Motor Milestones: Sensory Motor Trends of Young Children with Classic Galactosemia.

Speech problems affect about 66% of children with classic galactosemia (CG), but little is known about early motor and sensory motor development in this at-risk population (Rubio-Gozalbo et al., 2019). Research has been focused on speech and language development leaving a paucity of data on motor and sensory differences. This paper describes preliminary data regarding sensory motor and motor development patterns in young children with CG. Babble Boot Camp© (BBC) is an NIH-funded randomized control trial (RCT) implementing proactive interventions designed to support the speech language development of infants with CG. Cases were randomly assigned to a motor-first group (Motor Milestones), receiving virtual occupational therapy through 14 months, or a speech-first group, receiving virtual speech therapy through 14 months. All cases received speech and language therapy from 15 to 24 months. Controls, typically developing infants, did not receive occupational therapy or speech therapy. Participants were recruited through social media, advertisements, metabolic clinics, and the Galactosemia Foundation. Infants in the motor milestones group were assessed with the Developmental Assessment of Young Children and Sensory Profile-2 pre-enrollment (< 6 months of age) and post-treatment follow-up at 2.5, 3.5, and 4.5 years of age. Results show that 17.5% of participants with CG had delays in gross motor, 22.5% in fine motor, and 45% in sensory processing. Data from the Motor Milestones portion of BBC is important emerging evidence for occupational therapy in early intervention, preschool, and outpatient settings. This research supports the need for occupational therapy services during early intervention to minimize or prevent long-term motor and sensorimotor delays in infants with CG. Understanding patterns and addressing literature gaps helps support the need for occupational therapists to address motor delays, improve activities of daily living, play, promote functional independence, and provide caregiver education to best support the occupational performance of children with CG.

Fathers' unmodulated prosody in child-directed speech.

Mothers and fathers modify prosodic characteristics of child-directed speech relative to adult-directed speech. Evidence suggests that mothers and fathers may differ in how they use child-directed speech as communicative partners. Thus, fathers create communicative challenges during father-child interaction that facilitate the child's adaptation to a wider potential range of interlocutors. In this paper, speech production differences are examined between mothers and fathers in child-directed speech to toddlers as compared to adult-directed speech. Using a longitudinal, large-scale design of audio recordings in naturalistic environments and automatic speech processing techniques, it was found that mothers, but not fathers, increased their fundamental frequency when addressing their toddlers. The results suggest that fathers do not modulate the prosody of their speech in the same way as mothers when communicating with their toddlers. Findings have implications for emotional and communicative practices of fathers compared to mothers and the differential role each plays in child development.

Comparing Scores on the Peabody Picture Vocabulary Test and Receptive One-Word Picture Vocabulary Test in Preschoolers With and Without Hearing Loss.

PURPOSE: We sought to compare raw scores, standard scores, and age equivalences on two commonly used vocabulary tests, the Peabody Picture Vocabulary Test (PPVT) and the Receptive One-Word Picture Vocabulary Test (ROWPVT). METHOD: Sixty-two children, 31 with hearing loss (HL) and 31 with normal hearing (NH), were given both the PPVT and ROWPVT as part of an ongoing longitudinal study of emergent literacy development in preschoolers with and without HL. All children were between 3 and 4 years old at administration, and the two tests were administered within 3 weeks of each other. Both tests were given again 6 months later. Standard scores and age equivalencies were calculated for both tests using published guidelines. RESULTS: There was no significant effect of test for any of our analyses. However, there was a main effect of time, with both standard scores and age equivalencies being significantly higher at the second test. Children with NH had significantly higher standard scores and age equivalencies than children with NH, but there was no interaction between hearing status and time, suggesting that the two groups were growing at the same rate. CONCLUSIONS: Clinicians can be comfortable administering both the PPVT and ROWPVT to estimate children's vocabulary levels, but there may be practice effects when administering the tests twice within a calendar year. These data also indicate that children with HL continue to lag behind their peers with NH on vocabulary development. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.23232848.

Virtual Post-Intervention Speech and Language Assessment of Toddler and Preschool Participants in Babble Boot Camp.

