Effects of Caffeine on Auditory- and Vestibular-Evoked Potentials in Healthy Individuals: A Double-Blind Placebo-Controlled Study

Background and Objectives@#The blockage of adenosine receptors by caffeine changes the levels of neurotransmitters. These receptors are present in all parts of the body, including the auditory and vestibular systems. This study aimed to evaluate the effect of caffeine on evoked potentials using auditory brainstem responses (ABRs) and cervical vestibular-evoked myogenic potentials (cVEMPs) in a double-blind placebo-controlled study. @*Subjects and Methods@#Forty individuals (20 females and 20 males; aged 18-25 years) were randomly assigned to two groups: the test group (consuming 3 mg/kg pure caffeine powder with little sugar and dry milk in 100 mL of water), and the placebo group (consuming only sugar and dry milk in 100 mL water as placebo). The cVEMPs and ABRs were recorded before and after caffeine or placebo intake. @*Results@#A significant difference was observed in the absolute latencies of I and III (p0.050). @*Conclusions@#It seems that the extent of caffeine’s effects varies for differently evoked potentials. Latency reduction in ABRs indicates that caffeine improves transmission in the central brain auditory pathways. However, different effects of caffeine on auditory- and vestibular-evoked potentials could be attributed to the differences in sensitivities of the ABR and cVEMP tests.

[Risk factors for ankle sprain injury among lranian athletes]

Ankle sprains are the most common musculoskeletal injuries that occur in athletes all over the world. Ankle sprains can also cause longterm disability such as ankle pain, Functional ankle instability, postural disorders, recurrent ankle sprain and etc. The purpose of this study was to examine prospectively intrinsic and extrinsic risk factors for ankle sprains in 125 Iranian athletes that were divided into two groups: Healthy and Injured groups. Ankle range of motions, Achilles Tendon's flexibility and Calf's size were measured and related questionnaire was completed. Ankle sprains were more common in soccer, basketball and volleyball than other sports. Severe ankle inversion was the most common [94/4%] mechanism of ankle sprain. Fatigue, not warming up, improper landing, ankle rotations were expressed by the athletes as the main reasons causing their ankle sprains. There were no significant differences between ages, weight, height, training sessions, playing surfaces, foot wears and ankle sprains. Most interestingly was the significant relation between balance training and ankle sprain prevention. [P value = 0.00574]. The intrinsic factors such as fatigue, not warming up, improper landing were most common risk factors for ankle sprain in Iranian athletes. One of the main findings of the present study was the positive role of balance training as a key factor in prevention of ankle sprains.

[Evaluation of phonological awareness in stutterer and non stutterer children of aged 4 to 8 years in Tehran]

The relationship between language and stuttering is an important issue in development of children because initiation of stuttering is generally contemporaneous with the period of rapid language development in children. Phonological awareness is part of language function which simultaneously develops with language and is the basis for oral and aural skills. The purpose of this research is to evaluate the relationship between stuttering and phonological awareness and the importance of phonological awareness in the process of evaluation and treatment of stuttering. It was a cross-sectional comparative study. Conducted on 53 children aged 4 to 8 years in Tehran. Participants' profile was made by examiner through interview with participants' therapist, parents and instructor. Voice of stutterer children was recorded and the phonological awareness test was performed. Obtained data was analyzed. Regarding the scores of phonological awareness test there were significant differences between stutterer and non-stutterer groups and also between different ages [p<0.05]. Scores of phonological awareness test in children with different stuttering severities were not significantly different. Children younger than 4 years had the least scores while children older than 7 years had the most and the differences were statistically significant [p<0.05]. This shows that the score improves by aging. Phonological awareness, age, type and severity of stuttering should be considered in assessment and treatment of Persian stutterer children aged 4 to 8 years old.

