Treatment of Intractable Vertigo

Vertebrobasilar Insufficiency

Patients with vertebrobasilar occlusive disease most commonly have weakness in the extremities, ataxia, and oculomotor or oropharyngeal cranial nerve palsies. In these patients, vertigo is also a frequent finding. Patients with cerebellar infarctions may report vertigo, diplopia, nystagmus, nausea, and ataxic gait. Wallenberg syndrome, produced by unilateral infarction of the dorsolateral medulla, manifests with vertigo, hoarseness, ataxia, Horner syndrome, and loss of pain and temperature sensation ipsilaterally in the face but contralaterally in the trunk and limbs. Subclavian steal syndrome is an unusual variant of vertebrobasilar insufficiency that may cause vertigo, although the association is controversial.

Migrainous Vertigo

Migrainous vertigo is the second most common cause of recurrent vertigo and occurs in approximately 10% of all patients with migraine headaches. The disorder arises at any age and has a strong female preponderance. ^, During acute episodes, patients often exhibit nystagmus and a Romberg sign. Auditory symptoms are rarely present, but vague ear fullness is rather common. The clinical findings may be quite variable, thus making precise

diagnosis difficult, particularly given the fact that many times there is no associated headache. In fact, there is no broad consensus regarding diagnostic criteria for this disorder. Epidemiologic data indicate that (1) symptoms may be associated with typical migraine symptoms, including auras, photophobia, phonophobia, and severe headache; (2) the vertigo may be spontaneous or provoked by motion and last from seconds to several days; and (3) the temporal relationship between headache and the onset of vertigo may vary considerably. At present, there is no clear consensus regarding the treatment of migrainous vertigo, although many different therapeutic regimens have been studied.

Tumors

Tumors of the cerebellopontine angle are rare but potentially important causes of vertigo. These tumors more commonly produce ataxia and disequilibrium; however, they are believed to produce vertigo by a variety of mechanisms, including compression of the cerebellum or brainstem, invasion of the bony labyrinth, compression of the membranous labyrinth, or neoplastic transformation of the vestibular nerve itself. ^, Vestibular schwannomas, for instance, may cause unilateral hearing loss, tinnitus, and disequilibrium or vertigo, depending on the nature of the labyrinthine involvement. Intralabyrinthine schwannoma, a less common variant of vestibular schwannoma with only 47 reported cases since 1917, produces vertigo in the majority of patients.

Paraneoplastic Syndromes

Several paraneoplastic syndromes have been associated with vertigo, probably through an autoimmune mechanism. Paraneoplastic encephalomyelitis is an autoimmune disease associated with small cell lung cancer. The disease typically manifests with vertigo with other cranial nerve deficits secondary to degeneration of vestibular and cranial nerve nuclei. Paraneoplastic cerebellar degeneration is associated with lung cancer, lymphoma, and breast and ovarian cancer. Patients experience rapidly progressive symptoms, including vertigo, ataxia, oscillopsia, diplopia, dysarthria, and dysphagia. MRI typically reveals atrophy of the cerebellum. In some cases the vestibular symptoms produced by these disorders may precede the diagnosis of malignancy.

Demyelinating Disorders

Multiple sclerosis (MS) is a relatively uncommon cause of central vertigo. Although dizziness is a frequent complaint of patients with MS, only 5% to 10% of these patients experience true vertigo. Important to note, benign paroxysmal positional vertigo (BPPV) is frequently underappreciated in MS patients because the signs and symptoms of MS blur the distinction between central and peripheral causes of vertigo. ^,

Benign Paroxysmal Positional Vertigo

BPPV is the most common cause of recurrent vertigo. It can occur throughout life, with the peak age at onset during the fifth and sixth decades. The annual incidence of BPPV is 107 cases per 100,000 population, and it is twice as common in women as in men. Risk factors for BPPV include a history of vestibular neuritis or head trauma, although most cases are idiopathic.

BPPV is thought to result from canalithiasis in the majority of cases. Otoconia from the utricle dislodge and enter the endolymph of the semicircular canal system, most commonly the posterior semicircular canal, and stimulate flow of endolymph in response to changes in head position. An alternative form is cupulolithiasis, in which the dislodged otoconia adhere to the cupula ampullaris, thereby creating an abnormal mechanical stimulus that produces protracted deviation of the cupula in response to changes in the gravitational vector.

Canalithiasis accounts for vertigo elicited by particular rotational movements of the head. Common positional triggers include lying down, extension of the neck to look up, bending forward, and sitting up from a supine position. A typical vertiginous episode lasts from 10 to 30 seconds and is often associated with nausea and visible nystagmus. Episodes of vertigo often occur in clusters, with asymptomatic intervals between attacks. Several randomized placebo-controlled trials have demonstrated that a significant proportion of cases resolve spontaneously within a few months of onset, but the percentage of patients with self-limited cases varies considerably among these trials, ranging from 27% to 84%.

