Capturing nystagmus during vertigo attacks using a smartphone: adherence, characteristics, pearls and pitfalls

OBJECTIVE

To investigate adherence, characteristics, and first clinical experiences of capturing ictal nystagmus at home, which can be performed to complement the diagnostic process in patients with episodic vestibular symptoms.

METHODS

Patients were recruited at a tertiary referral center in case capturing ictal nystagmus could contribute to the diagnostic process (e.g., to detect or rule out BPPV). They were asked to capture ictal nystagmus with their own smartphone at home, using a smartphone-based adapter (Nystagmocatcher, Balansdiagnos, Stockholm, Sweden). All recordings were analyzed by the last author (RvdB), and the adherence, characteristics, and first clinical experiences were evaluated.

RESULTS

Seventy patients with vestibular symptoms were asked to participate in this study. Sixty-two (89%) agreed to participate. The median period of participation was 86 days. Fifty-one patients experienced attacks during the study period. Eventually, 51% of them provided eye movement recordings sufficient for analysis. Different types of nystagmus were observed: positional nystagmus related to BPPV, positional nystagmus not related to BPPV, functional eye movements, and the absence of nystagmus or functional eye movements. Capturing ictal nystagmus could contribute to the diagnostic process in several ways, including to detect or rule out BPPV, to detect or rule out vestibular origin of symptoms, to determine the affected side, telemedicine, to monitor attack frequency, and to detect malingering. Furthermore, strict guidance of patients was necessary, which could be time-consuming.

CONCLUSION

Capturing ictal nystagmus can contribute to the diagnostic process in several ways, which motivates to rethink current clinical workflow in vestibular medicine. However, strict guidance is necessary and not all patients provide ictal recordings. In an outpatient setting, it would be advised to use ictal nystagmus recordings on indication, to complement the diagnostic process.

Outcome of canalith repositioning manoeuvre in benign paroxysmal positional vertigo in children and adolescents: A systematic review

BACKGROUND

Benign paroxysmal positional vertigo (BPPV) is a debilitating condition that has been significantly described in adults. Recent data points out that BPPV occurs in children as well. Canalith repositioning manoeuvre (CRM) has shown promising results amongst adult patients with BPPV.

OBJECTIVE

We reviewed the literature to determine the outcome of CRM in children and adolescents with BPPV.

METHODS

A literature search was conducted over 1 month (March 2022). The primary outcome was defined as the resolution of positional nystagmus and symptoms, and secondary outcomes were determined by the presence of recurrence and the number of attempts of CRM.

RESULTS

Ten articles were selected based on our objective and selection criteria. A total of 242 patients were included, with a mean of 10.9 years. BPPV was diagnosed based on history and positional nystagmus in all patients (100%). CRM was performed in 97.9% of patients, whereby 80.5% recovered following a single attempt of CRM. Recurrence of symptoms was identified in 10% of patients with no reported major complications.

CONCLUSION

CRM has demonstrated promising results in children and adolescents. The quality of evidence is limited until a better-quality study involving randomised controlled studies with a larger sample size is completed.

Clinical Characteristics of persistent geotropic horizontal direction-changing positional nystagmus: Experience in 189 participants

BACKGROUND

The etiology and mechanism of persistent geotropic horizontal direction-changing positional nystagmus (DCPN) are still unclear. Whether this pattern of nystagmus is a subtype of benign paroxysmal positional vertigo (BPPV) remains controversial.

OBJECTIVE

The goal of this study was to observe the clinical characteristics of persistent geotropic horizontal DCPN involving the lateral semicircular canal.

METHODS

The analysis was performed to participants with episodic positional vertigo in our clinic from 2014 to 2021. Participants were included via positional test. We observed and summarized the distribution data, vertigo history, follow-up tests, and recurrence situations of 189 persistent geotropic horizontal DCPN participants.

