Investigators were able to identify strategic areas of infarcts in the brain that were associated with increased risk for post-stroke cognitive impairment (PSCI), according to a study published online on April 23 in The Lancet Neurology.
Previous studies had identified specific infarct regions associated with the development of PSCI, but they were largely based on small case series, and there were inconsistencies in the quality of the mapping data and the areas of the brain covered, the researchers noted.
The current study was based on a large-scale, pooled analysis of CTs and MRIs on 2,950 patients from 12 cohorts. The large sample size enabled researchers to stratify different stroke subtypes and pinpoint unique patterns associated with different cognitive domains.
The investigators, led by Nick A. Weaver, PhD, of the University Medical Centre Utrecht Brain Center in the Netherlands, defined PSCI based on performance on multiple neuropsychological tests and scores lower than the fifth percentile of local normative data on at least one cognitive domain.
Patients were administered cognitive evaluations up to 15 months following acute ischemic stroke onset; most were evaluated with multiple tests in different cognitive domains. About 44 percent had PSCI.
The investigators used voxel-based lesion-symptom mapping to calculate voxel-wise odds ratios for PSCI, mapping them in a three-dimensional brain template to visualize PSCI risk per location. Inter- and intra-rating reliability were all high, three clinicians found.
Infarcts in the left thalamus, right parietal lobe, and left frontotemporal lobes were strongly associated with PSCI.
“Our results formed the basis of a prediction score that could allow for a robust and individualized post-stroke cognitive impairment risk assessment in the clinical setting, solely based on a patient's infarct location on brain CT or MRI," the researchers wrote.
They added that the mapping of infarcts provides an easy-to-use visual rating scale for clinicians to determine those patients at risk. The scale could help to identify patients who should undergo cognitive evaluations, to allow for timely use of rehabilitative therapy strategies, and enable cognitive prognostication.
The authors stressed, however, that “infarct locations predictive of PSCI do not necessarily imply causality. If lesion-symptom mapping is being used to determine neuroanatomical correlates of cognitive deficits, then confounding factors such as the interdependency between infarct locations, clinical history, white matter hyperintensities, and previous infarcts should all be considered.
Some limitations of the study were that data on pre-stroke cognitive status were not available for a considerable portion of the cohort, and the pooled cohort only included Asian and European patients, which limits the generalizability of the data, the researchers noted.
“With future developments of harmonization and quantification of imaging markers, such as white matter hyperintensities, previous infarcts, and brain atrophy, more elaborate PSCI prediction models could be developed, although clinical implementation might be challenging," the researchers concluded.
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Weaver NA, Kuijf H, Aben HP, et al. Strategic infarct locations for post-stroke cognitive impairment: a pooled analysis of individual patient data from 12 acute ischaemic stroke cohorts. Lancet Neurol 2021; Epub 2021 Apr 23.