Screening for cognitive dysfunction in corticobasal syndrome: utility of Addenbrooke's cognitive examination.

INTRODUCTION: The motor features of corticobasal syndrome (CBS) are well recognized but the fact that many, if not all, affected patients develop cognitive impairment is still underrecognized. The dementia of CBS overlaps most with a language variant of frontotemporal dementia: progressive nonfluent aphasia (PNFA). The aim of this study was to determine the usefulness of Addenbrooke's Cognitive Examination-Revised (ACE-R) in the evaluation of CBS and to document similarities and differences between CBS and PNFA. MATERIALS AND METHODS: Patients with well-defined CBS or PNFA from two tertiary referral centers were selected along with matched controls. RESULTS: Twenty-one patients with CBS, 23 patients with PNFA and 47 age- and education- matched controls were included. Both CBS and PNFA groups showed substantial impairment on the ACE-R (f = 17.3-80.2, p < 0.001) and were significantly impaired in all domains (p < 0.001). The only significant difference between CBS and PNFA was in the visuospatial domain (p < 0.009), being worse in CBS. Using a cutoff of 88/89 out of 100, 90% of CBS and 82.6% of PNFA patients were impaired. At this cutoff of 88/89, ACE-R in CBS had sensitivity and specificity values of 91 and 98%, respectively.