BPPV caused by posterior semicircular canalithiasis may be revealed through the Dix-Hallpike maneuver. Proposed in 1952, in this bedside maneuver the patient quickly moves from an upright seated to a supine position and then the head is turned to one side and slightly extended at the neck. The procedure is then repeated by turning the head to the other side and observing the patient for nystagmus. Patients with horizontal canal BPPV may not demonstrate nystagmus with this maneuver.

Meniere Disease

Endolymphatic hydrops, or Meniere disease, was first described by the Parisian physician Prosper Meniere in 1861. Meniere disease is relatively rare, with a prevalence of 218 per 100,000 persons. However, it is a relatively common cause of acute recurring episodic vertigo. Meniere disease may be overdiagnosed in the primary care setting.

The classic manifestation consists of recurrent episodes of spontaneous rotational vertigo coupled with fluctuating hearing loss, tinnitus, and aural fullness. The vertiginous episodes generally last several hours and are associated with nausea and

vomiting. Hearing loss is typically progressive, predominantly affects the lower frequencies initially, and may ultimately lead to unilateral deafness ( Fig. 128.1 ). Bilateral hearing loss develops in approximately 50% of patients. Management of bilateral cases is exceedingly complex.

Since its description, Meniere disease has been the subject of intense scientific inquiry. Even so, understanding its pathogenesis remains elusive. Current theories suggest that dysfunction of mechanisms governing the production and reabsorption of endolymph leads to distention and periodic rupture of the membranous labyrinth, which causes unilateral vestibular dysfunction. The cause of the dysfunction is unknown, although a viral insult in predisposed individuals has been proposed.

Labyrinthitis

The most common cause of labyrinthitis is viral infection. Viral labyrinthitis is classically described as a sudden onset of severe vertigo associated with nausea, vomiting, and auditory symptoms, including tinnitus and hearing loss. Identification of the viral pathogens responsible for viral labyrinthitis is an ongoing scientific endeavor, the principal challenge being the demonstration of Koch’s postulates for a variety of presumptive agents. ^,

Bacteria can infiltrate the labyrinth through direct extension from a nearby focus of infection (otitis media, otomastoiditis, or meningitis) to cause a more serious form of labyrinthine infection. Serous labyrinthitis is characterized by the sudden onset of vertigo in association with otitis media, but it causes only mild to moderate hearing loss. Suppurative bacterial labyrinthitis results in severe hearing loss, vertigo, nausea, and vomiting. Patients with suppurative labyrinthitis often appear toxic and febrile. Although viral labyrinthitis is a self-limited condition, bacterial labyrinthitis requires intravenous antibiotics and sometimes urgent surgical labyrinthectomy to prevent serious complications such as meningitis. Permanent hearing loss is inevitable.

Vestibular Neuritis

The clinical manifestation of vestibular neuritis involves the acute onset of vertigo over a period of hours, which becomes quite severe for several days before it gradually subsides. There may be a flu-like prodrome. Auditory symptoms (tinnitus, aural fullness, and hearing loss) are characteristically absent, which helps distinguish the disorder from labyrinthitis. The most likely cause of vestibular neuritis is viral infection of the superior division of the vestibular nerve. Patients with vestibular neuritis are predisposed to secondary forms of BPPV, an association suggestive of a viral mechanism for otoconial displacement.

Vestibular neuritis is often described as a self-limited condition that persists for several weeks, depending on the rate of vestibular compensation. However, chronic morbidity is a significant problem given that 30% to 40% of patients will develop persistent dizziness secondary to incomplete vestibular compensation, a condition termed uncompensated vestibular neuritis. ^, This distinction is particularly important for surgeons evaluating patients with intractable vertigo because patients with uncompensated vestibular neuritis are typically poor surgical candidates.

Perilymphatic Fistula

Perilymphatic fistula (PLF) is an abnormal connection between the fluid-filled inner ear and the air-filled tympanic cavity. First proposed a century ago by Meniere, PLF remains a controversial diagnosis among neuro-otologists. Previous studies have documented variable signs and symptoms, and it is often difficult to identify a definite site of leakage. Nonetheless, a recent meta-analysis of these studies has revealed certain clinical patterns: (1) patients report sudden loss or rapid deterioration of their hearing, (2) the hearing loss tends to involve fluctuations in speech discrimination, (3) dizziness is the most common symptom and is usually described as a continuous disequilibrium with occasional episodes of positional vertigo, and (4) most patients have a combination of symptoms. In a significant proportion of documented cases, patients exhibited the symptom constellation of fluctuating hearing loss, tinnitus, dizziness, and aural fullness. This clustering of symptoms is very similar to Meniere disease, thus confounding accurate diagnosis and treatment of these patients.

Risk factors for this disorder include a history of stapedectomy surgery, penetrating middle ear trauma, and barotrauma.