Central mimics of benign paroxysmal positional vertigo: an illustrative case series.

Benign paroxysmal positional vertigo (BPPV) is the most common peripheral vestibular disorder that is diagnosed based solely on clinical findings. Rarely, central lesions can present with positional vertigo and nystagmus, mimicking BPPV. Recognised red flags that may help distinguish central mimics from BPPV include the presence of additional neurological symptoms and signs, atypical nystagmus patterns, and the absence of a sustained response to repositioning manoeuvres. We present seven cases that illustrate how heuristic bias may affect the detection of these features in practice. Furthermore, our cases suggest that isolated downbeat positional nystagmus (simulating anterior canal BPPV) and apogeotropic horizontal nystagmus on the supine roll test (simulating horizontal canal BPPV) should be considered additional red flags.

Correction to: The CAPOS mutation in ATP1A3 alters Na/K-ATPase function and results in auditory neuropathy which has implications for management.

The following information was inadvertently omitted in the original publication.

The CAPOS mutation in ATP1A3 alters Na/K-ATPase function and results in auditory neuropathy which has implications for management.

Cerebellar ataxia, areflexia, pes cavus, optic atrophy and sensorineural hearing impairment (CAPOS) is a rare clinically distinct syndrome caused by a single dominant missense mutation, c.2452G>A, p.Glu818Lys, in ATP1A3, encoding the neuron-specific alpha subunit of the Na+/K+-ATPase α3. Allelic mutations cause the neurological diseases rapid dystonia Parkinsonism and alternating hemiplegia of childhood, disorders which do not encompass hearing or visual impairment. We present detailed clinical phenotypic information in 18 genetically confirmed patients from 11 families (10 previously unreported) from Denmark, Sweden, UK and Germany indicating a specific type of hearing impairment-auditory neuropathy (AN). All patients were clinically suspected of CAPOS and had hearing problems. In this retrospective analysis of audiological data, we show for the first time that cochlear outer hair cell activity was preserved as shown by the presence of otoacoustic emissions and cochlear microphonic potentials, but the auditory brainstem responses were grossly abnormal, likely reflecting neural dyssynchrony. Poor speech perception was observed, especially in noise, which was beyond the hearing level obtained in the pure tone audiograms in several of the patients presented here. Molecular modelling and in vitro electrophysiological studies of the specific CAPOS mutation were performed. Heterologous expression studies of α3 with the p.Glu818Lys mutation affects sodium binding to, and release from, the sodium-specific site in the pump, the third ion-binding site. Molecular dynamics simulations confirm that the structure of the C-terminal region is affected. In conclusion, we demonstrate for the first time evidence for auditory neuropathy in CAPOS syndrome, which may reflect impaired propagation of electrical impulses along the spiral ganglion neurons. This has implications for diagnosis and patient management. Auditory neuropathy is difficult to treat with conventional hearing aids, but preliminary improvement in speech perception in some patients suggests that cochlear implantation may be effective in CAPOS patients.

The Pediatric Vestibular Symptom Questionnaire: A Validation Study.

OBJECTIVE: To develop and validate the Pediatric Vestibular Symptom Questionnaire (PVSQ) and quantify subjective vestibular symptom (ie, dizziness, unsteadiness) severity in children. STUDY DESIGN: One hundred sixty-eight healthy children (female, n = 91) and 56 children with postconcussion dizziness or a vestibular disorder (female, n = 32), between ages 6 and 17 years, were included. The PVSQ contains questions regarding vestibular symptom frequency during the previous month. The Strengths and Difficulties Questionnaire (SDQ), a brief behavioral screening instrument, was also completed. RESULTS: The PVSQ showed high internal consistency (10 items; Cronbach α = 0.88). A significant between-group difference was noted with higher (ie, worse) PVSQ scores for children with vestibular symptoms (P < .001); no significant differences were noted between patient groups. The optimal cut-off score for discriminating between individuals with and without abnormal levels of vestibular symptoms was 0.68 out of 3 (sensitivity 95%, specificity 85%). Emotional and hyperactivity SDQ subscale scores were significantly worse for patients compared with healthy participants (P ≤ .01). A significant relationship was noted between mean PVSQ and SDQ (parent-rated version) hyperactivity and total scores for patients (P ≤ .01) and the SDQ (self-rated) emotional, hyperactivity, and total score (P ≤ .01) in healthy controls. However, mean SDQ subscale and total scores were within normal ranges for both groups. CONCLUSIONS: Self-reported vestibular symptoms, measured by the PVSQ, discriminated between children presenting with vestibular symptoms and healthy controls and should be used to identify and quantify vestibular symptoms that require additional assessment and management.