RESULTS

The mean age at the first time showing of persistent geotropic horizontal DCPN was 56±14.7 and more women than men were affected by persistent geotropic horizontal DCPN (female-to-male ratio 2.4 : 1). Overall, 58.7% (57/94) of participants who came for the first-week follow-up test were asymptomatic. Thirty-three participants experienced recurrence (female-to-male ratio: 4.5 : 1). Fifty-three (28.0%) participants experienced the conversion of the patterns of DCPN in the history, the follow-up tests and the recurrence compared to the first showing of persistent geotropic horizontal DCPN. 24(12.1%) participants still experienced persistent geotropic horizontal DCPN attack in the follow-up tests and the recurrences without benign paroxysmal positional vertigo history.

CONCLUSION

Persistent geotropic horizontal DCPN affected more women than men. The persistent geotropic horizontal DCPN that with conversion to transient geotropic horizontal DCPN or to persistent apogeotropic horizontal DCPN might be a subtype of BPPV or in a stage of BPPV process. However, the persistent geotropic horizontal DCPN without conversion might be an independent disease that is not related to BPPV.

[Three-dimensional characteristics of torsional nystagmus in induced by posterior semicircular canals canalithasis]

Objective:The three-dimensional direction feature of torsional nystagmus induced by posterior semicircular canal canalithasis （PSC-Can） was recorded and analyzed using three-dimensional video nystagmography （3D-VNG）. Methods:Sixty patients （22 on the left side and 38 on the right side） with PSC-Can were enrolled for torsional nystagmus evoked by Dix-Hallpike test in the affected-side head-hanging and sitting positions, and the direction characteristics of the horizontal, vertical and torsional components were analyzed. Results:Vertical torsional nystagmus was induced in 60 PSC-Can patients in the head-hanging and sitting positions evoked by Dix-Hallpike test, respectively. Horizontal, vertical, and torsional components of were presented in the 3D-VNG. In the head-hanging position, the direction of horizontal component in the left/right PSC-Can nystagmus was contralateral in 46 cases（the other 14 cases were ipsilateral）, the vertical component was upward, and the torsional component was upward/downward, respectively. The intensity of nystagmus induced in the three components in the sitting position is weaker than in the head-hanging position, and the direction of nystagmus was reversed in both vertical and torsional components compared with the head-hanging position. However, the direction of the horizontal component was reversed in 39 cases and not reversed in 21 cases in the sitting position. Conclusion:The horizontal, vertical and torsional components of the torsional nystagmus in PSC-Can patients recorded by 3D-VNG, which provided more comprehensive and objective information for the analysis of PSC-Can and the study of semicircular canal physiological function.

Clinical Interpretation of Positional Nystagmus Provoked by both Dix-Hallpike and Supine Head-Roll Tests

Background:

Methods:

Results:

Conclusion:

Analysis of the nystagmus characteristics of cupula diseases: A case report

INTRODUCTION

Clinically, there is a kind of patients with positional vertigo or dizziness, which occurs when they turn left or right, look down or up, lie down or sit up. With a long duration and varying frequency, it is not consistent with the manifestations of benign paroxysmal positional vertigo (BPPV). In addition, the persistent geotropic direction-changing positional nystagmus (PG-DCPN) was observed in a supine head-roll test.

PATIENT CONCERNS

With no apparent trigger for visual rotation and a sense of self instability, an 81-year-old female patient had suffered from vertigo for 3 days. The vertigo occurred every day, lasting several minutes each time, and associated with head movements and changes in body position. In a supine head-roll test, it appeared persistent geotropic direction-changing positional nystagmus for a long time, without latency, fatigability and in the presence of 3 zero planes.

DIAGNOSIS

Light cupula.

INTERVENTIONS

Difenidol hydrochloride 25 mg orally 3 times/day for 2 weeks and betahistine hydrochloride 12 mg orally 3 times/day for 1 month were administered.

OUTCOMES

After 1 month of treatment, the patient's vertigo symptoms disappeared. And in the supine head-roll test, the persistent geotropic direction-changing positional nystagmus disappeared.

CONCLUSION

We report the characteristics of nystagmus produced in a typical patient with light cupula during the supine head-roll test. After reviewing the relevant literatures, we believe that a simpler method can be used to identify canalolithiasis and cupula disease, to distinguish light and heavy cupula, and to determine the pathological semicircular canal to which the lesion belongs.

