Hyperventilation-induced nystagmus in peripheral vestibulopathy and cerebellopontine angle tumor

Can hyperventilation test and duration of spontaneous nystagmus help differentiate between vascular and inflammatory aetiology of acute unilateral vestibular deficit?

Objective

To relate clinically the duration of spontaneous nystagmus and hyperventilation-induced nystagmus (HVIN) to vascular or inflammatory aetiology of acute unilateral vestibulopathy observed in a very early stage.

Methods

This is a retrospective study on 198 patients with acute unilateral vestibulopathy.

Results

In the short-lasting nystagmus group (spontaneous nystagmus < 48 h), mean age and cardiovascular risk were significantly higher; the rates of negative HVIN and paretic HVIN were 41.7% and 58.3%, respectively. In the long-lasting nystagmus group (spontaneous nystagmus > 48 h), mean age and vascular risk were lower; HVIN was absent in 12.6% of the cases, HVIN excitatory patterns were observed in 40.3% of cases and a paretic pattern in 47.1%.

Conclusions

A vascular aetiology should be considered the most likely in patients with spontaneous nystagmus < 48 hours: all patients were > 60 years old, cardiovascular risk was higher and HVIN was always absent or paretic. In the group with nystagmus > 48 hours, similarly, data indicate a higher incidence of paretic HVIN in older patients and higher vascular risk, even if the data does not allow us to lean clearly towards one of the two aetiological hypotheses.

Vestibular paroxysmia: clinical characteristics and long-term course

In 2016, the Bárány Society defined new diagnostic criteria for the neurovascular compression syndrome of the eighth nerve, called “vestibular paroxysmia” (VP), differentiating between definite (dVP) and probable (pVP) forms. The aim of this study was (1) to describe clinical symptoms and laboratory findings in a well-diagnosed large patient cohort according to those criteria, and (2) to evaluate the long-term course over years in dVP. We identified 146 patients (73 dVP, 73 pVP) from our tertiary dizziness center registry. Data of structured history-taking, clinical neurological, neuro-ophthalmological/-otological examinations as well as MRI imaging were extracted for analyses. Overall, attack frequency ranged between 5 and 30 attacks per day; spinning vertigo was the most frequent type. In two-thirds of patients, attacks occurred spontaneously; in one-quarter, they were triggered by head movements. The majority (approximately 70%) reported no accompanying symptoms; in those with symptoms, mild unilateral cochlear symptoms prevailed. One-third of patients initially showed hyperventilation-induced nystagmus without specific direction, and a deviation of the subjective visual vertical between 3° and 6°. Complete loss of peripheral vestibular function was never evident. dVP and pVP significantly differed concerning the vertigo type, e.g., spinning vertigo was more frequent in dVP. Fortunately, three-quarters of dVP patients remained attack-free during follow-up (mean 4.8 years, standardized questionnaire), more than half of them even without any medication. Patients with ongoing attacks showed significantly higher attack frequency at baseline, but reported persistent frequency reduction. Overall, the long-term prognosis of VP appears favorable, not necessarily requiring ongoing treatment.

