Pattern-reversal visual evoked potentials in children with migraine: a correlation analysis.

Visual potentials evoked by pattern reversal (PRVEPs) were studied in 64 normal children (age range 7 to 15 years) and in 20 age-matched patients with common and complicated migraine (age range 6 to 16 years). Most of them were studied before and during prophylactic therapy. A Quadristim set (Alvar) was used to present checkerboard patterns on a TV monitor, to amplify the EEG signals and to average and plot the evoked potentials. The potentials were elicited by binocular full-field 2/s checkerboard reversal, recorded from an electrode 4 cm above the inion, and analyzed for latency, amplitude and waveform morphology. The degree of similarity between pairs of PRVEPs was determined by the correlation coefficient. In all our patients no pronounced influence of the disease itself was demonstrated on the PRVEP latencies and amplitudes, but in most of them the correlation coefficients were significantly different from that showing the measure of normal PRVEP variations. Prophylactic medication influenced non-significant increase of the coefficient. This increase seems to be related to recovery from medication in terms of attack frequency. No significant difference in PRVEP results of common and complicated migraine was noticed. The PRVEP distortion can be revealed by the correlation coefficient but not by other PRVEP parameters. Therefore, this parameter may be useful as a sensitive measure of both PRVEP distortion and PRVEP improvement. Our results give further evidence that non-demyelinating disorders, but with ischemic damage and abnormalities in neurotransmitters, can produce measurable changes in PRVEP morphology.