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|Year : 2020 | Volume
| Issue : 1 | Page : 108-110
Outcome Assessment Following Aneurysmal Subarachnoid Hemorrhage – Need for a Comprehensive Tool
Department of Neurosurgery, Kasturba Medical College, Manipal, Karnataka, India
|Date of Web Publication||28-Feb-2020|
Dr. Girish Menon
Department of Neurosurgery, Kasturba Medical College, Manipal - 576 104, Karnataka
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Menon G. Outcome Assessment Following Aneurysmal Subarachnoid Hemorrhage – Need for a Comprehensive Tool. Neurol India 2020;68:108-10
Despite recent advances in microsurgical and interventional neuroradiological techniques, outcome following aneurysmal subarachnoid hemorrhage (aSAH) remains dismal with a cumulative fatality rate of nearly 50%.,, Among the survivors, only one-third regain their premorbid level of functioning., Even minor, neuropsychological dysfunction can be quite disturbing for the patient and his family. Neurosurgeons and interventional neuroradiologists are often confronted with such so-called excellent and good outcome patients unable to integrate with their professional colleagues as well as their family members. However, the quantum of this problem is often neglected and seldom discussed in neurosurgical forums. This attempt by the authors to evolve a standardized protocol and outcome assessment tool for aSAH patients is noteworthy.
Critical analysis of the current practices of outcome assessment following aSAH opens up a Pandora's box. What constitutes good outcome following an aSAH? How does one assess outcome following aSAH? Is it neurological outcome, cognitive outcome, or overall functional outcome? Do we have standard measuring scales or do we need to evolve one comprehensive scale customized to each region? Does surgery for unruptured aneurysms carry a similar outcome as for a bled aneurysm? Does the outcome differ between coiling and clipping? Is not it important to compare cognitive outcome while comparing outcome following clipping and coiling? Other parameters remaining same, does the location and morphology of the aneurysm determine cognitive outcome? Answers for most of the above questions remain elusive or, rather, have not been searched for. Dey et al. need to be complimented for attempting to solve some parts of what essentially remains a mysterious jigsaw puzzle.
An outcome assessment tool for aSAH should measure the outcome caused by both neurological and cognitive impairments. Unfortunately, a common single tool for assessing both neurological and cognitive impairments does not exist. Gross functional and neurological outcome is often assessed by the modified Rankin score or the Glasgow Outcome Score (GOS). The GOS and its extended version the Glasgow Outcome Scale – Extended (GOSE) have standardized, to a great extent, outcome reporting following traumatic brain injury. A similar score for outcome analysis is lacking for post-aSAH patients. Cognitive, intellectual, and behavioral deficits are grossly underreported and often masked by motor and other neurological deficits. Cognitive impairment even if it is mild can be devastating and is often missed during assessment of functional outcome. The most common cognitive screening assessment tool is the Mini-Mental State Examination (MMSE), which was essentially designed for screening dementia. An alternate, the Montreal Cognitive Assessment (MoCA) is another valid screening tool for mild cognitive impairment and non-Alzheimer-type cognitive impairment. It screens for tasks involving frontal executive function and attention, language abilities, memory, and complex visuospatial processing – some of the commonly seen deficits following aSAH. However, neither the neurological outcome nor the cognitive outcome scores have been standardized for assessment in post-aSAH patients. In addition, there exists several missing links between the outcome assessment tools for neurological outcome and the one for cognitive screening, with a good outcome in one not necessarily translating into a good outcome in the other.
Dey et al., through this article, have essentially tried to find and bridge these missing links. The authors attempt to determine the correlation of cognitive and neurological impairment with functional outcome after aSAH. Fifty-six patients underwent assessment at 6 months after discharge for neurological deficits, cognitive impairment, and functional outcome using the National Institute of Health and Social Sciences (NIHSS) score, National Institute of Mental Health and Neurosciences Neuropsychology Test Battery, and GOSE, respectively. The results were compared with 51 healthy volunteers who simultaneously underwent neurological examination and neuropsychological assessment. The authors observed that at 6 months, patients with SAH had significant neurological and cognitive impairment as compared to controls. The cognitive domains affected were attention, mental flexibility, visual working memory, verbal fluency, response inhibition, visual constructive ability, and visual memory. The profile of deficits indicates the involvement of diffuse areas of brain, particularly premotor, prefrontal, and medial inferior frontal lobes. At 6 months, both neurological and cognitive impairment equally contributed to the functional outcome, as assessed by GOSEs. They conclude that there is a significant correlation of NIHSS and neuropsychological scores with GOSE indicating that both the neurological deficits and cognitive impairment determine functional outcome after SAH. A similar attempt was made by Wong et al., who compared MMSE and MoCA with functional independence. Their study, which was the first study of its kind in English literature, arrived at similar conclusion to that by Dey et al., ascertaining the importance of cognitive screening in outcome scores.
The reasons for this disparity can be varied. Attempts have been made to asses if the outcome varies between bled aneurysm and unruptured incidental aneurysms (UIA). The incidence of neuropsychological deficits is found to be more with bled aneurysms than UIA. Cognitive impairments are believed to be the consequences of the direct insult secondary to SAH rather than a result of the complication of its treatment. This can probably be attributed to the transient cessation of circulation and the consequent reduced perfusion and decreased metabolism of specific brain regions. The location of the aneurysm assumes significance with aneurysmal bleeds adjacent to cognitively eloquent areas causing more deficits. Anterior communicating artery aneurysms are, thus, specifically associated with increased risk of cognitive deficits due to its medial basifrontal location. Studies have also attempted to compare outcome following clipping with that following coiling. Apart from the N-ISAT study, most studies comparing long-term cognitive outcome in patients treated with either surgical clipping or endovascular coiling have yielded inconsistent findings. Bonares et al. systematically reviewed the literature on the effects of treatment of aneurysms on cognition between 1998 and 2013, including studies on patients who had undergone cognitive assessment before and after aneurysmal repair. They observed that the treatment modality does not seem to affect cognitive functioning in the long term. Executive functions and verbal memory domains showed a trend toward posttreatment impairment and visual memory tasks a trend toward posttreatment improvement. Bründl et al. evaluated cognitive outcome before and after treatment of incidental aneurysms with regard to both clipping and coiling. Their initial observation too suggests that both clipping and coiling for UIA in the anterior circulation do not affect overall neurocognitive processing in the short term. However, subtest analyses showed significant impairment in several domains such as psychomotor and executive functioning, and auditory–verbal memory after surgery. In general, on neuropsychological assessment at 1-year posttreatment, clipped patients were found to be significantly more impaired than the coiled group on measures of verbal IQ and memory. In most of the published studies, surgery under anesthesia with its associated factors such as the use of retractors, temporary clip, gyrus rectus resection, etc., may explain this disparity in outcome.
Available studies have unequivocally reaffirmed the fact that the routine use of cognitive outcome improves the sensitivity of aSAH outcome assessment and its inclusion in future clinical aSAH studies cannot be overemphasized. The Swiss Study on Aneurysmal Subarachnoid Hemorrhage study group have already established a standardized nationwide comprehensive protocol for assessing neuropsychological, psychosocial, and health-related quality-of-life aspects for patients with aSAH., The investigators recommend screening between days 14 and 28 after aSAH and at 3 and 12 months after bleeding. A similar approach is lacking in India and other developing countries. Studies from the Indian subcontinent on the neuropsychological outcome following aSAH are sparse and limited. In this context, this attempt by Dey et al. is an important value addition.
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