Chapter 168 Central Vestibular Disorders PDF

168 Central Vestibular Disorders Benjamin T. Crane, David M. Kaylie KEY POINTS The first task of an otolaryngologist examining a patient with...

168 Central Vestibular Disorders Benjamin T. Crane, David M. Kaylie KEY POINTS The first task of an otolaryngologist examining a patient with dizziness is to determine if the symptom is of central or peripheral Determining central versus peripheral origin of vertigo origin2 (Table 168.1). Some central causes of acute vertigo can requires an assessment of the precise symptom and the be life threatening and may require immediate intervention.3 presenting circumstances, as well as the physical The differentiation can almost always be made using physical findings. examination based on the type of nystagmus, result of head impulse test, severity of imbalance, and presence or absence of other Understanding the role of migraine as a common cause neurologic signs. of dizziness in patients presenting to an otolaryngologist Spontaneous nystagmus of peripheral origin is typically in the provides a valuable clinical tool in managing this highly plane of one of the semicircular canals and thus is horizontal or prevalent disorder that commonly manifests vestibular horizontal with a torsional component and does not change symptoms. direction relative to the head with direction of gaze. Spontaneous The diagnosis of migraine-associated vertigo relies nystagmus of central origin can also be purely horizontal but is critically on the history and can be substantiated by often purely vertical or torsional and usually changes direction monitoring the longitudinal response to diet with changes in gaze.2 manipulation and medical management. The head impulse test involves the examiner grasping the Effective, definitive treatment of migraine-associated patient’s head and applying a brief, high-acceleration head rotation, vertigo requires the patient’s understanding of the first in one direction and then the other.4 The patient fixates on importance of lifestyle modification in order to promote the examiner’s nose, and the examiner watches for corrective rapid compliance. Medical treatment includes beta blockers, eye movements (saccades), which are a sign of decreased vestibular tricyclic antidepressants, serotonin reuptake inhibitors, response (i.e., the eyes move with the head rather than remain and anticonvulsants. fixed in space). If a “catch-up” saccade occurs after head thrusts in one direction but not the other, a peripheral lesion (including Meniere disease and benign paroxysmal positional the labyrinth and the eighth cranial nerve on its course from the vertigo are commonly associated with migraine. brainstem) on that side is likely. The “catch-up” saccade can be Vascular disorders are a common cause of vertigo in the difficult to pick up at the bedside, but covert saccades may be elderly population. uncovered, and sensitivity may be increased by randomly varying Several types of strokes can present with vertigo, early the amplitude of the head thrust.5 imaging studies can be normal, and overt neurologic Patients with an acute peripheral vestibular lesion typically signs absent. Bedside tests such as head-impulse, can stand but may veer toward the side of a lesion. By contrast, nystagmus, test of skew (HINTS) have a high sensitivity patients with vertigo of central origin are often unable to stand and specificity for vascular origin disease. without support. Associated neurologic signs such as dysarthria, incoordination, numbness, or weakness suggest a central origin. Neoplasms can present with vertigo. Vestibular Dizziness and vertigo can be caused by diverse pathology of schwannoma is the most likely tumor to present with the central nervous system (CNS). To differentiate these disorders vertigo or dizziness, although tumors in the brainstem from those of peripheral labyrinthine origin, the otolaryngologist and cerebellum can also cause these symptoms. should know the associated signs and symptoms of CNS processes, Screening for neoplasm should be considered in patients their natural history, and their appearance. Definitive diagnostic with progressive symptoms, particularly when other evaluation and management usually involve cooperation with cranial nerve or central nervous system deficits exist. neurologists or neurosurgeons. A classification of CNS disorders The otolaryngologist should be aware that multiple capable of eliciting vestibular symptoms includes intracranial sclerosis, normal pressure hydrocephalus, focal seizure complications of suppurative otitis, vascular disorders, neoplasms, disorders, and cerebellar ataxia syndromes can produce disorders of the craniovertebral junction, multiple sclerosis (MS), vertigo. familial ataxia syndromes, and focal seizure disorders. INTRACRANIAL COMPLICATIONS OF OTITIC INFECTIONS INTRODUCTION Epidural or subdural abscesses, as well as those of the temporal Pathologic dizziness can be classified into several categories on bone, petrous apex, or cerebellum can cause vestibular com- the basis of the etiology: peripheral vestibular, cardiovascular, plaints. Such processes are usually associated with other signs of neurologic, psychiatric, and metabolic.1 In addition, dizziness, often infection such as fever or sepsis and are rare in the modern era with motion sickness, can occur in normal patients when they are of antibiotics. exposed to unnatural patterns of motion, for example, during sea and car travel. Overlaid on all types of dizziness can be the psy- chological consequences of extremely distressing symptoms, and Vestibular Migraine vice versa, dizziness can be a symptom of a psychiatric disorder Vestibular migraine (VM) is probably the most common cause of such as panic and anxiety syndromes and depression. Many central central vertigo symptoms in both adults and children.6 VM is a conditions can cause each of these types of dizziness. subset of migraine characterized by recurrent headaches associated 2536 Descargado para Anonymous User (n/a) en National Autonomous University of Mexico de ClinicalKey.es por Elsevier en junio 25, 2020. Para uso personal exclusivamente. No se permiten otros usos sin autorización. Copyright ©2020. Elsevier Inc. Todos los derechos reservados.  CHAPTER 168 Central Vestibular Disorders2536.e1 Abstract Keywords 168 Determining central versus peripheral origin of vertigo requires Vestibular migraine an assessment of the precise symptom and the presenting circum- Meniere disease stances, as well as the physical findings. vascular disorders Understanding the role of migraine as a common cause of vestibular schwannoma dizziness in patients presenting to an otolaryngologist provides a central vertigo valuable clinical tool in managing this highly prevalent disorder PPPD that commonly manifests vestibular symptoms. The diagnosis of migraine-associated vertigo relies critically on the history and can be substantiated by monitoring the longitudinal response to diet manipulation and medical management. Effective, definitive treatment of migraine-associated vertigo requires the patient’s understanding of the importance of lifestyle modification in order to promote compliance. Medical treatment includes beta blockers, tricyclic antidepressants, serotonin reuptake inhibitors, and anticonvulsants. Meniere disease and benign paroxysmal positional vertigo are commonly associated with migraine. Vascular disorders are a common cause of vertigo in the elderly population. Several types of strokes can present with vertigo, early imaging studies can be normal, and overt neurologic signs absent. Bedside tests such as head-impulse, nystagmus, test of skew (HINTS) have a high sensitivity and specificity for vascular origin disease. Neoplasms can present with vertigo; vestibular schwannoma is the most likely tumor to present with these symptoms, although tumors in the brainstem and cerebellum can also cause these symptoms. Screening for neoplasm should be considered in patients with progressive symptoms, particularly when other cranial nerve or central nervous systems exist. The otolaryngologist should be aware that multiple sclerosis, normal pressure hydrocephalus, focal seizure disorders, and cerebel- lar ataxia syndromes can produce vertigo. Descargado para Anonymous User (n/a) en National Autonomous University of Mexico de ClinicalKey.es por Elsevier en junio 25, 2020. Para uso personal exclusivamente. No se permiten otros usos sin autorización. Copyright ©2020. Elsevier Inc. Todos los derechos reservados.  