RT Journal Article SR Electronic T1 Calabar, Nigeria JF Practical Neurology JO Pract Neurol FD BMJ Publishing Group Ltd SP 237 OP 239 DO 10.1136/jnnp.2009.182436 VO 9 IS 4 A1 U E Williams YR 2009 UL http://pn.bmj.com/content/9/4/237.abstract AB