Fluctuating Posterior Canal Function in Benign Paroxysmal Positional Vertigo Depending on How and Where Otoconia Are Disposed

OBJECTIVE

Though fluctuations in vestibular function represent a common finding in Menière's disease, we describe how benign paroxysmal positional vertigo (BPPV) may result in fluctuations of vestibulo-ocular reflex for the involved canal depending on the disposition of otoliths.

PATIENT

A 54-year-old woman suffering from refractory posterior canal (PC)-BPPV resulting in fluctuating PC function.

INTERVENTIONS

Diagnostic evaluation and rehabilitative treatment for BPPV involving the affected PC.

MAIN OUTCOME MEASURES

Video-Frenzel and video-head impulse test (vHIT) findings before and after canalith repositioning procedures for PC-BPPV.

RESULTS

BPPV involving the nonampullary arm of right PC was diagnosed based on presenting positional downbeat nystagmus and selective right PC hypofunction at the vHIT. During physical treatment, nystagmus first became positional paroxysmal upbeat likely due to a shift of debris into the ampullary arm of the canal, then turned to spontaneous downbeat nystagmus consistently with a plug effect exerted by particles entrapped within the nonampullary arm of PC and finally receded proving an otoliths fall within the utriculus. Simultaneously, vHIT documented fluctuations for right PC vestibulo-ocular reflex gain as it first increased to normal values, then severely declined and finally normalized, respectively. High-resolution computed tomography scan detected ipsilateral superior canal dehiscence.

CONCLUSIONS

In accordance with recently reported vHIT findings in different types of BPPV, fluctuation of PC function could be likely explained by the effect of particles on cupular dynamic responses depending on the portion of the canal gradually involved. Superior canal dehiscence may have played a role facilitating otoliths mobilization by reducing labyrinthine impedance.

Efficacy of a New Treatment Maneuver for Posterior Canal Benign Paroxysmal Positional Vertigo

Existing treatment maneuvers for posterior canal benign paroxysmal positional vertigo (PC-BPPV) include the Semont liberatory maneuver (SLM) and canalith repositioning maneuver (CRM). Independent investigations reveal that these maneuvers provide an excellent outcome for most patients. However, certain aspects of these maneuvers, such as hyperextension of the neck for CRM and brisk lateral motion for the SLM, are contraindicated for patients with vertebrobasilar insufficiency, cervical spondylosis, back problems, and so forth. A hybrid approach, the Gans repositioning maneuver (GRM) was developed for use with these patients. The purpose of this project was to assess efficacy of the GRM for treatment of PC-BPPV. Two-hundred seven participants were enrolled in this prospective study. All participants were treated with the GRM. Six different clinicians performed the treatments. Participants returned for follow-up at one-week intervals until it was determined that the PC-BPPV was clear. On average, 1.25 GRM treatments were required to resolve the PC-BPPV. The majority of the participants (80.2%) were cleared with one GRM treatment, and 95.6% were clear after two treatments. Recurrence rate was 5%. There was no difference in outcome based on clinician. The GRM is an efficacious treatment maneuver for PC-BPPV and may be preferential for use in patients with neck, back, hip, and/or mobility issues that contraindicate the use of SLM or CRM.

Orthotropic nystagmus in predicting the efficacy of treatment in posterior canal benign paroxysmal positional vertigo

OBJECTIVE

To observe the type of nystagmus in each position of posterior semicircular canal benign paroxysmal positional vertigo (BPPV) after treatment with the Epley maneuver and analyze the relationship between the type of nystagmus in the second and third positions of the Epley maneuver and the effect of treatment. Then, the role of orthotropic nystagmus in predicting the success of posterior semicircular canal BPPV treatment was explored.

METHODS

Two hundred seventy-six patients diagnosed with posterior semicircular canal BPPV who were admitted from September 2018 to October 2019 to Zhejiang Hospital were included. All patients were treated with BPPV diagnosis and treatment system (Epley maneuver). During the treatment, we observed and recorded the type of nystagmus in the second and third positions, including the direction and duration of nystagmus. One hour after the first treatment, all patients were evaluated by both the Dix-Hallpike and Roll tests to determine whether the treatment was successful. The difference in the success rate of treatment between different types of nystagmus was compared, and the differences in sensitivity and specificity of orthotropic nystagmus in the second and third positions in predicting the effect of treatment were compared.

