Effect of Weak Electromagnetic Fields on the Amplitude of the Pattern Reversal Vep Response in Parkinson's Disease

Abstract

Visual evoked potential (VEP) studies are widely used for the diagnosis of multiple sclerosis (MS) and are also useful in monitoring the effects of various therapeutic modalities in the disease. Prolongation of the VEP latencies has been demonstrated in patients with MS and in other neurodegenerative disorders including Parkinson's disease (PD), a disorder characterized by deficient cerebral dopamine (DA) functions. Pharmacological and biochemical studies have demonstrated a positive correlation between the amplitude of the VEP response and cerebral DA levels. Since brief, extracerebral applications of picotesla (pT) range flux intensity electromagnetic fields (EMFs) of low frequency have been shown to produce rapid improvement in motor and cognitive symptoms in PD, it is expected that application these EMFs would lead also to an increase in the amplitude of VEP response. This report documents three randomly selected PD patients who, following two successive brief extracerebral applications of pT range EMFs, showed an almost 3-fold increase of the mean pretreatment amplitude of the pattern reversal VEP in response to monocular stimulation. One patient underwent also a placebo EMF treatment which did not result in a significant change in the posttreatment amplitude. The study demonstrates that in Parkinsonian patients extracerebral application of these EMFs rapidly increases in amplitude of the VEP response and, by inference, cerebral DA levels presumably by increasing DA release.

Electromagnetic field of mobile phones affects visual event related potential in patients with narcolepsy

“…The EM ®eld stimulatory effect has been observed with the use of low frequencies. Some authors have reported a signi®cant increase in the amplitude of visual evoked potentials on short term exposure in patients with multiple sclerosis with a history of optic neuritis [Sandyk, 1996b] and in patients with Parkinson's disease [Sandyk, 1996a]. In connection with a low frequency EM ®eld, healthy persons were seen to have experienced a positive effect in the form of N1 amplitude enhancement in a dichotic listening task and a negative effect in the form of prolonged reaction time and visual ERP P2 latency [Crasson et al, 1999].…”