Severe cognitive impairment in aneurysmal subarachnoid hemorrhage: Predictors and relationship to functional outcome

Abstract

Background: Cognitive impairment is common after aneurysmal subarachnoid hemorrhage (SAH). However, compared to predictors of functional outcome, meaningful predictors of cognitive impairment are lacking.

Objective: Our goal was to assess which factors during hospitalization can predict severe cognitive impairment in SAH patients, especially those who might otherwise be expected to have good functional outcomes. We hypothesized that the degree of early brain injury (EBI), vasospasm, and delayed neurological deterioration (DND) would predict worse cognitive outcomes.

Methods: We retrospectively reviewed SAH patient records from 2013 to 2019 to collect baseline information, clinical markers of EBI (Fisher, Hunt-Hess, and Glasgow Coma scores), vasospasm, and DND. Cognitive outcome was assessed by Montreal Cognitive Assessment (MoCA) and functional outcomes by modified Rankin Scale (mRS) at hospital discharge. SAH patients were compared to non-neurologic hospitalized controls. Among SAH patients, logistic regression analysis was used to identify predictors of severe cognitive impairment defined as a MoCA score <22.

Results: We screened 288 SAH and 80 control patients. Cognitive outcomes assessed via MoCA at discharge were available in 105 SAH patients. Most of these patients had good functional outcome at discharge with a mean mRS of 1.8±1.3. Approximately 56.2% of SAH patients had MoCA scores <22 compared to 28.7% of controls. Among SAH patients, modified Fisher scale was an independent predictor of cognitive impairment after adjustment for baseline differences (OR 1.638, p=0.043). MoCA score correlated inversely with mRS (r=-0.3299, p=0.0006); however, among those with good functional outcome (mRS 0-2), 48.7% still exhibited cognitive impairment.

Conclusions: Severe cognitive impairment is highly prevalent after SAH, even among patients with good functional outcome. Higher modified Fisher scale on admission is an independent risk factor for severe cognitive impairment. Cognitive screening is warranted in all SAH patients, regardless of functional outcome.

Keywords: Cognitive impairment; Delayed neurological deterioration; Fisher scale; Functional outcome; Montreal cognitive assessment; Subarachnoid hemorrhage.

Figure 1.

Retrospective study design with inclusion and exclusion criteria for SAH patients.

Figure 2.

SAH patients exhibit significant cognitive impairment compared to non-neurological hospitalized controls. (A) Average MoCA score for SAH patients was significantly higher than controls (19.9 ± 5.4 vs. 23.3 ± 3.7, p<0.0001) (B) Percentage of patients with MoCA <22 or ≥22 in SAH and control groups. Cognitive impairment was observed in 56.6% of SAH patients compared to 28.7% of hospitalized controls (p<0.0001).

Figure 3.

Patients with a good functional outcome still experience significant cognitive impairment. (A) Median modified Rankin scale (mRS) of cognitively impaired patients was significantly higher in SAH patients with MoCA <22 compared to those with MoCA ≥22 (2 vs. 1, p=0.002). (B) MoCA score showed an inverse correlation with mRS suggesting that as functional outcome worsens, so does cognitive outcome (p<0.0001, r=−0.3410). (C) Percentage of patients with MoCA <22 or ≥22 based on functional outcome shows that 76.7% of patients with poor neurologic outcome while 48.7% of patients with good neurologic outcome have cognitive impairment (p=0.010).