CHAPTER 168 Central Vestibular Disorders 2537 TABLE 168.1 Differentiation of Central and Peripheral Vertigo BOX 168.2 Criteria for Diagnosis of Vestibular Migraine 168 Feature Central Origin Peripheral Origin VESTIBULAR MIGRAINE* Imbalance Severe Mild to moderate Neurologic symptoms Frequent Rare A. At least five episodes of vestibular symptoms of moderate or Nystagmus Changes direction on Unidirectional severe intensity lasting 5 min to 72 h. lateral gaze Decreases with B. Current or prior history of migraine according to the No change with fixation fixation International Classification of Headache Disorders (ICHD). Hearing loss Rare Frequent C. One or more migraine features with at least 50% of the Nausea Variable Severe vestibular episodes. This may include migraine headache, Recovery Slow Rapid photophobia or phonophobia, and visual aura. D. Not better accounted for by another vestibular or ICHD diagnosis. PROBABLE VESTIBULAR MIGRAINE BOX 168.1 Diagnostic Criteria for Migraine A. At least five episodes of vestibular symptoms of moderate or severe intensity lasting 5 min to 72 h. MIGRAINE WITHOUT AURA B. Only one of aforementioned criteria B and C is fulfilled (i.e., A. At least five attacks fulfilling B–D. migraine history or migraine features during the episode). B. Headache lasting 4–72 h when untreated. C. Not better accounted for by another diagnosis. C. Headache has at least two of the following characteristics: unilateral location, pulsating quality, moderate or severe *Vestibular symptoms rated as “moderate” means that they interfere with intensity, and aggravation by physical activity. but do not prohibit daily activities. They are rated as “severe” if daily D. During the headache, either nausea and vomiting or activity cannot be continued. photophobia. From Lempert T, Olesen J, Furman J, et al.: Vestibular migraine: diagnostic E. Not attributed to another disorder. criteria. J Vestib Res 22(4):167–172, 2012. TYPICAL AURA WITH MIGRAINE HEADACHE A. At least two attacks fulfilling B–D. B. Fully reversible visual, sensory, or aphasic aura symptoms with no motor weakness. dizziness, migraine-related vestibulopathy, and migrainous vertigo. C. At least two of the following: homonymous positive features or For the purpose of this chapter, the condition will be referred to unilateral sensory symptoms, at least one symptom develops as VM, even when citing authors who used different terms. The gradually over more than 5 min, and each symptom lasts diagnostic criteria for VM have historically been controversial 5–60 min. and may continue to evolve. Neuhauser et al.15 proposed criteria D. Headache follows aura with a free interval of less than 60 min. for VM that are still widely used. These criteria are: (1) episodic E. Not attributed to another disorder. vestibular symptoms (rotational vertigo, other illusory self or object motion, positional vertigo, and head motion intolerance) of at From Silberstein SD, Olesen J, Bousser MG, et al: The International least moderate severity; (2) migraine according to IHS criteria; Classification of Headache Disorders, 2nd Edition (ICHD-II)—revision of (3) at least one of the following migrainous symptoms during at criteria for 8.2 Medication overuse headache. Cephalalgia 25(6):460– least two vertiginous attacks: migrainous headache, photophobia, 465, 2005. phonophobia, and visual or other auras; and (4) other causes ruled out by appropriate investigations. Probable VM was chosen for patients who did not meet definite criteria but were still believed to have VM as the most likely diagnosis. This requires criteria 1 with nausea, vomiting, and hypersensitivity to light, sound, and and 4 from the list, plus at least one of the following: migraine smell.7 Although migraine is frequently thought of as primarily a according to IHS criteria; migrainous symptoms during vertigo; headache disorder, it is important for otolaryngologists to recognize migraine-specific precipitants of vertigo (e.g., specific foods, sleep that these patients may present with dizziness.8 Neurologic aura irregularities, and hormonal changes); and response to antimigraine symptoms are present in a third of patients with migraine. Migraine drugs. The most current diagnostic criteria16 for definite and affects nearly 25% of women, 15% of men,9,10 and 5% of children.11 probable VM have been proposed as a result of a collaboration In the prepubertal period, boys with migraine slightly outnumber between the International Headache Society Classification Com- girls, but at puberty, migraine decreases in boys and increases in mittee and the Committee for Classification of Vestibular Disorders girls, so that a 2 : 1 female preponderance is established by adult- of the Barany Society (Fig. 168.1). A recent long-term follow-up hood,12 and in VM, the female preponderance may be as high as of the patients with VM found that after a mean follow-up of 4 : 1.13 Migraine typically begins in young adulthood with symptoms 8.75 years, the diagnosis was confirmed with a positive predictive beginning after the age of 40 years in only 10% of patients. Whereas value of 85%.17 However, the pathophysiology of VM remains headache symptoms are usually more prominent in younger patients, unclear, and the diagnostic criteria have not been validated with the mean age of onset of VM is in middle age.13,14 therapeutic outcomes.18 Although the prevalence of both migraine The diagnosis and classification of migraine and other headache and vertigo is common in the general population, it coincides disorders have been a controversial issue. The most recent effort more than would be expected by chance alone suggesting a causal of the Headache Classification Committee of the International relationship19 (Box 168.2). Headache Society (IHS)7 sets up criteria that allow meaningful comparisons of groups of patients between centers. The IHS classifies the most common type of migraine as migraine with Vestibular Symptoms and without aura (Box 168.1); there are also other classified types of migraine headache, but this is out of the scope of this chapter, Nonspecific Dizziness as they will only rarely be encountered by the otolaryngologist. Nonspecific dizziness occurs frequently in patients with either VM is currently the mostly widely accepted term, although tension or migraine headaches and does not in itself differentiate the condition has also been known as migraine-associated vertigo/ between the two groups, although dizziness is more common and Descargado para Anonymous User (n/a) en National Autonomous University of Mexico de ClinicalKey.es por Elsevier en junio 25, 2020. Para uso personal exclusivamente. No se permiten otros usos sin autorización. Copyright ©2020. Elsevier Inc. Todos los derechos reservados. 2538 PART VII Otology, Neurotology, and Skull Base Surgery Treatment of Migraine-Associated Vertigo Migraine control diet Regular sleep Aerobic exercise If symptoms are not controlled after 6 to 8 weeks, consider pharmacotherapy Class β-blockers Tricyclic Anti- SSRIs antidepressants convulsants Drug Propranolol Nortriptyline Venlafaxine Gabapentin Starting dose 60 mg/day 5-10 mg/day 37.5 mg/day 300 mg/day Therapeutic dose 120-180 mg/day 50-200+ mg/day 75-225 mg/day 1200-2400 mg/day Fatigue Dry mouth Loss of sexual Sedation Common Hypotension Sedation desire Peripheral side effects Worsening Weight gain Dry mouth edema depression Insomnia Dizziness Fig. 168.1 Flowchart of suggested migraine treatment. Lifestyle modification is usually a good first option because it is not associated with side effects and will provide symptomatic improvement in most patients. Pharmacotherapy should be considered if more conservative measures fail. severe in patients with migraine. This condition may have some seizure disorders, and learning disabilities or neurologic perceptual overlap with chronic subjective dizziness (CSD).8 impairments.27 In adults, a similarly significantly greater incidence of motion sickness has been observed in patients with classic migraine compared with patients with tension and cluster head- Vertigo aches.21 In the Kayan and Hood20 series of 200 unselected patients Vertigo is extremely common in patients with migraine and with migraine, 51% reported motion sickness compared with 20% occurred in 26.5% of Kayan and Hood’s group of patients with of the patients with tension headache. migraine compared with 7.8% of those with tension headache (P A subset of patients with migraine experiences disabling motion <.001).20 Other studies have found the incidence of vertigo in sickness. These patients limit their head motion to a minimum, patients with classic