Department of Otolaryngology Head and Neck Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
Other papers by authors:
Sri Kiran Chennupati, Jessica Levi, Patricia Loftus, Carly Jornlin, Thierry Morlet, Robert C O'Reilly
St. Christopher's Hospital for Children, Division of Otolaryngology, 3601 A Street, Philadelphia, PA 19134, United States.
OBJECTIVE At least 1-5 children per 1000 suffer from congenital hearing loss, and 50% of these cases can be attributed to genetic causes. It has been estimated that 1% of pre-lingual hearing loss is due to mutations in mitochondrial DNA. Previous literature reports audiometric data for few patients, usually less than 20 per study. The goal of this study was to characterize the hearing loss associated with mitochondrial mutations and determine whether previously characterized patterns of hearing loss in these patients (progressive, sensorineural, high frequency losses) are found in our population as well. METHODS An IRB-approved retrospective chart review of the electronic medical records in the Nemours/Alfred I. dupont Hospital for Children system from January 2004 to October 2009 (a five-year period) was undertaken using ICD-9 codes 277.87 (mitochondrial disorder) and 359.89BA (mitochondrial myopathy). These 149 records were then evaluated for audiologic data, resulting in 26 charts with both a mitochondrial disorder and hearing evaluation. RESULTS Of 26 patients with known mitochondrial disorders and audiometric documentation, 15 (58%) had hearing loss, and 11 patients had normal hearing (42%). Ten patients had sensorineural hearing loss (38%), two patients had conductive hearing loss (7.7%), one patient had a mixed hearing loss (3.8%), and two patients had an as yet undefined hearing loss (ABR had not yet been performed at the time of this study)(7.7%). CONCLUSION In comparison with previous studies, generally including less than 20 patients, this is one of the largest collections of audiometric data on children with mitochondrial disorders. Unlike prior studies describing a progressive, sensorineural loss across all frequencies or mainly affecting high frequencies, the hearing loss in our patients was more variable including low frequency losses, mid-frequency losses, and conductive losses and was often not progressive or even improved. Our overall 38% rate of sensorineural hearing loss correlates well with previous case series; this study clearly justifies the use of routine audiometric screening in children with mitochondrial disorders, including use of ABR and OAEs as ASND can be seen in this population, as well as repeat testing over time to evaluate for progression.
Robert C O'Reilly, Jewell Greywoode, Thierry Morlet, Freeman Miller, John Henley, Chris Church, Jeffrey Campbell, Jason Beaman, Anne Marie Cox, Emily Zwicky, Charles Bean, Stephen Falcheck
Division of Pediatric Otolaryngology, Alfred I. duPont Hospital for Children, Wilmington, Delaware 19899, USA. firstname.lastname@example.org
To describe the spectrum of balance disease in a large population of children presenting to a tertiary care vestibular and balance laboratory. Case series with chart review. Tertiary care pediatric hospital. Results of audiometric, vestibular, and balance tests and final diagnosis. Retrospective review of audiometric, vestibular, balance testing, and final diagnosis from a patient database. Between September 2003 and September 2007, 132 children were evaluated at the Alfred I. duPont Hospital for Children Vestibular Disorders Program. Sixty-nine of the patients were boys and 63 were girls. The average age was 9.7 ± 5.0 years (range, 1-17 years). Although not all were able to complete the entire test battery (99 children completed at least 50% of the tests in the protocol), a diagnosis was achieved in most cases. The most common diagnoses were peripheral vestibulopathy (29.5%), migraine/benign recurrent vertigo of childhood (24.2%), motor/developmental delay (10.6%), traumatic brain injury (9.8%), and central nervous system structural lesion (9.1%). Peripheral vestibular deficits and migraine disease account for most of the pathology in the pediatric population. With a multidisciplinary approach, diagnosis of the source of vertigo and imbalance is possible in most children.
