Cluster headache: lack of central modulation?

Activation of the SPergic pathway may be responsible for the starting of both painful and autonomic symptoms during a typical cluster headache (CH) attack. We utilized Brainstem Auditory Evoked Potentials (BAEPs) and Visual Evoked Potentials (VEPs) to evaluate the possibility of underlying asymmetries in central functions in CH attacks. We studied 14 CH (7 right and 7 left cluster) and 14 normal subjects. All the CH patients showed a significant VEP asymmetry; the mean P 100 amplitude was significantly reduced on the side of the pain and I-V latency of BAEP was increased on the symptomatic side. No check was made for any significant variation underlying asymmetries in the normal subjects. We postulate that such an asymmetry in VEP and BAEP responses could suggest a neurotransmitters disorder with a different manifestation in each hemisphere.