Exploring the Effect of Specimen Size on Elastic Properties of Fused-Filament-Fabrication-Printed Polycarbonate and Thermoplastic Polyurethane.

Additive manufacturing (AM) is often used to create designs inspired by topology optimization and biological structures, yielding unique cross-sectional geometries spanning across scales. However, manufacturing defects intrinsic to AM can affect material properties, limiting the applicability of a uniform material model across diverse cross-sections. To examine this phenomenon, this paper explores the influence of specimen size and layer height on the compressive modulus of polycarbonate (PC) and thermoplastic polyurethane (TPU) specimens fabricated using fused filament fabrication (FFF). Micro-computed tomography imaging and compression testing were conducted on the printed samples. The results indicate that while variations in the modulus were statistically significant due to both layer height and size of the specimen in TPU, variations in PC were only statistically significant due to layer height. The highest elastic modulus was observed at a 0.2 mm layer height for both materials across different sizes. These findings offer valuable insights into design components for FFF, emphasizing the importance of considering mechanical property variations due to feature size, especially in TPU. Furthermore, locations with a higher probability of failure are recommended to be printed closer to the print bed, especially for TPU, because of the lower void volume fraction observed near the heated print bed.

Voice acoustic characteristics of children with late-onset cochlear implantation: Correlation to auditory performance.

OBJECTIVES: To study the voice acoustic parameters of congenitally deaf children with delayed access to sounds due to late-onset cochlear implantation and to correlate their voice characteristics with their auditory performance. METHODS: The study included 84 children: a control group consisting of 50 children with normal hearing and normal speech development; and a study group consisting of 34 paediatric cochlear implant (CI) recipients who had suffered profound hearing loss since birth. According to speech recognition scores and pure-tone thresholds, the study group was further subdivided into two subgroups: 24 children with excellent auditory performance and 10 children with fair auditory performance. The mean age at the time of implantation was 3.6 years for excellent auditory performance group and 3.2 years for fair auditory performance group. Voice acoustic analysis was conducted on all study participants. RESULTS: Analysis of voice acoustic parameters revealed a statistically significant delay in both study groups in comparison to the control group. However, there was no statistically significant difference between the two study groups. DISCUSSION: Interestingly, in both excellent and fair performance study groups, the gap in comparison to normal hearing children was still present. While late-implanted children performed better on segmental perception (e.g. word recognition), suprasegmental perception (e.g. as demonstrated by objective acoustic voice analysis) did not progress to the same extent. CONCLUSION: On the suprasegmental speech performance level, objective acoustic voice measurements demonstrated a significant delay in the suprasegmental speech performance of children with late-onset CI, even those with excellent auditory performance.

The challenge of a mature final diagnosis of hearing loss severity and early cochlear implantation.

PURPOSE: Despite the recent trend of cochlear implantation (CI) at the age of six or even four months is prevalent in many centers around the world, clinicians should be cautious because perinatal risk factors of auditory neuropathy and/or delayed maturation carry the possibility of reversible hearing loss, yielding better auditory performance at the age of one year. The purpose of this study is to raise awareness that early CI may not be universal for all patients. In addition, we specify the factors to be considered in the pre-operative evaluation of CI in infants younger than one year. METHODS AND RESULTS: This study describes four cases provisionally diagnosed with severe to profound sensorineural hearing loss that were presented to the CI clinic to determine candidacy for implantation. Two cases had histories of prematurity, one had Down syndrome, and one had a family history of hearing loss. None of the study cases were candidates for CI, as they had varying degrees of hearing improvement. CONCLUSION: Although early CI may yield better auditory performance, the final diagnosis should be made only after repeated subjective and objective measurements as well as family feedback on the child's auditory performance, especially in preterm children. Early auditory brainstem response (ABR) prior to the age of one year in children with cognitive, neurologic, or developmental comorbidities should be interpreted with caution, as ABR "alone" could not accurately represent the child's true hearing ability in this patient population.

The Difficulties Encountered by Pediatric Cochlear Implant Patients and Their Parents during the COVID-19 Pandemic.

