The value of combining auditory brainstem responses and acoustic reflex threshold measurements in neuro-otological diagnosis

Audiological Findings in Children with PLA2G6-Associated Neurodegeneration

BACKGROUND

 Audiological manifestations of patients with PLA2G6-associated neurodegeneration are limited.

OBJECTIVE

 To analyze the audiological findings in a cohort of 13 children with infantile neuroaxonal dystrophy (INAD).

METHOD

 Patients underwent a battery of audiological tests including tympanometry, distortion product otoacoustic emissions, impedance audiometry, and Brainstem Auditory Evoked Potentials (BAEPs).

RESULTS

 Audiological studies of 13 children indicated sensorineural hearing loss in six children and auditory neuropathy spectrum disorder in four children.

CONCLUSION

 This study may extend the auditory findings for INAD. Additional studies on quality of life and cognitive-brain degeneration related to this disease are required before making appropriate recommendations for aural rehabilitation.

A Hearing Screening Protocol for Stroke Patients: An Exploratory Study

Background: Auditory impairment post stroke is common and may be due to both peripheral hearing loss and or central auditory processing disorder (CAPD). When auditory impairment remains untreated, it may impact on patient communication and rehabilitation after stroke. Offering a comprehensive audiological assessment to all stroke patients would be both costly and time-consuming. A brief hearing screening is thus required. Objective: The aim of this study was to determine whether a two-tiered hearing screening approach, with use of a handheld hearing screener and two validated hearing questionnaires could be used as a hearing screening for peripheral hearing loss and CAPD in stroke survivors. The sensitivity and specificity of the screening method was analyzed. Methods: This was a prospective study conducted in a tertiary neurology hospital. Forty-two consecutive stroke patients were recruited and tested within 3-12 months post-onset of their stroke. Three screening tools for the identification of hearing impairment were evaluated in this study: A handheld hearing screener for determination of peripheral audiometric hearing loss and two validated questionnaires (The Amsterdam Inventory Auditory for Disability (AIAD) and the Hearing Handicap Inventory for Elderly (HHIE) questionnaires) for determination of peripheral hearing loss and/or CAPD. Results: The hearing screener had a sensitivity of 92. 59% detecting a hearing loss and specificity of 100%. The greatest test accuracy in identifying a central auditory processing type hearing impairment in stroke patients was found when the handheld hearing screener and the AIAD questionnaire were combined. Conclusion: This study is a first step toward addressing the complex auditory needs of stroke survivors in a systematic manner, with the ultimate aim to support their communication needs and long-term recovery and wellbeing. Registration: Project Identification number 11/0469 and REC ref 11/LO/1675.

Audiological findings in Infantile Refsum disease

Audiological manifestations in a four-year-old child with Infantile Refsum disease are reported. He was born to non-consanguineous parents and had normal birth history and mildly delayed milestones prior to presentation. Clinical features were characterized by neuroregression, retinitis pigmentosa, hearing loss, peripheral neuropathy and white matter signal changes on magnetic resonance imaging. Biochemical evaluation showed elevated serum levels of long chain fatty acid and phytanic acid confirming the diagnosis. The audiological profile was characterized by absent auditory brainstem responses with robust otocoustic emissions, which indicated auditory neuropathy as the possible cause of hearing loss.

Quantification of the stapedial reflex reveals delayed responses in autism

Autism is a developmental disorder characterized, in part, by sensory abnormalities. It is well established that most if not all patients with autism have problems with auditory processing, ranging from deafness to hyperacusis, and physiological testing of auditory function (i.e. auditory brain stem responses) implicates brain stem dysfunction in autism. Additionally, previous research from this lab has revealed significantly fewer auditory brain stem neurons in autistic subjects as young as 2 years of age. These observations have led us to hypothesize that objective, noninvasive measures of auditory function can be used as an early screening tool to identify neonates with an elevated risk of carrying a diagnosis of autism. Here, we provide a detailed quantitative investigation of the acoustic stapedial reflex (ASR), a three- or four-neuron brain stem circuit, in young autistic subjects and normal developing controls. Indeed, we find significantly lower thresholds, responses occurring at significantly longer latency and right-left asymmetry in autistic subjects. The results from this investigation support deficits in auditory function as a cardinal feature of autism and suggest that individuals with autism can be identified by their ASR responses.

ABR in the diagnosis of vestibular schwannomas: a meta-analysis

PURPOSE

The aim of this study is to rigorously evaluate the role of auditory brainstem response (ABR) testing in the diagnosis of vestibular schwannomas (VS).

