Brainstem Auditory Evoked Response Testing Research Articles

Revisiting Friedreich's Ataxia: Phenotypic and Imaging Characteristics.

Friedreich's ataxia (FRDA) is a common cause of autosomal recessive cerebellar ataxia. The phenotype is dependent on the repeat size and duration of the disease. We aimed to study the clinical, electrophysiologic, and radiologic profiles in a large Indian cohort of genetically proven FRDA patients. A retrospective cross-sectional, descriptive analysis of genetically proven FRDA patients was performed. A detailed review of all the hospital case records was done to analyze the clinical, radiologic, and electrophysiologic details. A total of 100 FRDA patients were selected for the analysis. Eighty-six patients had an age at onset between 5 and 25 years. Eight patients (8%) were classified as late-onset FRDA and six patients (6%) as early-onset FRDA. The median age at presentation was 19 years. The median age at onset was 14 years, and the median duration of illness was 4 years. All patients had gait ataxia as the initial symptom. Gait ataxia, loss of proprioception, and areflexia were seen in all patients. Dysarthria, nystagmus, amyotrophy, spasticity, extensor plantars, pes cavus, and scoliosis occurred in one-third of patients. Cardiomyopathy (18%) and diabetes (5%) were less common. Sensory polyneuropathy (87.5%) was the most common nerve conduction abnormality. Cortical somatosensory evoked responses were absent in all 43 tested patients (100%). Brainstem auditory evoked response test was done in 24 patients and it showed absent reactions in six patients (25%). Visual evoked potential was tested in 24 patients and it showed absent P100 responses in five patients (21%). Cerebellar and cord atrophy was seen on magnetic resonance imaging in 50% of patients. Most FRDA patients (86%) had an age at onset of less than 25 years, with typical symptoms of gait ataxia, areflexia, and loss of proprioception found in all patients. Dysarthria, nystagmus, amyotrophy, spasticity, extensor plantars, pes cavus, scoliosis, cardiomyopathy, and diabetes were not seen in all patients. Cerebellar atrophy can occur in FRDA patients. Knowledge regarding the clinical, radiologic, and electrophysiologic profile of FRDA will aid in proper phenotypic characterization.

A de novo 2.3 kb structural variant in MITF explains a novel splashed white phenotype in a Thoroughbred family.

Splashed white in horses is characterized by extensive white patterning on the legs, face and abdomen and may be accompanied by deafness. To date, seven variants in microphthalmia-associated transcription factor (MITF) and two variants in Paired Box 3 (PAX3) have been identified to explain this phenotype. A splashed white Thoroughbred stallion, whose sire and dam were not patterned, was hypothesized to have a de novo variant leading to his white coat pattern. A whole-genome sequencing candidate gene approach identified two single nucleotide variants (SNVs) in SOX10, four SNVs in MITF and a 2.3 kb deletion in MITF with the alternative allele present in this stallion but absent in the other 18 horses analyzed. All six SNVs were annotated as modifiers and were not further considered. The deletion in MITF (NC_009159.3:g.21555811_21558139delinsAAAT) encompasses exon 9 encoding a part of the helix-loop-helix domain required for DNA binding. Sanger sequencing and parentage testing confirmed that this deletion was a de novo mutation of maternal origin. Consistent with the published nomenclature, we denote this likely causal variant as SW8. Genotyping three of this stallion's offspring identified SW8 only in the nearly all-white foal that was confirmed deaf by brainstem auditory evoked response testing. This foal was also a compound heterozygote for dominant white variants (W20/W22), but to date, W variants alone have not been connected to deafness. SW8 marks the fourth de novo MITF variant in horses reported to cause white patterning. The link between deafness and all MITF variants with and without other variants impacting melanocyte development and function needs to be further explored.

