1. Wellcome Department of Cognitive Neurology, Institute of Neurology, University College London, Queen Square, London
2. Autonomic Unit, National Hospital for Neurology and Neurosurgery, Institute of Neurology, University College London, Queen Square, London
3. Department of Respiratory Medicine, National Heart and Lung Institute, St Mary's Hospital, Imperial College School of Medicine, London, UK
4. Unit of Neurovascular Medicine, St Mary's Hospital, Imperial College School of Medicine, London, UK