Objective: Predicting underlying pathology in CBS.

Background: Corticobasal syndrome (CBS) is pathologically heterogeneous.  CBS is one of the clinical phenotypes of corticobasal degeneration (CBD) but may also be caused by Alzheimer’s disease (AD), progressive supranuclear palsy (PSP) and frontotemporal lobar degeneration (FTLD), making accurate diagnosis in life a challenge. We reviewed the neuropathology, neuropsychometry and cerebrospinal fluid (CSF) neurodegenerative markers of a series of patients with CBS in an attempt to improve ante-mortem diagnosis.

Methods: We identified patients with a clinical diagnosis of CBS who had post-mortem pathological diagnosis. Where CSF had been taken and total-tau and Ab1-42 measured using ELISA, an AD-like profile was defined as total-tau/Ab1-42 ratio >1 .  Where psychology was available, we determined individuals with impaired right parietal function (<5% in one or more subsets of the visual object and perception battery (VOSP) or memory (<5% on the recognition memory test (RMT) for words and/or faces). 

Results: Of 69 patients with a clinical syndrome of CBS, 25 had pathologically diagnosed PSP (36%), 16 CBD (23%), 13 AD (19%), 7 FTLD: including FTLD-Tau, FTLD-FUS, FTLD-TDP1, FTLD-TDP3 and MST (10%), 2 multiple system atrophy (3%), and 5 other diagnoses (7%). 22 patients had either neurodegenerative CSF markers and/or psychometry available (9 CBD, 5 AD, 5 PSP, 2 FTLD and 1 other diagnosis). The positive predictive value (PPV) for clinical CBS predicting CBD pathology was 23% (16/69). Based on a small number of cases (n=6), including AD-like CSF as exclusion criteria for CBD increased the PPV to 100%.  Using performance on the VOSP as a single additional exclusion criteria for CBD increased PPV to 62.5%. Memory (RMT) was abnormal in the majority of both AD and CBD cases and was not useful in determining the pathology. Combining AD-like CSF and poor performance on the VOSP as exclusion criteria for CBD increased PPV to 82%.

Conclusions: Based on a small numbers of cases we show that CSF is helpful in determining which patients with CBS have AD pathology. Whilst memory impairment was not useful in distinguishing AD from CBD poor performance on the VOSP was useful in identifying patients with underlying AD. In light of these initial findings we aim to identify additional cases and incorporate genetic and imaging analysis with psychometry and CSF in our studies of retrospective and prospective cases. 

« Back to 2017 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/clinicopathological-analysis-of-corticobasal-syndrome-a-retrospective-study/