[Comparison of gap in noise test results between congenital blind and slighted subjects with normal hearing

Main feature of auditory processing abilities is temporal processing including temporal resolution, temporal ordering, temporal integration and temporal masking. Many studies have shown the superiority of blinds in temporal discrimination over sighted subjects. In this study, temporal processing was compared in congenital blind subjects with sighted controls via gap in noise test [GIN]. This analytic -prescriptive non-invasive cohort study was conducted on 22 congenital blinds [11 males and 11 females] with a mean age of 26.22 years and 22 sighted control subjects [11 males and 11 females] with a mean age of 24.04 years with normal hearing in faculty of Rehabilitation Tehran University of Medical Sciences. Gap in noise test results, approximate threshold and percent of corrected answers, were obtained and then, were analyzed by Mann-Whitney non-parametric statistical test. There was a significant difference in the approximate threshold and the percent of corrected answers between congenital blinds and sighted control subjects [p<0.05]. However, there was no significant difference between males and females in this regard [p>0.05]. Auditory temporal resolution ability, the lower approximate threshold and the more corrected answers in gap in noise, in blind subjects is better than the sighted control group and it might be related to the compensative neuroplasticity after visual deprivation

[Comparison of auditory event-related potential P300 in sighted and early blind individuals]

Following an early visual deprivation, the neural network involved in processing auditory spatial information undergoes a profound reorganization. In order to investigate this process, event-related potential provide accurate information about time course neural activation as well as perception and cognitive processes. In this study, the latency and amplitude of auditory P300 were compared in sighted and early blind individuals in age range of 18-25 years old. In this cross-sectional study, auditory P300 potential was measured in conventional oddball paradigm by using two tone burst stimuli [1000 and 2000 Hz] on 40 sighted subjects and 19 early blind subjects with mean age 20.94 years old. The mean latency of P300 in early blind subjects was significantly smaller than sighted subjects [p=0.00]. There were was no significant in amplitude between two groups [p > 0.05]. Reduced latency of P300 in early blind subjects in comparison to sighted subjects probably indicates the rate of automatic processing and information categorization is faster in early blind subjects because of sensory compensation. It seems that neural plasticity increases the rate of auditory processing and attention in early blind subjects

[Effects of caffeine on auditory brainstem response]

Blocking of the adenosine receptor in central nervous system by caffeine can lead to increasing the level of neurotransmitters like glutamate. As the adenosine receptors are present in almost all brain areas like central auditory pathway, it seems caffeine can change conduction in this way. The purpose of this study was to evaluate the effects of caffeine on latency and amplitude of auditory brainstem response [ABR]. In this clinical trial study 43 normal 18-25 years old male students were participated. The subjects consumed 0, 2 and 3 mg/kg BW caffeine in three different sessions. Auditory brainstem responses were recorded before and 30 minute after caffeine consumption. The results were analyzed by Friedman and Wilcoxone test to assess the effects of caffeine on auditory brainstem response. Compared to control group the latencies of waves III, V and I-V interpeak interval of the cases decreased significantly after 2 and 3mg/kg BW caffeine consumption. Wave I latency significantly decreased after 3mg/kg BW caffeine consumption [p<0.01]. Increasing of the glutamate level resulted from the adenosine receptor blocking brings about changes in conduction in the central auditory pathway

Comparison of middle latency auditory evoked potentials in learning disability and normal 7-12 year- old children

Learning disability [LD] is one of the most prevalent problems among elementary school children. Approximately 10 percent of all elementary school children suffer from this problem. It has been determined that learning disability is predominantly accompanied with subtle impairment in central auditory nervous system. The main idea of this study was to evaluate middle latency auditory evoked potential [MLAEPs] in learning disabled children. This cross-sectional study investigated middle latency auditory evoked potential in children with learning disability [n = 31] compared to normal children [n = 31]. Latencies and amplitudes of MLAEPs results with different stimulus intensity and binaural stimulation were compared between two groups. Compared to control group, learning disabled children exhibited smaller amplitudes for all the components except the right ear Na and Pa. There is no significant difference between two groups for latencies of the components. It seems that middle latency auditory evoked potential may be useful in diagnosis and evaluation of learning disabled children although more investigation is required

[Arachnoid cysts in cerebellopontine angle: a case report]

Arachnoid cysts are cerebrospinal fluid-filled sacs that are located between the brain or spinal cord and the arachnoid membrane, one of the three membranes that cover the brain and spinal cord. They are usually located within subarachnoid space with a membrane consisting of arachnoid cells and collagen fibers and are filled with CSF. It is naturally considered as a congenital cyst because of its common appearance in the infancy. Typical symptoms of an arachnoid cyst around the brain include headache, nausea and vomiting, seizures, hearing and visual disturbances, vertigo, and difficulties with balance and walking. MRI and CT can help in diagnosis. Arachnoid cysts are benign and the vast majority remains asymptomatic throughout life. If they are deemed to be causing symptoms then surgery can be contemplated. Here, we are aimed at describing a case of Arachnoid cysts involved cerebellopontine angle that has been reffered to audiology clinic in Tehran University of Medical Sciences. The experiments and results of radiographic techniques has been brought here

[Temporary threshold shift by otoacoustic emission in a group of 18-25 years old with normal hearing]

Method and Material: This study was performed on 36 normal-hearing subjects aged 18-25 years for survey of temporary threshold shift [TTS] by transient evoked otoacoustic emissions

Finding: Noise can affect the pure-tone thresholds and [TEOAEs] amplitudes. When cochlea affected by noise, evaluating TEOAE is more suitable than pure-tone audiometry. Because of this test, is objective an unaffected by attention and alertness and can be evaluated in difficult to test subject and also have high carefulness and can be performed in a quiet, but not sound-proof room