migraine to be as high as 42%,21 although limit their daily activities accordingly, frequently rest during the closer to 30% is more likely.22 The severity of vertigo in patients day, and when symptomatic may need to remain motionless for with migraine tends to be greater than that in those with tension up to an hour until symptoms abate. If they cannot avoid vestibular headaches. Vertigo severe enough to seek medical attention for stimulation, a full-blown migraine attack can be triggered. Caloric relief occurred in 5% of patients with migraine but less than 1% responses in these patients tend to be symmetric and very brisk, of the tension headache group.20 often culminating in emesis. If treatment provides a dramatic Awareness of the temporal relationship of vertiginous spells response, the patients often are surprised at how much they have with migraine headaches is important. Vertigo does not usually restricted their lifestyle. Often, neither the patients nor their present as an aura immediately preceding the headache as a physician suspects that migraine had any association with the prodrome. Of the 53 patients with vertigo and migraine interviewed other symptoms. Patients often only discuss the vestibular symptoms by Kayan and Hood,20 the vertigo immediately preceded the and ignore or discount any effects of the underlying problem. headache in only 15%, whereas it occurred during the headache Prophylactic migraine therapy often yields dramatic improvement in 47% of patients and during the headache-free interval in in symptoms. 36% of patients. In a series of 50 patients with basilar migraine, Olsson23 and Cutrer and Baloh24 also found vertigo to occur more often during the headache-free interval than as a prodrome before Auditory Symptoms the headache. Of the patients studied by Kayan and Hood,20 20% complained of hearing loss, tinnitus, or pitch distortion, and one fourth of the 20% had multiple auditory symptoms. In descending order of Motion Sickness frequency, these symptoms occurred during the headache, during The relationship between migraine and motion sickness is well the headache-free interval, and immediately before the headache. established.25 In his seminal study of 9000 Swedish schoolchildren, The temporal relationship of these symptoms mirrors the relation- Bille26 matched children with more pronounced migraine to a ship of vertigo with headache in this same series. similar group without migraine. Severe motion sickness was present in 49% of the children with migraine and in only 10% of the control group. Barabas et al. found that 45% of 60 children with Hearing Loss migraine experienced at least three episodes of motion sickness The association of hearing loss to migraine is reported to be culminating in vomiting compared with 5% to 7% of three similar about 4% to 7%.14,20 Hearing loss is a more prominent symptom sized control groups of patients with nonmigraine headaches, in patients with basilar migraine. In Olsson’s study,23 52% noticed Descargado para Anonymous User (n/a) en National Autonomous University of Mexico de ClinicalKey.es por Elsevier en junio 25, 2020. Para uso personal exclusivamente. No se permiten otros usos sin autorización. Copyright ©2020. Elsevier Inc. Todos los derechos reservados.  CHAPTER 168 Central Vestibular Disorders 2539 a change in hearing as part of the aura immediately preceding the associated with migraine cannot be fully explained by a vascular migraine headache; 50% of patients had a fluctuating low-frequency theory. Neural-based spreading of depression activity has been 168 sensorineural hearing loss. A group of patients with migraine implicated,40-42 although this neurophysiology does not completely who developed hearing loss thought to be due to vasospasm has explain the disease. Other theories point to metabolic shifts, which been reported.28 lead to overproduction of noradrenalin and dopamine.43 A positive family history of migraine is present in approximately 40% to 90% of affected individuals compared with 5% to 20% Tinnitus of unaffected patients. When patients with migraine with and Tinnitus was experienced by 15% of patients with migraine, but without aura are examined separately, patients who have migraine none with tension headache,20 and in more than 60% of patients with aura are more likely to have affected family members. When with basilar migraine.23 twins are studied, the concordance of migraine is only 10% to 34% depending on the country, suggesting that both genetic and environmental factors play a role.44 Distortion Familial hemiplegic migraine (FHM) is a rare type of migraine, Although distortion was noted by only 4% of patients in the which affects only 0.01% of the general population.45 However, Kayan and Hood series,20 its actual prevalence may be higher. the underlying cellular cause is relatively well understood. Unlike More attention may be given to more bothersome symptoms, and most migraine, FHM has a clear autosomal dominant pattern of auditory distortion may be ignored by physicians and patients inheritance. So far, mutations have been found in three different alike as unimportant. genes that determine neuronal excitability. Management. Treatment of migraine has historically focused on Phonophobia headache symptoms. Management of migraine headache can be Loud noise aversion distinguishes patients with migraine from divided into two categories: symptomatic and prophylactic. Some those with other types of headaches. Only 12% of patients with interventions are useful in ameliorating the symptoms of the acute tension headache experienced phonophobia, but 81% of those attack, whereas others are designed to reduce the frequency or with migraine had the symptom.20 Olsson23 detected phonophobia severity of attacks. Symptomatic management includes analgesics, in patients with basilar migraine at a rate of 70% during headache antiemetics, antivertiginous drugs, sedatives, and vasoconstrictors.46 and 76% during headache-free intervals. Furthermore, he docu- In many patients, over-the-counter analgesics such as ibuprofen, mented an abnormal loudness discomfort level in 78% of these aspirin, or acetaminophen and rest are all that is needed to relieve patients, whereas only 14% had abnormal speech reception headache symptoms. Decreased gastric motility occurs during and thresholds. About 40% of those with VM have phonophobia,14 between migraine attacks, which may decrease absorption of oral with photophobia being about as common. drugs contributing to nausea and vomiting.47 Metoclopramide promotes normal gastric motility and may improve absorption of oral medication. Migraine Associated With Neurotologic Symptoms Nutrition may play a significant role in the frequency and severity of migraine headaches and migraine-associated dizziness,48,49 Basilar Migraine and dietary modification can be an effective method of managing Bickerstaff29 described a form of migraine ascribed to ischemia in symptoms. Riboflavin (vitamin B2) has been shown to be more the distribution of the basilar artery. This syndrome is currently effective than placebo in reducing the frequency of migraine known as basilar migraine replacing basilar artery migraine and headache when given in a dose of 400 mg daily.50 High-dose posterior fossa migraine, which occasionally appear in the older magnesium has also been implicated to have a therapeutic effect literature. This subtype of migraine was similar to classic migraine on migraine; suggested mechanisms have included inhibiting in that it consisted of an aura followed by a severe headache. platelet aggregation, counteracting vasospasm, stabilizing cell However, the majority of patients were adolescent girls, in whom membranes, and antiinflammatory effects.51 Patients with migraine the migraine attacks often occurred premenstrually. Later observers symptoms have been found to have lower levels of magnesium, emphasized other aspects of the clinical picture such as stupor,30 and infusion of magnesium can relieve symptoms,52 although loss of consciousness,31 neurologic symptoms,32 hearing loss, and evidence to support it remains weak.53 Magnesium given orally vertigo.33 These symptoms are thought to be due to involvement at the dose of 600 mg daily has also been shown to decrease of the brainstem, cerebellum, cranial nerve nuclei, and occipital headache symptoms54; however, diarrhea is a potential side effect lobe cortex.34 at these doses. Butterbur extract may have some benefit but also has a risk of toxicity.55 Food sensitivity may trigger migraine symptoms in a significant Migraine Without