RESULTS

Among the 234 patients who had successful repositioning for the first time, the proportion of orthotropic nystagmus during the third position of the Epley maneuver was 88.9%, which was significantly higher than 23% in the unsuccessful group (42 cases) (P < 0.05) The proportion of patients with reversed nystagmus (4.7% vs 33.3%, P < 0.05) and no nystagmus (6.4% vs 42.9%, P < 0.05) was lower in the successful group than in the unsuccessful group. The proportion of orthotropic nystagmus during the second position of the Epley maneuver was 50.9%, which was also higher than the 19% in the unsuccessful group (P < 0.05). The proportion of reversed nystagmus (13.7% vs 31%, P < 0.05) was lower in the successful group than in the unsuccessful group. Additionally, the proportion of no nystagmus (35.5% vs 50%, P = 0.074) was lower in the successful group than in the unsuccessful group, but the difference was not statistically significant. The sensitivity of orthotropic nystagmus in the third position (88.9%) of the Epley maneuver in predicting the efficacy of treatment was higher than that of orthotropic nystagmus in the second position (50.9%), but there was no significant difference in specificity between the two.

CONCLUSION

Orthotropic nystagmus during the Epley maneuver, especially in the third position, has certain value in predicting the efficacy of posterior semicircular canal BPPV repositioning, which is better than its predictive effect in the second position, whereas reversed nystagmus or no nystagmus in the third position is suggestive of unsuccessful repositioning. Therefore, clinicians can carry out individualized treatments based on nystagmus types during repositioning to improve the effect of treatment.

Reference ranges and stability of auditory and vestibular measures in a comprehensive assessment battery for traumatic brain injury

BACKGROUND

Audiology clinics have many tools available to evaluate auditory and vestibular complaints. However, many tools lack established normative ranges across the life span. We conducted this study to establish reference ranges across the life span for audiology/vestibular measures commonly used to evaluate patients with traumatic brain injury.

MATERIALS AND METHODS

In this repeated measures study, 75 adults, ages 18-65 years, without a history of traumatic brain injury, underwent robust auditory/vestibular evaluations three times over six months, including rotational chair, videonystagmography, computerized dynamic posturography, vestibular evoked myogenic potentials, and retinal fundoscopy.

RESULTS

Age effect was notable for transient evoked otoacoustic emissions, pure-tone audiometry, auditory brainstem response, auditory middle latency response, and auditory-steady state response at 4000 hertz (Hz). Older participants (50-65 years) were more likely to have delayed latency horizontal saccades, positional nystagmus, slowed lower-extremity motor control responses, and delayed latency ocular vestibular evoked myogenic potentials. Low to mid-frequency horizontal (0.003-4 Hz) and mid-frequency vertical (1-3 Hz) vestibulo-ocular reflex, otolith-mediated reflexes, dynamic visual acuity and balance measures were generally not influenced by age. Females had larger static subjective visual testing offset angles, longer cervical vestibular evoked myogenic potential P1 latency, faster velocity horizontal saccades, and quicker motor control latency for large backward translations than age-matched males.

CONCLUSION

These reference ranges can be used to discern impairment within the auditory and vestibular pathway following traumatic brain injury in young to middle-aged adults.

ID

TRIAL REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT01925963.

[Horizontal semicircular canals light cupulopathy: 2 cases report]

SummaryAnalyze 2 cases of horizontal semicircular canals light cupulopathy patient history, clinical manifestations, vestibular function and hearing test results, summarize the clinical features of the disease. All of the 2 patients showed a typicaln light cupulopathy nystagmus. That is, the nystagmus of the Roll-Test test is sustained to the ground, and there is no latency and attenuation with null plane. When the patient's nystagmus is characterized by direction changing positional nystagmus and head deflection nystagmus disappearance（null plane）, the possibility of horizontal semicircular canals light cupulopathy is to be thought of. In this paper, 2 cases of horizontal semicircular canals light cupulopathy received in our hospital are reported as follows.