Episodic Vestibular Syndrome with Hyperventilation-Induced Downbeat Nystagmus

Hyperventilation-induced downbeat nystagmus (HV-DBN) has been reported in cerebellar disorders and explained by a loss of the inhibitory cerebellar output via a metabolic effect on cerebellar Ca²⁺ channels. The aim of this study was to determine the clinical characteristics and underlying pathogenesis of episodic vestibular syndrome (EVS) with HV-DBN. Of 667 patients with EVS, we recruited 22 with HV-DBN and assessed their clinical characteristics, video-oculographic findings, and the results of molecular genetic analyses. The age at symptom onset was 47.5 ± 13.0 years (mean ± SD), and there was a female preponderance (n = 15, 68%). The duration of vertigo/dizziness attacks ranged from minutes to a few days, and 11 patients (50%) fulfilled the diagnostic criteria for vestibular migraine. HV-induced new-onset DBN in 8 patients, while the remaining 14 showed augmentation of spontaneous DBN by HV. The maximum slow-phase velocity of HV-DBN ranged from 2.2 to 11.9°/s, which showed a statistical difference with that of spontaneous DBN (median = 4.95, IQR = 3.68-6.55 vs. median = 1.25, IQR = 0.20-2.15, p < 0.001). HV-DBN was either purely downbeat (n = 11) or accompanied with small horizontal components (n = 11). Other neuro-otologic findings included perverted head-shaking nystagmus (n = 11), central positional nystagmus (n = 7), saccadic pursuit (n = 3), and horizontal gaze-evoked nystagmus (n = 1). Gene expression profiling with a bioinformatics analysis identified 43 upregulated and 49 downregulated differentially expressed genes (DEGs) in patients with EVS and HV-DBN and revealed that the downregulated DEGs were significantly enriched in terms related to the ribosome pathway. Our results suggest that the underlying cerebellar dysfunction would be responsible for paroxysmal attacks of vertigo in patients with EVS and HV-DBN.

Video Head Impulse Test in Vestibular Schwannoma: Relevance of Size and Cystic Component on Vestibular Impairment

OBJECTIVES

Tumor factors that influence vestibular function in vestibular schwannoma (VS) have not been properly described. We evaluated whether cystic VSs have different vestibular function than solid VS. Tumor size on vestibular function was also evaluated.

STUDY DESIGN

Cross-sectional study.

SETTING

Tertiary referral center.

PATIENTS

Forty-one cases of sporadic, untreated VS.

INTERVENTION

Evaluation with video head impulse test and MRI.

MAIN OUTCOME MEASURES

Tumors were classified as solid, heterogeneous, or cystic and by size using the Hannover classification. Vestibulo-ocular reflex (VOR) gain was correlated to tumor size and cystic status.

RESULTS

Large VS had worse VOR gain than small lesions (p < 0.001). Cystic lesions had lower VOR gain than all other tumors (p = 0.001), Hannover T3 and T4 (p = 0.014), Hannover T4 (p = 0.015), solid tumors (p < 0.001), solid Hannover T3 and T4 (p = 0.003), and solid Hannover T4 (p = 0.008). Heterogeneous VSs had lower VOR gain compared to solid tumors (p = 0.02), solid Hannover T3 and T4 (p = 0.08), and solid Hannover T4 (p = 0.14). Heterogeneous and cystic VSs had lower VOR gain than solid tumors (p < 0.001), solid Hannover T3 and T4 (p = 0.004), and solid Hannover T4 (p = 0.02). VOR gain of solid T4 lesions was not significantly lower than solid Hannover T1-T3 (p = 0.33).

CONCLUSION

Cystic status is directly associated with a worse vestibular dysfunction. Size did not significantly impact vestibular function in solid VS.

An Algorithm for the Diagnosis of Vestibular, Cerebellar, and Oculomotor Disorders Using a Systematized Clinical Bedside Examination

The bedside examination associated with their clinical history remains the most critical means to accurately diagnose the cause for most of the signs and symptoms related to pathology of the cerebellum and vestibular system in patients presenting with dizziness and imbalance. This paper focuses on those critical bedside examinations, suggests when laboratory testing might be useful to confirm the clinical suspicion, and considers the shared neural circuitry within the visual and vestibular systems to offer an algorithmic approach in conducting the clinical bedside examination.

When the Room Is Spinning: Experience of Vestibular Neuritis by a Neurotologist

Vestibular neuritis (VN) is the most common cause of acute prolonged spontaneous vertigo, and is characterized by acute unilateral vestibular hypofunction, probably due to inflammation of the vestibular nerve. VN is diagnosed at the bedside when there is spontaneous horizontal-torsional nystagmus beating away from the side of the lesion, abnormal head impulse tests for the semicircular canals involved on the lesion side, and when other neurological symptoms and signs are absent. Here, as a neuro-otologist, I describe my experience during an attack of VN and discuss how it may help physicians to better understand why and what a patient feels during attacks of vertigo.