Mobile telephone use effects on perception of verticality.

Low-level radiofrequency (RF) signals may produce disorientation and nausea. In experiment I, we assessed mobile phone effects on graviception in nine symptomatic subjects after mobile telephone use and 21 controls. The mobile handset was strapped to each ear for 30 min in pulsed emission, continuous RF emission, or no emission test mode, respectively. The subjective visual vertical and horizontal (SVV/SVH) were tested from min 25 of exposure. There was no exposure effect; however, there was an ear effect, with the SVV/SVH being shifted to the opposite direction of the ear exposed. This could be due to thermal or RF effects or handset weight. In experiment II, we assessed the handset weight effect on 18 normal controls. After baseline SVV/SVH, the switched off handset was strapped to either ear; the SVV/SVH was repeated 25 min later. A significant ear effect was found. We compared the observed ear effect SVV/SVH change in the experiment II group to the continuous exposure ear effect change in the experiment I group, and the difference was not significant. The ear effect was attributed to a minor head tilt due to the handset weight, or proprioceptive stimulation of neck muscle affecting the perception of verticality.

Natural history and retinal structure in patients with Usher syndrome type 1 owing to MYO7A mutation.

PURPOSE: To evaluate the phenotypic variability and natural history of ocular disease in a cohort of 28 individuals with MYO7A-related disease. Mutations in the MYO7A gene are the most common cause of Usher syndrome type 1, characterized by profound congenital deafness, vestibular arreflexia, and progressive retinal degeneration. DESIGN: Retrospective case series. PARTICIPANTS: Twenty-eight patients from 26 families (age range, 3-65 years; median, 32) with 2 likely disease-causing variants in MYO7A. METHODS: Clinical investigations included fundus photography, optical coherence tomography, fundus autofluorescence (FAF) imaging, and audiologic and vestibular assessments. Longitudinal visual acuity and FAF data (over a 3-year period) were available for 20 and 10 study subjects, respectively. MAIN OUTCOME MEASURES: Clinical, structural, and functional characteristics. RESULTS: All patients with MYO7A mutations presented with features consistent with Usher type 1. The median visual acuity for the cohort was 0.39 logarithm of the minimum angle of resolution (logMAR; range, 0.0-2.7) and visual acuity in logMAR correlated with age (Spearman's rank correlation coefficient, r = 0.71; P<0.0001). Survival analysis revealed that acuity ≤ 0.22 logMAR was maintained in 50% of studied subjects until age 33.9; legal blindness based on loss of acuity (≥ 1.00 logMAR) or loss of field (≤ 20°) was reached at a median age of 40.6 years. Three distinct patterns were observed on FAF imaging: 13 of 22 patients tested had relatively preserved foveal autofluorescence surrounded by a ring of high density, 4 of 22 had increased signal in the fovea with no obvious hyperautofluorescent ring, and 5 of 22 had widespread hypoautofluorescence corresponding to retinal pigment epithelial atrophy. Despite a number of cases presenting with a milder phenotype, there seemed to be no obvious genotype-phenotype correlation. CONCLUSIONS: MYO7A-related ocular disease is variable. Central vision typically remains preserved at least until the third decade of life, with 50% of affected individuals reaching legal blindness by 40 years of age. Distinct phenotypic subsets were identified on FAF imaging. A specific allele, previously reported in nonsyndromic deafness, may be associated with a mild retinopathy.

Peripheral vestibular dysfunction is prevalent in older adults experiencing multiple non-syncopal falls versus age-matched non-fallers: a pilot study.