MATERIALS AND METHODS

Searches were conducted in multiple online databases, supplemented by hand searches. From the studies chosen for final inclusion, relevant data were extracted and meta-analysis of pooled data was performed.

RESULTS

623 studies were identified from which 43 met inclusion criteria for analysis (1978 to 2009) including 3314 patients. Pooled sensitivity for ABR detection of vestibular schwannomas was 93.4% (95% CI 92.6-94.3, P=0.0000). For tumors less than 1cm (8 studies, 176 patients) sensitivity was 85.8% (95% CI 80.6-90.1, P=0.0116). For tumors greater than 1cm (6 studies, 251 patients) pooled sensitivity was 95.6% (95% CI 93.1-98.2, P=0.0660). Sensitivity of ABR to detect extracanalicular tumors was higher than for intracanalicular tumors, though pooled data were not statistically valid. Pooled specificity (8 studies, 2432 patients) was 82.0% (95% CI 80.5-83.6, P=0.0000).

CONCLUSIONS

Although MRI remains the gold standard, emerging trends towards more conservative management coupled with limited financial resources may prompt many clinicians to review the role of ABR testing in screening for retrocochlear pathology. In light of the high sensitivity and specificity of ABR testing for VS, we strongly urge its reconsideration as a useful diagnostic tool for patients with clinically suspected VS.

Survey of Audiological Immittance Practices

Purpose

The purpose of this study was to examine current immittance practices and trends over time, reasons why multifrequency (MF) and multicomponent (MC) tympanometry have been underused, and the prevalence of negative patient reactions to acoustic reflex (AR) testing.

Method

Two audiological practice surveys were conducted regarding tympanometry (2008, n = 156) and AR (2009, n = 90).

Results

Most respondents conduct tympanometry and AR threshold (ART) testing. MF and MC tympanometry were rarely reported, generally due to a lack of equipment and training. ART testing was reported most often using both ipsilateral and contralateral presentation. Contralateral testing has decreased over time. Patient complaints of discomfort following AR testing were common. Complaints of tinnitus or hearing loss were present, although rare.

Conclusion

Tympanometry and ART tests have remained popular for the past 30 years, whereas acoustic reflex decay (ARD) testing has decreased in popularity. MF and MC tympanometry are conducted infrequently. AR is frequently associated with discomfort but rarely associated with other symptoms. However, one respondent reported that AR testing had caused permanent tinnitus and hearing loss.

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.

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.

Hearing loss in adult Refsum's disease

Refsum's disease is characterized by defective peroxisomal alpha oxidation of phytanic acid, with clinical features that include retinitis pigmentosa, polyneuropathy, anosmia and hearing loss. Although hearing loss in Refsum's disease is common, there are few detailed assessments of the site of the abnormality. We examined the audiometric findings in patients with biochemically diagnosed Refsum's disease in order to assess the site of origin of the hearing loss. We found hearing loss, ranging from mild, predominantly high frequency to moderate degree, in seven out of nine patients with biochemically diagnosed adult Refsum's disease. In addition, we found evidence to suggest subtle auditory nerve involvement in six out of the seven patients with hearing loss and in one out of the two patients with a normal pure tone audiogram, on the basis of the ABR test results. We conclude that patients with Refsum's disease who report hearing difficulties should have full audiometric investigations in order to provide appropriate audiological rehabilitation.

The effect of lidocaine on chronic tinnitus: a quantitative cerebral perfusion study

The cerebral perfusion of a 55-year-old female patient with chronic tinnitus was investigated quantitatively by single photon emission computed tomography (SPECT) with the xenon133 inhalation method. The first investigation was performed under standard conditions, the second during suppression of tinnitus with intravenous injection of lidocaine. As a reference a healthy volunteer was included under the same conditions. The global cortical perfusion was identical on both sides except for increased perfusion in the auditory cortex, especially on the right side when tinnitus lasted during the first measurement. The second investigation under treatment with lidocaine and during the tinnitus-free interval showed a decrease of the global cortical perfusion with a slightly higher value at the temporal cortex bilaterally. In comparison to the first investigation, a difference between right and left auditory cortex could no longer be demonstrated, and also the difference between regional and global perfusion decreased. A cerebral effect under treatment of tinnitus with lidocaine was shown by the quantitative measurement of brain perfusion. It is debatable whether this effect on cerebral activity results from the medication or as a reaction to the tinnitus-free interval.