Cervicogenic causes of vertigo.

PURPOSE OF REVIEW: Herein we discuss the recent literature concerning cervicogenic vertigo including vertigo associated with rotational vertebral artery syndrome, as well as whiplash and degenerative disturbances of the cervical spine. We conclude with a summary of progress regarding diagnostic methods for cervicogenic vertigo. RECENT FINDINGS: Several additional single case studies of the exceedingly rare rotational vertebral artery syndrome have been added to the literature over the last year. Concerning whiplash and degenerative disturbances of the cervical spine, four reviews were published concerning using physical therapy as treatment, and two reviews reported successful surgical management. Publications regarding diagnostic methodology remain few and unconvincing, but the cervical torsion test appears the most promising. SUMMARY: Little progress has been made over the last year concerning cervicogenic vertigo. As neck disturbances combined with dizziness are commonly encountered in the clinic, the lack of a diagnostic test that establishes that a neck disturbance causes vertigo remains the critical problem that must be solved.

Clinical characteristics of cervicogenic-related dizziness and vertigo.

Cervical vertigo has long been a controversial entity and its very existence as a medical entity has advocates and opponents. Supporters of cervical vertigo claim that its actual prevalence is underestimated due to the overestimation of other diagnostic categories in clinics. Furthermore, different pathophysiological mechanisms have been attributed to cervical vertigo. Here the authors discuss the clinical characteristics of rotational vertebral artery vertigo, postwhiplash vertigo, proprioceptive cervical vertigo, and cervicogenic vertigo of old age. A clinical entity named subclinical vertebrobasilar insufficiency appears in the context of cervical osteoarticular changes. Migraine-associated vertigo may explain why some patients suffering from cervical pain have vertigo while others do not.

Bilateral vestibular loss.

Bilateral vestibular loss is a rare cause of visual disturbance (oscillopsia) and imbalance. When severe, the most common cause is iatrogenic-gentamicin ototoxicity. Bilateral loss is easily diagnosed at the bedside with the dynamic illegible E test. If this test is omitted, it can easily be misdiagnosed as a cerebellar syndrome. Treatment is largely supportive. Care should be taken to avoid medications that suppress vestibular function, and to encourage activity.

Vestibular Testing.

PURPOSE OF REVIEW: Vestibular testing, both at the bedside and in the laboratory, is often critical in diagnosing patients with symptoms of vertigo, dizziness, unsteadiness, and oscillopsia. This article introduces readers to core concepts, as well as recent advances, in bedside and instrumented vestibular assessments. RECENT FINDINGS: Vestibular testing has improved immensely in the past 2 decades. While history and bedside testing is still the primary method of differential diagnosis in patients with dizziness, advances in technology such as the ocular vestibular-evoked myogenic potential test for superior canal dehiscence and the video head impulse test for vestibular neuritis have capabilities that go far beyond the bedside examination. Current vestibular testing now allows clinicians to test all five vestibular sensors in the inner ear. SUMMARY: Contemporary vestibular testing technology can now assess the entire vestibular periphery. Relatively subtle conditions, such as superior canal dehiscence or a subtle vestibular neuritis, can now be diagnosed with far greater certainty.

Square wave manoeuvre for apogeotropic variant of horizontal canal benign paroxysmal positional vertigo in neck restricted patients.

OBJECTIVE: We aimed to describe the clinical features of the apogeotropic variant of horizontal canal benign paroxysmal positional vertigo (HC BPPV-AG) in a cluster of patients with restrictive neck movement disorders and a new therapeutic manoeuvre for its management. METHODS: In a retrospective review of cases from an ambulatory tertiary referral center, patients with HC BPPV-AG in combination with neck movement restriction that prevented any classical manual repositioning procedure or who were refractory to canalith repositioning manoeuvres, were treated with a new manoeuvre comprised of sequential square-wave pattern of head and body supine rotations while nystagmus was being monitored, until either an apogeotropic to geotropic conversion or resolution of the nystagmus was observed. RESULTS: Fifteen patients were studied. All but one [14/15 cases] showed a positive therapeutic response to the repositioning procedure in a single session. In two cases, a direct relief of vertigo and elimination of nystagmus was observed without an intermediate geotropic phase. Although in three patients the affected ear was not initially identified, it was ultimately identified and successfully treated by the square wave manoeuvre in all of them. CONCLUSIONS: The square-wave manoeuvre is an alternative for HC BPPV-AG treatment in either cases with neck restriction, where the affected side is not well identified at the bedside or when other manoeuvres fail to resolve the HC BPPV-AG.