Robert C O'Reilly, Thierry Morlet, Brian D Nicholas, Gary Josephson, Drew Horlbeck, Larry Lundy, Arnel Mercado
Department of Otolaryngology, Alfred I. duPont Hospital for Children, Wilmington, Delaware 19899, USA. email@example.com
Determine the prevalence of vestibular and balance disorders in children, rate of complaints of imbalance, and odds ratio of related diagnoses. Retrospective review of pediatric health system during a 4-year period for International Classification of Diseases, 9th Revision, codes related to balance disorders. Identified records were searched for chief complaints related to balance and for codes of related otologic and neuro-otologic diagnoses. A total of 561,151 distinct patient encounters were found. Unspecified dizziness was diagnosed in 2,283 patients (0.4%). Also, 22% presented with balance complaints. Peripheral disorders were diagnosed in 159, and central disturbances were diagnosed in 109 (prevalence < 0.0002%). Cumulative prevalence of diagnoses related to balance was 0.45%(2,546/561,151). Of all patients, 5,793 (1.03%) had chief complaint related to balance, and 2,076 (35.84%) were also diagnosed with vestibular disorder. Moreover, 38% with peripheral disturbances and 21% with central disturbances had balance complaints. Odds ratio of syncope was 21× higher than the general pediatric population in patients with unspecified dizziness, and sensorineural hearing loss was 43 times higher in those with peripheral vestibular disorders. In patients with central disorders headache was 16× higher (p < 0.05). The prevalence of balance disorders in children is low. Children diagnosed with these disorders typically do not present with chief complaint related to balance. Significant associations exist between sensorineural hearing loss, syncope, and headache in children diagnosed with balance disorders.
Douglas R Johnston, Joseph M Curry, Brian Newborough, Thierry Morlet, Louis Bartoshesky, Sharon Lehman, Sara Ennis, Robert C O'Reilly
Department of Otolaryngology-Head and Neck Surgery, Alfred I. duPont Hospital for Children, Wilmington, Delaware, USA.
OBJECTIVE To determine the rate of ophthalmologic anomalies among patients with syndromic and nonsyndromic, congenital sensorineural hearing loss (SNHL) to assess the need for comprehensive ophthalmologic evaluation in these children. DESIGN Retrospective medical chart review of children with SNHL who underwent comprehensive evaluation by pediatric ophthalmologists and geneticists. SETTING Tertiary care pediatric hospital. PATIENTS Seventy-seven patients with SNHL. MAIN OUTCOME MEASURES Degree of hearing loss (HL) and presence of ophthalmologic and genetic disorders. RESULTS The overall rate of ophthalmologic disorders was 32%(25 of 77 patients). When children with multisystem genetic disorders known to be related to visual loss were excluded, the rate fell to 23%(12 of 53 vs 13 of 24; P =.006). There was no statistically significant difference in the degree of HL between patients with and without eye disorders (mean [SD], 46.5 [29.9] vs 49.1 [32.3] dB HL; P =.75). Patients with eye disorders were significantly more likely to have a multisystem genetic disorder (13 of 25 [52%] vs 11 of 52 [21%]; P =.006). No patients with ocular abnormalities had isolated otologic disorders, but 9 of 52 (17%) of those patients without ocular abnormalities did. CONCLUSIONS Comprehensive ophthalmologic examination revealed a rate of ophthalmologic disorders in children with SNHL in the lower end of the previously reported rates of 31% to 61%. Children with nonsyndromic SNHL have an approximately 2- to 3-fold increase in ocular abnormalities compared with the general pediatric population. Ophthalmologic and genetic consultations are warranted in patients with congenital SNHL.
Thomas Jefferson University Hospital, Philadelphia, PA.
OBJECTIVE To describe a novel technique of cartilage tympanoplasty, and review surgical and hearing results in children. STUDY DESIGN AND SETTING Retrospective chart review of all patients who had undergone tympanoplasty at a pediatric tertiary care hospital from August 2002 to July 2005. Forty-two patients were identified with a minimum follow-up time of 12 months. RESULTS Mean preoperative perforation size was 21.3 percent (range 10%-90%), and mean patient age was 7.9 years (range 3-16 years). Median clinical follow-up was 24 months. Tympanic membrane closure and graft integration were achieved in 40 of 42 patients (95.2%), and 35 of 42 (85.7%) patients maintained an intact, stable tympanic membrane on long-term follow-up. A total of 93.8 percent of patients achieved a postoperative air-bone gap of less than or equal to 20 dB, and mean improvement in the air-bone gap was 10.7 dB. CONCLUSION AND SIGNIFICANCE Cartilage interleave tympanoplasty is a versatile, stable, and effective technique for tympanic membrane repair in children.