BACKGROUND: vestibular disorders are common in the general population, increasing with age. However, it is unknown whether older adults who fall have a higher proportion of vestibular impairment compared with age-matched older adult non-fallers. OBJECTIVE: to identify whether a greater proportion of older adult fallers have a peripheral vestibular impairment compared with age-matched healthy controls. DESIGN: case-controlled study. SETTING: tertiary falls and neuro-otology clinics and local community centres, London, UK. PARTICIPANTS AND METHODS: community-dwelling older adults experiencing: (i) ≥2 unexplained falls within the previous 12-months (Group F, n = 25), (ii) a confirmed peripheral vestibular disorder (Group PV, n = 15) and (iii) healthy non-fallers (Group H, n = 16). All the participants completed quantitative vestibular function tests, the functional gait assessment (FGA), physiological profile assessment (PPA) and subjective measures for common vestibular symptoms (i.e. giddiness), balance confidence during daily activities and psychological state. RESULTS: a clinically significant vestibular impairment was noted for 80% (20/25) of Group F compared with 18.75% (3/16) for Group H (P < 0.01). Group F performed less well in complex gait tasks (FGA), and reported a greater number of falls than both Groups H and PV (P < 0.05). Vestibular symptom scores showed no significant difference between Groups F and PV. CONCLUSION: vestibular dysfunction is significantly more prevalent in older adult fallers versus non-fallers. Individuals referred to a falls clinic are older, more impaired and report more falls than those referred to a neuro-otology department. A greater awareness of vestibular impairments may lead to more effective management and treatment for older adult fallers.

Vestibular involvement in peripheral neuropathy: a review.

OBJECTIVE: This paper reviews the current literature on involvement of the vestibular division of the eighth cranial nerve in peripheral neuropathies. The literature abounds with references to auditory neuropathy, which is frequently related to more generalized neuropathies, but there is a marked paucity of work regarding vestibular neuropathy. A brief overview of neuropathies and the anatomy of the vestibulocochlear nerve provide the background for a review of the literature of vestibular nerve involvement in a range of neuropathies. DESIGN: A literature search including textbooks, and peer-reviewed published journal articles in online bibliographic databases was conducted. STUDY SAMPLE: Two databases for medical research were included in this review. RESULTS: The review of the literature indicates that vestibular involvement is a common and consistent finding in many peripheral neuropathies of different aetiologies. Specifically, if patients present unsteadiness/ataxia out of proportion to objective signs of somatosensory loss or muscle weakness. CONCLUSION: This review concludes that vestibular neuropathy, is common in peripheral neuropathy and should be identified to optimize patient management and rehabilitation.

Comprehensive sequence analysis of nine Usher syndrome genes in the UK National Collaborative Usher Study.

BACKGROUND: Usher syndrome (USH) is an autosomal recessive disorder comprising retinitis pigmentosa, hearing loss and, in some cases, vestibular dysfunction. It is clinically and genetically heterogeneous with three distinctive clinical types (I-III) and nine Usher genes identified. This study is a comprehensive clinical and genetic analysis of 172 Usher patients and evaluates the contribution of digenic inheritance. METHODS: The genes MYO7A, USH1C, CDH23, PCDH15, USH1G, USH2A, GPR98, WHRN, CLRN1 and the candidate gene SLC4A7 were sequenced in 172 UK Usher patients, regardless of clinical type. RESULTS: No subject had definite mutations (nonsense, frameshift or consensus splice site mutations) in two different USH genes. Novel missense variants were classified UV1-4 (unclassified variant): UV4 is 'probably pathogenic', based on control frequency <0.23%, identification in trans to a pathogenic/probably pathogenic mutation and segregation with USH in only one family; and UV3 ('likely pathogenic') as above, but no information on phase. Overall 79% of identified pathogenic/UV4/UV3 variants were truncating and 21% were missense changes. MYO7A accounted for 53.2%, and USH1C for 14.9% of USH1 families (USH1C:c.496+1G>A being the most common USH1 mutation in the cohort). USH2A was responsible for 79.3% of USH2 families and GPR98 for only 6.6%. No mutations were found in USH1G, WHRN or SLC4A7. CONCLUSIONS: One or two pathogenic/likely pathogenic variants were identified in 86% of cases. No convincing cases of digenic inheritance were found. It is concluded that digenic inheritance does not make a significant contribution to Usher syndrome; the observation of multiple variants in different genes is likely to reflect polymorphic variation, rather than digenic effects.

Patient-reported auditory functions after stroke of the central auditory pathway.