Classification of vestibular signs and examination techniques: Nystagmus and nystagmus-like movements

This paper presents a classification and definitions for types of nystagmus and other oscillatory eye movements relevant to evaluation of patients with vestibular and neurological disorders, formulated by the Classification Committee of the Bárány Society, to facilitate identification and communication for research and clinical care. Terminology surrounding the numerous attributes and influencing factors necessary to characterize nystagmus are outlined and defined. The classification first organizes the complex nomenclature of nystagmus around phenomenology, while also considering knowledge of anatomy, pathophysiology, and etiology. Nystagmus is distinguished from various other nystagmus-like movements including saccadic intrusions and oscillations.

View accompanying videos at http://www.jvr-web.org/ICVD.html

Approach to the Examination and Classification of Nystagmus

BACKGROUND AND PURPOSE

Physical therapists caring for patients with neurologic or vestibular disorders must routinely examine and characterize nystagmus and other oscillatory eye movements. Often, the diagnosis hinges on proper interpretation of the nystagmus pattern. This requires understanding the terminology surrounding the numerous attributes and influencing factors of nystagmus, a systematic approach to the examination, and a classification structure that guides practitioners to the specific nystagmus type and subsequent evaluation and management.

SUMMARY OF KEY POINTS

Nystagmus is an involuntary, rapid, rhythmic, oscillatory eye movement with at least 1 slow phase. Jerk nystagmus has a slow phase and a fast phase. Pendular nystagmus has only slow phases. Nystagmus is distinguished from other types of oscillatory eye movements, such as saccadic intrusions or oscillations. Characterizing nystagmus requires clearly describing its trajectory. This includes choosing a reference frame to describe the axes or planes and direction of eye movements. Several attributes are used to describe nystagmus: binocularity, conjugacy, velocity, waveform, frequency, amplitude, intensity, temporal profile, and age at first appearance. Several factors may influence nystagmus, including gaze position, visual fixation, vergence, and a variety of provocative maneuvers. Classification of nystagmus may be organized by physiologic or pathologic nystagmus versus other nystagmus-like movements. Pathologic nystagmus may be spontaneous, gaze-evoked, or triggered by provocative maneuvers. The combination of attributes allows differentiation between the many peripheral and central forms.

RECOMMENDATIONS FOR CLINICAL PRACTICE

Therapists should carefully examine and characterize the trajectory and other attributes and influencing factors of nystagmus to accurately classify it and arrive at the correct diagnosis.

Vertigo Induced During Coitus

Objectives: The aim of this study was to describe the clinical features of vertigo developed during sexual intercourse. Methods: We retrospectively reviewed the clinical and laboratory findings of seven patients who reported recurrent vertigo during sexual intercourse. Results: All the patients reported spinning sensation for a few minutes to 1 h, which developed during the coitus. Most patients (6/7, 86%) reported associated auditory symptoms including tinnitus (n = 4), ear fullness (n = 2), autophony (n = 1), hearing impairment (n = 1), or hyperacusis (n = 1). Four patients reported the vertigo to occur exclusively during sexual intercourse or masturbation while the other three patients also experienced vertigo during other physical activities. Underlying disorders included Meniere's disease (n = 3), superior canal dehiscence (n = 1), and high jugular bulb anomaly (n = 1) while the remaining two patients had no identifiable causes. Conclusions: Various disorders may cause coital vertigo probably due to disruption of the mechanism that normally refrains the increased intracranial pressure from being directly transferred to the peripheral vestibular organs.

Bilaterally Abnormal Head Impulse Tests Indicate a Large Cerebellopontine Angle Tumor

BACKGROUND AND PURPOSE

Tumors involving the cerebellopontine angle (CPA) pose a diagnostic challenge due to their diverse manifestations. Head impulse tests (HITs) have been used to evaluate vestibular function, but few studies have explored the head impulse gain of the vestibulo-ocular reflex (VOR) in patients with a vestibular schwannoma. This study tested whether the head impulse gain of the VOR is an indicator of the size of a unilateral CPA tumor.