Neonatal Hypertonia and Progressive Respiratory Failure due to Novel Heterozygous Mutation in ATAD1

ATAD1-related encephalopathy is a novel monogenic disorder first reported in 2017. 1 Ahrens-Nicklas Rebecca C. Umanah George K.E. Neal Sondheimer Deardorff Matthew A. Wilkens Alisha B. Conlin Laura K. Santani Avni B. et al. “Precision Therapy for a New Disorder of AMPA Receptor Recycling Due to Mutations in ATAD1.”. Neurology Genetics. February 1, 2017; 3https://doi.org/10.1212/NXG.0000000000000130 Crossref Scopus (30) Google Scholar ATAD1 encodes a thorase involved in mitochondrial and peroxisome function that regulates post-synaptic alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionate receptors (AMPAR). 2 Piard Juliette Essien Umanah George K Harms Frederike L Abalde-Atristain Leire Daniel Amram Chang Melissa Chen Rong et al. “A Homozygous ATAD1 Mutation Impairs Postsynaptic AMPA Receptor Trafficking and Causes a Lethal Encephalopathy.”. Brain. March 1, 2018; 141 (61): 651https://doi.org/10.1093/brain/awx377 Crossref Scopus (52) Google Scholar There are eight confirmed cases of ATAD1-related encephalopathy in five families due to three loss of function and one gain of function mutations. 2 Piard Juliette Essien Umanah George K Harms Frederike L Abalde-Atristain Leire Daniel Amram Chang Melissa Chen Rong et al. “A Homozygous ATAD1 Mutation Impairs Postsynaptic AMPA Receptor Trafficking and Causes a Lethal Encephalopathy.”. Brain. March 1, 2018; 141 (61): 651https://doi.org/10.1093/brain/awx377 Crossref Scopus (52) Google Scholar ,3 Bunod Roxane Doummar Diane Whalen Sandra Keren Boris Chantot-Bastaraud Sandra Kim Maincent Marie-Charlotte Villy et al. “Congenital Immobility and Stiffness Related to Biallelic ATAD1 Variants.”. Neurology Genetics. December 1, 2020; 6https://doi.org/10.1212/NXG.0000000000000520 Crossref Scopus (1) Google Scholar All but one family were consanguineous and all patients had homozygous mutations. 3 Bunod Roxane Doummar Diane Whalen Sandra Keren Boris Chantot-Bastaraud Sandra Kim Maincent Marie-Charlotte Villy et al. “Congenital Immobility and Stiffness Related to Biallelic ATAD1 Variants.”. Neurology Genetics. December 1, 2020; 6https://doi.org/10.1212/NXG.0000000000000520 Crossref Scopus (1) Google Scholar The syndrome is characterized by progressive peripheral hypertonia with onset at birth, absent or near absent spontaneous movements, respiratory distress and other symptoms including tremor, clinical seizures, feeding difficulties, hernias, abnormal electroencephalogram (EEG), normal initial neuroimaging with varied abnormalities at later age, and abnormal brainstem auditory evoked response test. 1 Ahrens-Nicklas Rebecca C. Umanah George K.E. Neal Sondheimer Deardorff Matthew A. Wilkens Alisha B. Conlin Laura K. Santani Avni B. et al. “Precision Therapy for a New Disorder of AMPA Receptor Recycling Due to Mutations in ATAD1.”. Neurology Genetics. February 1, 2017; 3https://doi.org/10.1212/NXG.0000000000000130 Crossref Scopus (30) Google Scholar , 2 Piard Juliette Essien Umanah George K Harms Frederike L Abalde-Atristain Leire Daniel Amram Chang Melissa Chen Rong et al. “A Homozygous ATAD1 Mutation Impairs Postsynaptic AMPA Receptor Trafficking and Causes a Lethal Encephalopathy.”. Brain. March 1, 2018; 141 (61): 651https://doi.org/10.1093/brain/awx377 Crossref Scopus (52) Google Scholar , 3 Bunod Roxane Doummar Diane Whalen Sandra Keren Boris Chantot-Bastaraud Sandra Kim Maincent Marie-Charlotte Villy et al. “Congenital Immobility and Stiffness Related to Biallelic ATAD1 Variants.”. Neurology Genetics. December 1, 2020; 6https://doi.org/10.1212/NXG.0000000000000520 Crossref Scopus (1) Google Scholar , 4 Wolf Nicole I Zschocke Johannes Jakobs Cornelis Dietz Rating Hoffmann Georg F “ATAD1 Encephalopathy and Stiff Baby Syndrome: A Recognizable Clinical Presentation.”. Brain. June 1, 2018; 141: e49https://doi.org/10.1093/brain/awy095 Crossref Scopus (4) Google Scholar Loss of ATAD1 disrupts internalization of post-synaptic AMPA receptors, which result in excessive glutamatergic signaling in the brain. 2 Piard Juliette Essien Umanah George K Harms Frederike L Abalde-Atristain Leire Daniel Amram Chang Melissa Chen Rong et al. “A Homozygous ATAD1 Mutation Impairs Postsynaptic AMPA Receptor Trafficking and Causes a Lethal Encephalopathy.”. Brain. March 1, 2018; 141 (61): 651https://doi.org/10.1093/brain/awx377 Crossref Scopus (52) Google Scholar In the original report, Perampanel, an AMPAR antagonist, was trialed based on successful mouse data with improvement in patients’ hypertonicity and seizure resolution. 1 Ahrens-Nicklas Rebecca C. Umanah George K.E. Neal Sondheimer Deardorff Matthew A. Wilkens Alisha B. Conlin Laura K. Santani Avni B. et al. “Precision Therapy for a New Disorder of AMPA Receptor Recycling Due to Mutations in ATAD1.”. Neurology Genetics. February 1, 2017; 3https://doi.org/10.1212/NXG.0000000000000130 Crossref Scopus (30) Google Scholar Among prior cases, six of eight patients died of respiratory failure and/or cardiac sequalae of respiratory distress at a mean age of five months. 3 Bunod Roxane Doummar Diane Whalen Sandra Keren Boris Chantot-Bastaraud Sandra Kim Maincent Marie-Charlotte Villy et al. “Congenital Immobility and Stiffness Related to Biallelic ATAD1 Variants.”. Neurology Genetics. December 1, 2020; 6https://doi.org/10.1212/NXG.0000000000000520 Crossref Scopus (1) Google Scholar This case highlights unsuccessful Perampanel use in an infant with ATAD1-related encephalopathy.

