saeid abrishamkar professor, department of neurosurgery, school of medicine, isfahan university of medical sciences, isfahan, iran mostafa torkashvand resident, department of neurosurgery, school of medicine and student research committee, isfahan university of medical sciences, isfahan, iran arash momeni borujeni student of master, school of biomaterial (drug delivery system), amirkabir university of technology, tehran, iran amir momani borujeni general practitioner, school of medicine, isfahan university of medical sciences, isfahan, iran majid rezvani assistant professor, department of neurosurgery, school of medicine, isfahan university of medical sciences, isfahan, iran homayon tabesh assistant professor, department of neurosurgery, school of medicine, isfahan university of medical sciences, isfahan, iran