Cognitive impairment in angiographically negative subarachnoid haemorrhage: A case-matched prospective study 1-year post-incident

Introduction: Few studies investigate cognitive outcomes in patients with angiographically negative subarachnoid haemorrhage (anSAH), which is traditionally viewed as a condition with an excellent prognosis. The aim of this study was to assess neuropsychological outcomes in a prospective cohort of anSAH patients 1-year post-event. Method: This prospective case-controlled study of cognitive function in patients with anSAH (n = 38) recruited from the national centre for neurosurgery and compared matched controls (n = 28). The cognitive battery assessed memory, executive function, attention, visuo-spatial function, processing speed, social cognition, language, and mood. Patients were matched to controls on age, education, and premorbid intelligence. Results: Multivariate Analysis of Variance (MANOVA) were used. Patients performed significantly worse than controls on all cognitive domain composite scores. anSAH patients had a higher frequency of impairment within encoding, executive, and processing speed domains when compared to healthy controls. Discriminant Function Analysis (DFA) indicated high sensitivity and specificity to detect cognitive impairment between groups. Conclusion: Although the majority of patients with anSAH make an excellent physical recovery, our data show a high rate of cognitive dysfunction in patients 1-year post-incident. Cognitive impairment in anSAH is not a universal feature, and its manifestations may be more heterogeneous than previously recognised. Some impairment may be mediated by impaired speed of processing which negatively influences other cognitive domains. The profile of cognitive impairment supports a neurotoxicity hypothesis, which suggests that blood in the subarachnoid space, rather than the bleed per se, results in a diffuse pattern of cognitive deficits.