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Bachground and Aim: The involvement of central auditory nervous system is relatively prevalent in patients suffering from multiple sclerosis (MS). To understand cortex function and to investigate cognitive impairment, event related potential is considered as a valuable tool. This study was aimed to compare the amplitude and latency of the event related potentials of P300 in MS patients and normal individuals.
Methods: This cross sectional study was conducted on 21 MS patients and 27 normal cases aged 18-50 years. Auditory P300 was recorded with oddball paradigm, using two tone burst stimuli (1000 and 2000).
Results: In MS patients, mean latencies were significantly longer (p<0.001) and mean amplitude were significantly lower (p<0.001), in both males and females. Sex did not affect P300 latencies and amplitudes significantly.
Conclusion: MS patients show some degree of event related potential abnormalities. Combination of auditory P300 and neuropsychological tests may be useful to investigate cognitive impairment in MS patients.

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Background and Aim: Multiple sclerosis (MS) is characterized with inflammation, demyelization and gliosis. It may be relapsing, remitting, or progressive. Cognitive impairment is relatively prevalent in patients wit h multiple sclerosis and as duration of disease is longer as cognition impairment is more. To understand the cognitive impairment, event related potential can be considered as a valuable tool. This study aimed to investigate the influence of duration of disease and expanded disability status scale (EDSS) on the amplitude and latency of the event related potentials of P300 in patients with multiple sclerosis.

Methods: In this cross-sectional and non-intervention study, 21 patients with multiple sclerosis with mean age of 27.8 with SD 7.1 years (between 18 to 50 years) were enrolled. The patients were selected randomly. The correlation of P300 event-related potential and oddball paradigm was assessed, using two 1000 and 2000 Hz tone burst stimulus.

Results: There was a significant correlation between the latency of P300 wave and duration of disease and expanded disability status scale (p < 0.05) there was high correlation in both electrode sites (r>0.50). The correlation of amplitude of P300 and duration of disease and expanded disability status scale was not significant (p>0.05).

Conclusion: Significant correlation between the latency of P300 and the duration of multiple sclerosis and expanded disability status scale can be a sign of central nervous system changes. Besides, there is a relation between physical disability and cognitive impairments.

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Background and Aim: Omega-3 fatty acid have structural and biological roles in the body 's various systems . Numerous studies have tried to research about it. Auditory system is affected a s well. The aim of this article was to review the researches about the effect of omega-3 on auditory system.

Methods: We searched Medline , Google Scholar, PubMed, Cochrane Library and SID search engines with the "auditory" and "omega-3" keywords and read textbooks about this subject between 19 70 and 20 13.

Conclusion: Both excess and deficient amounts of dietary omega-3 fatty acid can cause harmful effects on fetal and infant growth and development of brain and central nervous system esspesially auditory system. It is important to determine the adequate dosage of omega-3.

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Background and Aim: Subjective tinnitus etiology has not been fully understood. Recently, in normal hearing subject one of the tinnitus theories, more specifically the medial olivocochlear tract, is related to the dysfunction of the efferent auditory system. The aim of this study was to determine the potential contribution of a defective cochlear efferent innervations to the chronic tinnitus in patients with normal hearing and determine the relation between tinnitus loudness and the amount of suppression of the transient evoked otoacoustic emission. Methods: This study was conducted on 20 tinnitus patients aged between 20-45 years and 20 controls matched for age and gender in School of Rehabilitation, Tehran University of Medical Sciences. Transient otoacoustic emission testing without and with contralateral white noise at 55 and 65 dB was performed on each subject. Results: The amplitudes of the emissions in the two groups was significantly different (p=0.001), but no correlation between tinnitus loudness and the amplitudes of the emissions in the presence (p=0.3) and absence (p=0.06) of contralateral noise. Conclusion: The suppression of the transient evoked otoacoustic emission by contralateral white noise did not reach statistically significant levels in tinnitus patients while the amplitude in control group reduced significantly.

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Background and Aim: One of the non-pathological factors affect otoacoustic emissions is body position. In the present study, the effect of side-lying position on evoked otoacoustic emission properties and related existing assumptions were investigated.

Methods: The cross-sectional study was performed on 42 adults aged 18-25 years. The results of Transient-evoked otoacoustic emissions (TEOAEs) test were recorded and analyzed in sitting, supine, and side-lying (Ipsi and Contra) positions to compare the total response level, whole wave reproducibility, signal to noise ratio in frequencies of 1 to 5 KHz, and the lasting time of the test.

Results: Changing of the body position had a significant effect on total response level, whole wave reproducibility, and lasting time of the test (p<0.010) while this effect on signal to noise ratio was just found at 1 KHz (p<0.001). The highest total response level and lowest lasting time of the test values were observed in side-lying (contra) position (p<0.050).

Conclusion: Side-lying position (contra) is the best position for the TEOAEs test. The results of this study partly confirm intracranial pressure change hypothesis that intracochlear fluid pressure increase in the auditory system although there are contradictions in this field.

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Background and Aim: The cochlea and vestibule are related developmentally. Therefore individuals with severe to profound sensourineural hearing loss have additional risk for vestibular dysfunction. The aim of this study was to assess saccular function using vestibular evoked myogenic potentials (VEMP) in children with severe to profound sensorineural hearing loss (SNHL) who are candidates for cochlear implant.

Methods: Thirty children (17 males and 13 females) with bilateral severe to profound sensorineural hearing loss in the age range of 3-15 years participated in this study. 17 children (9 males and 8 females) with normal hearing in the age range of 3-13 years participated as the control group. All children in each group were evaluated for saccular function by performing vestibular-evoked myogenic potentials in both ears.

Results: Comparison of mean threshold values between the two groups revealed statistically significant difference (p<0.05). In addition, comparison of mean amplitude values between the two groups revealed statistically significant difference (p<0.05). However, comparison of p1 3 and n23 latency values between the two groups revealed no significant difference (p>0.05). Out of the 30 children with bilateral severe to profound sensorineural hearing loss eight children (26.66%) had absent VEMP responses in both ears.

Conclusion: Children with severe to profound sensorineural hearing loss who are candidates for cochlear implant ha d more potential for saccular abnormalities compared to normal-hearing children. Therefore, assessment of vestibular function is very important in this population.