Paul B Rizzoli1, Licia Grazzi2. 1. Department of Neurology, Brigham and Women's Hospital, John R Graham Headache Center, Brigham and Women's Faulkner Hospital, Harvard Medical School, Boston, MA, USA. 2. Fondazione IRRCS IstitutoNeurologico C Besta, Dipartiimento Neuroalgologia Centro Cefalee, Milan, Italy.