Severity of Downgaze Palsy in the Context of Disease Duration Could Estimate Survival Duration in Patients With Progressive Supranuclear Palsy.

It is an unmet need to estimate survival duration for patients with progressive supranuclear palsy (PSP). The objective of this study was to identify factors associated with the survival duration in patients with PSP. We followed up 23 patients with probable PSP-RS (Richardson syndrome) or PSP-P (parkinsonism) in our PSP center until death from 2011 to 2019. We prospectively and quantitatively rated their downgaze palsy whenever first noticed in our clinic. This was utilized along with the disease duration, motor function, medication use for parkinsonism, sex, age at onset of PSP, comorbid pulmonary and cardiovascular diseases, and the total survival duration from the onset of PSP to death for prediction analysis. A well-fitted linear regression model and a multivariant Cox model were applied to identify predicting factors for total survival duration. All patients had the specific hummingbird sign on brain MRI for PSP when downgaze palsy was documented. We found that the severity of downgaze palsy and the disease duration at the assessment were consistently correlated with the total survival duration in both models. The total survival duration could be further estimated by a formed regression equation. We conclude that severity and time to develop downgaze palsy could help to estimate the total survival duration in patients with probable PSP-RS and PSP-P, the major forms of PSP, which has significant clinical applications in clinical counseling and trial enrollment.

Symptoms in cervical vertigo.

OBJECTIVE: To use a unique, 41-question survey to identify patient features distinguishing cervical vertigo from vestibular causes of vertigo and vestibular migraine. METHODS: In this study, a unique, 41-question survey was administered to 48 patients diagnosed with cervical vertigo (n = 16), migraine (n = 16), and vestibular vertigo (eg, unilateral vestibular paresis, Meniere's disease) (n = 16) to test the hypothesis that a set of distinct symptoms can characterize cervical vertigo. Responses between the three diagnostic groups were compared to identify questions which differentiated patients based on their symptoms. RESULTS: Eight questions were successful in differentiating vestibular vertigo from migraine and cervical vertigo. Symptoms endorsed by subjects with cervical vertigo overlapped substantially with subjects with well-established vestibular disturbances as well as symptoms of subjects with migraine. Twenty-seven percent of cervical vertigo subjects reported having true vertigo, 50% having headache, and 94% having neck pain. CONCLUSION: Lacking knowledge of neck disturbance, the symptoms we elicited in our questionnaire suggest that cervical vertigo subjects may resemble migraine subjects who also have evidence of neck injury. Whether or not subjects with "cervical vertigo" also overlap with other diagnoses defined by a combination of symptoms and exclusion of objective findings such as chronic subjective dizziness and other variants of psychogenic dizziness remain to be established. LEVEL OF EVIDENCE: IV.

Interactions between auditory and somatosensory feedback for voice F0 control.

Previous studies have demonstrated the importance of both kinesthetic and auditory feedback for control of voice fundamental frequency (F0). In the present study, a possible interaction between auditory feedback and kinesthetic feedback for control of voice F0 was tested by administering local anesthetic to the vocal folds in the presence of perturbations in voice pitch feedback. Responses to pitch-shifted voice feedback were larger when the vocal fold mucosa was anesthetized than during normal kinesthesia. A mathematical model incorporating a linear combination of kinesthesia and pitch feedback simulated the main aspects of our experimental results. This model indicates that a feasible explanation for the increase in response magnitude with vocal fold anesthesia is that the vocal motor system uses both pitch and kinesthesia to stabilize voice F0 shortly after a perturbation of voice pitch feedback has been perceived.