Atypical presentation of geniculate ganglion venous malformation in a child: Conductive hearing loss without facial weakness.
Julie A Ames, Jessica R Levi, Douglas R Johnston, Colin A Drake, Thomas O Willcox, Robert C O'Reilly
Alfred I. duPont Hospital for Children, Wilmington, DE, United States.
We describe an unusual presentation of geniculate ganglion venous malformation, a rare facial nerve lesion, emphasizing the importance of the differential diagnosis, imaging characteristics, and controversies in management. A child presented with moderate right-sided conductive hearing loss and a House-Brackmann grade I facial nerve function bilaterally. Computed tomography and magnetic resonance imaging showed a mass demonstrating features consistent with a geniculate ganglion venous malformation. To our knowledge, this is the first pediatric case of geniculate ganglion venous malformation presenting solely with conductive hearing loss. Proper management requires differentiating this condition from other geniculate and temporal bone lesions.
Division of Pediatric Otolaryngology, Nemours/Alfred I. duPont Hospital for Children, P.O. Box 269, Wilmington, DE 19899, USA. firstname.lastname@example.org.
Otitis media is the most common reason for antibiotic prescription in the United States. Whether due to disease virulence or growing antimicrobial resistance, complications of otitis media seem to be seen more frequently. These complications may be difficult to identify and treat. This article focuses on the pathophysiology of these complications and address medical and surgical approaches to safe treatment.
Pamela Dalton, Julie A Mennella, Christopher Maute, Sara M Castor, Aleida Silva-Garcia, Jerry Slotkin, Christopher R Grindle, William Parkes, Edmund A Pribitkin, James S Reilly
Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA. email@example.com
OBJECTIVES/HYPOTHESIS This study evaluated two versions of a test for olfactory function to determine suitability for use in a pediatric population. STUDY DESIGN Cross-sectional cohort study. METHODS In phase 1, 369 children (ages 3-17 years) and 277 adults (parents) were tested. Children began with identification and familiarity judgments to pictures representing target odors and distractors. Odors were administered via a six-item scratch and sniff test. Each answer sheet contained the correct odor source and three distractors. In phase 2, 50 children (ages 3-4 years) and 43 adults were given a revised version with eight odors judged more representative of the source and familiar to children. RESULTS Both completion time and identification accuracy in phase 1 improved with age. Accuracy of children 5 years old and above equaled adults for two of the three best odors. In phase 2, adults' accuracy significantly improved relative to phase 1 (92% vs. 68%), and exceeded that of 4 year olds for four of eight odors and 3 year olds for seven of eight odors. CONCLUSIONS Children as young as 3 years of age can perform olfactory testing, but take longer than do older children and adults (7.44 vs. 5.66 vs. 3.71 minutes). Identification accuracy also increases as a function of age. The current six-item National Institutes of Health Toolbox Odor Identification Test is a brief, easily conducted test for evaluating olfactory ability. Collection of normative data for children of all ages and adults is needed to determine the clinical utility of the test and its interpretations for pathological conditions.
Connecticut Children's Medical Center, Hartford, Connecticut 06106, USA. firstname.lastname@example.org
OBJECTIVE/HYPOTHESIS Adenoidectomy is a frequently performed procedure in the pediatric population. Revision rates and indications for a second procedure in children are scarce. STUDY DESIGN Retrospective cohort study. METHODS Patient records at a multistate pediatric healthcare system were searched for all CPT codes that included adenoidectomy in children less than 12 years of age for a 5-year period (2005-2010). A subset of patients was identified for whom the same CPT codes appeared more than once in this 5-year period. The indication, age, gender, adenoid size, and technique of adenoidectomy were recorded. RESULTS A total of 23,612 occurrences of the CPT codes were identified. The subset of patients with multiple CPT codes, indicating revision adenoidectomy, included 304 records (1.3%). Mean age at first procedure was 2.8 years (SD = 1.7 years). Mean age at second procedure was 4.7 years (SD = 1.99 years). Mean interval between procedures was 1.8 years (SD = 1.1 years). CONCLUSIONS Revision adenoidectomy occurs at a rate of 1.3%. Reasons for revision include persistence symptoms ranging from adenoiditis to recurrent otitis to obstructive sleep apnea.
