1. Department of Neurosurgery, Istituto Nazionale Neurologico “C. Besta,” Milan, Italy and Department of Neurological Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland
2. Department of Neurological Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland
3. Department of Neurosurgery, Istituto Nazionale Neurologico “C. Besta,” Milan, Italy
4. Department of Radiology, Istituto Nazionale Neurologico “C. Besta,” Milan, Italy
5. Neuroepidemiology Service, Istituto Nazionale Neurologico “C. Besta,” Milan, Italy