Landgrebe M, Frick U, Hauser S, Hajak G, Langguth B. (2009). Association of tinnitus and electromagnetic hypersensitivity: hints for a shared pathophysiology? PLoS ONE. 4(3):e5026.
Tinnitus, the perception of a meaningless sound in the absence of an external sound, is experienced by 10-20% of adults. The underlying biological mechanism of tinnitus is poorly understood, but evidence suggests that dysfunctional neural processes in the brain are involved. Studies have shown that exposure to electromagnetic fields (EMF) and especially mobile phone emissions can influence neuronal processing in the central auditory system. Nonetheless, recent epidemiological studies have not found an association between mobile phone use and tinnitus.
To investigate whether tinnitus is more common among those who suffer from self-perceived hypersensitivity to EMF than among those who do not and to explore any clinical characteristics that point to a common mechanism for both tinnitus and electromagnetic hypersensitivity.
Those with subjective EMF hypersensitivity were patients who experienced unspecific health complaints that they attributed to exposure to EMF (e.g. mobile phone base stations, TV sets, etc.). Of the 135 screened EMF hypersensitive patients, 89 met the inclusion criteria and agreed to participate. Cases nominated one or more age and gender-matched control from their workplace or area of residence, resulting in 107 non-EMF hypersensitive controls. Tinnitus occurrence, duration, and severity were assessed by questionnaire.
Questionnaires were returned by 77.5% of cases and 74.8% of controls. Those with major depression at their initial interview were significantly less likely to return the questionnaire than were those without depression. Major depression, anxiety disorder, and somatoform disorders were more frequent in the EMF-sensitive group than in the control group. Tinnitus occurred in 50.72% of the case group and in 17.5% of the control group (p<0.0001) but with no difference between groups in tinnitus duration or severity. Tinnitus was more common among males, those with the subjective belief of being EMF hypersensitive, those with reduced sleep quality, and those with reduced ability to discriminate real versus sham electromagnetic pulses. A history of exposure to noise, as well as the amount of mobile phone use, did not influence the risk of tinnitus (p=0.5187 and p=0.5116, respectively).
Interpretation and Limitations
The prevalence of tinnitus among controls, as well as the higher prevalence in males and the co-morbid sleep disturbances, was in accordance with previous studies. The surprising finding was the high prevalence of tinnitus among EMF-sensitive patients. Tinnitus could represent another unspecified health complaint among EMF-sensitive patients, or both disorders could share a common biological mechanism. This study is limited by its cross-sectional design as opposed to a prospective design and by the self-report of tinnitus.
Tinnitus is much more common among subjective EMF hypersensitive patients. There is no evidence of a relationship between tinnitus and exposure to EMF. The association between tinnitus and electromagnetic hypersensitivity may be due to the vulnerability of an individual’s neuronal processes to external stimuli.