Abstract
Dear Sir We agree with Drs Truni and Barbanti that the study of trigeminal somatosensory evoked potentials (TSEP) requires both experience and accuracy in implication and interpretation of the results. We were aware of Leandri's study, warning against the danger that TSEPs evoked by electrical skin stimulation have in the past been assigned to local muscle signals rather than to true somatosensory-evoked neural activity. However, the discussion did not end with this study from 1987. In our present study (1) we followed more recently published methods on TSEPs, and found results consistent with those studies (2, 3). In addition, we wholeheartedly agree that laser-evoked potentials may be useful in the assessment of unmyelinated trigeminal pathways (4).
As for our results showing effects in a direction contrary to that expected, we would like to stress that the abnormalities should be related to the timing of a cluster period. As in migraine, our results suggest that the nature of the dysfunction changes over time, and that the time since the last period and before the next one must be taken into account to understand results. In effect, our results agree with current concepts of cluster headache pathophysiology, as well as with other neurophysiological studies of cluster headache (5, 6).