Patterns of nystagmus conversion in sudden sensorineural hearing loss with vertigo

The patients with sudden sensorineural hearing loss (SSNHL) may complain of vertigo. Although there have been many reports on SSNHL with vertigo (SSNHL_V), changes in the pattern of nystagmus have not been studied as yet. This study is a retrospective study and aims to investigate the characteristic changes in type of nystagmus and clinical features in patients with SSNHL_V who experienced a change in their nystagmus pattern during follow-up. Among 50 patients with SSNHL_V between January 2012 and December 2015, we identified 15 patients with SSNHL_V whose pattern of nystagmus changed. Initial nystagmus was classified into 5 subgroups: paretic type, irritative type, persistent geotropic direction-changing positional nystagmus (PG-DCPN), persistent apogeotropic direction-changing positional nystagmus (PA-DCPN), and posterior semicircular canal benign paroxysmal positional vertigo. The most common pattern of initial nystagmus was PG-DCPN (n = 7). The change of initial nystagmus pattern occurred on day 2 to 75 from symptom onset, and 2 (of 15) patients showed further conversion. The most common pattern of final nystagmus was PA-DCPN (n = 9). Hearing improvement after treatment was not significantly different (P = .59) between SSNHL_V patients with nystagmus change (25 ± 17 dB, n = 15) and those without nystagmus change (28 ± 18 dB, n = 35). In conclusion, clinician's attention is required in evaluating the vertigo symptom in patients with SSNHL_V because the initial patterns of nystagmus can be converted to another type of nystagmus. The presence of nystagmus change during follow-up may not be a prognosticator for hearing recovery in patients with SSNHL_V.

The effective clinical outcomes of the Gufoni maneuver used to treat 91 vertigo patients with apogeotropic direction-changing positional nystagmus (apo-DCPN)

This study aimed to observe and analyze the effects and outcomes of patients with apogeotropic direction-changing positional nystagmus (apo-DCPN) who received Gufoni maneuver.A total of 91 patients with positional vertigo admitted to the specialized dizziness clinic in Zhejiang Provincial People's Hospital from February 2014 to August 2017 were included. The immediate treatment responses to the Gufoni maneuver were observed and recorded. The patients in whom the treatment was ineffective were followed up for 4 weeks to observe the outcome of apo-DCPN.In 21 patients, the apo-DCPN was transformed after Gufoni maneuver, and 7 patients developed transformation within 4 weeks of follow-up. Spontaneous remission of apo-DCPN within the follow-up period was observed in 55 patients who were unresponsive to the Gufoni maneuver. The prevalence of migraine was significantly higher in the early remission group (P < .05) and the period between the initial visit and nystagmus remission was significantly shorter in the group of patients with migraine history (P < .05).This study demonstrates that the immediate treatment efficacy of the Gufoni maneuver is poor in positional vertigo patients with apo-DCPN. We believe that the reason for the low efficacy is that the Gufoni maneuver is only effective for some patients with apo-DCPN type HSC-BPPV. In patients with early spontaneous remission and a history of migraine, central positional nystagmus of probable vestibular migraine (VM) or benign recurrent vertigo should be considered for the mechanisms of apo-DCPN generation.

Pseudo-spontaneous nystagmus in patients with geotropic direction-changing positional nystagmus

Background

Pseudo-spontaneous nystagmus has been reported in patients with direction-changing positional nystagmus (DCPN). Recently, the concept of a “light cupula” has been introduced as a pathophysiology that can exhibit persistent geotropic DCPN. Patients with persistent DCPN could have different characteristics of nystagmus. Therefore, we investigated the pseudo-spontaneous nystagmus in patients with transient (canalolithiasis) and persistent (belong to light cupula theory) geotropic DCPN.

Methods

In this study, prospectively, 49 patients with persistent geotropic DCPN and 67 patients with transient geotropic DCPN were enrolled. We compared the incidence of pseudo-spontaneous nystagmus between persistent and transient DCPN patients and characteristics of pseudo-spontaneous nystagmus and positional nystagmus by the head roll test in these patients. A prospective study was conducted at a dizziness clinic.