INTRODUCTION: The daily escalation in incidence and mortality caused by Coronavirus disease (COVID-19) has mandated forced curfew in our country (same as many other countries) to limit the spread of infection. This is predicted to have a more negative impact on cochlear implant (CI) patients since this group of patients needs a unique type of psychological, medical, and technical care in addition to a daily rehabilitation program. METHODS: A cross-sectional study based on Arabic questionnaire that looked into the collateral consequences of COVID-19 on the pediatric CI patients. The questionnaire was designed to highlight different problems such as exposure to head trauma or ear infection, difficulties in device maintenance and getting spare parts, impacts of the delay of programing or switch on appointments, and the impacts of missing rehabilitation sessions. Different ways of management of these problems are presented and discussed. RESULTS: A total of 174 parents responded to the questionnaire. The main problem met by the patients was missing their device programing and rehabilitation sessions. Many children had device maintenance and spare parts problems. Virtual clinics were helpful in solving different problems. Additionally, children who needed device programing were scheduled for remote programing sessions. CONCLUSION: Although the inevitable consequences of the COVID-19 pandemic are catastrophic, they are forcing the medical field to explore new opportunities by sitting up an infrastructure for future usage of telemedicine. Telemedicine is cost-effective and more convenient and enables health-care providers to be immune to future circumstances.

Prevalence and risk factors of cognitive impairment in children with sickle cell disease in Egypt.

Little is known about cognitive impairment in patients with sickle cell disease in Africa. This study aimed to assess cognitive impairment and identify possible risk factors in patients with sickle cell disease in Egypt. This study was conducted at Cairo University Children Hospital. Patients with sickle cell disease, between ages of 6-20 years were enrolled. Cognitive ability was tested using the Stanford Binet intelligence quotient (IQ) test, fourth edition. Transcranial Doppler, magnetic resonance imaging and magnetic resonance angiography of the brain were performed within a week of the IQ test. Among the 40 enrolled patients, 55% had a Full Scale IQ at least 1 standard deviation below the mean, and 27.5% had an IQ 2 standard deviations below the mean. High lactate dehydrogenase was significantly associated with low IQ (p = 0.004). In univariate analyses, IQ was significantly correlated with older age (p = 0.025), high lactate dehydrogenase (p = 0.008) and older age at the start of hydroxyurea (p = 0.025). Impaired cognition is prevalent among sickle cell disease patients. Early initiation of hydroxyurea therapy, which should also reduce hemolysis and lactate dehydrogenase, may be a simple measure to preserve mental abilities in these patients.

Vestibular migraine and benign paroxysmal positional vertigo, close presentation dilemma.

Background: Not only an association between benign paroxysmal positional vertigo (BPPV) and migraine have been recognized in the literature, but also, there are close similarities between BPPV and vestibular migraine (VM) presentations as both can be presented by very similar positional nystagmus.Aims/objectives: To prescribe relatively uncommon cases of positional nystagmus caused by VM that mimics positioning nystagmus of BPPV.Material and method: 12 patients were reviewed retrospectively in this study. All were subjected to full history taking, videonystagmography testing (VNG) and brain magnetic resonance imaging (MRI) with contrast. Provisionally, they were diagnosed with BPPV. After three attempts of repositioning sessions none of them improved. After exclusion of central insults using brain MRI, trial of anti-migraine medical treatment (50-100 Topiramate tablets once per day) for at least one month was prescribed to them.Results: 10 patients were completely cured on medical treatment and finally were diagnosed VM. Only 2 patients did not improve on medical treatment (for one month), were managed again by repeated repositioning maneuvers till finally improved and were diagnosed as resistant BPPV.Conclusions/significance: VM positional nystagmus can mimic BPPV nystagmus in some patients.

Impact of auditory cortical asymmetry in cochlear implantation.

OBJECTIVE: Is there a cochlear implant ear advantage for speech perception? Patients A total number of 68 cochlear implant recipients were evaluated retrospectively. They were 20 adults implanted in right ear, 20 matched adults implanted in left ear while 14 children implanted in right ear and 14 matched children implanted in left ear. METHODS: Behavioral responses & age based speech perception tests were evaluated at 6 months and 1 year post implantation. RESULTS: Adult showed no statistical difference in all tests at 6 months evaluation while 1 year evaluation showed significant better performance for right implanted group in monosyllabic discrimination test. Children showed statistical significant performance in monosyllabic identification and minimal pairs testes at 6 months evaluation; and in monosyllabic identification only at 1 year evaluation. CONCLUSION: The present data support that right ear implantation would fasten the development of auditory skills especially in young children, an issue to be considered in unilateral implantation.