PURPOSE: Babble Boot Camp (BBC) is a parent-implemented telepractice intervention for infants at risk for speech and language disorders. BBC uses a teach-model-coach-review approach, delivered through weekly 15-min virtual meetings with a speech-language pathologist. We discuss accommodations needed for successful virtual follow-up test administration and preliminary assessment outcomes for children with classic galactosemia (CG) and controls at age 2.5 years. METHOD: This clinical trial included 54 participants, 16 children with CG receiving BBC speech-language intervention from infancy, age 2 years, five children receiving sensorimotor intervention from infancy and changing to speech-language intervention at 15 months until 2 years of age, seven controls with CG, and 26 typically developing controls. The participants' language and articulation were assessed via telehealth at age 2.5 years. RESULTS: The Preschool Language Scale-Fifth Edition (PLS-5) was successfully administered with specific parent instruction and manipulatives assembled from the child's home. The GFTA-3 was successfully administered to all but three children who did not complete this assessment due to limited expressive vocabularies. Referrals for continued speech therapy based on PLS-5 and GFTA-3 scores were made for 16% of children who received BBC intervention from infancy as compared to 40% and 57% of children who began BBC at 15 months of age or did not receive BBC intervention, respectively. CONCLUSIONS: With extended time and accommodations from the standardized administration guidelines, virtual assessment of speech and language was possible. However, given the inherent challenges of testing very young children virtually, in-person assessment is recommended, when possible, for outcome measurements.

Precision Medicine as a New Frontier in Speech-Language Pathology: How Applying Insights From Behavior Genomics Can Improve Outcomes in Communication Disorders.

PURPOSE: Precision medicine is an emerging intervention paradigm that leverages knowledge of risk factors such as genotypes, lifestyle, and environment toward proactive and personalized interventions. Regarding genetic risk factors, examples of interventions informed by the field of medical genomics are pharmacological interventions tailored to an individual's genotype and anticipatory guidance for children whose hearing impairment is predicted to be progressive. Here, we show how principles of precision medicine and insights from behavior genomics have relevance for novel management strategies of behaviorally expressed disorders, especially disorders of spoken language. METHOD: This tutorial presents an overview of precision medicine, medical genomics, and behavior genomics; case examples of improved outcomes; and strategic goals toward enhancing clinical practice. RESULTS: Speech-language pathologists (SLPs) see individuals with various communication disorders due to genetic variants. Ways of using insights from behavior genomics and implementing principles of precision medicine include recognizing early signs of undiagnosed genetic disorders in an individual's communication patterns, making appropriate referrals to genetics professionals, and incorporating genetic findings into management plans. Patients benefit from a genetics diagnosis by gaining a deeper and more prognostic understanding of their condition, obtaining more precisely targeted interventions, and learning about their recurrence risks. CONCLUSIONS: SLPs can achieve improved outcomes by expanding their purview to include genetics. To drive this new interdisciplinary framework forward, goals should include systematic training in clinical genetics for SLPs, enhanced understanding of genotype-phenotype associations, leveraging insights from animal models, optimizing interprofessional team efforts, and developing novel proactive and personalized interventions.

Feasibility of a Proactive Parent-Implemented Communication Intervention Delivered via Telepractice for Children With Classic Galactosemia.

PURPOSE: This study evaluated the feasibility of Babble Boot Camp (BBC) for use with infants with classic galactosemia (CG) starting at less than 6 months of age. BBC is a parent-implemented intervention delivered by speech-language pathologists (SLPs) entirely via telepractice with the potential to increase access to early preventative interventions. We evaluated BBC feasibility based on acceptability, implementation, and practicality. METHOD: We obtained data from 16 parents of infants with CG (mean age at enrollment = 3.38 months) involved in a large randomized clinical trial of BBC. BBC uses a teach-model-coach-review approach to provide parents with strategies to support their child's communication development. Families completed, on average, eighty-one 15-min sessions over a 20-month intervention period. We drew data from surveys completed by parents at the end of the intervention period, intervention logs maintained by the SLPs, and intervention fidelity checks completed by research assistants. RESULTS: Data drawn from parent surveys, intervention logs, and intervention fidelity checks revealed high parent acceptability, high rates of completion and compliance, and low costs in terms of parent and clinician time. CONCLUSION: Results suggest that BBC is feasible for families of infants with CG, warranting further examination of BBC across a broader range of children with CG as well as other infants who are at predictable risk for speech and language impairment.

