1. Department of Neurosurgery, University of Kagoshima, Kagoshima, Japan
2. Istituto di Neurologia, Universita Cattolica, Largo A. Gemelli 8, 00168 Rome, Italy
3. Neurofisiologia and Neurochirurgia Centro Traumatologico Ortopedico, Via S. Nemesio 21, 00145 Rome, Italy
4. MRC Human Movement and Balance Unit, Institute of Neurology and National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK