluid with the characteristic enhancement of the dura on MRI.
Vertigo of Brainstem Origin
Reference was made above to the occurrence of vertigo and nystagmus with lower and upper brainstem lesions. In these cases, vestibular nuclei and their connections are implicated. Auditory function is nearly always spared, because the vestibular and cochlear fibers diverge upon entering the brainstem at the junction of the medulla and pons. The vertigo of brainstem origin, as well as the accompanying nausea, vomiting, nystagmus, and disequilibrium, is generally more protracted but less severe than with labyrinthine lesions, but one can think of exceptions to this statement. Nevertheless, with brainstem lesions, one often observes marked nystagmus without the slightest degree of vertigo—which does not happen with labyrinthine disease. The nystagmus of brainstem origin may be uni- or bidirectional, purely horizontal, vertical or rotary, and is characteristically worsened by attempted visual fixation. In contrast, nystagmus of labyrinthine origin is unidirectional, usually with a rotary component, and past pointing and falling are in the direction of the slow phase; purely vertical nystagmus does not occur, and a purely horizontal nystagmus without a rotary component is unusual. Furthermore, labyrinthine nystagmus is inhibited by visual fixation and reverses direction with changes in the position of the head; nystagmus of brainstem origin generally displays none of these features. Either may have a positional- or movement-induced worsening, but this finding is more prominent in labyrinthine disease. Table 15-2 summarizes these findings.
Table 15-2 Differentiation of Peripheral from Central Nystagmus (See Text) ||Download (.pdf)
Table 15-2 Differentiation of Peripheral from Central Nystagmus (See Text)
Vertigo and nausea
Direction of nystagmus
• Mixed torsional-vertical
• Pure horizontal
• Mixed torsional–horizontal
• Pure vertical
• May be pure -horizontal
• Pure torsional
Influence of gaze
Does not change direction with gaze
Direction changes with gaze
Does not affect nystagmus
Latency following repositioning maneuver
Up to 20 s
Direction changing with reversal of head position
Present and characteristic
Signs of brainstem or cerebellar disease
The central localization of vertigo is confirmed mainly by finding signs of involvement of other structures within the brainstem (cranial nerves, sensory and motor tracts, etc.). The mode of onset, duration, and other features of the clinical picture depend on the nature of the causative disease, which may be vascular, demyelinative, or neoplastic.
Vertigo is a prominent symptom of ischemic attacks and of brainstem infarction occurring in the territory of the vertebrobasilar arteries, particularly the Wallenberg syndrome of lateral medullary infarction.
On the other hand, our colleague C.M. Fisher had pointed out that vertigo as the sole manifestation of brainstem ischemia from basilar arterial disease is rare. Unless other symptoms and signs of a brainstem disorder appear contemporaneously or soon after the vertigo, one can usually postulate an aural origin and nearly always exclude vascular disease of the brainstem. However, we have encountered rare patients with repeated brief attacks of vertigo that later proved to be caused by basilar artery stenosis, but in whom only a few episodes were associated with signs of brainstem disease such as dysarthria, facial numbness, or diplopia. In other words, frequent and sudden episodes of vertigo lasting a minute or so may infrequently be related to transient brainstem ischemia.
Vertigo of cerebellar origin is exceptional in this respect in that it may rarely be the sole manifestation of cerebellar infarction or hemorrhage, as described earlier in the introductory sections of the chapter and in Chap. 34. It follows that isolated vertigo may be the result of occlusion of the posterior inferior cerebellar artery or its parent vertebral artery although most often, there are additional features related to damage to the lateral medulla. In instances of isolated vertigo, one seeks confirmation that there are no features pointing to a central origin or conversely, if there are signs such as nystagmus in more than one direction of gaze with a single position of the head, or vertical nystagmus, there is concern for ischemia of the brainstem. The nystagmus and ataxia of gait (more of a propelling, or pulsion, to one side) that accompany acute cerebellar lesions are toward the same side (the side of the lesion), while in acute vestibulopathies, nystagmus beats away from the side of the lesion and pulsion is still toward the affected side.
