Colletti, V.; Mandala, M.; Manganotti, P.; Ramat, S.; Sacchetto, L., and Colletti, L. Intraoperative observation of changes in cochlear nerve action potentials during exposure to electromagnetic fields generated by mobile phones. J Neurol Neurosurg Psychiatry. 2010 Dec 16.
The auditory system is most frequently and directly exposed to electromagnetic fields (EMFs) from mobile phones. Recently, alterations in bioelectric activity of the auditory system have been demonstrated in long-term and intensive mobile phone users. Bioelectric activity of the cochlear nerve may be safely and reliably recorded during cerebellopontine angle surgery. Real-time recordings of the acoustically evoked cochlear compound nerve action potentials (CNAPs) directly from the exposed auditory nerve allow investigating the effect of the EMFs on bioelectric activity of the nerve.
The objective was to investigate the effect of EMFs from a mobile phone on acoustically evoked cochlear compound nerve action potentials.
Twelve patients undergoing retrosigmoid vestibular neurectomy (VN) for unilateral Ménière’s disease participated in this study. Seven patients were exposed for 5 min to the 900 MHz signal from a Nokia 6310i mobile phone placed over the craniotomy. The highest specific absorption rate for this model of the mobile phone was 0.82 W/kg. Five control patients were sham-exposed for 5 minutes to the same mobile phone in standby mode. The ear undergoing the operation was stimulated by alternating click stimuli. CNAPs were recorded for 2 min prior to the exposure (T0), throughout the 5-min exposure (T1) and for 10 min post-exposure (T2). CNAPs latency of the first negative peak (N1) and normalized absolute amplitude of N1 were evaluated.
No significant changes in the basal CNAPs latency and amplitude were observed during the T0 period in either the EMF-exposed or in the sham-exposed group. In EMF-exposed patients, a decrease in CNAPs amplitude and an increase in latency started in T1 and continued (to a lesser extent) over the T2 period. These changes were significant compared to the respective T0 values during the 5-min exposure and for 5 min after cessation of exposure. No significant changes in CNAPs latency and amplitude were observed in sham-exposed patients.
Interpretation and Conclusion
The authors have concluded that the results suggest a significant CNAPs deterioration caused by short-term exposure to EMFs from a mobile phone. They discuss limitations of their study, in particular the direct exposure of the nerve to EMFs without any biological tissues in between, a condition that is far from the real life exposure scenario. The authors point out that the long-term effects of EMF exposure of the cochlear nerve could not be assessed in this study.