Role of loading on head stability and effective neck stiffness and viscosity.

This experiment tests the hypothesis that loading the head would increase head stability. In particular, we hypothesized that an arrangement of the head so that muscle activation is required to counteract a load would significantly increase effective neck stiffness and viscosity, which would be associated with lower peak head angular velocity following abrupt force perturbations applied to the head. Seven young healthy subjects had their head loaded (preload) using a weight/pulley apparatus. Then, the head was pulled either forward or backward by dropping an additional weight onto the preload, causing an impulse of force followed by an increase in load. We recorded the applied force and head angular velocity. Neck viscoelastic properties as a function of loading were estimated by fitting experimental data to a second-order mathematical model of the head biomechanics. Across preloads varying from 2.22 to 8.89 N, peak head angular velocity decreased by 18.2% for the backward and by 19.9% for forward perturbations. As preload increased, simulated effective neck stiffness and viscosity significantly increased leading to lower peak angular velocity. These results demonstrated that loading reduces peak head angular velocity and that change in muscle stiffness and viscosity is a feasible explanation for this effect. We propose that reduction in peak head velocity could be caused by modulation of the strength of the vestibulo-collic reflex.

The Gain-Time Constant Product Quantifies Total Vestibular Output in Bilateral Vestibular Loss.

Patients with inner ear damage associated with bilateral vestibular impairment often ask "how much damage do I have." Although there are presently three clinical methods of measuring semicircular canal vestibular function; electronystagmography (ENG or VENG), rotatory chair and video head-impulse (VHIT) testing; none of these methods provides a method of measuring total vestibular output. Theory suggests that the slow cumulative eye position can be derived from the rotatory chair test by multiplying the high frequency gain by the time constant, or the "GainTc product." In this retrospective study, we compared the GainTc in three groups, 30 normal subjects, 25 patients with surgically induced unilateral vestibular loss, and 24 patients with absent or nearly absent vestibular responses due to gentamicin exposure. We found that the GainTc product correlated better with remaining vestibular function than either the gain or the time constant alone. The fraction of remaining vestibular function was predicted by the equation R = (GainTc/11.3) - 0.6. We suggest that the GainTc product answers the question "how much damage do I have," and is a better measure than other clinical tests of vestibular function.

Bilateral Vestibular Weakness.

Bilateral vestibular weakness (BVW) is a rare cause of imbalance. Patients with BVW complain of oscillopsia. In approximately half of the patients with BVW, the cause remains undetermined; in the remainder, the most common etiology by far is gentamicin ototoxicity, followed by much rarer entities such as autoimmune inner ear disease, meningitis, bilateral Ménière's disease, bilateral vestibular neuritis, and bilateral vestibular schwannomas. While a number of bedside tests may raise the suspicion of BVW, the diagnosis should be confirmed by rotatory chair testing. Treatment of BVW is largely supportive. Medications with the unintended effect of vestibular suppression should be avoided.

Fluctuating Vestibulo-Ocular Reflex in Ménière's Disease.

OBJECTIVES: To describe the fluctuating high velocity vestibular ocular-reflex (VOR) during the Ménière's attacks and correlate those features with pathophysiology. PATIENTS: A patient with unilateral Ménière's disease (MD) was evaluated closely during and after acute vertigo episodes. MAIN OUTCOME MEASURES: The spontaneous nystagmus and the dynamic VOR changes were measured by the video head impulse test (VHIT) at different stages of the vertigo crisis and during the quiescent phase of the condition. RESULTS: During the Ménière's attack, the VOR gain showed large changes on the affected side; however, on recovery a return to the normal value was evident. The VOR gain also showed fluctuation on follow up, paralleling symptoms. The greatest reduction of the VOR was during the paralytic nystagmus phase. CONCLUSIONS: The present case documents rapid vestibular fluctuation documented with VHIT testing in MD. The ionic-chemical perilymphatic intoxication and the endolymphatic space collapse due to membrane rupture could explain those features. VHIT fluctuation is a promising tool for diagnosis of patients with episodic vestibular symptoms.