Quantity and duration of exposure to general anesthesia for pediatric patients with retinoblastoma

To quantify the duration of anesthesia required for optimal management of retinoblastoma (Rb), stratified by clinical factors. The medical records of Rb patients treated at Phoenix Children's Hospital between January 2011 and January 2022 were reviewed retrospectively. Demographic, tumor, and treatment data were collected. Anesthesia time was recorded for procedures requiring general anesthesia, including intra-arterial chemotherapy (IAC), enucleation, brainstem auditory evoked response testing (BAER), port placement, magnetic resonance imaging (MRI), and examination under anesthesia (EUA). Descriptive statistics were used to summarize patient and clinical characteristics. Total anesthesia time was 48,991 minutes for 610 procedures in 43 patients. The median follow-up time was 36 months (range, 12-114 months). Average anesthetic durations per exposure were 274, 152, 81.8, 62.5, 60.7, and 45 minutes for IAC, enucleation, BAER, port placement, MRI, and EUA, respectively. Patients with bilateral Rb underwent a median of 1,659 minutes of total anesthesia, compared with 397 minutes for those with unilateral disease. In patients with unilateral Rb, median total anesthesia time was 2,651, 1681, 312, 397 minutes for International Classification of Retinoblastoma grades B, C, D, and E tumors, respectively. Patients who received IAC as their primary treatment had the highest median anesthesia duration (2,100 minutes), followed by systemic chemo (654 minutes) and enucleation (289 minutes). Treatment of Rb requires prolonged and repeated exposure to general anesthesia. Future studies are required to determine the potential effects of these childhood anesthetic exposures.

Brainstem auditory-evoked responses among children afflicted by severely hypoxic CHD.

To electrophysiologically determine the impact of moderate to severe chronic hypoxia (H) resulting from a wide array of CHD (HCHD) conditions on the integrity of brainstem function. Applying brainstem auditory-evoked response methodology, 30 chronically afflicted HCHD patients, who already had undergone heart surgery, were compared to 28 healthy control children (1-15 yo) matched by age, gender and socioeconomic condition. Blood oxygen saturation was clinically determined and again immediately before brainstem auditory-evoked response testing. Among HCHD children, auditory wave latencies (I, III and V) were significantly longer (medians: I, 2.02 ms; III, 4.12 ms, and; V, 6.30 ms) compared to control (medians: I, 1.67ms; III, 3.72 ms, and; V, 5.65 ms), as well as interpeak intervals (HCHD medians: I-V, 4.25 ms, and; III-V, 2.25ms; control medians: I-V, 3.90 ms and, III-V, 1.80 ms) without significant differences in wave amplitudes between groups. A statistically significant and inverse correlation between average blood oxygen saturation of each group (control, 94%; HCHD, 78%) and their respective wave latencies and interpeak intervals was found. As determined by brainstem auditory-evoked responses, young HCHD patients manifestly show severely altered neuronal conductivity in the auditory pathway strongly correlated with their hypoxic condition. These observations are strongly supported by different brainstem neurological and image studies showing that alterations, either in microstructure or function, result from the condition of chronic hypoxia in CHD. The non-altered wave amplitudes are indicative of relatively well-preserved neuronal relay nuclei.

