Tvedskov JF et al. (2005) No increase of calcitonin gene-related peptide in jugular blood during migraine. Ann Neurol 58: 561–568

A key discovery in the field of headache research has been the association between migraine attacks and raised concentrations of calcitonin gene-related peptide (CGRP) in external jugular venous blood. Recent work from a Danish group, however, has cast serious doubt on this finding, by showing that CGRP levels within an individual patient do not differ during and outside an attack.

The team obtained external jugular and cubital venous blood samples from 17 patients recruited through an outpatient headache clinic. A further four patients provided cubital venous blood samples only. Using a pager system, whereby the patient alerted the researchers at the onset of symptoms, it was possible to take samples during migraine attack without aura while the patient was at rest at home. Control samples from each patient were taken at least 7 days later, in the absence of migraine or other headache.

Next, two different assays were used to measure the concentration of CGRP in each blood sample. Both tests showed that the mean concentration of the peptide in external jugular venous blood was similar during and outside an attack. The same was true for the cubital venous blood samples. In addition, there was no significant difference in the mean CGRP concentration between the external jugular and peripheral blood samples.

Tvedskov and colleagues conclude that CGRP is not, in fact, increased in external jugular or peripheral blood during a migraine attack without aura, and they caution against using the peptide as a biomarker.