[Comparison of intonation production in cochlear-implanted children and normal hearing children]

Due to defects of auditory feedback, children with hearing loss have inappropriate speech intonation. Consistently, results of previous studies have shown that cochlear implanted children have some difficulties in their intonation. Intonation shows the type of the sentence which can be statement or question sentences. The purpose of this study was comparison of speech intonation in cochlear-implanted children and normal hearing children. The present study was performed on 25 cochlear-implanted children and 50 normal hearing children. Different pictures were shown to the subjects and they said statement and question sentences. All sentences were heard by eight speech therapists and perceptually judged. Using praat software mean base frequency and pitch alterations were measured. In cochlear-implanted group, mean speech base frequency was higher and mean pitch alteration was lower than the control group. Mean experts' scores in cochlear-implanted group were lower than the control group. Differences in all three variables were statistically significant [p<0.05]. There was a significant direct correlation between duration of time that the children had cochlear implant and perceptual judgment scores [p<0.05]. According to the results, cochlear implant prosthesis has limited efficacy in improving speech intonation; although their ability to produce speech intonation improves by increasing duration of the time that children have cochlear implant. Thus speech therapists should consider intervening on speech intonation in treatment program of cochlear-implanted children.

[Brain activity throughout audiovisual speech perception by functional magnetic resonance imaging]

Neuroimaging techniques in audiovisual speech processing are innovative approach to neuroscience investigation that steadily influences the deep survey of highly mechanisms involved in this process. The purpose of this study was to evaluate brain activity via functional magnetic resonance imaging throughout audiovisual speech perception in Persian language. Functional MRI was used to assess 19 normal 20-30 year old women while they had been presented syllable /ka/ visually and /pa/ auditory using block design method, in which it would provide two series of imaging, functional and T1-weighted. Subsequently, the results were analyzed and compared by FSL software. The results of this study pointed out that both middle and cortical regions of brain are activated in visual stimuli and its middle regions are activated in response to auditory stimuli. Hence, left anterior supramarginal, some parts of motor speech system including insular and cingulated cortex-precentral cortex were stimulated with visual stimulus and left posterior supramarginal as well as right supramarginal gyrus were stimulated with auditory stimulus. Moreover, in this investigation, McGurk effect was behaviorally proven in fifteen subjects. It was hypothesized that the activation of unique region, supramarginal gyrus, with both audio and visual stimuli indicated the presence of commonplace region for phonologic processing of sensory inputs. In addition, auditory stimuli develop more intense activity; and on the other hand, broaden-maximum voxel-as well as extra regions are demonstrated in response to visual stimuli. These points represent the unfamiliarity of normal individual brain to percept visual speech stimuli

[Vestibular evoked myogenic potential in congenitally blind patients versus normal subjects]

Conventional balance test such as electronystagmography and videonystagmography, which are vision-dependant, are not practical in blind patients. Instead, vestibular evoked myogenic potential, not needing any vision, seems to be a more appropriate test for evaluating the vestibular system, in these patients. This study aimed to assess the prevalence and the latencies of p13 and n23 waves among congenitally blind and sighted participants evaluated by vestibular evoked myogenic potential. In a cross-sectional study, vestibular evoked myogenic potential was recorded for 20 slighted and 20 congenitally blind subjects, aged 18 to 30 years old, using 500 Hz-tone bursts [95 dBnHL]. Vestibular evoked myogenic potentials responses were present in all [100%] of the participants. Considering the results of the both ears, there was no significant difference between mean p13 and n23 latencies of the two groups [p>0.05]. Formation of vestibular evoked myogenic potentials reflex arc and neural pathway in congenitally blind patients is similar to slighted individuals; hence, the development of this pathway is independent of the visual system. Vestibular evoked myogenic potentials test is a useful test to assess vestibular function of the blinds

[Providing a non word repetition test in 4-year-old Persian children and determining its validity and reliability]

Phonological working memory is an important factor in speech and language development and the treatment of related disorders. Assessment of this kind of memory is based on non word repetition. The aim of this study was providing a non word repetition test to examine the capacity of phonological working memory and determining its validity and reliability. This is a cross-sectional study. Initially 60 words were selected based on common Persian syllable structures. Then non words were created by changing one or two phonemes in each of the words. Words and non words were assessed by experts for the content validity and 25 non words were selected. 16 boys and 14 girls aged 4 years to 4 years and eleven months were selected by nonprobability sampling from the childcares centers in regions 2 and 6 of Tehran. The test was performed twice by a single examiner to evaluate the reliability of test. Children non word repetition scores were determined and correlation analysis was conducted using the Pearson's correlation coefficient. Our results show that a high coefficient correlation between different performances 0.76 [p<0.001]. These findings show that non word repetition test has high validity and reliability

