PT - JOURNAL ARTICLE ED - , TI - Correction AID - 10.1136/jnnp.2008.154799corr1 DP - 2009 Feb 01 TA - Practical Neurology PG - 1--1 VI - 9 IP - 1 4099 - http://pn.bmj.com/content/9/1/1.2.short 4100 - http://pn.bmj.com/content/9/1/1.2.full SO - Pract Neurol2009 Feb 01; 9