Accepted for Publication: June 15, 2011.
Author Contributions: Drs Steenweg and van der Knaap had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study and concept and design: Steenweg and van der Knaap. Acquisition of data: Steenweg, Wolf, Schieving, Fawzi Elsaid, Friederich, and Østergaard. Analysis and interpretation of data: Steenweg, Wolf, Østergaard, Barkhof, Pouwels, and van der Knaap. Drafting of the manuscript: Steenweg and Fawzi Elsaid. Critical revision of the manuscript for important intellectual content: Steenweg, Wolf, Schieving, Fawzi Elsaid, Friederich, Østergaard, Barkhof, Pouwels, and van der Knaap. Administrative, technical, and material support: Wolf, Fawzi Elsaid, Østergaard, and Barkhof. Study supervision: Wolf and van der Knaap.
Financial Disclosure: None reported.
Funding/Support: This study was supported by grant 9120.6002 from the Dutch Organization for Scientific Research and by the Optimix Foundation for Scientific Research.
Role of the Sponsors: The funding agencies had no direct involvement with the contents of the study.
Additional Contributions: We thank all of the patients, families, and colleagues who contributed to our studies.