BACKGROUND AND PURPOSE: Auditory functional limitations experienced by patients after stroke of the central auditory pathways remain underinvestigated. Purpose- To measure patient-reported hearing difficulties in everyday life in nonaphasic patients with stroke of the auditory brain versus normal control subjects. To examine how hearing difficulties correlate with auditory tests and site of lesion in individual cases. METHODS: We recruited 21 individuals with auditory brain stroke (excluding those with aphasia) diagnosed on the basis of a brain MRI conducted 1 to 2 weeks after the stroke and assessed in the chronic stage of stroke. Twenty-three controls matched for age and hearing were also recruited. All subjects completed the Amsterdam Inventory for Auditory Disability (consisting of subscales of sound detection, recognition, localization, speech in quiet, speech in noise) and underwent baseline audiometry and central auditory processing tests (dichotic digits, frequency and duration patterns, gaps in noise). RESULTS: Sound recognition and localization subscores of the inventory were significantly worse in case subjects versus control subjects, with severe and significant functional limitation (z score >3) reported by 9 out of 21 case subjects. None of the inventory subscales correlated with audiometric thresholds, but localization and recognition subscales showed a moderate to strong correlation with dichotic digits (left ear) and pattern tests. CONCLUSIONS: A substantial proportion of patients may experience and report severe auditory functional limitations not limited to speech sounds after stroke of the auditory brain. A hearing questionnaire may help identify patients who require more extensive assessment to inform rehabilitation plans.

Diagnostic accuracy and usability of the EMBalance decision support system for vestibular disorders in primary care: proof of concept randomised controlled study results.

BACKGROUND: Dizziness and imbalance are common symptoms that are often inadequately diagnosed or managed, due to a lack of dedicated specialists. Decision Support Systems (DSS) may support first-line physicians to diagnose and manage these patients based on personalised data. AIM: To examine the diagnostic accuracy and application of the EMBalance DSS for diagnosis and management of common vestibular disorders in primary care. METHODS: Patients with persistent dizziness were recruited from primary care in Germany, Greece, Belgium and the UK and randomised to primary care clinicians assessing the patients with (+ DSS) versus assessment without (- DSS) the EMBalance DSS. Subsequently, specialists in neuro-otology/audiovestibular medicine performed clinical evaluation of each patient in a blinded way to provide the "gold standard" against which the + DSS, - DSS and the DSS as a standalone tool (i.e. without the final decision made by the clinician) were validated. RESULTS: One hundred ninety-four participants (age range 25-85, mean = 57.7, SD = 16.7 years) were assigned to the + DSS (N = 100) and to the - DSS group (N = 94). The diagnosis suggested by the + DSS primary care physician agreed with the expert diagnosis in 54%, compared to 41.5% of cases in the - DSS group (odds ratio 1.35). Similar positive trends were observed for management and further referral in the + DSS vs. the - DSS group. The standalone DSS had better diagnostic and management accuracy than the + DSS group. CONCLUSION: There were trends for improved vestibular diagnosis and management when using the EMBalance DSS. The tool requires further development to improve its diagnostic accuracy, but holds promise for timely and effective diagnosis and management of dizzy patients in primary care. TRIAL REGISTRATION NUMBER: NCT02704819 (clinicaltrials.gov).

Sudden sensorineural hearing loss.

Sudden sensorineural hearing loss is usually unilateral and can be associated with tinnitus and vertigo. In most cases the cause is not identified, although various infective, vascular, and immune causes have been proposed. A careful examination is needed to exclude life threatening or treatable causes such as vascular events and malignant diseases, and patients should be referred urgently for further assessment. About half of patients completely recover, usually in about 2 weeks. Many treatments are used, including corticosteroids, antiviral drugs, and vasoactive and oxygen-based treatments. Although no treatment is proven, we recommend a short course of oral high-dose corticosteroids. There is much to learn about pathogenesis of sudden sensorineural hearing loss, and more clinical trials are needed to establish evidence-based management.

Mutations in the USH1C gene associated with sector retinitis pigmentosa and hearing loss.

