Monthly Archives: April 2009

Foreign accent syndrome as a developmental motor speech disorder

This paper for the first time documents two patients who presented with FAS on a developmental basis. The finding that FAS does not only occur in the context of acquired brain damage or psychogenic illness but also exists as developmental motor speech impairment requires a re-definition of FAS as a clinical syndrome.

from Cortex

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Integration of lexical and sublexical processing in the spelling of regular words: A multiple single–case study in Italian dysgraphic patients

We first analysed whether a double functional lesion was sufficient to explain the mixed dysgraphia, checking acoustic-to-phonological conversion by means of the repetition of words and non-words: the answer was positive in five cases and uncertain in three. We tested the remaining four cases to see if there was an interaction between lexical and sublexical processing of regular words, quantifying for each patient, on a probabilistic basis, the separate contribution of the residual lexical and sublexical resources. We investigated whether the processing along these routes was simultaneous but independent (“independent cooperation”) or if instead there was “interaction”, i.e., the simultaneous activity led to an added increase of efficiency over and above the mere combination of separate success probabilities. For one case the processing along the two routes was independent, in the other three cases an interaction resulted. Following the same approach, we found that for the five cases with a double functional lesion, the observed success on regular word spelling was higher than that expected on a probabilistic basis, but the interpretation of this finding was different.

from Cortex

Syntax without language: Neurobiological evidence for cross-domain syntactic computations

Abstract
Not all conceivable grammars are realized within human languages. Rules based on rigid distances, in which a certain word must occur at a fixed distance from another word, are never found in grammars of human languages. Distances between words are specified in terms of relative, non-rigid positions. The left inferior frontal gyrus (IFG) (Broca’s area) has been found to be involved in the computation of non-rigid but not of rigid syntax in the language domain. A fundamental question is therefore whether the neural activity underlying this non-rigid architecture is language-specific, given that analogous structural properties can be found in other cognitive domains. Using event-related functional magnetic resonance imaging (fMRI) in sixteen healthy native speakers of Italian, we measured brain activity for the acquisition of rigid and non-rigid syntax in the visuo-spatial domain. The data of the present experiment were formally compared with those of a previous experiment, in which there was a symmetrical distinction between rigid and non-rigid syntax in the language domain. Both in the visuo-spatial and in the language domain, the acquisition of non-rigid syntax, but not the acquisition of rigid syntax, activated Brodmann Area 44 of the left IFG. This domain-independent effect was specifically modulated by performance improvement. Thus, in the human brain, one single “grammar without words” serves different higher cognitive functions.

from Cortex

The role of the striatum in phonological processing. Evidence from early stages of Huntington’s disease

In Experiment 1 we used a same–different task with isolated words to evaluate whether phoneme perception is intact in HD. In Experiment 2 a word detection task in phrasal contexts allowed for assessing both phoneme perception and perceptual compensation for the French regressive assimilation rule. Results showed that HD patients have normal performance with both phoneme perception in isolated words and regressive assimilation rules. However, in phrasal contexts they display reduced abilities of phoneme discrimination.

These findings challenge the striatum-rule claim and suggest a more fine-grained function of striatal structures in linguistic rule processing. Alternative explanatory frameworks of the striatum-language link are discussed.

from Cortex

Development of Ebselen, a Glutathione Peroxidase Mimic, for the Prevention and Treatment of Noise-Induced Hearing Loss

The development of therapeutics for the prevention and treatment of sensorineural hearing loss remains an elusive goal for auditory scientists and clinicians worldwide. While much research has focused on the histopathology associated with exposure to intense noise or ototoxins (i.e., loss of hair cells), the biochemical and genetic mechanisms that evoke or mediate hair cell death and dysfunction are still under investigation and debate. Many have observed an early oxidative burst in the cochlea that leads to an increase in lipoperoxidation and the activation of cell death pathways, ultimately resulting in apoptosis. In support of this hypothesis, many have protected the cochlea and preserved auditory function by injecting high doses of antioxidants or inhibitors of cell death activation prior to intense noise or ototoxin exposure. Here we discuss a compound currently in Phase II clinical testing for the prevention and treatment of noise-induced hearing loss. This article will review the historic background and pertinent preclinical and clinical data available for ebselen, a novel drug that mimics the activity of glutathione peroxidase, a catalytic antioxidant enzyme that is essential for the peripheral auditory system.

from Seminars in Hearing

Hearing Impairment and Traumatic Brain Injury among Soldiers: Special Considerations for the Audiologist