Results

Patients with persistent geotropic DCPN exhibited significantly higher incidence of pseudo-spontaneous nystagmus than patients with transient geotropic DCPN. Patients with transient DCPN showed a significantly higher mean SPV value during the head roll test than patients with persistent DCPN. All patients exhibiting pseudo-spontaneous nystagmus in patients with persistent DCPN had a null plane, and all patients had nystagmus beats to the opposite side of the null plane or the lesion side.

Conclusion

Our results support the possibility that the mechanism between persistent and transient geotropic DCPN may be different. However, more studies are needed on the pathogenesis and mechanism of the two diseases, including the occurrence of pseudo-spontaneous nystagmus in the disease entity.

Benign paroxysmal positional vertigo: Diagnostic criteria Consensus document of the Committee for the Classification of Vestibular Disorders of the Bárány Society

This article presents operational diagnostic criteria for benign paroxysmal positional vertigo (BPPV), formulated by the Committee for Classification of Vestibular Disorders of the Bárány Society. The classification reflects current knowledge of clinical aspects and pathomechanisms of BPPV and includes both established and emerging syndromes of BPPV. It is anticipated that growing understanding of the disease will lead to further development of this classification.

The mammalian efferent vestibular system plays a crucial role in vestibulo-ocular reflex compensation after unilateral labyrinthectomy

The α9-nicotinic acetylcholine receptor (α9-nAChR) subunit is expressed in the vestibular and auditory periphery, and its loss of function could compromise peripheral input from the predominantly cholinergic efferent vestibular system (EVS). A recent study has shown that α9-nAChRs play an important role in short-term vestibulo-ocular reflex (VOR) adaptation. We hypothesize that α9-nAChRs could also be important for other forms of vestibular plasticity, such as that needed for VOR recovery after vestibular organ injury. We measured the efficacy of VOR compensation in α9 knockout mice. These mice have deletion of most of the gene (chrna9) encoding the nAChR and thereby lack α9-nAChRs. We measured the VOR gain (eye velocity/head velocity) in 20 α9 knockout mice and 16 cba129 controls. We measured the sinusoidal (0.2-10 Hz, 20-100°/s) and transient (1,500-6,000°/s2) VOR in complete darkness before (baseline) unilateral labyrinthectomy (UL) and then 1, 5, and 28 days after UL. On day 1 after UL, cba129 mice retained ~50% of their initial function for contralesional rotations, whereas α9 knockout mice only retained ~20%. After 28 days, α9 knockout mice had ~50% lower gain for both ipsilesional and contralesional rotations compared with cba129 mice. Cba129 mice regained ~75% of their baseline function for ipsilesional and ~90% for contralesional rotations. In contrast, α9 knockout mice only regained ~30% and ~50% function, respectively, leaving the VOR severely impaired for rotations in both directions. Our results show that loss of α9-nAChRs severely affects VOR compensation, suggesting that complimentary central and peripheral EVS-mediated adaptive mechanisms might be affected by this loss.NEW & NOTEWORTHY Loss of the α9-nicotinic acetylcholine receptor (α9-nAChR) subunit utilized by the efferent vestibular system (EVS) has been shown to significantly affect vestibulo-ocular reflex (VOR) adaptation. In our present study we have shown that loss of α9-nAChRs also affects VOR compensation, suggesting that the mammalian EVS plays an important role in vestibular plasticity, in general, and that VOR compensation is a more distributed process than previously thought, relying on both central and peripheral changes.

Spontaneous inversion of nystagmus without a positional change in the horizontal canal variant of benign paroxysmal positional vertigo

OBJECTIVE

We investigated the neuro-otological findings, including nystagmus, and the clinical course of patients with the horizontal canal variant of benign paroxysmal positional vertigo (HC-BPPV), who showed spontaneous inversion of nystagmus without a positional change. Furthermore, we speculated on the possible mechanism of spontaneous inversion of nystagmus without a positional change.

PATIENTS AND METHODS

The characteristics of spontaneous inversion of positional nystagmus without a positional change were analyzed in 7 patients with HC-BPPV.

RESULTS

All patients were diagnosed as having HC-BPPV. During the positional test, the spontaneous inversion of nystagmus was observed in the same head position in all patients. Spontaneous inversion was observed on both sides in 5 patients, and only on 1 side in 2 patients. All patients presented with geotropic nystagmus in the first phase, and ageotropic nystagmus in the second phase.