Translating principles of precision medicine into speech-language pathology: Clinical trial of a proactive speech and language intervention for infants with classic galactosemia.

Precision medicine is an emerging approach to managing disease by taking into consideration an individual's genetic and environmental profile toward two avenues to improved outcomes: prevention and personalized treatments. This framework is largely geared to conditions conventionally falling into the field of medical genetics. Here, we show that the same avenues to improving outcomes can be applied to conditions in the field of behavior genomics, specifically disorders of spoken language. Babble Boot Camp (BBC) is the first comprehensive and personalized program designed to proactively mitigate speech and language disorders in infants at predictable risk by fostering precursor and early communication skills via parent training. The intervention begins at child age 2 to 5 months and ends at age 24 months, with follow-up testing at 30, 42, and 54 months. To date, 44 children with a newborn diagnosis of classic galactosemia (CG) have participated in the clinical trial of BBC. CG is an inborn error of metabolism of genetic etiology that predisposes up to 85% of children to severe speech and language disorders. Of 13 children with CG who completed the intervention and all or part of the follow-up testing, only one had disordered speech and none had disordered language skills. For the treated children who completed more than one assessment, typical speech and language skills were maintained over time. This shows that knowledge of genetic risk at birth can be leveraged toward proactive and personalized management of a disorder that manifests behaviorally.

Conversation Initiation of Mothers, Fathers, and Toddlers in their Natural Home Environment.

In a conversational exchange, interlocutors use social cues including conversational turn-taking to communicate. There has been attention in the literature concerning how mothers, fathers, boys, and girls converse with each other, and in particular who initiates a conversation. Better understanding of conversational dynamics may deepen our understanding of social roles, speech and language development, and individual language variability. Here we use large-scale automatic analysis of 186 naturalistic daylong acoustic recordings to examine the conversational dynamics of 26 families with children about 30 months of age to better understand communication roles. Families included 15 with boys and 11 with girls. There was no difference in conversation initiation rate by child sex, but children initiated more conversations than mothers, and mothers initiated more than fathers. Results support developmental theories of the different and variable roles that interlocutors play in a social context.

Vocal Turn-Taking in Families With Children With and Without Hearing Loss.

OBJECTIVE: Vocal turn-taking is an important predictor of language development in children with and without hearing loss. Most studies have examined vocal turn-taking in mother-child dyads without considering the multitalker context in a child's life. The present study investigates the quantity of vocal turns between deaf and hard-of-hearing children and multiple members of their social environment. DESIGN: Participants were 52 families with children who used hearing aids (HA, mean age 26.3 mo) or cochlear implants (CI, mean age 63.2 mo) and 27 families with normal-hearing (NH, mean age 26.6 mo) children. The Language ENvironment Analysis system estimated the number of conversational turns per hour (CTC/hr) between all family members (i.e., adult female, adult male, target child, and other child) during full-day recordings over a period of about 1 year. RESULTS: The CTC/hr was lower between the target child and the adult female or adult male in the CI compared with the HA and NH groups. Initially, CTC/hr was higher between the target child and the adult female than between the adult male or the other child. As the child's age increased, turn-taking between the target child and the adult female increased in comparison to that between the target child and the adult male. Over time, turn-taking between the target child and the other child increased and exceeded turn-taking between the target child and the adult caregivers. The increase was observed earlier in families with siblings compared with those without. CONCLUSIONS: The quantity of vocal turn-taking depends on the degree of child hearing loss and the relationship between the children and the members of their social environment. Longitudinally, the positive effect of an assistive device on the quantity of turns between the children and their family members was found. The effect was stronger in families with siblings.

Toward Preventing Speech and Language Disorders of Known Genetic Origin: First Post-Intervention Results of Babble Boot Camp in Children With Classic Galactosemia.

