1. Department of Neurosurgery; Tianjin Medical University General Hospital; Tianjin 300052 China
2. Tianjin Neurological Institute; Tianjin 300052 China
3. Key Laboratory of Post-Neurotrauma Neuro-repair and Regeneration in Central Nervous System; Ministry of Education and Tianjin City; Tianjin 300052 China
4. Department of Neurology; Henry Ford Hospital; Detroit Michigan 48202 USA