Headache number of patients.51 Although some patients have observed that Migraine should not be eliminated as a cause for vertigo just consuming a certain food will reliably provoke a headache, the because headaches are not present. Whitty35 reported a series of effect of diet is more subtle. Foods that should be avoided include patients with symptoms typically experienced during a migraine red wine, aged cheeses, beer, chocolate, caffeine, and yogurt.56 aura but had no headaches. These patients sometimes developed Alcohol itself does not appear to be a trigger, as vodka does not typical headaches later in life or had auras, which were only provoke attacks.57 Dietary modification may be considered as intermittently related to headaches. Other observers have described first-line therapy for migraine prophylaxis, although there is little similar patients using the term migraine equivalent36-38 or migraine solid data to support it (see Fig. 168.1). accompaniments.39 A history of motion sickness, premenstrual VM symptoms are often not directly related to the headache clustering of attacks, or headaches associated with some of the symptoms, and in some cases, dizziness can occur almost continu- attack is frequently present. Personal or family history of migraine ously. Treatment of VM has tended to mirror that of traditional is also helpful in diagnosing these patients. migraine symptoms, and medications that alleviate headache symptoms also tend to be effective for vertigo symptoms.58 However, Etiology. Historically, migraine headache was thought to result because the migraine-associated dizziness is often much more from dilation of intracranial and dural arteries causing stretching frequent than the headaches, prophylactic treatment is usually of pain fibers in the walls of the arteries. The complex phenomena necessary, and several prophylactic treatments are available.59 Descargado para Anonymous User (n/a) en National Autonomous University of Mexico de ClinicalKey.es por Elsevier en junio 25, 2020. Para uso personal exclusivamente. No se permiten otros usos sin autorización. Copyright ©2020. Elsevier Inc. Todos los derechos reservados. 2540 PART VII Otology, Neurotology, and Skull Base Surgery Sumatriptan (Imitrex), a 5HT1D receptor agonist, has become Acetazolamide (Diamox) has been shown to be effective in the principal drug to abort severe migraine headache. Initial trials preventing migraine headaches and episodic vertigo in families indicate that in 90% of cases, the drug effectively aborts the who also exhibit essential tremor.68 However, it has not been shown symptoms of migraine headache within an hour of their onset to have an effect on larger migraine headache population.69 It when used subcutaneously, and 70% to 85% may be aborted within may be effective in ameliorating motion-induced vestibular 2 hours.60 Common side effects include sensations of heaviness symptoms in patients with migraine. and pressure in the chest, with coronary artery vasospasm being a rarer side effect. Although sumatriptan is remarkably effective in relief of early migraine headaches, breakthrough is common, and Vestibular Disorders Associated With Migraine the drug has limited efficacy for concurrent vestibular symptoms. Propranolol (Inderal) is the most common drug for preventing Benign Paroxysmal Positional Vertigo migraine episodes. Approximately 50% to 70% of patients with Benign paroxysmal positional vertigo (BPPV) is the most common headache symptoms derive benefit from prophylactic propranolol cause of peripheral vertigo (see Chapter 167). The disorder is therapy, and the therapy may also be beneficial for vertigo symp- likely due to free-floating particles in the semicircular canal toms.32 The medication is contraindicated by asthma, congestive (canalithiasis), which usually collect in the posterior semicircular heart failure, peripheral vascular disease, diabetes, and hypothyroid- canal because of its low point with respect to gravity. Classic ism. Principal side effects include fatigue, lethargy, and dizziness, symptoms include brief (less than 1 minute) episodes of vertigo which usually occurs when rising from a seated or supine position. when the head is tilted backward or during rolling over in bed. Side effects are minimized by slowly increasing the dose from a An extensive discussion of diagnosis and treatment of this common low starting level. Doses of 80 to 180 mg/day are usually effective. disorder is outside the scope of the current chapter. However, The medication should be continued for at least 2 to 3 months BPPV is more common in patients with migraine.70 Furthermore, at the highest level of tolerance before it is considered a failure. migraine and motion sickness are three times more common in Discontinuation should be gradually tapered over several days. A patients with BPPV than in the general population, with 59% of variety of beta-adrenergic agents have also been used for migraine patients having a family history of migraine.71 prophylaxis. Atenolol (Tenormin), metoprolol (Lopressor), nadolol (Corgard), and timolol (Blocadren) are likely as effective as propranolol. However, a number of other β-adrenergic antagonists Meniere Disease (e.g., acebutolol, oxprenolol, and alprenolol) do not appear to be Meniere disease classically presents with unilateral, low-frequency effective in migraine prophylaxis. It has been suggested that pure fluctuating hearing loss, aural fullness, and dizziness lasting several beta-adrenergic antagonism without intrinsic sympathomimetic minutes to hours.72 However, the presence and severity of these activity is required for efficacy. symptoms are variable and can overlap with migraine.73 Unselected Calcium channel blockers (nifedipine, verapamil) have also been migraine patients have a 7% incidence of hearing loss and 26% reported to reduce the frequency of migraine attacks, but the incidence of vertigo.20 In patients with Meniere disease, the lifetime effect is likely only a modest one.61 Diltiazem (Cardizem) does incidence of migraine is 56% versus only 25% in controls.74 The not appear to have any effect in migraine prevention. frequent co-occurrence of Meniere disease and migraine suggests Tricyclic antidepressants have also been shown to decrease the a pathophysiologic link between the two syndromes,75 although frequency and severity of migraine attacks. Amitriptyline is perhaps others have suggested that the co-occurrence may be due to chance the most studied drug in this category, with several studies showing alone.76 It is likely that both Meniere disease and migraine are its efficacy.62 Starting doses are usually 10 to 25 mg daily, which not homogeneous disorders but may be caused by a spectrum of is usually given at bedtime to avoid the side effects of sedation genetic and environmental influences. The potential link between and anticholinergic activity. Weight gain is a side effect, which these two disorders likely depends at least in part on how the limits patients’ compliance with therapy in some populations. populations are defined. Therapeutic doses are usually 50 to 100 mg, with some patients who also develop depressive symptoms requiring doses of up to 400 mg. Nortriptyline is less sedating than amitriptyline and has Benign Paroxysmal Vertigo of Childhood a dosage profile similar to amitriptyline. Basser77 described a clinical entity in children younger than 4 The role of selective serotonin reuptake inhibitors (SSRIs) for years that he called benign paroxysmal vertigo. This should not be the treatment of migraine remains controversial. There is some confused with the much more common BPPV. Children with this evidence that they may be less effective than tricyclic antidepres- disorder usually become suddenly frightened, cry out, cling to the sants63 for headache symptoms. However, in patients with persistent parent, stagger as though drunk, and exhibit pallor, diaphoresis, perceptual-postural dizziness as their primary symptom, SSRIs and frequent vomiting. Symptoms are worsened by head motion. appear to be effective.64 The episodes last less than 5 minutes, after which the child is Clinical trials have shown gabapentin (Neurontin) to be effective normal again. The symptoms usually present at the age of 2 to 3 at dosages of 1200 to 2400 mg/day,65 which is usually divided into years and gradually decrease until they resolve before the age of three doses daily. Dizziness, peripheral edema, and somnolence 8 years. When the clinical picture is clear, treatment is not needed. are common side effects. Six of seven of these patients