Multiple sclerosis may be the explanation of persistent vertigo in an adolescent or young adult, sometimes with little or no nystagmus.
The relationship of migraine to vertigo was mentioned earlier. This refers to otherwise mundane migraine in which the vertigo is perhaps an aura, or to episodes of paroxysmal vertigo in adults that are considered to be migraine equivalents. In addition, attacks of vertigo followed by an intense unilateral and often suboccipital headache and vomiting are the characteristic features of basilar artery migraine. The prodromal visual symptoms take the form of blindness or of photopsia that occupies all of the visual fields. Between headaches, tests of cochlear and vestibular function in these patients are normal. Some authorities have stated that most cases of recurrent vertigo without hearing loss over many years can be attributed to migraine and not to Ménière disease. An instructive series of such cases has been published by Dieterich and Brandt.
Finally, mention should be made of a familial vestibulocerebellar syndrome, beginning in childhood or early adult life and characterized by recurrent episodes of vertigo and imbalance. Diplopia and dysarthria complicate some attacks, which seem to be precipitated by extreme exertion and emotion. Repeated attacks are followed by a mild, persistent ataxia, mainly of the trunk. This disorder was first described by Farmer and Mustian and more recently by Baloh and Winder, who have pointed out that both the episodic vertigo and ataxia are markedly reduced or abolished by the administration of acetazolamide. This process is most likely related to the inherited acetazolamide-responsive ataxic channelopathy syndrome described in Chap. 5. A form that is kinesigenic, i.e., brought on by activity, has a similar appearance.
In summary, the nature of the nystagmus, instability of the eyes during the head impulse test, and the other features of the neurologic examination allow a distinction to be made between central and peripheral cases of vertigo. Associated hearing loss favors a vestibular cause of vertigo. Tables 15-2 and 15-3 summarize the features of the various vertiginous syndromes.
Table 15-3 Vertiginous Syndromes with Lesions of Different Parts of the Vestibular System ||Download (.pdf)
Table 15-3 Vertiginous Syndromes with Lesions of Different Parts of the Vestibular System
DISORDERS OF EQUILIBRIUM
TYPE OF NYSTAGMUSa
Labyrinths (postural vertigo, trauma, Ménière disease, aminoglycoside toxicity, labyrinthitis)
Ipsilateral past pointing and lateral propulsion to side of lesion
Horizontal or rotary to side opposite lesion, positional and position changing, fatigable
Normal or conduction or neurosensory deafness with recruitment
Vestibular paresis by caloric testing, directional preponderance
Vestibular nerve and ganglia (vestibular neuronitis, herpes zoster)
Auditory eighth and seventh cranial nerve abnormalities; abnormal head impulse test to affected side
Ipsilateral past pointing and lateral propulsion to side of lesion
Sometimes sensorineural deafness, without recruitment (vestibulo- labyrinthitis)
Imaging may be normal or abnormal
Vestibular paresis on caloric testing
Cerebellopontine angle (acoustic neuroma, glomus and other tumors)
Ipsilateral fifth, seventh, ninth, tenth cranial nerves, cerebellar ataxia
Increased intracranial pressure (late)
Ataxia and falling ipsilaterally
Gaze-paretic, positional, coarser to side of lesion
Sensorineural deafness without recruitment
Vestibular paresis on caloric testing
Increased CSF protein
Brainstem and cerebellum (infarcts, tumors, viral infections)
Multiple cranial nerves, brainstem tract signs, cerebellar ataxia
Ataxia present with eyes open
Coarse horizontal and vertical, gaze-paretic
Hyperactive labyrinths or directional preponderance on caloric testing
Imaging, and BAEPs abnormal in most cases
Higher (cerebral) connections
Aphasia, visual field, hemimotor, hemisensory, and other cerebral abnormalities, seizures
No change in caloric responses
Imaging and electro- encephalogram may be abnormal