Aneurysmal SAH is a devastating subtype of stroke affecting relatively young people who have a mean premorbid life expectancy of 30 years. Case fatality can reach 35%, and many survivors experience long-term disability and cognitive impairments across multiple cognitive domains [13]. These cognitive impairments reduce a patient’s quality of life, participation in work, and social activities. However, few studies have directly explored the functional outcomes of young patients with good-grade SAH. Moreover, although many studies have compared cognitive outcomes in microsurgical procedures and endovascular coiling, none of these studies excluded patients with very poor-grade SAH or with serious complications such as hydrocephalus, delayed cerebral ischemia, and intracranial rebleeding [14–18]. Poor-grade SAH and serious complications have, however, been found to significantly affect the cognitive outcome of patients with SAH [19–21]. In addition, elderly patients included in these previous studies may have had other age-related cognitive dysfunctions, which may have led to a variety of biases. In many studies, cognitive impairments were nevertheless attributed to SAH itself, and not assigned to the complications of SAH or the treatment. In this cohort of young patients with ruptured ACoA aneurysms, we therefore excluded patients with poor-grade SAH (Hunt and Hess grade 4–5), postoperative hydrocephalus, or intracranial rebleeding, to control for the possible confounding effects of these factors.
On the one hand, cognitive impairment may be caused by the transient cessation of circulation and the blood entering the brain at the time of the aneurysm rupture [7, 14]. On the other hand, these factors reduce perfusion in some regions of the brain and decrease metabolism; therefore, the subsequent cognitive impairments could be related to the location of the aneurysm [22]. ACoA aneurysms are among the most commonly identified ruptured aneurysms [23, 24], and ACoA aneurysm rupture and treatment are more strongly associated with cognitive and behavioural deficits than aneurysms at other locations [25]. In earlier studies, impairments in both short-term and long-term memory, amnesia, confabulation, and personality changes were described as the main symptoms that influenced by the rupture of ACoA aneurysms [22, 25]. These symptoms can be attributed to the intraoperative challenges unique to ACoA-related aneurysms and to damage to anterior cerebral structures such as the frontal cortex, the ventromedial prefrontal (orbitofrontal) cortex, or the striatum [26].
Factors Associated with Quality of Life and Cognitive Outcome Between Microsurgical Clipping and Endovascular Coiling
Shen et al. investigated 152 patients with aneurysmal SAH treated with endovascular coiling, and found that 59 patients (39%) developed cognitive impairment six months later. The authors also reported that ACoA aneurysms, delayed cerebral ischemia, and hydrocephalus was independently associated with a higher risk of mild cognitive impairment after aneurysmal SAH [27]. After adjustments for age, Wong et al. found that admission World Federation of Neurosurgical Societies (WFNS) grade, mode of aneurysm treatment, and delayed cerebral infarction were independently associated with reduced cognitive outcomes [28].After excluding patients with poor Hunt and Hess grades (4–5), postoperative hydrocephalus, intracranial rebleeding, and symptomatic delayed cerebral ischemia, the multivariate COX regression analysis showed that higher mRS scores at discharge, female sex, and aneurysm size < 5 mm were independent risk factors associated with cognitive impairment after treatment for ruptured ACoA aneurysms. One of the more novel findings of our study is that small ACoA aneurysms in young patients were more prone to cognitive impairment. A possible reason for this observation is that small-sized aneurysms are difficult to clamp or embolize, and it is therefore easy to cause potential brain function damage during the operation. This finding needs to be verified by further prospective large data research.
Comparison of Quality of Life and Cognitive Outcome Between Microsurgical Clipping and Endovascular Coiling
Endovascular coiling could be the primary choice in patients with ruptured ACoA aneurysms when the configuration is appropriate. Still, microsurgical clipping also supplies an option that allows the patient to attain the same quality of life, functional outcome, and executive function [29]. Many studies suggest that microsurgical clipping may lead to more severe cognitive impairment and higher rates of patient dependency compared with endovascular coil embolization, possibly caused by retraction injury to the frontal lobe or other causes of cerebral infarction [30–32]. Frontal lobe infarction and RAH infarction are more common after surgical clipping of ruptured ACoA aneurysms, and coiled patients have better outcomes at discharge and are more likely to be functionally independent than clipped patients [33]. However, results regarding cognitive functions of young and low-grade patients remain limited, and studies analyzing cognition outcomes in terms of treatment procedure are rare. Thus, our analyses provide a unique opportunity to compare the cognitive consequences of coiling and clipping treatment for the ACoA location. In this study with a long-term follow-up of more than two years, patients treated with microsurgical clipping had higher rates of good clinical outcomes (mRS scores 0–2) than patients treated with endovascular coiling. Otherwise, the mean IADL score was higher in the microsurgical group than in the endovascular group, but this difference was not statistically significant. As for cognitive outcomes, those treated with microsurgical clipping had similar TICS-m scores at the latest follow-up than patients treated with endovascular coiling. These results are not entirely consistent with previous studies, suggesting that clinical outcomes (measured with the mRS and the IADL) and cognitive function outcomes for microsurgical clipping and endovascular treatment are similar in younger patients (< 50 years) with low-grade SAH.
Limitations
There are several limitations to our study. Firstly, although we excluded patients with symptomatic delayed cerebral ischemia, this study did not consider brain damage on postoperative MR imaging (because only a subset of patients had undergone MRI scanning). Thus, we were unable to assess whether patients had cerebral infarctions after treatment, which might affect cognitive outcomes. Secondly, the size of the patient group did not allow for subgroup analyses regarding age and aneurysms size. Thirdly, our study did not use other reported cognitive screening tests such as the Montreal Cognitive Assessment [34] or the Mini-Mental State Examination [35]. This is because these screening tests require face-to-face interviews, which are challenging to conduct in a group of patients from all over the country. Fourthly, our study could not assess the relative impact of mild cognitive impairment on the total degree of cognitive impairment (defined by two or more cognitive domain deficits) for the small number of patients. Finally, as patients did not complete cognitive evaluations of TICS-m when they were admitted to the hospital, we were unable to retrospectively determine whether they had cognitive impairments before onset or surgery.