Am J Otolaryngol. ;33 (1):178-80 21715048
Inadvertent insertion of nasogastric tube into the brain stem and spinal cord after endoscopic skull base surgery.
Department of Neurological Surgery, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
A significant number of neurosurgical patients require feeding tube placement via a nasogastric route. It is used as a temporary access for enteral feeding until patients are able to swallow or receive permanent access. Despite how commonly feeding tubes are used, they are not without potential complications. We report a case of inadvertent placement of small-bore feeding tube into the brain stem and spinal cord in a patient with a history of previous endoscopic transnasal resection of clival chordoma. We discuss the management of this complication and the strategies that have been developed to avoid this complication in the future.
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Myung Woul Han, Joong Ho Ahn, Joong Koo Kang, Eun Mi Lee, Jeong Hyun Lee, Jung Hyun Bae, Jong Woo Chung
Department of Otolaryngology, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, South Korea.
In temporal lobe epilepsy (TLE) there may be functional abnormalities or structural lesions that can manifest as a central auditory processing disorder, which is defined as a disorder in the recognition, discrimination, ordering, grouping, and localization of sounds, with emphasis on the processing of nonspeech sounds. We performed frequency pattern, duration pattern, and dichotic tests in 28 patients with TLE with normal hearing on pure tone audiometry. The scores on the frequency pattern, duration pattern, and dichotic tests were abnormal in 78.6, 57.1, and 20.6% of patients, respectively, with no significant differences with the laterality of TLE. Patients with hippocampal sclerosis performed significantly worse than patients with normal MRI findings in frequency tests. Longer duration of epilepsy is negatively correlated with both the duration pattern and dichotic tests (P<0.05). Our results suggest that patients with TLE may be at risk for impairment of central auditory processing, which is increased in patients with hippocampal sclerosis or a longer duration of epilepsy.
Laryngorhinootologie. 2010 Apr 12;: 20387193
Sektion für Phoniatrie und Pädaudiologie der HNO Univ.-Klinik (Prof. Dr. G. Rettinger), Ulm.
HOW DO RESULTS IN BAKO 1-4 AND H-LAD-TEST CORRELATE WITH AUDITORY PROCESSING?OBJECTIVE: An increasing number of children seem to have a deficiency in Central Processing as a reason for reading and writing difficulties (RWD) and attention deficit disorder (ADD). There is often also a delay in phonological consciousness. A test would therefore be useful to distinguish children with RWD and ADD. MATERIAL AND METHODS: This study involved 75 consecutive schoolchildren from the 1 (st) to 5 (th) classes (ages 6-11), and was carried out at the Department of Phoniatric-Paediatric Audiology at the University ENT Clinic Ulm. Various tests were undertaken: hearing tests for peripheral hearing, central auditory tests, tests of phonological competence and a questionnaire completed with the parents. Statistical calculations were used to verify correlations with clinical findings and the questionnaire. RESULTS: BAKO 1-4 and H-LAD test phonological awareness and the T-values showed a good correlation, as expected. These are therefore reliable tests. No gender specific differences could be found. The BAKO 1-4 test was better statistically and this confirms other groups' findings. The questionnaire is not ready to be used for diagnosis. It is not possible to distinguish different diagnoses (central auditory processing disorder, writing difficulties, delayed speech acquisition and delay in phonological consciousness) by means of auditory tests. CONCLUSIONS: This means that the capacity to distinguish phonemes is not directly correlated to central auditory functions. Equally, one can also say that not every child with such problems has deficits in central auditory processing which require therapy. They all require an interdisciplinary management tailored to their own needs and underlying causes.
In Vivo. ;24 (2):201-9 20363995
Associate Professor, Department of Phoniatrics and Pedaudiology, Clinic of Otorhinolaryngology, Head and Neck Surgery, University Hospital, Martin Luther University Halle-Wittenberg, Magdeburger Strasse 12, D-06097 Halle (Saale), Germany. email@example.com.
