Acute unilateral PCA infarction involving the hippocampus is associated with multidomain and possibly network-mediated early cognitive dysfunction with more extensive impairment after left-hemispheric lesions independent of thalamic involvement.
Key Findings
Results
Acute unilateral PCA infarction involving the hippocampus produces a broad range of cognitive deficits across multiple domains rather than an isolated amnestic disturbance.
78 patients with unilateral PCA stroke involving the hippocampus were assessed at a median of 5 days (IQR, 3–7 days) after symptom onset.
32 patients had right-hemispheric and 46 had left-hemispheric infarctions.
The study used cognitive symptoms at onset, structured behavioral observations, standardized clinical tasks, and formal norm-referenced neuropsychological testing.
Results
Left-hemispheric PCA infarctions were more frequently associated with amnestic symptoms at onset compared to right-hemispheric lesions.
Left-hemispheric infarctions showed higher rates of subjective memory complaints.
Left-hemispheric lesions were associated with objective impairment in episodic memory.
Aphasic symptoms occurred exclusively in the left-hemispheric infarction group.
Left-sided lesions were also associated with greater deficits in language production and comprehension.
Results
Formal neuropsychological testing revealed more frequent deficits in naming, categorical word fluency, verbal recall, verbal recognition, and visual recall in left-hemispheric infarctions compared to right-sided lesions.
Deficits in naming and categorical word fluency were more common after left-hemispheric lesions.
Verbal recall and verbal recognition were also more impaired in the left-hemispheric group.
Visual recall deficits were also more frequent following left-hemispheric infarctions.
Comparisons were made between the 46 left-hemispheric and 32 right-hemispheric infarction patients.
Results
Lesion side emerged as the main predictor of neuropsychological impairment in multivariate logistic regression analyses.
Multivariable logistic regression analyses were performed to identify predictors of cognitive dysfunction.
Lesion side (left vs. right hemisphere) was the dominant predictor across cognitive domains.
Additional thalamic ischemia did not significantly improve prediction of neuropsychological impairment.
This finding indicates that hemispheric lateralization rather than thalamic involvement drives the pattern of cognitive deficits.
Discussion
The acute neuropsychological syndrome following unilateral hippocampal PCA infarction may be network-mediated rather than solely attributable to local hippocampal damage.
The authors characterize the early cognitive dysfunction as 'multidomain and possibly network-mediated.'
Cognitive impairment was more extensive after left-hemispheric lesions independent of thalamic involvement.
The breadth of deficits across domains such as attention and executive function suggests involvement beyond the hippocampus alone.
The retrospective observational design included 78 patients assessed in the acute stroke phase.
What This Means
This research suggests that strokes affecting the posterior cerebral artery (PCA) — particularly when they damage the hippocampus, a brain region critical for memory — cause a much wider range of thinking and cognitive problems than previously recognized. Rather than producing only memory loss (amnesia), these strokes in 78 patients led to difficulties across multiple areas including attention, language, executive functioning, and visual-spatial skills, all assessed within about one week of the stroke occurring. This challenges the common assumption that hippocampal strokes mainly cause amnesia.
The study also found that which side of the brain is affected matters considerably. Strokes on the left side of the brain caused more severe and widespread cognitive problems, including greater memory impairment, language difficulties (such as trouble finding words and understanding speech), and deficits in naming and verbal fluency. Importantly, language problems (aphasia) occurred only in patients with left-sided strokes. Notably, whether the stroke also affected a nearby brain region called the thalamus did not significantly change these outcomes, suggesting that the side of the brain affected is the key factor driving cognitive impairment.
This research matters because it highlights that patients recovering from PCA strokes involving the hippocampus should be evaluated for a broad spectrum of cognitive difficulties — not just memory — especially when the stroke is on the left side. The findings also suggest that the cognitive effects may arise from disruption of brain networks rather than damage to the hippocampus alone, which has implications for understanding recovery and for tailoring rehabilitation strategies.