aYale School of Medicine, Department of Neurology, New Haven, CT

bStanford School of Medicine, Department of Neurology, Stanford, CA, USA

Correspondence to Karen G. Hirsch, MD, Associate Professor, Neurology, Stanford University School of Medicine; 453 Quarry Road, Palo Alto, CA 94304, USA. Tel: +1 650 723 4448; e-mail: [email protected]