The term 'central auditory processing disorder'(CAPD; in German-speaking countries:'auditive Verarbeitungs- und Wahrnehmungsstörung', AVWS) embraces various complex disorders of central auditory function. The purpose of this preliminary study was to develop a functional magnetic resonance imaging (fMRI) test set in order to extend the diagnostic work-up to include imaging, and thus to improve both diagnostic performance and the monitoring of treatment outcome. fMRI was performed in 11 healthy children ranging in age from 7 to 10 years and in 11 healthy adults (age range: 23 to 31 years). Three tests, used for diagnosis of CAPD, served as the basis for fMRI paradigms: the Hannover phoneme discrimination test (HPDT); the auditory memory span test (MST) and the dichotic listening test (DLT). In the HPDT, activations in the dorsal part of the superior temporal gyrus (STG) were found on both sides, in the Broca area and in the left middle temporal gyrus, typical for phonemic tasks. The MST showed bilateral activations of the STG, typical for processing of pseudo-words. In addition, bilateral activation of the hippocampus was found. However, there was no clear activity in the left supramarginal gyrus, where the phonological store is thought to be located. The DLT showed activations of the bilateral STG and of the left inferior frontal gyrus. Predominantly, the paradigms showed typical activation patterns of the examined central auditory functions. These results can serve as a reference for future examinations in children with AVWS/CAPD.
Cognitive Neuroimaging Group, MRC Cyclotron Unit, Hammersmith Hospital, London W120NN, UK. firstname.lastname@example.org
Focal brain lesions are assumed to produce language deficits by two basic mechanisms: local cortical dysfunction at the lesion site, and remote cortical dysfunction due to disruption of the transfer and integration of information between connected brain regions. However, functional imaging studies investigating language outcome after aphasic stroke have tended to focus only on the role of local cortical function. In this positron emission tomography functional imaging study, we explored relationships between language comprehension performance after aphasic stroke and the functional connectivity of a key speech-processing region in left anterolateral superior temporal cortex. We compared the organization of left anterolateral superior temporal cortex functional connections during narrative speech comprehension in normal subjects with left anterolateral superior temporal cortex connectivity in a group of chronic aphasic stroke patients. We then evaluated the language deficits associated with altered left anterolateral superior temporal cortex connectivity in aphasic stroke. During normal narrative speech comprehension, left anterolateral superior temporal cortex displayed positive functional connections with left anterior basal temporal cortex, left inferior frontal gyrus and homotopic cortex in right anterolateral superior temporal cortex. As a group, aphasic patients demonstrated a selective disruption of the normal functional connection between left and right anterolateral superior temporal cortices. We observed that deficits in auditory single word and sentence comprehension correlated both with the degree of disruption of left-right anterolateral superior temporal cortical connectivity and with local activation in the anterolateral superior temporal cortex. Subgroup analysis revealed that aphasic patients with preserved positive intertemporal connectivity displayed better receptive language function; these patients also showed greater than normal left inferior frontal gyrus activity, suggesting a possible 'top-down' compensatory mechanism. These results demonstrate that functional connectivity between anterolateral superior temporal cortex and right anterior superior temporal cortex is a marker of receptive language outcome after aphasic stroke, and illustrate that language system organization after focal brain lesions may be marked by complex signatures of altered local and pathway-level function.
Laura D Ruiz-Allec, Yolanda R Peñaloza-López, Nieves del R Ocaña-Plante, Teresa Valdez-González, Ellery López-Star
Instituto Nacional de Rehabilitación, Servicio de Audiología, México DF, México. email@example.com
OBJECTIVE: To identify and describe peripheral and central audiological abnormalities of patients with Vogt Koyanagi Harada syndrome. MATERIALS AND METHODS: Prospective, cross-sectional, observational, descriptive study. Vogt Koyanagi Harada patients referred from an ophthalmologic centre were assessed for signs and symptoms of auditory pathology. Peripheral audiological and central auditory processing tests were performed. To standardize the latter, methodological controls were matched for sex, age and audiometric chart. RESULTS: 21 patients were included (3 male, 18 female), mean age 40.7 years (+/-11.82). Nine of the 21 complained of tinnitus and nine suspected hearing loss. Exclusively or mainly sensorial abnormalities of pure tone audiometric chart were documented in 61.9%(mainly selective troughs at 4 and 8 kHz); 95.3% of patients had deficit in high-frequency audiometry. Five of the patients had sensorial disorders in the speech audiometry. No central auditory processing disorder was seen. CONCLUSIONS: Most of the patients with Vogt Koyanagi Harada syndrome had objective peripheral audiological abnormalities, although few revealed any symptoms.
Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
Recent auditory oddball studies using syntactic stimuli report a syntactic effect on the mismatch negativity (sMMN) around 100 - 200 ms. For morphosyntactic violations, this sMMN effect has been localized in the left superior temporal cortex. Independently, a recent visual sentence processing study introduced a "sensory hypothesis" which postulates that sensory cortices are sensitive to syntactic violations when these are overtly marked by closed-class morphemes, and thus contribute to early syntax-related effects in EEG and MEG. The present study aimed to test the sensory hypothesis in the auditory modality by localizing the neuronal sources of the sMMN to phrase structure violations. Using whole head magnetoencephalography, two-word utterances which were syntactically correct, uncommon or incorrect due to a word category violation were presented in an auditory oddball paradigm. In the sMMN time window (100-180ms), incorrect phrases elicited strongest activation in the left Sylvian fissure (including the primary auditory cortex) and in the left superior temporal sulcus. Prior to this, a very early grammaticality effect (40-80 ms), focused in the left Sylvian fissure, was found. An additional grammaticality effect in a later time window (280-380 ms) was localized in the anterior part of the superior temporal gyrus, the planum polare. Processing of an uncommon phrase did not differ from processing a correct phrase in any of the time windows, indicating the genuinely syntactic nature of the sMMN effect. Our results are in line with previous studies localizing the sMMN to morphosyntactic violations and are furthermore compatible with the sensory hypothesis of closed-class morphology based syntactic processes.
Detection of differential speech-specific processes in the temporal lobe using fMRI and a dynamic "sound morphing" technique.
Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway. firstname.lastname@example.org
Contrary to the classical view, recent neuroimaging studies claim that phonological processing, as part of auditory speech perception, is subserved by both the left and right temporal lobes and not the left temporal lobe alone. This study seeks to explore whether there are variations in the lateralization of response to verbal and nonverbal sounds by varying spectral complexity of those sounds. White noise was gradually transformed into either speech or music sounds using a "sound morphing" procedure. The stimuli were presented in an event-related design and the evoked brain responses were measured using fMRI. The results demonstrated that the left temporal lobe was predominantly sensitive to gradual manipulation of the speech sounds while the right temporal lobe responded to all sounds and manipulations. This effect was especially pronounced within the middle region of the left superior temporal sulcus (mid-STS). This area could be further subdivided into a more posterior area, which showed a linear response to the manipulation of speech sounds, and an anteriorly adjacent area which showed the strongest interaction between the speech and music sound manipulations. Such a differential and selective response was not seen in other brain areas and not when the sound "morphed" into a music stimulus. This gives further experimental evidence for the assumption of a posterior-anterior processing stream in the left temporal lobe. In addition, the present findings support the notion that the left mid STS area is more sensitive to speech signals compared to the right homologue.
Reduced neural integration of letters and speech sounds links phonological and reading deficits in adult dyslexia.
University of Maastricht, Faculty of Psychology and Neuroscience, Department of Cognitive Neuroscience, PO Box 616, 6200 MD Maastricht, The Netherlands. email@example.com
Developmental dyslexia is a specific reading and spelling deficit affecting 4% to 10% of the population. Advances in understanding its origin support a core deficit in phonological processing characterized by difficulties in segmenting spoken words into their minimally discernable speech segments (speech sounds, or phonemes) and underactivation of left superior temporal cortex. A suggested but unproven hypothesis is that this phonological deficit impairs the ability to map speech sounds onto their homologous visual letters, which in turn prevents the attainment of fluent reading levels. The present functional magnetic resonance imaging (fMRI) study investigated the neural processing of letters and speech sounds in unisensory (visual, auditory) and multisensory (audiovisual congruent, audiovisual incongruent) conditions as a function of reading ability. Our data reveal that adult dyslexic readers underactivate superior temporal cortex for the integration of letters and speech sounds. This reduced audiovisual integration is directly associated with a more fundamental deficit in auditory processing of speech sounds, which in turn predicts performance on phonological tasks. The data provide a neurofunctional account of developmental dyslexia, in which phonological processing deficits are linked to reading failure through a deficit in neural integration of letters and speech sounds.
