[Endogenous potentials evoked by acoustic stimulus in children with idiopathic headache--preliminary report]

Endogenous evoked potentials (P300) are elicited by several stimuli, and are electrophysiological consequence of cognitive processing. Abnormalities have often been reported in dementive syndromes, demyelinating diseases, metabolic disorders, CNS tumors, phacomatoses, neuroinfections, attention deficit hyperactivity disorder and epilepsy. The role of this element of neurophysiological characteristics is debated in migraine, pato-genetically undefined, and other primary headaches.

The aim of this research was to determine whether the parameters of endogenous responses to the transient auditory stimulation in children with migraine differ from parameters obtained from children with tension-type headache, and whether the results are different in children with primary headaches compared with headache-free controls.

56 patients, 27 girls and 29 boys aged from 10 to 18 years, recruited from the Department of Pediatric Neurology and Headache Outpatient Clinic of University Children's Hospital of Cracow were studied between 1.04.2004 and 31.08.2004. 21 children affected with migraine, 17 with aura, 4 without aura, and 15 children with frequent episodic tension-type headache (ETTH) were diagnosed according to IHS criteria, and compared with 20 sex- and age-matched headache-free controls. Endogenous evoked potentials P300 were performed in all children using auditory oddball paradigm, averaging 60 responses to stimuli different from the background activity. Responses were recorded using superficial electrodes placed on the frontal (Fz), middle (Cz) and parietal (Pz) region, while reference electrodes on the ear lobes. The procedure of average out of target and non target stimuli was repeated three times in each patient.

The parameters of latency and amplitude of P300 were not significantly different between children with migraine, without aura and ETTH, and healthy controls. On the contrary, the amplitude of responses was lower in children with ETTH than in controls. However the latency was shortened in children with migraine compared with children with other primary headaches and with headache-free controls. There was no significant correlation between parameters.

The findings of shortened latency of P300 potentials in children with migraine, esp. migraine with aura may contribute to migraine pathogenesis. There were no significant differences in the latency and amplitude of P300 potentials in children with migraine without aura compared with the frequent ETTH. This finding does not add further information to the differentiation of both types of primary headaches.