1. Unit of Functional Neurosurgery, University College London Institute of Neurology, Queen Square, London;
2. Victor Horsley Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, Queen Square, London;
3. Department of Clinical Microbiology, University College London Hospital, London, United Kingdom; and
4. Department of Clinical Neuroscience, Umeå University, Umeå, Sweden