Erratum to: J Headache Pain DOI 10.1007/s10194-009-0159-6

Due to an error in the manuscript submitted for publication, Marta Allena was listed as affiliated to the University of Rome la Sapienza. In fact, her sole affiliation is:

IRCCS Neurological Institute C. Mondino Foundation, University Centre for Adaptive Disorders and Headache, Pavia Section, Pavia, Italy.