Clinical implications of a mathematical model of benign paroxysmal positional vertigo.

Benign paroxysmal positional vertigo (BPPV) is the most commonly diagnosed vertigo syndrome. It is caused by movement of detached otoconia within the inner ear (canalithiasis) or otoconia adherent to the cupula (cupulolithiasis). A mathematical model incorporating fluid dynamics of BPPV, which results in the following insights, has been developed recently: (1) The characteristic latency of BPPV is explained by movement of detached otoconia through the ampulla, as pressure caused by moving otoconia is negligible until otoconia enter the narrow duct of the semicircular canal. Typical otoconia move at a rate of 0.2 mm/s, or about 1% of the circumference of the canal each second. (2) Particle-wall interactions can account for the considerable variability in duration and latency of BPPV. (3) Dispersion of a clump of otoconia creates more rather than less nystagmus. Thus, dispersion is not a viable explanation of fatigability. (4) Cupulolithiasis is predicted to cause a far weaker nystagmus than canalithiasis. (5) Inertial effects of treatment maneuvers cause negligible movement of otoconia.

Delayed quick spins after vestibular nerve section respond to anticonvulsant therapy.

OBJECTIVE: To describe the clinical features of patients with failed vestibular nerve section that have a response to anticonvulsant medication. STUDY DESIGN: Retrospective case review. SETTING: Ambulatory tertiary referral center. PATIENTS: We report three patients who were afflicted with frequent brief spinning spells, or "quick spins," after vestibular neurectomy for Meniere's disease. INTERVENTION: Treatment with anticonvulsants. MAIN OUTCOME MEASURE: Relief of vertigo. RESULTS: All cases had an excellent therapeutic response to carbamazepine or oxcarbazepine, agents conventionally used for neuralgia, suggesting that these symptoms are caused by a hyperexcitable vestibular nerve. CONCLUSION: Treatment of neuralgia should be considered when the symptom of quick spins arises after vestibular neurectomy.

Pharmacological treatment of vertigo.

This review discusses the physiology and pharmacological treatment of vertigo and related disorders. Classes of medications useful in the treatment of vertigo include anticholinergics, antihistamines, benzodiazepines, calcium channel antagonists and dopamine receptor antagonists. These medications often have multiple actions. They may modify the intensity of symptoms (e.g. vestibular suppressants) or they may affect the underlying disease process (e.g. calcium channel antagonists in the case of vestibular migraine). Most of these agents, particularly those that are sedating, also have a potential to modulate the rate of compensation for vestibular damage. This consideration has become more relevant in recent years, as vestibular rehabilitation physical therapy is now often recommended in an attempt to promote compensation. Accordingly, therapy of vertigo is optimised when the prescriber has detailed knowledge of the pharmacology of medications being administered as well as the precise actions being sought. There are four broad causes of vertigo, for which specific regimens of drug therapy can be tailored. Otological vertigo includes disorders of the inner ear such as Ménière's disease, vestibular neuritis, benign paroxysmal positional vertigo (BPPV) and bilateral vestibular paresis. In both Ménière's disease and vestibular neuritis, vestibular suppressants such as anticholinergics and benzodiazepines are used. In Ménière's disease, salt restriction and diuretics are used in an attempt to prevent flare-ups. In vestibular neuritis, only brief use of vestibular suppressants is now recommended. Drug treatments are not presently recommended for BPPV and bilateral vestibular paresis, but physical therapy treatment can be very useful in both. Central vertigo includes entities such as vertigo associated with migraine and certain strokes. Prophylactic agents (L-channel calcium channel antagonists, tricyclic antidepressants, beta-blockers) are the mainstay of treatment for migraine-associated vertigo. In individuals with stroke or other structural lesions of the brainstem or cerebellum, an eclectic approach incorporating trials of vestibular suppressants and physical therapy is recommended. Psychogenic vertigo occurs in association with disorders such as panic disorder, anxiety disorder and agoraphobia. Benzodiazepines are the most useful agents here. Undetermined and ill-defined causes of vertigo make up a large remainder of diagnoses. An empirical approach to these patients incorporating trials of medications of general utility, such as benzodiazepines, as well as trials of medication withdrawal when appropriate, physical therapy and psychiatric consultation is suggested.

