RT Journal Article SR Electronic T1 Erratum JF Journal of Neurology, Neurosurgery & Psychiatry JO J Neurol Neurosurg Psychiatry FD BMJ Publishing Group Ltd SP 852 OP 852 DO 10.1136/jnnp.54.9.852-c VO 54 IS 9 YR 1991 UL http://jnnp.bmj.com/content/54/9/852.4.abstract AB