RT Journal Article SR Electronic T1 Neurology at high altitude JF Practical Neurology JO Pract Neurol FD BMJ Publishing Group Ltd SP 230 OP 237 DO 10.1136/jnnp.2006.097915 VO 6 IS 4 A1 Charles Clarke YR 2006 UL http://pn.bmj.com/content/6/4/230.abstract AB