Assessment of potential effects of the electromagnetic fields of mobile phones on hearing

BACKGROUND: Mobile phones have become indispensable as communication tools; however, to date there is only a limited knowledge about interaction between electromagnetic fields (EMF) emitted by mobile phones and auditory function. The aim of the study was to assess potential changes in hearing function as a consequence of exposure to low-intensity EMF's produced by mobile phones at frequencies of 900 and 1800 MHz. METHODS: The within-subject study was performed on thirty volunteers (age 18–30 years) with normal hearing to assess possible acute effect of EMF. Participants attended two sessions: genuine and sham exposure of EMF. Hearing threshold levels (HTL) on pure tone audiometry (PTA) and transient evoked otoacoustic emissions (TEOAE's) were recorded before and immediately after 10 min of genuine and/or sham exposure of mobile phone EMF. The administration of genuine or sham exposure was double blind and counterbalanced in order. RESULTS: Statistical analysis revealed no significant differences in the mean HTLs of PTA and mean shifts of TEOAE's before and after genuine and/or sham mobile phone EMF 10 min exposure. The data collected showed that average TEOAE levels (averaged across a frequency range) changed less than 2.5 dB between pre- and post-, genuine and sham exposure. The greatest individual change was 10 dB, with a decrease in level from pre- to post- real exposure. CONCLUSION: It could be concluded that a 10-min close exposure of EMFs emitted from a mobile phone had no immediate after-effect on measurements of HTL of PTA and TEOAEs in young human subjects and no measurable hearing deterioration was detected in our study

Bilateral effects of unilateral thalamic deep brain stimulation: A case report

A recent study has proved that unilateral deep brain stimulation (DBS) of the subthalamic nucleus has bilateral effects. However, it is still unclear whether unilateral ventral intermediate thalamic nucleus (Vim) DBS exerts exclusively contralateral or bilateral effects on tremor. Previous studies demonstrated a clinically irrelevant improvement on the nontarget side after thalamic stimulator implantation, which was considered to be solely the result of mechanical effects. We report here the case of a 55-year-old woman in whom unilateral thalamic DBS can stop the disabling postural-kinetic tremor in both hands. Simultaneous surface electromyography (sEMG), accelerometry, and video recordings were obtained to evaluate the underlying mechanism. After the right Vim DBS was turned off, moderate rest tremor appeared in both hands accompanied by bilateral bursts on sEMG. Because right hand tremor cannot simply reflect the mechanical overflow of the left side, the bilateral improvement caused by right Vim DBS is probably due to an active tremor reduction in this particular case. ? 2007 Movement Disorder Society

The impact of bilateral subthalamic deep brain stimulation on long-latency event-related potentials

The analysis of long-latency event-related potentials (ERPs) is of importance in the evaluation of certain cognitive functions and in following their subsequent changes. The aim of the present study was to investigate whether deep brain stimulation (DBS) itself can cause changes in the configuration of the ERPs. Using a standard oddball auditory paradigm, we elicited auditory cognitive ERPs in 23 Parkinson's disease patients (in both DBS-ON and DBS-OFF conditions) and in 14 healthy controls. The P200 and P300 amplitudes and latencies, the motor reaction times and the accuracy of button pressing were compared between the DBS-ON and DBS-OFF states and subsequently correlated with the applied stimulation voltage and disease duration. Comparison of the DBS-ON and DBS-OFF conditions revealed that neither the amplitude nor the latency of the examined ERP components changed significantly. However, the behavioral and attentional aspects (e.g. the accuracy of the button pressing responses to the target signal) definitely improved after the DBS was turned on. Positive correlations were demonstrated between the P300 amplitudes over the central and frontal regions and the optimal stimulation voltage and between the disease duration and P300 latencies over the Cz and Fz sites. In conclusion, our data indicate that DBS may have different impacts on various electrophysiological parameters during the oddball paradigm. ? 2008 Elsevier Ltd. All rights reserved

Effects of UMTS cellular phones on human hearing: results of the European project EMFnEAR

The European project EMFnEAR was undertaken to assess potential changes in human auditory function after a short-term exposure to radiofrequency (RF) radiation produced by UMTS (Universal Mobile Telecommunication System) mobile phones. Participants were healthy young adults with no hearing or ear disorders. Auditory function was assessed immediately before and after exposure to radiofrequency radiation, and only the exposed ear was tested. Tests for the assessment of auditory function were hearing threshold level (HTL), distortion product otoacoustic emissions (DPOAE), contralateral suppression of transiently evoked otoacoustic emission (CAS effect on TEOAE), and auditory evoked potentials (AEP). The exposure consisted of speech at a typical conversational level delivered via an earphone to one ear, plus genuine or sham RF-radiation exposure produced by a commercial phone controlled by a personal computer. Results from 134 participants did not show any consistent pattern of effects on the auditory system after a 20-min UMTS exposure at the maximum output of the phone with 69 mW/kg SAR in the cochlea region in a double blind comparison of genuine and sham exposure. An isolated effect on the hearing threshold at high frequencies was identified, but this was statistically nonsignificant after correction for multiple comparisons. It is concluded that UMTS short-term exposure at the maximum output of consumer mobile phones does not cause measurable immediate effects on the human auditory syste