METHODS

Twenty-eight patients (21 women; age=64±12 years, mean±SD) with a unilateral CPA tumor underwent a recording of the HITs using a magnetic search coil technique. Patients were classified into non-compressing (T1-T3) and compressing (T4) groups according to the Hannover classification.

RESULTS

Most (23/28, 82%) of the patients showed abnormal HITs for the semicircular canals on the lesion side. The bilateral abnormality in HITs was more common in the compressing group than the non-compressing group (80% vs. 8%, Pearson's chi-square test: p<0.001). The tumor size was inversely correlated with the head impulse gain of the VOR in either direction.

CONCLUSIONS

Bilaterally abnormal HITs indicate that a patient has a large unilateral CPA tumor. The abnormal HITs in the contralesional direction may be explained either by adaptation or by compression and resultant dysfunction of the cerebellar and brainstem structures. The serial evaluation of HITs may provide information on tumor growth, and thereby reduce the number of costly brain scans required when following up patients with CPA tumors.

Vibration- and hyperventilation-induced nystagmus in patients with Ramsay Hunt syndrome with vertigo

OBJECTIVES

The aims of this study were to compare vibration-induced nystagmus (VIN) and hyperventilation-induced nystagmus (HVIN) findings in patients with Ramsay Hunt syndrome with vertigo (RHS-V), sudden sensorineural hearing loss with vertigo (SSNHL-V), and vestibular neuritis (VN) during the acute stage and to address the possible lesion sites of vestibular deficit in RHS-V.

STUDY DESIGN

Case series with chart review.

SETTING

Tertiary referral center.

METHODS

We conducted a retrospective case series study in 27 patients with SSNHL-V, 104 patients with VN, and 17 patients with RHS-V and evaluated the findings of VIN and HVIN tests.

RESULTS

An abnormal VIN was observed in 91% of the patients with VN, 89% of those with SSNHL-V, and 94% of those with RHS-V, and the prevalence of abnormal VIN was not significantly different (P = .436). An abnormal HVIN was observed in 51% of the patients with VN, 22% of those with SSNHL-V, and 59% of those with RHS-V. While the prevalence of an abnormal HVIN was significantly different between SSNHL-V and VN groups (P = .007) and between SSNHL-V and RHS-V groups (P = .014), that between VN and RHS-V groups did not show a significant difference (P = .547).

CONCLUSION

Since the results of HVIN in RHS-V patients were more similar to those in VN patients than those in SSNHL-V patients, a lesioned site may be more likely within the vestibular nerve than the inner ear as a cause for vestibular deficit in patients with RHS-V who show caloric canal paresis of 25% or greater.

Hyperventilation-induced nystagmus in patients with vestibular schwannoma

MAIN OBJECTIVE

To determine the utility of the hyperventilation test (HVT) in the diagnosis of vestibular schwannoma (VS).

STUDY DESIGN

A retrospective analysis of hyperventilation-induced nystagmus (HVIN) in 45 patients with unilateral VS.

SETTING

A tertiary referral center.

PATIENTS

Forty-five patients with VS; 30 patients with chronic vestibular neuritis; 20 healthy subjects with normal hearing and without symptoms or a history of vertigo, migraine, or neurological diseases (control group).

INTERVENTIONS

Audiological and vestibular examination; "side-stream" measurement of end-tidal CO2 pressure (P(EtCO2)) to standardize the procedure; magnetic resonance imaging (MRI) centered on the cerebellopontine angle.

MAIN OUTCOME MEASURES

An analysis of HVIN, its patterns, and its appearance threshold via the measurement of P(EtCO2) correlations with the tumor size.