Normative wideband acoustic immittance patterns for middle ear evaluation in dogs.

The objective of this study was to investigate the clinical use of wideband acoustic immittance (WAI) reflectance for middle ear assessment in dogs. Otoscopy and brainstem auditory evoked response testing was performed on all dogs prior to the WAI assessment. Following calibration, dogs were comfortably restrained while the probe was placed into the ear canal to obtain recordings. Testing was repeated for replicability. Repeatable WAI reflectance patterns were observed in 24 dogs, characterized by low-reflectance resonant peaks at approximately 1500-1800 Hz and 3000-4000 Hz. Observed patterns suggest WAI may be a practical means of assessing middle ear function in dogs.

Hepatosplenomegaly and Periventricular Cyst in a Neonate with Direct Hyperbilirubinemia

Hepatosplenomegaly and Periventricular Cyst in a Neonate with Direct Hyperbilirubinemia

A Comparative Study of Insert Earphones and Circumaural Earphones in the Brainstem Auditory-Evoked Response Test of Dogs

A Comparative Study of Insert Earphones and Circumaural Earphones in the Brainstem Auditory-Evoked Response Test of Dogs

Decline in prevalence of congenital sensorineural deafness in Dalmatian dogs in the United Kingdom.

BackgroundCongenital sensorineural deafness (CSD) is the most common type of deafness in Dalmatian dogs.ObjectivesTo use results of CSD screening in Dalmatian dogs in the United Kingdom in genetic analysis and to determine any changes in the prevalence of CSD in this breed over time.AnimalsA total of 8955 Dalmatian puppies undergoing hearing function screening using brainstem auditory evoked response (BAER) between July 1992 and February 2019.MethodsResults of BAER testing and pigmentation phenotypic data were linked to the UK Kennel Club Dalmatian pedigree database. Mixed model analysis was used to estimate variance parameters.ResultsThe overall prevalence of CSD was 17.8% (13.4%, unilateral; 4.4%, bilateral). Heritability of CSD was approximately 0.3 (across models) and significantly >0. Genetic correlations between CSD and blue irises (+0.6) and pigmented head patch (−0.86) were large in magnitude and significantly different form 0. Significant improving phenotypic and genetic trends were identified, likely as the result of selection against deafness, equivalent to avoiding breeding with the 4% to 5% of animals with the highest genetic risk of CSD.Conclusions and Clinical ImportanceA decrease in the prevalence and genetic risk of CSD implies breeders have been selecting for hearing dogs. Selective breeding based on estimated breeding values (EBVs) can help further decrease the prevalence of CSD in Dalmatians in the future.

Brainstem Auditory Evoked Response (BAER) in Canine Otitis Externa

The objective of this study was to assess the brainstem auditory evoked response (BAER) wave pattern in normal dogs as well as those with otitis externa (OE). The BAER test was performed on twenty five dogs with varying degrees of OE. Our study found that BAER of ears with severe OE had prolonged latencies of all waves and lower wave I to wave V amplitude ratio compared to the mildly affected or normal ears. However the inter – peak latencies were unaffected. Thus BAER can be a useful diagnostic tool to assess the hearing impairment due to conductive deafness in OE.

Feasibility of Acupuncture to Induce Sleep for Brainstem Auditory Evoked Response Testing.