The increased use of explosive devices and mines in warfare and excessive noise of weapons has created an unprecedented amount of auditory dysfunction among soldiers. Blast-related injuries may damage the auditory processing and/or balance centers resulting in hearing loss, dizziness, tinnitus, and/or central auditory processing disorders. Some also lead to traumatic brain injury (TBI), postconcussive syndrome (PCS), and/or posttraumatic stress disorder. Some PCS symptoms such as dizziness, loss of balance, hearing difficulty, and noise sensitivity also can signify auditory or vestibular dysfunction and should not be obscured with the PCS package. This article provides information about the mechanisms of blast injury with emphasis on auditory dysfunction and TBI. Audiologists must be prepared to identify those at risk for TBI or mental health problems and adapt audiologic clinical practices to this population. An interdisciplinary comprehensive evaluation of peripheral, central, and vestibular components of the auditory system should be employed in patients with TBI to ensure that auditory dysfunction is accurately diagnosed and that appropriate rehabilitation can be performed.

from Seminars in Hearing

Hearing Protection in the 21st Century: They’re Not Your Father’s Earplugs Anymore

Noise-induced hearing loss is one of the most common occupational illnesses among American workers. This is particularly tragic because this type of hearing loss can be prevented. When engineering or administrative controls have not eliminated a given hearing hazard, wearing hearing protectors remains the best way to prevent noise-induced hearing loss. Over the past several decades, technology has greatly improved hearing protector capabilities. Nevertheless, many workers fail to wear hearing protectors because they do not know when and how they should be worn. Applying health communication theory to develop hearing protection training can substantially improve attitudes, beliefs, and behaviors associated with hearing protector use. This article discusses how to identify barriers to hearing protector use, as well as how to promote self-efficacy as a means for improving hearing protector effectiveness.

from Seminars in Hearing

Noise-Induced Hearing Injury among Army Active Duty Soldiers Deployed to the Central Command Area of Operations

A 2005 assessment of noise-induced hearing injury (NIHI) among Army audiology clinic patients seen between April 2003 and March 2004 found elevated rates of NIHI among soldiers returning from deployment. Because of study limitations, it was not possible to extrapolate the findings to the entire Army soldier population in relation to deployment status. We performed this study to determine patterns of NIHI incidence among soldiers as a function of deployment status and to determine the accuracy and completeness of provider use of NIHI-related ICD-9CM codes. These refinements to the 2005 study were made with the goal of developing a surveillance process compatible with emerging Defense Injury Surveillance processes. NIHI among soldiers diagnosed during admissions or outpatient visits from all clinics were evaluated for fiscal years 2003 through 2005. Deployment status to the Central Command Area of Operations was confirmed by referencing medical data to personnel data from two separate personnel data systems. The refined analysis demonstrated higher postdeployment rates of NIHI consistent with the previous analysis. Additionally, vertigo and imbalance disorders were evaluated. This study demonstrates the capability for noise injury surveillance to be integrated into an overall Department of Defense injury surveillance process and identifies additional measures to enhance this analytic process with further data integration and study.

from Seminars in Hearing

Potentiation of Chemical Ototoxicity by Noise

High-intensity and/or prolonged exposure to noise causes temporary or permanent threshold shifts in auditory perception. Occupational exposure to solvents or administration of clinically important drugs, such as aminoglycoside antibiotics and cisplatin, also can induce permanent hearing loss. The mechanisms by which these ototoxic insults cause auditory dysfunction are still being unraveled, yet they share common sequelae, particularly generation of reactive oxygen species, that ultimately lead to hearing loss and deafness. Individuals are frequently exposed to ototoxic chemical contaminants (e.g., fuel) and noise simultaneously in a variety of work and recreational environments. Does simultaneous exposure to chemical ototoxins and noise potentiate auditory dysfunction? Exposure to solvent vapor in noisy environments potentiates the permanent threshold shifts induced by noise alone. Moderate noise levels potentiate both aminoglycoside- and cisplatin-induced ototoxicity in both rate of onset and in severity of auditory dysfunction. Thus, simultaneous exposure to chemical ototoxins and moderate levels of noise can potentiate auditory dysfunction. Preventing the ototoxic synergy of noise and chemical ototoxins requires removing exposure to ototoxins and/or attenuating noise exposure levels when chemical ototoxins are present.

from Seminars in Hearing

Changes in Transient-Evoked Otoacoustic Emissions in the First Month of Life.