CONCLUSIONS

The coexistence of cupulolithiasis and canalolithiasis appears to be a possible mechanism of the spontaneous inversion of positional nystagmus.

Paroxysmal vertigo with nystagmus in children

INTRODUCTION

A pathological nystagmus is an objective sign that a patient feels vertigo. However, there have been few opportunities to observe and record pathological nystagmus during a paroxysmal vertigo attack. Furthermore, it can be difficult to obtain cooperation in pediatric patients. We present two cases of paroxysmal vertigo in children in whom we successfully recorded and analyzed their pathological nystagmus during a vertigo attack.

METHODS

Of a total sample of 4349 patients seen at our hospital for dizziness in the last decade, a retrospective analysis revealed that 68 were children (<15 years old; 1.6%). Of these 68 children, we successfully identified pathological nystagmus during paroxysmal vertigo in only two (2.9%).

RESULTS

Case 1 was a 4-year-old girl. She felt vertigo the strongest when her left ear was down in the supine position. We observed and recorded her nystagmus during a vertigo attack with her mother's permission. Her positional nystagmus in the supine position was horizontal persistent apogeotropic nystagmus. Rightward nystagmus in the left-ear-down supine position was stronger than leftward nystagmus in the right-ear-down supine position. Therefore, the diagnosis was right lateral canal type of benign paroxysmal positional vertigo, of which the pathophysiology was cupulolithiasis. The other patient was an 11-year-old boy. He had a family history of migraines. His vertigo attacks occurred after onset of a severe migraine and lasted between 2 and 48 h. During an attack that we observed, he showed nystagmus, which was direction-fixed right torsional and rightward in darkness. His mother had noticed that his eyes moved abnormally and that his left eye did not shift to the left side when he looked leftward. He was old enough to clearly express his own symptoms. Other neurological examinations were normal. The diagnosis was vestibular migraine.

CONCLUSIONS

We analyzed a pathological nystagmus during paroxysmal vertigo in two children. We conclude that children can be diagnosed with a combination of careful history taking and accurate examinations of a pathological nystagmus.

Prospective Study of Positional Nystagmus in 100 Consecutive Patients

Objectives:

The purpose of this study was to investigate the various diagnoses of patients who present with positional nystagmus.

Methods:

Positional maneuvers were systematically performed in the plane of the posterior canal (PC; Dix-Hallpike maneuver) and the horizontal canal (HC; patients were rolled to either side in a supine position) on 490 consecutive patients essentially referred for vertigo and/or gait unsteadiness.

Results:

One hundred patients (20%) presented positional nystagmus. This nystagmus had a peripheral origin in 83 patients, including 80 patients with benign paroxysmal positional vertigo (BPPV). In BPPV, the PC was involved in 61 patients, the HC in 18 patients (geotropic horizontal nystagmus in 11 and ageotropic in 7; changing from geotropic to ageotropic or the reverse in 4 patients), and both the PC and HC in 1 patient. There was evidence of central positional nystagmus in 12 patients, including positional downbeat nystagmus during the Dix-Hallpike maneuver in 7 patients with various neurologic disorders, and ageotropic horizontal nystagmus during the HC maneuver in 2 patients with, respectively, cerebellar ischemia and definite migrainous vertigo. The peripheral or central origin of the positional nystagmus could not be ascertained in 5 patients, including 1 patient with probable migrainous vertigo and another with possible anterior canal BPPV.

Conclusions:

A rotatory-upbeat nystagmus in the context of PC BPPV, a horizontal nystagmus, whether geotropic or ageotropic, due to HC BPPV, and a positional downbeat nystagmus related to various central disorders are the 3 most common types of positional nystagmus. Geotropic horizontal positional nystagmus and, most certainly, horizontal positional nystagmus changing from geotropic to ageotropic or the reverse point to HC BPPV. In contrast, an ageotropic horizontal positional nystagmus that is not changing (from ageotropic to geotropic) may indicate a central lesion.

[Efficacy of surgery on congenital nystagmus with convergence damping]

OBJECTIVE

To evaluate the efficacy of surgery in the treatment of congenital nystagmus with convergence damping.