Purpose Brainstem auditory evoked response (BAER) testing is often performed under general anesthesia for children unable to complete behavioral audiologic evaluation. Alternatively, acupuncture treatment may be considered appropriate for BAER. Reports of acupuncture treatment in pediatric patients are scarce but are needed to demonstrate effectiveness. This study had 2 main objectives: (a) to examine the feasibility and effectiveness of acupuncture to achieve sleep to perform diagnostic BAER testing in medically complex (Cohort I) and nonmedically complex (Cohort II) children and (b) to assess acceptability to parents and audiologists of acupuncture as an alternative to anesthesia for BAER testing. Method A prospective feasibility study at Seattle Children's Hospital Outpatient Audiology Clinic from August 2015 through December 2018 was performed. A total of 31 pediatric patients were included. The median age for Cohort I was 29 months (interquartile range: 19-37 months), and the median age for Cohort II was 25.5 months (interquartile range: 16-32 months). Variables included number of BAER thresholds obtained, sleep indicators, and acceptability. The cost of BAER with acupuncture and the cost of BAER under anesthesia were compared. Results Acupuncture treatment effectively contributed to an adequate sleep state to obtain BAER results for most patients in both cohorts. Across cohorts, most patients (81%) fell asleep after acupuncture treatment. Complete test results were obtained in 48% of patients. Audiologists and parents reported high satisfaction rates with this procedure (87%). There were no adverse safety effects. Acupuncture treatment was less costly than anesthesia for BAER testing. Conclusions Acupuncture to induce sleep for BAER testing is effective, safe, and cost-efficient in small samples of medically and nonmedically complex pediatric patients. This procedure allowed earlier detection of hearing status and avoided potential adverse effects of anesthesia. Audiologists and parents reported that acupuncture treatment was an acceptable alternative to anesthesia for the BAER procedure.

Prevalence of congenital sensorineural deafness in a population of client-owned purebred kittens in the United Kingdom.

BackgroundData about congenital sensorineural deafness (CSD) in white blue‐eyed cats derive mainly from research colonies, and information about client‐owned cats is limited.ObjectivesTo describe the prevalence of CSD in a client‐owned population of white purebred kittens and colored littermates in the United Kingdom.AnimalsOne hundred thirty‐two solid white client‐owned purebred kittens and 61 colored littermates, 6 to 21 weeks of age.MethodsRetrospective (56 cases) and prospective (137 cases) study. Hearing was assessed by brainstem auditory evoked response testing, and the entire litter was tested.ResultsCongenital sensorineural deafness was diagnosed only in solid white kittens, with a prevalence of 30.3% (15.9% bilateral, 14.4% unilateral). The prevalence of CSD was significantly higher in white kittens with 1 (44.4%) or 2 (50%) blue irises than in those without blue irises (22.2%). Kittens with at least 1 blue iris were 3.2 times more likely to have CSD than kittens without blue irises. In solid white kittens, CSD was diagnosed in 7 of 15 (46.7%) Turkish Vankedisi, 8 of 18 (44.0%) Maine Coon, 18 of 41 (43.9%) Norwegian Forest, 3 of 11 (27.3%) British Shorthair, 2 of 12 (16.7%) Devon Rex, 2 of 12 (8.3%) Persian, 1 of 21 (4.8%) Russian, and 0 of 2 Sphinx. The prevalence of CSD was significantly different in Norwegian Forest, Maine Coon, and Turkish Vankedisi kittens compared with Persian or Russian kittens.Conclusion and Clinical ImportanceWe identified a high prevalence of CSD in a population of client‐owned purebred white kittens in the United Kingdom and suggest differences in breed‐specific prevalence of CSD.

Effects of an enrofloxacin-silver sulfadiazine emulsion in the ears of rabbits with perforated tympanic membranes.

To determine whether an enrofloxacin-silver sulfadiazine emulsion (ESS) labeled for treatment of otitis externa in dogs has ototoxic effects in rabbits following myringotomy. 6 healthy adult New Zealand White rabbits. Rabbits were anesthetized for brainstem auditory-evoked response (BAER) tests on day 0. Myringotomy was performed, and BAER testing was repeated. Saline (0.9% NaCl) solution and ESS were then instilled in the left and right middle ears, respectively, and BAER testing was repeated prior to recovery of rabbits from anesthesia. Application of assigned treatments was continued every 12 hours for 7 days, and rabbits were anesthetized for BAER testing on day 8. Rabbits were euthanized, and samples were collected for histologic (6 ears/treatment) and scanning electron microscopic (1 ear/treatment) examination. Most hearing thresholds (11/12 ears) were subjectively increased after myringotomy, with BAER measurements ranging from 30 to 85 dB in both ears. All day 8 hearing thresholds exceeded baseline (premyringotomy) values; results ranged from 30 to 85 dB and 80 to > 95 dB (the upper test limit) in saline solution-treated and ESS-treated ears, respectively. All ESS-treated ears had heterophilic otitis externa, epithelial hyperplasia of the external ear canal, various degrees of mucoperiosteal edema, and periosteal new bone formation on histologic examination. Scanning electron microscopy revealed that most outer hair cells in the ESS-treated ear lacked stereocilia or were absent. Results supported that ESS has ototoxic effects in the middle ear of rabbits. Further research is needed to confirm these findings. Myringotomized laboratory rabbits may be useful to study ototoxicity of drugs used in human medicine.