[ acoustic analysis of voice onset time in cochlear implanted children and normal-hearing controls]

Hearing has an important role in speech production and making phonological distinction, especially voicing distinction. Voice onset time [VOT] has been a reliable acoustic cue of voicing differences in plosive consonants. The purpose of this study was to measure VOT in initial Persian [Farsi] oral plosives produced by cochlear implanted children, comparing to normal hearing children. In this cross-sectional study, 20 cases and 20 controls were assessed. Cases were prelingually deaf children who were cochlear implanted 4.5 years prior to test. Controls were normal hearing children at 4.5 years of age. VOT were measured while children uttered oral plosives. The effect of hearing status, voicing, and gender on VOT were assessed. The amount of VOT of plosives produced by girls was higher than boys, in both groups. This difference was significantly higher in voiceless plosives than in voiced ones. In both groups, voiceless plosives had long-positive VOT value; while the amount of VOT was short-positive regarding voiced plosives. It was demonstrated that VOT is significantly correlated with voicing. In voiceless plosives, VOT could not be considered as a phonetic correlate of hearing status; whereas it made significant differences between cochlear implanted children and hearing controls. Furthermore, it was confirmed that concerning voiceless plosives, the amount of VOT of girls was significantly higher than boys. On the contrary, in voiced plosives, gender had no significant effect on the amount of VOT

Comparison of middle latency auditory evoked potential in children and adults

Middle latency auditory evoked potentials [MLAEPs] development takes longer time than the auditory brainstem response [ABR] development does, which makes them difficult to record in some children. The purpose of this study was to investigate the age effect on characteristics and detection of MLAEPs in children and adults. This cross sectional study was conducted on 15 children aged 7-12 yr and 31 adults aged 20-50 yr with normal peripheral hearing. To investigate precisely, children were divided in two subgroups of older and younger than 10 years old, as well. The MLAEPs amplitudes and latencies were recorded by conventional protocol and compared. Adult Na mean latency, 20.86 ms, was less than that of children, 22.86 ms, [p = 0.0025]. In contrast, the adult Nb mean latency, 44.93 ms, was longer [p = 0.0001]. Children Nb mean latency was 42.02 ms. There was no significant difference in MLAEP amplitudes and latencies between two children subgroups, although variance was more in younger children. MLAEPs are reliably recorded after 7 years old. Characteristics of MLAEPs are different in adults and children so that the primary MLAEPs generators have a course of development extending beyond the first decade of life. As those potentials were recorded in all children, it is suggested to be used in their test batteries for hearing evaluation

Correlation of sperm nuclear chromatin condensation staining method with semen parameters and sperm functional tests in patients with spinal cord injury, varicocele, and idiopathic infertility

Our aim was to investigate sperm nuclear chromatin condensation and its correlation with semen parameters and vitality test in infertile patients with spinal cord injury [SCI], varicocele, and idiopathic infertility. Sperm chromatin condensation was determined by aniline blue staining in 22 SCI-injured infertile men, 20 with varicocele, and 28 with idiopathic infertility. The results were compared with the semen analysis parameters and the hypo-osmotic swelling test results. Three grades of staining for sperm heads were distinguished: unstained, showing sperm maturity [G0]; partially stained [G1]; and completely stained, showing sperm immaturity [G2]. The total score was calculated as: [G0 * 0] + [G1 * 1] + [G2 * 2]. In all groups, the total staining score was higher than 75%, corresponding to a high degree of immaturity of sperm. Patients with SCI had a less sperm nuclear chromatin condensation and chromatin stability than patients with idiopathic infertility and varicocele [total scores, 98% versus 89% and 88%, respectively; P <.01]. All of the patients had normal hypo-osmotic swelling test results. Sperm counts for all patients were within the reference range. The mean percentages for normal motility and morphology of the sperm were 15.5% and 15% for patients with SCI, 43% and 15% for patients with varicocele, and 62.5% and 54% for patients with idiopathic infertility. There was no correlation between sperm nuclear chromatin condensation and semen analysis parameters. Aniline blue staining for sperm nuclear chromatin condensation is a method independent of semen analysis and demonstrates the internal structural defects of sperm. This method may have a predictive value in assessing fertility