RT Journal Article SR Electronic T1 Exploring the Subdural Space JF Regional Anesthesia & Pain Medicine JO Reg Anesth Pain Med FD BMJ Publishing Group Ltd SP 7 OP 8 DO 10.1016/j.rapm.2003.11.003 VO 29 IS 1 A1 Craig Palmer YR 2004 UL http://rapm.bmj.com/content/29/1/7.abstract AB