METHODS

Retrospective and comparative case series. Eight patients diagnosed as congenital nystagmus with convergence damping at Beijing Children's Hospital between September 2010 and September 2012 were enrolled in this study. The ages were 9.5 (12, 6) years old, and follow-up was 9 (24, 6) months. All patients received prism induced convergence and the same surgery of bimedial rectus recession and bilateral rectus tenotomy. The best corrected visual acuity, the range of fusion and the nystagmus waveforms were analyzed before and after surgery.

RESULTS

The range of fusion was -3.75±1.83° to +19.38±3.16° before surgery and -3.88±1.55° to +19.00±3.02° after surgery; there was no significant difference (t=0.24, P=0.82). The binocular visual acuity increased from 0.21±0.15 without convergence to 0.28±0.18 using convergence; there was significant difference (t=-4.43, P=0.00). The visual acuity was 0.32±0.20 after surgery, significantly different from that before surgery without convergence (t=-5.29, P=0.00), but not significantly different from that before surgery using convergence (t=-2.12, P=0.07). Patients had significant improvements in the frequency (t=3.28, 3.02, P<0.05) and intensity of the nystagmus waveforms when using convergence and postoperatively (t=3.27, 3.48; P<0.05), but there was no significant improvement in the amplitude of the waveforms (t=1.31, 1.57, 0.31, P>0.05).

CONCLUSIONS

Surgery for congenital nystagmus with convergence damping can provide expectations for ocular motor and visual results. The range of fusion should be wide enough, and the effect of convergence on the frequency is greater than that on the amplitude.

Contribution of vestibular efferent system alpha-9 nicotinic receptors to vestibulo-oculomotor interaction and short-term vestibular compensation after unilateral labyrinthectomy in mice

Sudden unilateral loss of vestibular afferent input causes nystagmus, ocular misalignment, postural instability and vertigo, all of which improve significantly over the first few days after injury through a process called vestibular compensation (VC). Efferent neuronal signals to the labyrinth are thought to be required for VC. To better understand efferent contributions to VC, we compared the time course of VC in wild-type (WT) mice and α9 knockout (α9(-/-)) mice, the latter lacking the α9 subunit of nicotinic acetylcholine receptors (nAChRs), which is thought to represent one signaling arm activated by the efferent vestibular system (EVS). Specifically, we investigated the time course of changes in the fast/direct and slow/indirect components of the angular vestibulo-ocular reflex (VOR) before and after unilateral labyrinthectomy (UL). Eye movements were recorded using infrared video oculography in darkness with the animal stationary and during sinusoidal (50 and 100°/s, 0.5-5 Hz) and velocity step (150°/s for 7-10s, peak acceleration 3000°/s(2)) passive whole-body rotations about an Earth-vertical axis. Eye movements were measured before and 0.5, 2, 4, 6 and 9 days after UL. Before UL, we found frequency- and velocity-dependent differences between WT and α9(-/-) mice in generation of VOR quick phases. The VOR slow phase time constant (TC) during velocity steps, which quantifies contributions of the indirect component of the VOR, was longer in α9(-/-) mutants relative to WT mice. After UL, spontaneous nystagmus (SN) was suppressed significantly earlier in WT mice than in α9(-/-) mice, but mutants achieved greater recovery of TC symmetry and VOR quick phases. These data suggest (1) there are significant differences in vestibular and oculomotor functions between these two types of mice, and (2) efferent signals mediated by α9 nicotinic AChRs play a role during VC after UL.

Distribution of retinal ganglion cells projecting into the nucleus of the optic tract in rat

The present study indicates that visual signals responsible for OKN are conducted through the retinal ganglion cells mainly contralaterally, and only in the ventral region of the retina ipsilateral to the injection site. The retinal ganglion cells projecting into the NOT ipsilateral to the injection site were identified as small- and medium-sized cells in the rat. The density of the ventral ganglion cells of the retina contralateral to the injection site was lower than that in any other regions of the retina except for the dorsal region of the retina, and the density of the ventral ganglion cells ipsilateral to the injection site was about 4 times greater than that on the contralateral side. This finding requires physiological investigation in the future.