Normative Data Obtained in Testing the Sense of Hearing in Kangal Shepherd Dogs

Sense of hearing is of crucial importance for dogs to perform their duties. There is no study to determine the reference latency intervals of dogs' sense of hearing. The aim of this study is to identify normative data that can be used as the reference interval for the wave latencies I, III and V at 80 dB with respect to the sense of hearing of Kangal shepherd dogs. The Brainstem Auditory Evoked Response test was applied to 106 Kangal shepherd dogs in Sivas province. The animals have been grouped by age, sex and general. Normative data were identified for the reference latency intervals for each wave of the right and left ears of the groups and statistical differences between the wave latency intervals were also examined. One-Way ANOVA and post-hoc Duncan test were used in the age group comparison and independent samples t-test was used in the comparison of the other groups. All statistical analyses were performed using the SPSS v.22 software. When the groups are compared, only statistically significant difference was found in the age group at the wave latency V at 80 dB HL. No statistically significance was found in all other groups. The average values of the wave latencies I, III and V were found to be 1.37-2.36-3.65 ms, 1.37-2.35-3.63 ms, 1.38-2.36-3.68 ms, 1.35-2.37-3.79 ms, 1.30-2.26-3.57 ms and 1.41-2.39-3.59, general, female, male, 20 day -9 month, 10-30 month and 31 months and older, respectively. Since normative data on the sense of hearing of Kangal shepherd dogs have been identified for the first time with this study, it is expected to make a significant contribution to the literature. This normative data can be used as reference interval in clinical examinations and future studies on the sense of hearing of Kangal shepherd dogs.

Deafness Risk Estimation Analysis of Native Genetic Resource Kangal Shepherd Dog Breed: Sivas Province Example

Kangal shepherd dogs have excellent sensory organs and perform missions perfectly. For this reason, in many countries of the world, they are preferred for herd guard and as shepherd dog. One of these sensory organs is hearing. The aim of this study was to evaluate the deafness risk estimation analysis of Kangal shepherd dogs breeding in Sivas province of Turkey. The Brainstem Auditory Evoked Response test was applied to 160 Kangal shepherd dogs in Sivas province city center and districts. During the application, the dogs were kept in the present natural environment. The dogs were divided into groups according to their general, gender and age and their responses to frequencies ranging from 20, 40, 60 and 80 decibels (dB) for the right and left ears were investigated. One-Way ANOVA and Duncan multiple comparison test were used in the age group comparison and independent samples t-test was used in the comparison of the other groups. All statistical analysis were performed in the SPSS v.15 software. As a result, the presence of unilateral deafness was detected in 2 dogs in totally. It was also shown that the sense of hearing did not improve in puppies up to 11 days old. Group comparisons were provided statistical significance for right ear in 40 and 60 dB for age groups and right ear in 80 dB for gender groups (P 0.05). This is the first study that deafness estimation was conducted in Kangal shepherd dogs.

Recurrent cerebrovascular accidents caused by intravascular lymphoma in a dog

An eight-year-old, neutered male labrador was presented with recent recurrent vestibular episodes. MRI was consistent with multiple lacunar ischaemic infarcts in the thalamus and medulla oblongata. The imaging diagnosis was...

Unilateral Deafness Diagnosed using the Brainstem Auditory Evoked Response Test in a Shih-tzu Dog

Unilateral Deafness Diagnosed using the Brainstem Auditory Evoked Response Test in a Shih-tzu Dog

Congenital Cytomegalovirus Infection and Permanent Hearing Loss in Rural North Indian Children.

