1. The National Institute of Neurological Disorders and Stroke, Bethesda, Maryland.
2. Spaulding Rehabilitation Hospital, Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, Massachusetts.
3. Department of Physical Medicine and Rehabilitation, Craig Hospital, Englewood, Colorado.
4. Department of Physical Medicine and Rehabilitation, University of Colorado, Denver, Colorado.
5. Department of Neurological Surgery, University of California, San Francisco, San Francisco, California.
6. Seton Brain and Spine Institute, Austin, Texas.
7. Departments of Physical Medicine and Rehabilitation, Neurology and Radiology, Baylor College of Medicine, Houston, Texas.
8. Michael E. DeBakey VA Medical Center, Houston, Texas.