Predicting the Pathology of Corticobasal Syndrome Using Modified Clinical Criteria, MRI and FDG PET (P06.047)

OBJECTIVE: To evaluate the utility of modified clinical criteria and visual interpretations of MRI and FDG-PET for predicting corticobasal syndrome (CBS) due to Alzheimer9s disease (AD). BACKGROUND: Group comparisons have revealed that patients with CBS due to AD have greater temporoparietal clinical deficits and neuroimaging patterns than patients with non-AD pathology. The predictive value for individual patients is not known. DESIGN/METHODS: 22 patients meeting CBS core criteria with PIB-PET had clinical records, neuropsychological testing, MRI and FDG scans reviewed blinded to PIB results. Positive PIB scan was considered a surrogate underlying AD pathology. Patients were designated as temporoparietal variant (tpvCBS) if they had either (1) logopenic aphasia; (2) elements of Gerstmann or Balint syndromes (3) episodic memory or visuospatial greater than executive dysfunction. Frontal-variant CBS (fvCBS) designation included either (1) Agrammatic or motor speech deficits; (2) Apathy, disinhibition, loss of empathy; (3) lower extremity apraxia; (4) executive greater than memory or visuospatial impairment. MRI and FDG-PET were classified as frontal or temporoparietal based on the predominant atrophy/hypometabolism pattern. RESULTS: Of the 10 patients with a final classification of tpvCBS, 6 were PIB+ and 4 were PIB- (sensitivity 67%, specificity 69% for AD). Visual MRI reads had 67% sensitivity and 42% specificity for PIB+ with intra-rater reliability kappa=0.42 (re-review of 10 scans). Visual FDG reads had higher sensitivity (89%) than MRI reads with perfect intra-rater reliability (kappa=1.00), though specificity remained low (50%). PIB results were confirmed in all four patients who have undergone autopsy (2 PIB+ with confirmed AD, 2 PIB- with CBD). CONCLUSIONS: Describing frontal vs. temporoparietal variants of CBS can help predict underlying AD, but criteria require further refinement. Temporoparietal-predominant neuroimaging patterns are sensitive but not specific for AD. Disclosure: Dr. Sha has nothing to disclose. Dr. Ghosh has nothing to disclose. Dr. Lee has nothing to disclose. Dr. Jagust has received personal compensation for activities with Genentech, Inc., Synarc, Janssen, TauRx, and Siemens. Dr. Jagust has received research support from the National Institutes of Health. Dr. Rankin has nothing to disclose. Dr. Boxer has received personal compensation from BMS, Plexxikon and Phloronol for consulting. Dr. Boxer has received research support from Elan, Forest, Genentech, Medivation, BMS, Janssen and Pfizer Pharmaceuticals. Dr. Miller has received personal compensation for activities with Allon Therapeuctics, Inc. and TauRx Therapeutics, Ltd. Dr. Miller has received research support from Novartis. Dr. Rabinovici has received personal compensation for activities with Eli Lilly u0026 Company......Dr. Rabinovici has received research support from Avid Radiopharmaceuticals and Eli Lilly u0026 Company.