Visual evoked potentials in migraine patients: alterations depend on pattern spatial frequency

Abstract

Visual information is conducted by two parallel pathways (luminance- and contour-processing pathways) which are thought to be differentially affected in migraine and can be investigated by means of pattern-reversal visual evoked potentials (VEPs). Components and habituation of VEPs at four spatial frequencies were compared between 26 migraineurs (13 without aura, MO; 13 with aura, MA) and 28 healthy volunteers. Migraineurs were recorded in the headache-free interval (at least 72 h before and after an attack). Five blocks of 50 responses to chequerboards of 0.5, 1, 2 and 4 cycles per degree (c.p.d.) were sequentially averaged and analysed for latency and amplitude. Differences in VEPs were dependent on spatial frequency. Only when small checks were presented, i.e. at high spatial frequency (2 and 4 c.p.d.), was the latency of N2 significantly prolonged in MA and did it tend to be delayed in MO subjects. Habituation behaviour was not significantly different between groups under the stimulating conditions employed. Prolonged N2 latency might be explained by the lack or attenuation of a contour-specific component N130 in migraineurs, indicating an imbalance of the two visual pathways with relative predominance of the luminance-processing Y system. These results reflect an interictally persisting dysfunction of precortical visual processing which might be relevant in the pathophysiology of migraine.

Visual evoked potentials in migraine: Is the “neurophysiological hallmark” concept still valid?

“…As far as we know, only one study has reported lower first block amplitude in migraineurs (Afra et al, 1998). Two studies have reported increased first block amplitude in migraineurs (Oelkers et al, 1999;Sand et al, 2009), while most studies, including the present study, found no significant differences (Afra et al, 2000a;Coppola et al, 2007b;Coppola et al, 2011;Coppola et al, 2010b;Coppola et al, 2010a;Coppola et al, 2013b;Di Clemente et al, 2005;Oelkers-Ax et al, 2005;Ozkul and Bozlar, 2002;Sand and Vingen, 2000;Schoenen et al, 1995;Vigano et al, 2013;Wang et al, 1999).…”

“…Neither N70-P100 nor P100-N145 habituation measures were significantly different between groups. Independent confirmation of the habituation-deficit has been achieved only by two groups (Bednar et al, 2014;Ozkul and Bozlar, 2002), whereas it has not been confirmed in five studies by two other groups (Oelkers-Ax et al, 2005;Oelkers et al, 1999;Omland et al, 2013;Sand et al, 2009;Sand et al, 2008). In addition, lack of habituation was not observed in subset of migraineurs in study by a third group (Khalil et al, 2000).…”

“…Several studies reported increased VEP amplitude in migraineurs (Diener et al, 1989;Khalil et al, 2000;Oelkers et al, 1999;Sand et al, 2008;Shibata et al, 1997Shibata et al, , 1998, while other studies could not confirm this (Coppola et al, 2007b;Kennard et al, 1978;Mariani et al, 1988;Oelkers-Ax et al, 2005;Polich et al, 1986;Sand and Vingen, 2000;Sener et al, 1997). In other words, the results of VEP measurements in migraine are contradictory in general, and not just regarding habituation.…”

“…As far as we know, lack of VEP habituation been independently confirmed in two studies (Bednar et al, 2014;Ozkul and Bozlar, 2002), while two other groups have not managed to reproduce this finding (Oelkers-Ax et al, 2005;Oelkers et al, 1999;Omland et al, 2013;Sand et al, 2008). Furthermore, studies that applied blinding of diagnosis when recording VEPs have not found lack of habituation in migraine (Omland et al, 2013;Sand et al, 2008).…”

“…These claims are disputed for VEP because lack of habituation has not been reproduced in several VEP studies (Oelkers-Ax et al, 2005;Oelkers et al, 1999;Omland et al, 2013;Sand et al, 2008;Vigano et al, 2013). Interestingly, studies that reported lack of habituation in migraine applied 3.1 reversals per second (rps), while most other studies applied slower reversal rates.…”