Abstract
Dear Sir, Edvinsson and Goadsby (1) have recently presented a comprehensive review of the measurement of vasoactive neuropeptides in biological materials in this journal. Their paper contains much of value, but the discussion of our previous paper (2) which demonstrated no increase of calcitonin gene-related peptide (CGRP) in external jugular venous blood during migraine attack without aura is unacceptable. Edvinsson and Goadsby (1) state that, because samples were taken in patients’ homes, it would take time until the samples were centrifuged and, therefore, it is to be expected that little CGRP would be left and a negative result would be obtained. Our study contradicts several previous reports and must have been very disappointing for Edvinsson and Goadsby. However, the fact is that samples were taken according to the best advice from experts, breakdown of CGRP was prevented by the addition of a peptidase inhibitor and there was ample CGRP in all the samples. Our design using intrapatient comparison is much stronger than the design used in previous studies which compared patients to healthy controls. I am unable to understand why this futile critique of our study continues. The easy way forward would be for Edvinsson and Goadsby to prove that their previous studies are correct. They should conduct a new study using the much stronger intrapatient comparison design. That could once and for all solve the dilemma between the conflicting results obtained by their group and our own. We have considered doing such a study, but that would only be met with the same kind of unfounded criticism presented in the paper by Edvinsson and Goadsby (1). Therefore, it must be authors of the previous positive papers who repeat their study with a better methodology.