Purpose Babble Boot Camp (BBC) is a package of proactive activities and routines designed to prevent speech and language disorders in infants at predictable risk. It is implemented via parent training and currently undergoing clinical trial in children with a newborn diagnosis of classic galactosemia (CG), a metabolic disease with high risk of speech and language disorders. The purpose of this study is to provide updates to a previous pilot study and to present the first set of post-intervention results. Method The intervention and data collection occurred during child ages < 6-24 months, with follow-up assessments of speech and language at ages 2.5 and 3.5 years. Treatment targets included earliest vocalization rates, babble complexity, speech production accuracy, and vocabulary and syntactic growth. The oldest 15 children with CG (including three untreated controls) completed the first set of follow-up assessments. Aggregate data up to 10 months were available for 17 treated children with CG, six untreated children with CG, and six typical controls. Results At ages 7-9 months, babbling complexity, as measured with mean babbling level, was higher in the treated children with CG than in the untreated children with CG and the typical controls. Prior to 24 months of age, the treated children with CG had greater expressive but not receptive vocabulary sizes than an untreated control. Follow-up testing showed typical language scores for all 12 treated children with CG and typical articulation scores for 11 of these, whereas one of three untreated children with CG had low articulation and expressive language scores. Conclusions The BBC appears to be a viable intervention to support the speech and expressive language development of children with GC. Future studies will evaluate the relative contributions of the earliest and later BBC components to outcomes.

Developmental Changes in Tongue Strength, Swallow Pressures, and Tongue Endurance.

Maximum tongue strength, mean swallow pressures, and tongue endurance were measured in 324 children ages 6-12 years. The purpose of this study was to measure saliva swallow pressures in absolute terms (i.e., kilopascals) and as a percentage of maximum tongue strength to determine functional reserve in across ages in children and to examine factors that may influence tongue strength and swallow pressures including age, tongue endurance, and tongue-tie. The study results showed that maximum tongue strength and swallow pressures increased with age, while tongue endurance did not. Swallow pressures averaged 44% of maximum tongue strength across ages, indicating that children typically have a functional reserve of 56%. Tongue strength and swallow pressures were not decreased in the 20 children with tongue-tie. A sample clinical case is discussed.

Rethinking Emergent Literacy in Children With Hearing Loss.

Long-term literacy outcomes for children with hearing loss, particularly those with severe-to-profound deafness who are fitted with cochlear implants (CIs) lag behind those of children with normal hearing (NH). The causes for these long-term deficits are not fully clear, though differences in auditory access between children who use CIs and those with NH may be a partial cause. This paper briefly reviews the emergent literacy model as proposed by Whitehurst and Lonigan (1998). We then examine the development of each of Whitehurst and Lonigan's identified factors in children who use CIs and how the extant knowledge of language and literacy development in children who use CIs may bear on the emergent literacy model. We then propose to modify the model for children who use CIs based on their unique developmental trajectories, influenced at least in part by their unique auditory access. We conclude with future directions for further development of an evidence-based emergent literacy model for children who use CIs and how this model could be used to inform intervention.

Use of the LENA Autism Screen with Children who are Deaf or Hard of Hearing.

Background and Objectives: This systematic review reports the evidence from the literature concerning the potential for using an automated vocal analysis, the Language ENvironment Analysis (LENA, LENA Research Foundation, Boulder, CO, USA) in the screening process for children at risk for autism spectrum disorder (ASD) and deaf or hard of hearing (D/HH). ASD and D/HH have increased comorbidity, but current behavioral diagnostic and screening tools have limitations. The LENA Language Autism Screen (LLAS) may offer an additional tool to disambiguate ASD from D/HH in young children. Materials and Methods: We examine empirical reports that use automatic vocal analysis methods to differentiate disordered from typically developing children. Results: Consensus across the sampled scientific literature shows support for use of automatic methods for screening and disambiguation of children with ASD and D/HH. There is some evidence of vocal differentiation between ASD, D/HH, and typically-developing children warranting use of the LLAS, but additional empirical evidence is needed to better understand the strengths and weaknesses of the tool. Conclusions: The findings reported here warrant further, more substantive, methodologically-sound research that is fully powered to show a reliable difference. Findings may be useful for both clinicians and researchers in better identification and understanding of communication disorders.

Tongue Strength in Children With and Without Speech Sound Disorders.

