Abstract
Objectives: Aneurysmal subarachnoid hemorrhage (aSAH) accounts for less than 5% of strokes but is associated with significant morbidity and mortality. Amongst survivors, neurocognitive complaints are common, often despite normal imaging. We used magnetoencephalography (MEG) to investigate neurophysiological function during a visual working memory task in aSAH survivors with good recovery and normal structural imaging.Methods: Patients with aSAH treated with coiling and exhibiting good outcome measured by Glasgow Outcome Scale (GOS) and without related parenchymal structural lesions in post-treatment MRI, were recruited and compared to age- and sex-matched controls. All participants underwent intelligence and cognitive screening, structural MRI, and MEG testing in conjunction with a 1-back visual working memory task. Sensor-level global field power and virtual electrode source analysis of neuronal activity and connectivity in aSAH were assessed.Results: Thirteen patients and 13 matched controls were enrolled (age: 56 ± 11 years, 19 female). The 1-back task was completed with similar accuracy despite a trend for a longer reaction time in aSAH patients (p = 0.054). During encoding and recognition phases, aSAH patients showed significantly increased neuronal activation and hyperconnectivity in periventricular areas, specifically the anterior and posterior cingulate gyri.Conclusions: Increased posterior and anterior cingulate gyri neuronal activity is demonstrated in aSAH patients during visual working memory tasks, in the absence of structural lesions. These areas work mainly as a hub to “organize” memory storage and retrieval. Increased activity in these areas might be compensatory due to injury and consequently loss of neuronal response in connected areas in the working memory networks.
Highlights
Aneurysmal subarachnoid hemorrhage accounts for less than 5% of all strokes [1, 2]
Aneurysmal subarachnoid hemorrhage accounts for less than 5% of strokes but is associated with significant morbidity and mortality
The 1-back task was completed with similar accuracy despite a trend for a longer reaction time in aSAH patients (p = 0.054)
Summary
Aneurysmal subarachnoid hemorrhage (aSAH) accounts for less than 5% of all strokes [1, 2] It affects patients at a younger age than other types of stroke and has very high morbidity and mortality rates [1, 3]. Most survivors make a good recovery [5] by standard outcome measures, e.g., the Glasgow Outcome Scale (GOS). This clinical condition still presents as a major burden to both individuals and society, with up to 50% of survivors reporting persistent neurocognitive deficits, not returning to the same level of work [6], and reporting a poor quality of life [7]. We reported previously that MEG was feasible in this patient population [8], and later showed increased activity in frontal lobe regions related to deficits in inhibitory control and mental flexibility, suggesting a common final pathway underlying different cognitive manifestations in these two neurocognitive domains [9]
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