Results: TEOAE levels in infants significantly increased from birth to 1 mo of age across all frequencies tested, regardless of whether they passed or failed the screening at birth. The increase in TEOAE level was frequency dependent, with the greatest increases occurring in the highest frequency bands. No significant correlation between debris change and frequency-specific changes was found for either ear. Infants who failed the screening at birth but who subsequently passed at 1 mo of age had significantly lower TEOAE levels at the rescreening than did infants with passing TEOAE levels at birth. However, pass/fail status at birth was only a weak predictor of TEOAE levels at 1 mo of age.

Conclusions: The increase in TEOAE levels during the first month of life is frequency dependent, with greater increases occurring at higher frequencies. Increased TEOAE levels were not associated with changes in ear-canal debris.

from Ear and Hearing

The Association Between Hearing Status and Psychosocial Health Before the Age of 70 Years: Results From an Internet-Based National Survey on Hearing.

Results: Adjusting for confounding variables, significant adverse associations between hearing status and distress, somatization, depression, and loneliness are found. For every decibel signal to noise ratio (dB SNR) reduction of hearing status, both the distress and somatization scores increased by 2% [distress: b = 0.02, 95% confidence interval (CI) = 0.00 to 0.03, p = 0.03; somatization: b = 0.02, 95% CI = 0.01 to 0.04, p < 0.001]. The odds for developing moderate or severe depression increase by 5% for every dB SNR reduction in hearing (odds ratio = 1.05, 95% CI = 1.00 to 1.09, p = 0.03). The odds for developing severe or very severe loneliness significantly increase by 7% for every dB SNR reduction in hearing (odds ratio = 1.07, 95% CI = 1.02 to 1.12, p = 0.004). Different age groups exhibit different associations between hearing status and psychosocial health, with loneliness being an issue particularly in the youngest age group (18 to 30 yr). In the group of middle-aged adults (40 to 50 yr), the number of significant associations is highest.

Conclusions: Hearing status is negatively associated with higher distress, depression, somatization, and loneliness in young and middle-aged adults. The associations are different in different age groups. The findings underline the need to seriously address the adverse effects of limited hearing among young and middle-aged adults both in future research and in clinical practice.

from Ear and Hearing

The Effect of Instantaneous Input Dynamic Range Setting on the Speech Perception of Children with the Nucleus 24 Implant.

Results: Group mean CNC scores at 50 dB SPL with the 40 IIDR were significantly higher (p < 0.001) than with the 30 IIDR. Group mean CNC scores at 60 dB SPL, loudness ratings, and the signal to noise ratios-50 for Bamford-Kowal-Bench Speech in Noise Test were not significantly different for the two IIDRs. Significantly improved aided thresholds at 250 to 6000 Hz as well as higher Speech Intelligibility Indices afforded improved audibility for speech presented at soft levels (50 dB SPL).

Conclusion: These results indicate that an increased IIDR provides improved word recognition for soft levels of speech without compromising comfort of higher levels of speech sounds or sentence recognition in noise.

from Ear and Hearing

Uniform Degradation of Auditory Acuity in Subjects with Normal Hearing Leads to Unequal Precedence Effects.

Conclusions: These results indicate that a uniform unilateral degradation in auditory acuity leads to increased variability in performance on tasks measuring fusion in the precedence effect. The outcome suggests that variable perception of the precedence effect by individuals with clinically diagnosed hearing loss might be due to factors other than a reduction in auditory acuity per se.

from Ear and Hearing

Utility Measures of Health-Related Quality of Life in Patients Treated for Benign Paroxysmal Positional Vertigo.

Conclusions: Utilities as measured through the UMAA seem sensitive to changes in HRQoL after treatment of BPPV. Since the UMAA can be used to measure patient preference (i.e., utility), it may be useful for comparison of specific audiologic conditions, such as BPPV, to nonaudiologic conditions, such as cardiovascular disease and kidney disease.

from Ear and Hearing

Applications of Responsiveness to Intervention and the Speech-Language Pathologist in Elementary School Settings

This article addresses ways in which speech-language pathologists can play a proactive and substantive part in school-wide language and reading disability prevention and intervention efforts within the responsiveness to intervention framework. Within a collaborative working paradigm, specific student-focused instructional targets are presented in the areas of oral language, metacognition, and reading comprehension. A discussion of professional development focuses on enhancing teacher-student communication interaction, a critical yet often undervalued component of teacher training.

from Seminars in Speech and Language