Conception and design: Chang, Breshears. Acquisition of data: Chang, Breshears. Analysis and interpretation of data: Chang, Breshears. Drafting the article: Chang, Breshears. Critically revising the article: Breshears, Molinaro. Reviewed submitted version of manuscript: all authors. Statistical analysis: Breshears, Molinaro. Study supervision: Chang.
Portions of this work were presented in poster format at the Congress of Neurological Surgeons Annual Meeting in San Francisco, CA, October 21, 2013.