Purpose The purpose of this cross-sectional investigation was to expand the comparative database of pediatric tongue strength for children and adolescents with typical development, ages 3-17 years, and compare tongue strength among children with typical development, speech sound delay/disorders (SD), and motor speech disorders (MSDs). Method Tongue strength was measured using the Iowa Oral Performance Instrument in a total of 286 children and adolescents, 228 with typical development, 16 with SD, and 42 with MSDs, including classic galactosemia, a known risk factor for MSD ( n = 33) and idiopathic MSD ( n = 9). Results For all groups, tongue strength increased rapidly from 3 to 6.5 years of age and then continued to increase with age at a slower rate until 17 years of age. Children with SD's tongue strength did not differ from their typically developing (TD) peers. Children and adolescents with MSDs had decreased tongue strength compared to children with typical development or SD. Tongue strength was not related to severity of speech sound disorders in SD or MSD. Conclusion Weak tongue strength does not appear to contribute to speech errors in children with speech sound delays but does appear to be related to speech sound disorders that are neurologic in origin (developmental MSD).

A modular, extensible approach to massive ecologically valid behavioral data.

We explore here the application of modern computer hardware and software to the collection and analysis of behavioral data. We discuss the issues of ecological validity, storage and processing, data permanence, automation, validity, and algorithmic determinism. Taking the modern landscape into account, we demonstrate several varying projects we have recently undertaken as proofs of concept of the viability and utility of this approach. In particular, we describe four research projects, which involve work on child-directed speech; the application of automatic methods to clinical populations, including children with hearing loss; quality control and the assessment of validity; and the sharing of data in a public database. We conclude by pointing out how the methodology described here can be extended to a wide variety of interdisciplinary and detailed projects that are likely to lead to better science and improved outcomes for populations served by the behavioral, social, and health sciences.

Toward a paradigm shift from deficit-based to proactive speech and language treatment: Randomized pilot trial of the Babble Boot Camp in infants with classic galactosemia.

Background: Speech and language therapy is typically initiated reactively after a child shows delays. Infants with classic galactosemia (CG), a metabolic disease with a known high risk for both speech and language disorders, hold the keys towards evaluating whether preventive treatment is effective when the risks are known at birth. We present pilot data from a randomized parallel trial of an innovative proactive speech and language intervention program, the Babble Boot Camp (BBC).  Method: Five children with CG, otherwise healthy, participated in the study from approximately 2 to 24 months of age. One of these was randomly selected as control receiving conventional management, which typically starts at age 2-3 years. A pediatric speech-language pathologist met weekly via telepractice with the parents in the treatment cohort. Parents implemented the prespeech, speech, and language stimulation and expansion activities according to the intervention protocol. The control child was still too young for conventional treatment. Primary outcome measures were speech sound production complexity in babble and speech and expressive vocabulary size. Secondary outcome measures were vocalization rates and developmental milestones in communication, motor, and cognition. The trial is ongoing. Results:  All four treated children had higher speech sound skills in babble, three had higher speech sound skills in meaningful speech, two had higher expressive vocabularies, three had higher global developmental scores, and two had higher vocalization rates, compared to the control child with CG. Discussion: Given the high risk for speech and language delays in children with CG, finding on-schedule abilities in two or more of the treated children but not the untreated child is unexpected under random conditions. The trends toward beneficial effects of the BBC on speech sound production, expressive language, and communication milestones warrant appropriately powered larger clinical trials with full randomization. Trial registration: ClinicalTrials.gov NCT03838016 (12 th February 2019).

Pupillary Response and Phenotype in ASD: Latency to Constriction Discriminates ASD from Typically Developing Adolescents.

Brain imaging data describe differences in the ASD brain, including amygdala overgrowth, neural interconnectivity, and a three-phase model of neuroanatomical changes from early post-natal development through late adolescence. The pupil reflex test (PRT), a noninvasive measure of brain function, may help improve early diagnosis and elucidate underlying physiology in expression of ASD endophenotype. Commonly observed characteristics of ASD include normal visual acuity but difficulty with eye gaze and photosensitivity, suggesting deficient neuromodulation of cranial nerves. Aims of this study were to confirm sensitivity of the PRT for identifying adolescents with ASD, determine if a phenotype for a subtype of ASD marked by pupil response is present in adolescence, and determine whether differences could be observed on a neurologic exam testing cranial nerves II and III (CNII; CNIII). Using pupillometry, constriction latency was measured serving as a proxy for recording neuromodulation of cranial nerves underlying the pupillary reflex. The swinging flashlight method, used to perform the PRT for measuring constriction latency and return to baseline, discriminated ASD participants from typically developing adolescents on 72.2% of trials. Results further confirmed this measure's sensitivity within a subtype of ASD in later stages of development, serving as a correlate of neural activity within the locus-coeruleus norepinephrine (LC-NE) system. A brainstem model of atypical PRT in ASD is examined in relation to modulation of cranial nerves and atypical arousal levels subserving the atypical pupillary reflex. Autism Res 2018, 11: 364-375. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Milder forms of autism spectrum disorder (ASD) can be difficult to diagnose based on behavioral testing alone. This study used eye-tracking equipment and a hand-held penlight to measure the pupil reflex in adolescents with "high functioning" ASD and in adolescents without ASD. The ASD group showed a delay in pupil response. This is the first eye-tracking study to conduct this test as typically performed by a clinical provider, demonstrating differences in older individuals with a subtype of ASD.