A mathematical model for top-shelf vertigo: the role of sedimenting otoconia in BPPV.

Benign paroxysmal positional vertigo (BPPV) is a mechanical disorder of the vestibular system in which calcite particles called otoconia interfere with the mechanical functioning of the fluid-filled semicircular canals normally used to sense rotation. Using hydrodynamic models, we examine the two mechanisms proposed by the medical community for BPPV: cupulolithiasis, in which otoconia attach directly to the cupula (a sensory membrane), and canalithiasis, in which otoconia settle through the canals and exert a fluid pressure across the cupula. We utilize known hydrodynamic calculations and make reasonable geometric and physical approximations to derive an expression for the transcupular pressure DeltaPc exerted by a settling solid particle in canalithiasis. By tracking settling otoconia in a two-dimensional model geometry, the cupular volume displacement and associated eye response (nystagmus) can be calculated quantitatively. Several important features emerge: (1) a pressure amplification occurs as otoconia enter a narrowing duct; (2) an average-sized otoconium requires approximately 5 s to settle through the wide ampulla, where DeltaPc is not amplified, which suggests a mechanism for the observed latency of BPPV; and (3) an average-sized otoconium beginning below the center of the cupula can cause a volumetric cupular displacement on the order of 30 pL, with nystagmus of order 2 degrees/s, which is approximately the threshold for sensation. Larger cupular volume displacement and nystagmus could result from larger and/or multiple otoconia.

Prevalence of thyroid dysfunction in patients with Ménière's disease.

OBJECTIVE: To estimate the prevalence of hypothyroidism in a population of patients with Ménière's disease (MD). DESIGN: Retrospective case-control study comparing the use of thyroid hormone supplements between patients with MD and controls. SETTING: Outpatient neurology clinic specializing in the management of patients experiencing dizziness. PATIENTS: Fifty patients who met the 1995 American Academy of Otolaryngology criteria for MD and 50 controls matched for age and sex also experiencing dizziness. RESULTS: The 50 patients who met the criteria for MD were identified from a database of more than 2000 patients with dizziness seen over a 5-year period. Of these, 16 (32%) were taking thyroid hormone supplements in contrast to 2 (4%) of the 50 matched controls (P<.001). The median age of the patients with MD was 60 years, and 5 (19%) of the 26 patients younger than 60 years were taking thyroid hormone supplements, compared with 11 (46%) of 24 patients 60 years or older (P<.05). There were no statistically significant differences in the severity of hearing loss, pattern of hearing loss, or prevalence of bilateral hearing loss between patients with MD who were taking thyroid hormone supplements and patients with MD who were not. CONCLUSION: Ménière's disease is associated with corrected hypothyroidism.

Neurophysiology of vestibular rehabilitation.

The vestibular system is a sophisticated human control system. Accurate processing of sensory input about rapid head and postural motion is critical. Not surprisingly, the body uses multiple, partially redundant sensory inputs and motor outputs, combined with a very competent central repair capability. The system as a whole can adapt to substantial peripheral vestibular dysfunction. The Achilles' heel of the vestibular system is a relative inability to repair central vestibular dysfunction.

Migraine-associated vertigo.

This article presents a brief overview of migraine-associated vertigo for the practicing otolaryngologist. Discussion includes the definition of migraine-associated vertigo and its pathophysiology, clinical features, demographics, findings on physical examination, use of otologic and vestibular testing, differential diagnosis, treatment, and prognosis.