The neural processing of masked speech: evidence for different mechanisms in the left and right temporal lobes.
Institute of Cognitive Neuroscience, University College London, London, United Kingdom. firstname.lastname@example.org
It has been previously demonstrated that extensive activation in the dorsolateral temporal lobes associated with masking a speech target with a speech masker, consistent with the hypothesis that competition for central auditory processes is an important factor in informational masking. Here, masking from speech and two additional maskers derived from the original speech were investigated. One of these is spectrally rotated speech, which is unintelligible and has a similar (inverted) spectrotemporal profile to speech. The authors also controlled for the possibility of "glimpsing" of the target signal during modulated masking sounds by using speech-modulated noise as a masker in a baseline condition. Functional imaging results reveal that masking speech with speech leads to bilateral superior temporal gyrus (STG) activation relative to a speech-in-noise baseline, while masking speech with spectrally rotated speech leads solely to right STG activation relative to the baseline. This result is discussed in terms of hemispheric asymmetries for speech perception, and interpreted as showing that masking effects can arise through two parallel neural systems, in the left and right temporal lobes. This has implications for the competition for resources caused by speech and rotated speech maskers, and may illuminate some of the mechanisms involved in informational masking.
The listening in spatialized noise-sentences test (LISN-S): comparison to the prototype LISN and results from children with either a suspected (central) auditory processing disorder or a confirmed language disorder.
National Acoustic Laboratories, 126 Greville Street, Chatswood, NSW 2067, Australia. Sharon.Cameron@nal.gov.au
BACKGROUND The Listening in Spatialized Noise--Sentences test (LISN-S) is a revised version of the Listening in Spatialized Noise (Continuous Discourse) test (LISN; Cameron et al, 2006a). The software produces a three-dimensional auditory environment under headphones and was developed to assess auditory stream segregation skills in children. A simple repetition response protocol is utilized to determine speech reception thresholds (SRTs) for sentences presented from 0 degree azimuth in competing speech. The competing speech is manipulated with respect to its location in auditory space (0 degree vs.+ and -90 degrees azimuth) and the vocal quality of the speaker(s)(same as, or different to, the speaker of the target stimulus). Performance is measured as two SRT and three advantage measures. The advantage measures represent the benefit in dB gained when either talker, spatial, or both talker and spatial cues combined are incorporated in the maskers. PURPOSE To document LISN-S performance in a group of nine children with suspected (central) auditory processing disorder ([C]APD), who presented with difficulties hearing in the classroom in the absence of any routine audiological or language, learning or attention deficits to explain such a difficulty (SusCAPD group). The study also aimed to research the effect of higher-order deficits on LISN-S performance in a group of 11 children with a range of documented learning or attention disorders (LD Group). Correlation between performance on the LISN-S and a traditional (C)APD test battery was also compared. RESEARCH DESIGN In a descriptive design, SusCAPD and LD group performance on the LISN-S was compared to published normative data from 70 age-matched controls. A correlational design was used to compare performance on the various tests in the traditional (C)APD battery to the SRT and advantage measures of the LISN-S. RESULTS There were no significant differences between the SusCAPD, LD, or control groups on the conditions of the LISN-S where both the target and maskers emanated from 0 degree azimuth (low-cue SRT, p = 0.978; talker advantage, p = 0.307). However, there were significant differences between groups on the performance measures where the maskers were separated from the target by + and -90 degrees. Post hoc tests revealed that there were no significant differences between the LD group and controls on any of these measures. There were, however, significant differences between the SusCAPD group and the controls on all the conditions where the maskers were spatially separated from the target (high-cue SRT, p = 0.001; spatial advantage, p < 0.0001; total advantage, p < 0.0001). The LISN-S did not correlate significantly with any test in the traditional test battery, nor were the nonspatial and spatial performance measures of the LISN-S correlated. CONCLUSIONS The study supports the hypothesis that a high proportion of children with suspected (C)APD have a deficit in the mechanisms that normally use the spatial distribution of sources to suppress unwanted signals. The LISN-S is a potentially valuable assessment tool for assessing auditory stream segregation deficits, and is sensitive in differentiating various forms of auditory streaming.