Fidelity of Automatic Speech Processing for Adult and Child Talker Classifications.

Automatic speech processing (ASP) has recently been applied to very large datasets of naturalistically collected, daylong recordings of child speech via an audio recorder worn by young children. The system developed by the LENA Research Foundation analyzes children's speech for research and clinical purposes, with special focus on of identifying and tagging family speech dynamics and the at-home acoustic environment from the auditory perspective of the child. A primary issue for researchers, clinicians, and families using the Language ENvironment Analysis (LENA) system is to what degree the segment labels are valid. This classification study evaluates the performance of the computer ASP output against 23 trained human judges who made about 53,000 judgements of classification of segments tagged by the LENA ASP. Results indicate performance consistent with modern ASP such as those using HMM methods, with acoustic characteristics of fundamental frequency and segment duration most important for both human and machine classifications. Results are likely to be important for interpreting and improving ASP output.

HomeBank: An Online Repository of Daylong Child-Centered Audio Recordings.

HomeBank is introduced here. It is a public, permanent, extensible, online database of daylong audio recorded in naturalistic environments. HomeBank serves two primary purposes. First, it is a repository for raw audio and associated files: one database requires special permissions, and another redacted database allows unrestricted public access. Associated files include metadata such as participant demographics and clinical diagnostics, automated annotations, and human-generated transcriptions and annotations. Many recordings use the child-perspective LENA recorders (LENA Research Foundation, Boulder, Colorado, United States), but various recordings and metadata can be accommodated. The HomeBank database can have both vetted and unvetted recordings, with different levels of accessibility. Additionally, HomeBank is an open repository for processing and analysis tools for HomeBank or similar data sets. HomeBank is flexible for users and contributors, making primary data available to researchers, especially those in child development, linguistics, and audio engineering. HomeBank facilitates researchers' access to large-scale data and tools, linking the acoustic, auditory, and linguistic characteristics of children's environments with a variety of variables including socioeconomic status, family characteristics, language trajectories, and disorders. Automated processing applied to daylong home audio recordings is now becoming widely used in early intervention initiatives, helping parents to provide richer speech input to at-risk children.

Facial and Lingual Strength and Endurance in Skilled Trumpet Players.

UNLABELLED: Trumpet players produce and manipulate sound through their instrument by articulating the lips, cheeks, and tongue to create a proper airflow. These sustained muscle contractions may result in increased facial and lingual strength and endurance. The purpose of this study was to determine if adult trumpet players who practice at least 6 hrs/wk differed from adult non-trumpet-playing controls in strength and endurance of the lips, cheeks, and tongue. METHODS: This case-control study involved 16 trumpet players, 16 healthy controls balanced for age and sex, and 1 trumpet player 25 years post-Bell's palsy. Strength and endurance of lip, cheek, and tongue muscles were measured using the Iowa Oral Performance Instrument (IOPI Medical, Redmond, WA). Maximum strength was the greatest pressure value of three encouraged trials. Endurance was the length of time the participant was able to sustain 50% of maximum strength. RESULTS: The findings indicate that trumpet players had greater facial strength and endurance, which was objectively quantified using commercially available equipment. The trumpet players had greater cheek strength and greater lip endurance than controls. Tongue strength and endurance did not differ between the trumpet players and controls. Tongue strength was negatively associated with age, which is consistent with previous studies. The trumpet player with a history of Bell's palsy had decreased cheek strength and endurance on his affected side compared to his unaffected side, although this difference was comparable to the differences between right and left cheek strength in trumpet players without a history of facial nerve damage.