followed long-term eventually develop Zonisamide is a sulfonamide anticonvulsant that is also a weak classic migraine.78 It should be noted that the standard VM criteria carbonic anhydrase inhibitor.66 The medication has been shown do not have any age restrictions; so, the diagnosis of VM can also to be effective for migraine prophylaxis and may be better tolerated be made in children.79 than topiramate.67 Similar to many migraine prophylaxis medica- tions, it is frequently started at a low dose such as 25 mg/day and slowly increased until effective doses are reached, which is frequently Paroxysmal Torticollis in the range of 100 to 400 mg/day. Snyder80 described a series of 12 infants who developed recurrent Valproic acid derivatives such as divalproex (Depakote) are attacks of head tilt before 8 months of age. The spells lasted effective in migraine prevention. However, the need to monitor from a few hours to 3 days and were occasionally accompanied levels and the side effect profile of these medications, which includes by pallor, vomiting, and agitation. Subsequent observers have nausea, fatigue, weight gain, teratogenicity, hepatic toxicity, and suggested a familial occurrence81 and that symptoms may also tremor, have made them to be infrequently used. involve the trunk and extremities.82 The spells usually stop Descargado para Anonymous User (n/a) en National Autonomous University of Mexico de ClinicalKey.es por Elsevier en junio 25, 2020. Para uso personal exclusivamente. No se permiten otros usos sin autorización. Copyright ©2020. Elsevier Inc. Todos los derechos reservados.  CHAPTER 168 Central Vestibular Disorders 2541 spontaneously by the age of 5 years, and no treatment is needed. C. The disorder is triggered by events that cause vertigo, More than half of these patients eventually develop migraine unsteadiness, dizziness, or problems with balance, including 168 symptoms.83 acute, episodic, or chronic vestibular syndromes, other neurologic or medical illnesses, and psychological distress. a. When triggered by an acute or episodic precipitant, symp- PERSISTENT POSTURAL-PERCEPTUAL DIZZINESS toms settle into the pattern of criterion A as the precipitant Persistent postural-perceptual dizziness (PPPD) is classified in resolves, but may occur intermittently at first, and then the International Classification of Vestibular Disorders (ICVD) consolidate into a persistent course. as a chronic functional vestibular disorder.84 It is characterized as b. When triggered by a chronic precipitant, symptoms may nonspinning vertigo that is perceived as unsteadiness or chronic develop slowly at first and worsen gradually. swaying.85 It is exacerbated by upright posture and is improved D. Symptoms cause significant distress or functional impairment. with sitting or lying down, hence the postural component. There E. Symptoms are not better accounted for by another disease or are usually no associated test findings, hence the perceptual disorder. component.86 These patients generally have a preceding vestibular insult, and their symptoms are exacerbated by complex visual Patients may have a difficult time articulating their symptoms. environments.85 The Bárány Society recently classified this They often describe a sense of swaying like they are on a boat, that diagnosis, which also has historical roots. they are light-headed, or feel like they may fall. They generally do not describe a spinning sensation as the predominant symptom. They report that if they sit or lay down, symptoms improve or resolve. Historical Perspective Visual hypersensitivity is often the most debilitating symptom In the 1870s, three German physicians described patients with of PPPD. Patients will frequently avoid situations that provoke syndromes of dizziness that were provoked by complex visual symptoms, which can lead to significant social and occupational environments and had associated anxiety and avoidance of triggering impact. There is frequently a phobic reaction to situations that situations.84 They focused on problems with postural control and exacerbate the symptoms. Vestibular testing is important to assess spatial orientation, psychological aspects, and neuro-ophthalmologic for other conditions that can coexist and precipitate PPPD.85 processes as core of these disorders.84 Almost 100 years later, Brandt and Dieterich defined phobic postural dizziness (PPD) as a disorder of unsteadiness accompanied by anxiety in patients Precipitants of PPPD with obsessive-compulsive traits.84 Another condition, termed There is often an episode of vertigo that precedes the development space-motion discomfort (SMD) was described as abnormal sen- into PPPD.85 A central or peripheral vestibular precipitant is found sitivity to motion stimuli and discomfort with spatial orientation.84 in 25% of patients with PPPD, and migraine-associated vertigo Bronstein described another disorder, termed visual vertigo (VV) is a precipitating cause in another 20% of patients.84 Diseases in patients who developed persistent unsteadiness and uneasiness such as Meniere disease, migraine-associated vertigo, and BPPV with complex visual environment after an acute vestibular insult.87 may cause episodic bouts of vertigo and must be distinguished Staab and Ruckenstein88 described CSD in 2007 as a condition of from the chronic symptoms of PPPD. These disorders can coexist. persistent unsteadiness with increased sensitivity to self-motion Acute vestibular conditions, such as vestibular neuronitis, can or motion in the environment. In 2006, a working group of the precipitate the chronic sequelae of PPPD.84 It is imperative that Bárány Society developed the first ICVD. This group evaluated the physician evaluates for the underlying vestibular disorder and these historical diagnoses and determined that there is a core set also be vigilant for the coexistence of the separate PPPD symptoms. of symptoms that delineate a distinct vestibular disorder, which Other times, PPPD is a manifestation of chronic illness, whether they termed PPPD.84 psychiatric or medical. Some commonly seen conditions are anxiety and depressive disorder. Panic attacks and generalized anxiety disorder are among the most common diagnoses that coexist with Diagnosing PPPD PPPD.85 Patients may present with PPPD after a prolonged medical Diagnosis of PPPD is not a diagnosis of exclusion. It is based on illness without an associated vestibular insult. criteria defined by the Bárány Society, which is obtained by patient history. Proper diagnosis requires that all conditions set by the Bárány Society must be met. Symptoms are dominated by a Pathophysiology nonvertiginous dizziness that is present for greater than 3 months The exact pathophysiology of PPPD is not clear; however, recent and causes significant distress.85,86 These symptoms are exacerbated studies have elucidated possible mechanisms that can lead to by upright posture, active or passive motion, and complex visual development of the disorder.85,89,90 Higher cortical systems appear patterns.84 They are preceded by a variety of conditions including to fail in modulating postural control, and there is a shift in those that can cause dizziness, and they are also preceded by other processing spatial orientation from relying more on visual input medical, psychiatric, or neurologic disorders.84 The Bárány Society than on vestibular input.85 The normal response to the onset of diagnostic criteria are as follows85: dizziness is to activate high-risk postural control strategies such as stiffening of the trunk and ankle muscles and to rely on visual A. One or more symptoms of dizziness, unsteadiness, or nonspinning or somatosensory input over vestibular input.85 An illustrative vertigo on most days for at least 3 months. example would be walking on a wide hiking trail that has a large a. Symptoms last for prolonged periods of time but may wax drop on either side. Although the trail is wide enough to walk and wane in severity. safely on, the fear of falling will cause a shorter stride, stiffer b. Symptoms need not be present continuously throughout posture, and visual and somatosensory vigilance. The normal the entire day. response is to relinquish these strategies when the threat abates, B. Persistent symptoms occur without specific provocation but but patients with PPPD tend to maintain these strategies. Patients are exacerbated by three factors: with high anxiety and neurotic personality traits are at greater a. Upright posture. risk of developing these maladaptive mechanisms.91 Brandt and b. Active or passive motion without regard to direction or Dieterich suggested that patients become sensitized to brief position. discrepancies in the perceived and actual postural control, and c. Exposure to moving visual stimuli or complex visual patterns. they exert an undue amount of effort to control posture. This Descargado para Anonymous User (n/a) en National Autonomous University of Mexico de ClinicalKey.es por Elsevier en junio 25, 2020. Para uso personal exclusivamente. No se permiten otros usos sin autorización. Copyright ©2020. Elsevier Inc. Todos los derechos reservados. 