PURPOSE: To determine the molecular cause of sector retinitis pigmentosa and hearing loss in two affected siblings. METHODS: Direct DNA sequencing of the USH1C gene was performed in two affected siblings. Putative pathogenic sequence changes were assayed in their parent's chromosomes and in control chromosomes. Clinical examination included visual acuity measurement, visual field measurement, electrophysiologic assessment, and fine matrix mapping. Retinal imaging with fundus photography, scanning laser ophthalmoscope (fundus autofluorescence), and optical coherence tomography was performed. Hearing and vestibular function was also assessed. RESULTS: The siblings were aged 42 years and 40 years, and both were compound heterozygotes for the p.R103H missense change and the novel splice site change c.2227-1G>A in the USH1C gene. Both alleles were found to be in trans. Neither allele was identified in a panel of 866 control chromosomes, and both were considered pathogenic. Both siblings had sector retinitis pigmentosa restricted to the inferior and nasal retina. Fundus autofluorescence imaging showed a clear demarcation between normal and abnormal areas of retina, which corresponded to areas of reduced sensitivity on fine matrix mapping and loss of visual field. Both siblings had severe hearing loss but were able to develop language. CONCLUSION: We report a novel molecular cause of sector retinitis pigmentosa associated with hearing loss representing a new phenotype associated with mutations in the USH1C gene.

Nonsense mutation in TMEM126A causing autosomal recessive optic atrophy and auditory neuropathy.

PURPOSE: To define the phenotype and elucidate the molecular basis for an autosomal recessively inherited optic atrophy and auditory neuropathy in a consanguineous family with two affected children. METHODS: Family members underwent detailed ophthalmologic, electrophysiological, and audiological assessments. An autozygosity mapping strategy using high-density single nucleotide polymorphism microarrays and microsatellite markers was used to detect regions of genome homozygosity that might contain the disease gene. Candidate genes were then screened for mutations by direct sequencing. RESULTS: Both affected subjects had poor vision from birth and complained of progressive visual loss over time. Current visual acuity ranged from 6/60 to 6/120. Fundus examination revealed bilateral temporal optic nerve pallor in both patients with otherwise normal retinal findings. International-standard full-field electroretinograms were normal in both individuals, with no evidence of generalized retinal dysfunction. Pattern cortical visual evoked potentials were grossly abnormal bilaterally in both cases. The pattern electroretinogram N95:P50 ratio was subnormal, and the P50 was of shortened peak time bilaterally in both patients. The electrophysiological findings were consistent with bilateral retinal ganglion cell/optic nerve dysfunction. Audiological investigation in both siblings revealed abnormalities falling within the auditory neuropathy/dysynchrony spectrum. There were no auditory symptoms and good outer hair cell function (as demonstrated by transient evoked otoacoustic emissions) but impaired inner hair cell/neural function with abnormal stapedial reflex thresholds and abnormal or absent auditory brainstem-evoked responses. The single nucleotide polymorphism microarray data demonstrated a 24.17 Mb region of homozygosity at 11q14.1-11q22.3, which was confirmed by microsatellite marker analysis. The candidate target region contained the transmembrane protein 126A (TMEM126A) gene, and direct sequencing identified a previously described nonsense mutation (c.163C>T; p.Arg55X). CONCLUSIONS: We describe the first detailed phenotyping of patients with autosomal recessive TMEM126A-associated optic atrophy and auditory neuropathy. These findings will facilitate the identification of individuals with this recently described disorder.

Computer-based auditory training (CBAT): benefits for children with language- and reading-related learning difficulties.

This article reviews the evidence for computer-based auditory training (CBAT) in children with language, reading, and related learning difficulties, and evaluates the extent it can benefit children with auditory processing disorder (APD). Searches were confined to studies published between 2000 and 2008, and they are rated according to the level of evidence hierarchy proposed by the American Speech-Language Hearing Association (ASHA) in 2004. We identified 16 studies of two commercially available CBAT programs (13 studies of Fast ForWord (FFW) and three studies of Earobics) and five further outcome studies of other non-speech and simple speech sounds training, available for children with language, learning, and reading difficulties. The results suggest that, apart from the phonological awareness skills, the FFW and Earobics programs seem to have little effect on the language, spelling, and reading skills of children. Non-speech and simple speech sounds training may be effective in improving children's reading skills, but only if it is delivered by an audio-visual method. There is some initial evidence to suggest that CBAT may be of benefit for children with APD. Further research is necessary, however, to substantiate these preliminary findings.

Update on Usher syndrome.