Congenital cytomegalovirus infection (cCMV) is a leading nongenetic cause of permanent congenital or early-onset hearing loss (PCEHL). Although cCMV rates are high despite near-universal seroimmunity, the contribution of cCMV to PCEHL in the developing world is unclear. Neonates at a rural North Indian hospital were screened for cCMV by saliva polymerase chain reaction and hearing by distortion-product otoacoustic emission testing. Cytomegalovirus (CMV)-positive infants and those not passing newborn hearing screening (NHS) were evaluated by auditory brainstem response to confirm PCEHL. Infants with cCMV and those with PCEHL were tested for mutations within the GJB2 gene. Of the 1720 infants screened, 40 (2.3%) did not pass NHS and 20 (1.2%) were CMV positive. Auditory brainstem evoked response testing confirmed unilateral or bilateral PCEHL in 11 (0.64%) children who either did not pass NHS or CMV positive. PCEHL was 20-fold higher in neonates with cCMV (2/20, 10%) than those without (9/1700, 0.5%; P < 0.01). None of 11 infants with PCEHL had connexin 26 mutations. PCEHL incidence is high in India, with cCMV contributing significantly despite near-universal seroimmunity. Our findings also demonstrate the feasibility and the utility of simultaneous newborn screening for both cCMV and hearing loss in a resource-limited setting.

Comparison of the brainstem auditory evoked responses during sevoflurane or alfaxalone anaesthesia in adult cats

ObjectiveTo compare the effects of general anaesthesia using sevoflurane or alfaxalone on the brainstem auditory evoked response (BAER) test in adult healthy cats. Study designProspective, clinical, ‘blinded’, crossover study. AnimalsTen feral adult healthy cats. MethodsPremedication consisted of dexmedetomidine (0.01 mg kg–1) intramuscularly (IM). The first general anaesthesia was induced and maintained with sevoflurane (treatment S) for physical examination, BAER test, complete blood tests, thoracic radiographs and abdominal ultrasound. The second general anaesthesia was induced with alfaxalone (treatment A) IM (2 mg kg–1) and maintained with alfaxalone (10 mg kg–1 hour–1) for the BAER test, followed by neutering surgery.The BAER recordings were compared for differences in latencies, amplitudes and waveform morphology. Data were analysed using Student's t test and Wilcoxon rank test for paired samples for parametric and non-parametric data, respectively. Statistical significance was set at p < 0.05. ResultsGeneral anaesthesia was uneventful; normal BAER comprising five peaks could be identified in both treatments. Mean ± SD latencies were 1.05 ± 0.09, 1.83 ± 0.11, 2.52 ± 0.19, 3.43 ± 0.17 and 4.39 ± 0.15 ms and 1.03 ± 0.04, 1.81 ± 0.73, 2.53 ± 0.15, 3.37 ± 0.13 and 4.33 ± 0.13 ms in treatments S and A, respectively. Median (interquartile range) amplitudes were 2.83 (0.67), 1.27 (0.41), 0.30 (0.40), 1.05 (0.82), 0.61 (0.38) microvolts and 2.84 (1.21), 1.49 (1.18), 0.26 (0.32), 0.91 (0.50) and 0.92 (0.64) microvolts in treatments S and A, respectively. There were no statistically significant differences in mean latencies or median amplitudes between both the anaesthetics. Conclusions and clinical relevanceThis study demonstrates that there were no statistically significant differences between both the anaesthetics on the BAER test in adult healthy cats. Moreover, two possible anaesthetic protocols are described for cats undergoing this electrodiagnostic test.

Hearing disorders in cats.

Practical relevance: Auditory function is a sense that is central to life for cats - being important in situational awareness of potential predators, pursuit of prey, and for communication with conspecifics, humans and other species. Deafness in cats is most frequently the result of a genetic disorder, strongly associated with white fur and blue eyes, but may also result from acquired causes such as advancing age, ototoxic drugs, infection, environmental noise and physical trauma. Deafness can be sensorineural, where there is loss of cochlear hair cells, or conductive, where sound is muffled on its way to the inner ear. Clinical challenges: Establishing whether a cat is deaf can be difficult as behavioral testing of hearing is subjective and does not reliably detect unilateral deafness. Brainstem auditory evoked response testing is an objective measure but is limited in its availability. Currently, sensorineural deafness is irreversible because no treatments are available to restore lost hair cells. Conductive hearing loss can usually be treated, although full hearing recovery following otitis media may take weeks as the body clears the middle ear of debris. Evidence base: The author draws on the published literature and his extensive research on clinical aspects and molecular genetics of deafness, principally in companion animals, to review types and forms of deafness in cats. He also discusses current diagnostic approaches and provides brief advice for managing cats with hearing loss.