2542 PART VII Otology, Neurotology, and Skull Base Surgery leads to a maladaptive pattern of postural control92 and a cycle of distinguish from well-known end organ disorders. Clinical presenta- fear and avoidance manifested by anxiety and agoraphobia.93 tions vary for many reasons. Functional deficits may be restricted to one or both end organs or their parts, may involve the vestibular nuclei, or other peripheral or central regions. Diverse abnormal Treatment processes can result in permanent or temporary loss of function. The first step in treating patients with PPPD is to explain that this Permanent losses typically result from arterial occlusion or from is a well-known and treatable illness.85 Patients have frequently hemorrhagic infarction. Transient effects may accompany arterial been seen by many doctors and may be very frustrated by lack of stenosis, vascular spasm, inadequate perfusion pressure, or reversed diagnosis at prior visits. It is important to set these often anxious arterial flow with shunting such as subclavian steal syndrome. patients at ease by explaining a typical case history. Patients will Stroke is also more common in patients with migraine.97,98 Many usually find commonality with their symptoms and realize that symptom complexes are possible, but defined clinical entities are they have a doctor who understands their problem.85 A three- more common. pronged approach is found to be effective in treating these patients. The blood supply to the inner ear, brainstem, and cerebellum This includes vestibular rehabilitation, medication, and therapy.86 arises from the vertebrobasilar system. About half of vertebrobasilar Vestibular rehabilitation requires a physical therapist who is familiar transient ischemic attacks (TIAs) present with isolated vertigo, with PPPD, because the strategies differ from those used for a fixed which frequently lasts over an hour.99 Vertigo can occur from vestibular lesion. The exercises must be started slowly and gently. occlusion of any of the three major circumferential branches of They are aimed at breaking the abnormal postural reflexes and the vertebral or basilar arteries: the posterior inferior cerebellar reducing sensitivity and reliance on visual stimuli.86,94 Medication artery (PICA), the anterior inferior cerebellar artery (AICA), therapy consists of SSRIs and selective serotonin norepinephrine and the superior cerebellar artery (SCA) (Fig. 168.2). Vertigo due reuptake inhibitors (SSNRIs). These medications have been shown to loss of function of the inner ear is one potential cause. Blood to reduce dizziness and unsteadiness and have been studied in flow to the inner ear is provided by the internal auditory artery, multiple prospective, open-label studies.85 They can also help with which is a branch of AICA in 80% of people; in remaining individu- comorbid diagnosis of anxiety and depression. Cognitive behavioral als, it is a branch of PICA or directly from the basilar artery.100 therapy (CBT) helps patients identify situations that may trigger However, vertigo can occur with stroke even when inner ear dizziness, providing them with awareness that may allow them to function remains intact. prevent anxiety.86 One study has shown that CBT in combination with vestibular rehabilitation led to significant improvement in 75% of patients that was sustained over 6 months.95,96 Initial Evaluation Acute vestibular syndrome (AVS) is the sudden (over hours or faster) onset of vertigo, nausea/vomiting, gait unsteadiness, head VASCULAR DISORDERS motion intolerance, and nystagmus. This presentation most Abnormalities of blood flow to the vestibular system are relatively commonly occurs with vestibular neuritis, which is peripheral in common causes of vestibular symptoms and often are difficult to origin. Less than 1% of patients diagnosed with vertigo in the Anterior communicating artery Middle cerebral artery Anterior cerebral artery Oculomotor nerve Internal carotid artery (cranial nerve III) Posterior communicating artery Posterior cerebral artery Superior cerebellar artery Basilar artery Pontine arteries Internal auditory artery Vertebral artery Anterior inferior cerebellar artery Anterior spinal artery Posterior inferior cerebellar artery Fig. 168.2 The blood vessels supplying the brain. The brainstem is supplied by branches of the vertebral arteries and basilar artery. Note that while this figure shows the internal auditory artery arising directly from the basilar artery, it is commonly a branch off of the anterior inferior cerebellar artery instead. (From Kendell ER, Schwartz JH, Jessell TM: Principles of neural science, New York, 2000, McGraw-Hill, p 1303.) Descargado para Anonymous User (n/a) en National Autonomous University of Mexico de ClinicalKey.es por Elsevier en junio 25, 2020. Para uso personal exclusivamente. No se permiten otros usos sin autorización. Copyright ©2020. Elsevier Inc. Todos los derechos reservados.  CHAPTER 168 Central Vestibular Disorders 2543 emergency department developed a major vascular event during In most patients with nonacute presentation, treatment consists the subsequent 6 months.101 However, patients who are hospitalized of controlling risk factors such as diabetes, hypertension, and 168 for vertigo have a threefold higher risk for stroke than the general hyperlipidemia. In patients with symptomatic intracranial stenosis population.102 Although most AVS is not caused by a vascular of 50% to 99%, aspirin and warfarin are equally effective, but event, it is important to quickly differentiate vertigo of vascular warfarin caries a higher risk of hemorrhagic events115; thus, aspirin origin from peripheral vertigo such as vestibular neuritis. The is the treatment of choice. Anticoagulation with warfarin should presence of neurologic features such as ataxia, dysarthria, or other be considered if the patient has previously had an embolic stroke, neurologic signs can alert one to a vascular organ of AVS, but such which is cardiac in origin.110 Stenting of vertebral artery stenosis signs are absent in more than half of AVS presentations.103 Early has been tried with mixed results. Endarterectomy for extracranial imaging studies such as CT and MRI scans have a low sensitivity vertebral artery disease has also been successfully performed, but for acute infarction.104 indications for such procedures are still evolving. Head impulse testing can be important for differentiating peripheral and central vestibular lesions.105,106 The recently proposed HINTS extends this, and although the head impulse test remains Lateral Medullary Syndrome the most sensitive component, the combination is more sensitive The zone of infarction producing the lateral medullary syndrome than an early MRI.107 In this test, a head impulse test is performed (Wallenberg syndrome) consists of a wedge of the dorsolateral along with two other components. The examiner looks for nys- medulla just posterior to the olive (Fig. 168.3). The syndrome tagmus in primary gaze and lateral gaze and notes the presence usually results from occlusion of the ipsilateral vertebral artery and direction of nystagmus if present. The skew test involves the and rarely from occlusion of the PICA.116 Classic presentation examiner covering one of the patient’s eyes while they look at includes sensory deficits affecting the trunk and extremities on the examiner’s nose in primary gaze. A positive test will be if the the opposite side of the infarct and sensory and motor deficits uncovered eye deviates and then corrects when the other eye is affecting the face and cranial nerves ipsilateral to the infarct. uncovered. Another study found that in AVS if the horizontal Characteristic symptoms include vertigo, ipsilateral facial pain, head impulse test was normal (i.e., no catch-up saccade), there diplopia, dysphagia, and dysphonia. Neurologic examination may was skew deviation, abnormal vertical smooth pursuit, or central reveal an ipsilateral Horner syndrome, ipsilateral dysmetria, nystagmus (e.g., purely vertical or torsional nystagmus, nystagmus