RESULTS

HVIN was observed in 40 of 45 cases (88.9%) in the schwannoma group and in 12 of 30 cases (40%) in the chronic vestibular neuritis group; HVIN was not observed in the control group (0/20 cases) (p < 0.001). In the schwannoma group, HVIN was evoked at a mean P(EtCO2) value of 16.5 ± 1.15 mm Hg. The hypofunctional labyrinth was identified with high sensibility and specificity through caloric test, head shaking test, and head thrust test. The excitatory pattern, which included HVIN with slow phases that beat toward the hypofunctional side, and the paretic pattern, which included HVIN with slow phases that beat toward the hypofunctional side, were not significantly associated with VS size (19.04 ± 10.56 mm for the excitatory pattern and 19.06 ± 11.01 mm for the paretic pattern). The difference in the VS size in HVIN+ (19.05 ± 10.60 mm) and HVIN- (8.40 ± 2.19 mm) cases was significant (p = 0.009).

CONCLUSIONS

A 60-second hyperventilation event causes metabolic changes in the vestibular system and reveals a latent vestibular asymmetry. The presence of an excitatory pattern is the major criterion that suggests VS in patients with signs of unilateral vestibular deficit.

Bedside evaluation of dizzy patients

In recent decades there has been marked progress in the imaging and laboratory evaluation of dizzy patients. However, detailed history taking and comprehensive bedside neurotological evaluation remain crucial for a diagnosis of dizziness. Bedside neurotological evaluation should include examinations for ocular alignment, spontaneous and gaze-evoked nystagmus, the vestibulo-ocular reflex, saccades, smooth pursuit, and balance. In patients with acute spontaneous vertigo, negative head impulse test, direction-changing nystagmus, and skew deviation mostly indicate central vestibular disorders. In contrast, patients with unilateral peripheral deafferentation invariably have a positive head impulse test and mixed horizontal-torsional nystagmus beating away from the lesion side. Since suppression by visual fixation is the rule in peripheral nystagmus and is frequent even in central nystagmus, removal of visual fixation using Frenzel glasses is required for the proper evaluation of central as well as peripheral nystagmus. Head-shaking, cranial vibration, hyperventilation, pressure to the external auditory canal, and loud sounds may disclose underlying vestibular dysfunction by inducing nystagmus or modulating the spontaneous nystagmus. In patients with positional vertigo, the diagnosis can be made by determining patterns of the nystagmus induced during various positional maneuvers that include straight head hanging, the Dix-Hallpike maneuver, supine head roll, and head turning and bending while sitting. Abnormal smooth pursuit and saccades, and severe imbalance also indicate central pathologies. Physicians should be familiar with bedside neurotological examinations and be aware of the clinical implications of the findings when evaluating dizzy patients.

The bedside examination of the vestibulo-ocular reflex (VOR): an update

Diagnosing dizzy patients remains a daunting challenge to the clinician in spite of modern imaging and increasingly sophisticated electrophysiological testing. Here we review the major bedside tests of the vestibulo-ocular reflex and how, when combined with a proper examination of the other eye movement systems, one can arrive at an accurate vestibular diagnosis.

Nystagmus and saccadic intrusions

We review current concepts of nystagmus and saccadic oscillations, applying a pathophysiological approach. We begin by discussing how nystagmus may arise when the mechanisms that normally hold gaze steady are impaired. We then describe the clinical and laboratory evaluation of patients with ocular oscillations. Next, we systematically review the features of nystagmus arising from peripheral and central vestibular disorders, nystagmus due to an abnormal gaze-holding mechanism (neural integrator), and nystagmus occurring when vision is compromised. We then discuss forms of nystagmus for which the pathogenesis is not well understood, including acquired pendular nystagmus and congenital forms of nystagmus. We then summarize the spectrum of saccadic disorders that disrupt steady gaze, from intrusions to flutter and opsoclonus. Finally, we review current treatment options for nystagmus and saccadic oscillations, including drugs, surgery, and optical methods. Examples of each type of nystagmus are provided in the form of figures.

[Clinical and functional assessment of the vestibular nerve]

Clinical and functional assessment of the vestibular nerve is fundamental in demonstrating vestibular signs and searching for associated otological and neurological signs. This may help orient topographic diagnosis toward central or peripheral syndrome and etiologic diagnosis.