1. Neurosurgical Service, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts;
2. Departments of Neurosurgery and Interventional Neuroradiology, Louisiana State University Hospital, Shreveport, Louisiana;
3. Department of Neurosurgery, University of Alabama at Birmingham, Alabama;
4. Department of Neurosurgery, State University of New York at Buffalo, New York;
5. Department of Neurosurgery, Christian Doppler Clinic, and
6. Research Institute of Neurointervention, Paracelsus Medical University, Salzburg, Austria