dysrhythmia, spontaneous nystagmus, and contra lateral loss of independent of gaze direction, and direction-changing nystagmus), pain and temperature sensation. there was a 100% sensitivity and 90% specificity for stroke.108 Hearing loss is not observed because the lesion is caudal to One potential limitation of HINTS is that most studies of it have the cochlear nerve entry zone and cochlear nuclei; thus, the AICA examined it in the hands of experts, and less experienced physicians is not involved. will find it more difficult to interpret.109 Some patients will develop a prominent motor disturbance that causes their body and extremities to deviate toward the lesion side as if being pulled by an invisible force.117 This so-called lateral Vertebrobasilar Insufficiency pulsion also affects the oculomotor system, producing excessively Vertebrobasilar insufficiency is a significant cause of vertigo in large saccades directed toward the side of the lesion and abnormally the elderly population.110,111 Vertigo due to vertebrobasilar insuf- small saccades away from the lesion. Most patients with Wallenberg ficiency has abrupt onset, usually lasts several minutes, and is syndrome have residual neurologic deficits months or even years frequently associated with nausea and vomiting. Presentation with after the acute infarction. vertigo symptoms alone is extremely uncommon and occurs in less than 1% of patients.112 Usually, multiple symptoms are present, which often include headache, diplopia, ataxia, numbness, weakness, Lateral Pontomedullary Syndrome or oropharyngeal dysfunction. Repeated episodes of vertigo can Ischemia in the distribution of the anteroinferior cerebellar artery be possible with TIAs113 but without other symptoms suggest (AICA) results in infarction of the dorsolateral pontomedullary another diagnosis. region and the inferolateral cerebellum.118 The middle cerebellar Atherosclerosis of the subclavian, vertebral, or basilar arteries peduncle is typically the core of the affected territory (Fig. 168.4). is usually the underlying cause of vertebrobasilar insufficiency. Because the labyrinthine artery (sometimes known as internal The distribution of large-artery atherosclerosis differs according auditory artery) originates from the AICA in 80% of patients,100 to race and gender.114 European men tend to have atherosclerosis combined loss of vestibular and auditory function occurs in at the origin of the vertebral arteries near the subclavian. Intracranial 60% of cases.119 Severe vertigo, nausea, and vomiting are common large-artery atherosclerosis is more common among African initial symptoms. Other symptoms include ipsilateral hearing loss, Americans, Asians, and women. Hypertension increases the risk tinnitus, facial paralysis, and cerebellar asynergy. Spontaneous of lipohyalinotic thickening of these vessels, which increases the nystagmus is common. Contralateral loss of pain and temperature risk of infarction. sensation may be caused by crossed spinothalamic fibers. Onset Rarely, occlusion or stenosis of the subclavian or innominate of symptoms is acute followed by gradual improvement. Vertigo artery just proximal to the origin of the vertebral artery results may persist for several weeks due to damage of the central in subclavian steal syndrome. In patients with this syndrome, ver- compensation mechanisms. tebrobasilar insufficiency results from siphoning of blood down the vertebral artery from the basilar system to supply the upper extremities. Vertigo and other symptoms are precipitated by exercise Cerebellar Infarction of the upper extremities. Occlusion of the vertebral artery, the PICA, AICA, or the SCA If a patient is suspected to have had a stroke, a CT scan should may result in infarction confined to the cerebellum without be ordered to rule out the possibility of a hemorrhagic event. brainstem involvement120 (Fig. 168.5). Initial symptoms are severe If a patient has presented within 3 hours after the onset of vertigo, vomiting, and ataxia. Lack of typical brainstem signs may symptoms, the National Institute for Neurological Disorders and cause an incorrect diagnosis of an acute peripheral labyrinthine Stroke (NINDS) guidelines recommend administration of t-PA disorder. The key to the diagnosis is the presence of prominent intravenously. However, recommendations in this area are rapidly cerebellar signs such as gait ataxia and paretic evoked nystagmus. evolving, and acute patients should be treated by a neurologist The diagnosis may be confirmed using MRI, although it may not familiar with stroke. be diagnostic in the acute setting.104 After a latent interval of 24 Descargado para Anonymous User (n/a) en National Autonomous University of Mexico de ClinicalKey.es por Elsevier en junio 25, 2020. Para uso personal exclusivamente. No se permiten otros usos sin autorización. Copyright ©2020. Elsevier Inc. Todos los derechos reservados. 2544 PART VII Otology, Neurotology, and Skull Base Surgery Medial longitudinal fasciculus Nucleus ambiguus (motor nucleus of CN IX and X) Nucleus of CN XII Vestibular nucleus Tractus solitarius with nucleus Olivocerebellar fibers Inferior cerebellar peduncle Descending tract of CN V Lateral medullary syndrome (posterior inferior cerebellar artery) Descending sympathetic tract Medial lemniscus CN X Medial medullary Dorsal spinocerebellar tract syndrome (paramedian branches of basilar artery) Ventral spinocerebellar tract Spinothalamic tract Inferior olive Pyramid CN XII Fig. 168.3 Medulla cross-section with anatomic structures labeled on the right and vascular lesions on the left. (From Kandel ER, Schwartz JH, Jessell TM: Principles of neural science, New York, 2000, McGraw-Hill, p 1303.) Nucleus of CN VI Medial longitudinal fasciculus Nucleus of CN VII Vestibular nucleus Lateral inferior pontine syndrome (anterior inferior cerebellar artery) Dorsal cochlear nucleus Spinal tract and nucleus of CN V Inferior cerebellar peduncle CN VIII CN VII Spinothalamic tract CN VI Medial inferior pontine syndrome Medial lemniscus (paramedian branches of basilar artery) Pontine nuclei and pontocerebellar fibers Corticospinal and corticobulbar tracts Fig. 168.4 Lower pons cross section: anatomic structures are labeled; common sites of some vascular lesions are shown on the left (shaded areas). CN, cranial nerve. (From Kandel ER, Schwartz JH, Jessell TM: Principles of neural science, New York, 2000, McGraw-Hill, p 1303.) to 96 hours, some patients develop progressive brainstem dysfunc- symptoms and features of nystagmus can be very heterogeneous.127 tion caused by compression by a swelling cerebellum. Progression The symptoms often spontaneously resolve within a few days.126 to quadriplegia, coma, and death may follow unless surgical decompression is performed. Cerebellar Hemorrhage Spontaneous intraparenchymal hemorrhage into the cerebellum Central Positional Vertigo causes neurologic symptoms that often rapidly progress to coma BPPV is a common cause of dizziness in which brief episodes of and death.128,129 The initial symptoms are severe vertigo, vomiting, vertigo occur related to head position, most commonly tilting the and ataxia.130 Similar to cerebellar infarction, brainstem signs may head backward or rolling over in bed toward the affected side (see not initially be present, which may cause the condition to be Chapter 167). Similar symptoms can also be brought on by central confused with a peripheral vestibular problem. However, unlike lesions of the dorsolateral fourth ventricle or the dorsal vermis.121 cerebellar infarction, cerebellar hemorrhage rarely causes AVS. This syndrome is often referred to as central positional vertigo, Modern imaging studies such as CT and MRI have revolutionized central positional nystagmus, or central paroxysmal positional the diagnosis of this condition (Fig. 168.6). Mortality ranges from vertigo. Suggestive features include unusual nystagmus that as low as 20%131 to 74% depending on the series. The value and may be short latency, atypical direction, not fatigable, and not indications for surgical intervention remain controversial and likely responsive to the Epley maneuver.122 This classically occurs with depend on the size and location of the hematoma as well as the isolated infarction,123-126 although other etiologies are possible. The patients’ symptoms.128 Descargado para Anonymous User (n/a) en National Autonomous University of Mexico de ClinicalKey.es por Elsevier en junio 25, 2020. Para uso personal exclusivamente. No se permiten otros usos sin autorización. Copyright ©2020. Elsevier Inc. Todos los derechos reservados.  