1. MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, The National Hospital for Neurology and NeurosurgeryQueen Square LondonWC1N 3BG United Kingdom
2. Institute of NeurologyUniversity College LondonQueen Square London United Kingdom
3. Department of Neurology and NeurophysiologySt Thomas' Hospital, Guy's and St Thomas' NHS Foundation Trust and Department of Academic Neurosciences, Kings College London United Kingdom
4. Departments of Neurosurgery and Neurology, InselspitalBern University Hospital, University of BernBern Switzerland