PURPOSE OF REVIEW: The present review addresses the mechanisms, genetics and pathogenesis of Usher syndrome. RECENT FINDINGS: Recent molecular findings have provided more information regarding the pathogenesis of this disorder and the wide phenotypic variation in both audiovestibular and/or visual systems. Evidence has begun to emerge supporting a theory of a protein interactome involving the Usher proteins in both the inner ear and the retina. This interactome appears to be important for hair cell development in the ear but its role in the retina remains unclear. SUMMARY: Understanding clinical disease progression and molecular pathways is important in the progress towards developing gene therapy to prevent blindness due to Usher syndrome as well as delivering prognostic information to affected individuals.

Macular dystrophy associated with the A3243G mitochondrial DNA mutation. Distinct retinal and associated features, disease variability, and characterization of asymptomatic family members.

OBJECTIVES: To determine (1) detailed retinal and audiological features of probands harboring the A3243G mitochondrial DNA mutation (m.3243A>G) and their asymptomatic maternal relatives, (2) intrafamilial and interfamilial phenotypic variability, and (3) the presence of other systemic features. METHODS: Seven probands harboring the A3243G mitochondrial DNA mutation and 36 asymptomatic maternal relatives were ascertained. Participants underwent ophthalmologic examination, fundus photography, autofluorescence imaging, and audiological evaluation and completed a questionnaire. Blood samples were taken to test for diabetes, determine renal function, and screen relatives for the A3243G mutation. RESULTS: The A3243G mutation was associated with both intrafamilial and interfamilial variable expressivity regarding retinal appearance, hearing loss, diabetes, and other systemic features. The most common macular appearance in maternal relatives (one-third of those positive for the mutation) was mild abnormalities of the retinal pigment epithelium (more clearly identified using autofluorescence), which may therefore be a useful clinical indicator suggesting positive mutation status. Four probands and 13 mutation-positive relatives were found to have evidence of significant bilateral, cochlear, symmetrical age-adjusted hearing loss, predominantly affecting high frequencies. CONCLUSIONS: Hearing loss and macular disturbance were the most frequent findings in mutation-positive participants, with 95% of mutation-positive relatives having hearing loss. Diabetes was the least frequent finding. Patients with progressive hearing loss may merit ophthalmologic assessment to detect retinal abnormalities consistent with the A3243G mutation. Conversely, patients with macular features in keeping with the A3243G mutation should have audiological testing, even in the absence of diabetes or a positive family history.

Oculomotor function in multiple system atrophy: clinical and laboratory features in 30 patients.

We reviewed the clinical and laboratory oculomotor features in 30 patients with probable multiple system atrophy (MSA), 22 with MSA-P and 8 with MSA-C. Six patients were also examined post mortem, MSA being confirmed in four and excluded in two (Parkinson's disease and progressive supranuclear palsy). Clinical examination showed the following abnormalities; excessive square wave jerks--21 of 30 patients; mild vertical supranuclear gaze palsy--8 of 30; gaze-evoked nystagmus--12 of 30 patients, three of whom had no extraocular evidence of cerebellar dysfunction; positioning downbeat nystagmus--10 of 25; mild or moderate saccadic hypometria--22 of 30; impaired ("broken up") smooth pursuit--28 of 30; reduced VOR suppression--16 of 24. Electro-oculography and caloric testing did not add significant extra information. In patients presenting with an akinetic-rigid syndrome it can be difficult to differentiate idiopathic Parkinson's disease from MSA-P and other causes of atypical parkinsonism. Our findings suggest that the presence of excessive square wave jerks, mild-moderate hypometria of saccades, impaired VOR suppression, spontaneous nystagmus or positioning downbeat nystagmus may be oculomotor "red flags" or clues to the presence of MSA. Further, the presence of clinically slow saccades, or moderate-to-severe gaze restriction, suggests a diagnosis other than MSA.

Saccadic eye movements and anti-epileptic drugs.

Saccadic eye movements can be used to evaluate different aspects of brain function, and in this article we are concerned with possible applications in relation to anti-epileptic drug treatment. Recent improvements in the technology of measurement have improved the sensitivity and objectivity of the measures. Here we review the neurophysiology of saccades, their classification, their anatomical basis and cortical control, and then published research articles concerned with the influence of anti-epileptic drugs on saccades and their parameters. It seems likely that certain anti-epileptic drugs (especially those acting on ion channels) exert their effect on saccades through ion channels, and this may have relevance to clinical and pharmacogenetic studies.