CHAPTER 168 Central Vestibular Disorders 2545 Medial longitudinal fasciculus 168 Superior cerebellar peduncle Spinothalamic tract Lateral superior Lateral lemniscus pontine syndrome Central tegmental tract (superior cerebellar artery) Medial lemniscus Pontine nuclei and Medial superior pontocerebellar fibers pontine syndrome (paramedian Corticospinal tract branches of basilar artery) Fig. 168.5 Upper pons cross section: anatomic structures are labeled; common sites of some vascular lesions are shown on the left (shaded areas). (From Kandel ER, Schwartz JH, Jessell TM: Principles of neural science, New York, 2000, McGraw-Hill, p 1303.) presentations. It can present in patients who are at known risk for the condition such as those who have recently experienced trauma or those with known connective tissue disorders, although in many patients, there are no contributing factors. Thus, it is common for the condition to be initially mistaken for migraine or a musculoskeletal disorder.99 Although some cases are associated with sports injuries, abnormal head postures, or chiropractic manipulation, such history is present in fewer than half of presenta- tions. The annual incidence is thought to be about 1 in 100,000,133 and it accounts for about 2% of ischemic strokes. However, it is a relatively large fraction of strokes in patients younger than the age of 45 years, and the mean age at onset is 46 years,132 two decades younger than the general stroke population. The diagnosis of VAD can be made on CT or MRI angiography (see Fig. 168.9), although the appearance on imaging is frequently nonspecific.134 Antiplatelet and anticoagulation are considered reasonable first-line therapies, with endovascular treatment also possible.135 Imaging Physicians must suspect cerebrovascular disease when evaluating patients with acute spontaneous vertigo, particularly if they have Fig. 168.6 Noncontrast computed tomography of a cerebellar vascular risk factors. For patients with AVS, the initial bedside hematoma within the vermis. Surrounding edema and effacement of evaluation should include HINTS, which as previously described the superior aspect of the fourth ventricle exist. Resulting obstruction is more sensitive than an early CT or MRI imaging.107 When a of cerebrospinal fluid outflow may lead to hydrocephalus. (Courtesy of vascular event is suspected, imaging should be part of the workup. KD Flemming.) CT of the brain without contrast is often the first imaging test because it is widely available and shows intraparenchymal or subarachnoid blood. Hemorrhage can mimic any of the ischemic stroke syndromes and must be excluded with thin-section CT Vertebral Artery Dissection through the cerebellum, brainstem, and fourth ventricle. MRI Vertebral artery dissection (VAD) is frequently misdiagnosed and MRA are superior to CT for viewing the vertebrobasilar because presenting symptoms are often nonspecific and include vessels and their supplied structures because CT is often normal dizziness, neck pain, headache, and nausea or vomiting. Of these with cerebellar or brainstem infarction. MRI, on the other hand, symptoms, dizziness is the most frequent occurring in 58% of detects ischemic strokes in the brainstem and cerebellum early presentations,132 and the absence of any one symptom cannot rule on, as well as edema. Diffusion-weighted imaging with MRI can out VAD. In fact, in the majority of VAD patients, neck pain is now detect infarcts within the first hour of ischemia (Fig. 168.7). absent.132 The condition occurs when a tear occurs in the vertebral MRA has begun to replace conventional angiography in certain artery allowing blood to enter a false lumen in the wall of the circumstances. VAD and vertebral or basilar stenosis or occlusion artery and separate its layers, which can lead to stenosis or dilation can generally be identified with MRA of the cervical vessels of the vessel. It results in a stroke in about two thirds of performed with contrast (Fig. 168.8). Descargado para Anonymous User (n/a) en National Autonomous University of Mexico de ClinicalKey.es por Elsevier en junio 25, 2020. Para uso personal exclusivamente. No se permiten otros usos sin autorización. Copyright ©2020. Elsevier Inc. Todos los derechos reservados. 2546 PART VII Otology, Neurotology, and Skull Base Surgery R L A B Fig. 168.7 Magnetic resonance imaging of a lateral medullary infarction. (A) The FLAIR. (B) Diffusion- weighted images. Both show changes of an acute infarction involving the left dorsolateral medulla. (Courtesy of KD Flemming.) A B Fig. 168.8 (A) Frontal. (B) Lateral. Magnetic resonance angiogram showing a severe stenosis at the junction of the left vertebral artery (long arrow) and the basilar artery (short arrow). The right distal vertebral artery is also occluded (arrowhead). (From Lee H: Sudden bilateral simultaneous deafness with vertigo as a sole manifestation of vertebrobasilar insufficiency. J Neurol Neurosurg Psychiatry 74:540, 2003.) and treatment of vestibular neuromas is covered in depth elsewhere NEOPLASMS in this text. Space-occupying lesions can induce vestibular symptoms by compressing or by destroying neural tissue within the temporal bone, in the cerebellopontine angle, or intra-axially within the Brainstem Neoplasms brainstem and cerebellum. Symptoms can also be produced or Gliomas of the brainstem usually grow slowly and infiltrate the increased by vascular compression. brainstem nuclei and fiber tracts, producing progressive symptoms and signs. The typical history is relentlessly progressive involvement of one brainstem center after another, often causing death with Vestibular Schwannomas the destruction of the vital cardiorespiratory centers of the medulla. Vestibular schwannomas can present with vertigo symptoms, and These tumors are 5 to 10 times more common in children than these symptoms can be disabling in some patients,136 although in adults. Vestibular and cochlear signs and symptoms occur in they are present in less than 20% of patients with vestibular about half of patients; however, these patients will have many schwannomas.137 Vertigo symptoms are a predominating factor in other symptoms that indicate brainstem involvement. In the modern determining quality of life in this population.138 Although balance era, imaging studies such as CT or MRI are usually obtained dysfunction is also often present, the impact is probably less.139 when the first symptoms present, making the diagnosis obvious. These tumors can also present with hyperventilation-induced Tumors originating in the pons or midbrain are likely initially vertigo in the absence of hearing loss.140 Discussion of the diagnosis to cause long tract signs, cranial nerve deficits, and ataxia. Although Descargado para Anonymous User (n/a) en National Autonomous University of Mexico de ClinicalKey.es por Elsevier en junio 25, 2020. Para uso personal exclusivamente. No se permiten otros usos sin autorización. Copyright ©2020. Elsevier Inc. Todos los derechos reservados.  CHAPTER 168 Central Vestibular Disorders 2547 uncommon, tumors that originate in the medulla are likely to cause recurrent vertigo and vomiting. Radiation is the treatment DISORDERS OF THE CRANIOVERTEBRAL JUNCTION 168 of choice because surgical resection of this area is associated with Disorders of the craniovertebral junction are severe problems that significant morbidity. are poorly understood and relatively uncommon. The patients Tumors originating in the fourth ventricle and compressing frequently are referred to surgeons because of brainstem or lower the vestibular nuclei in its floor can also produce vestibular cranial nerve signs and symptoms such as tinnitus, vertigo, hearing symptoms. Medulloblastomas, occurring primarily in children and loss, pharyngeal dysfunction, hoarseness, or airway obstruction. adolescents, are rapidly growing, highly cellular tumors that Physical examination can be difficult and misleading, and radio- originate in the posterior midline or vermis of the cerebellum graphic findings are often not sufficient to establish a diagnosis. and invade the fourth ventricle and adjacent cerebellar hemispheres. An understanding of these problems may facilitate appropriate Headaches and vomiting occur early from obstructive hydrocephalus evaluation and prevention of inappropriate management such as and associated increased intracranial pressure. An attack of headache, middle ear explorations and endolymphatic sac surgery. vertigo, vomiting, and visual loss may result from a change in The physiologic problem common to these disorder