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|Year : 2018 | Volume
| Issue : 6 | Page : 1718-1720
Outcome assessment following aneurysmal subarachnoid hemorrhage – need for a comprehensive tool
Department of Neurosurgery, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India
|Date of Web Publication||28-Nov-2018|
Dr. Girish Menon
Department of Neurosurgery, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, 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 2018;66:1718-20
Despite recent advances in microsurgical and interventional neuroradiological techniques, outcome following aneurysmal subarachnoid haemorrhage (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 who are 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.
Critical analysis of the current practices of outcome assessment following aneurysmal subarachnoid haemorrhage opens up a Pandora's box. What constitutes good outcome following an aneurysmal subarachnoid haemorrhage? How does one assess outcome following aneurysmal subarachnoid haemorrhage? 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 customised 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 it not 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 outcomes are often assessed by the modified Rankin score or the Glasgow outcome score (GOS). The GOS and its extended version, the Glasgow outcome score extended (GOSE) have standardised, to a great extent, the outcome reporting following traumatic brain injury. A similar score for outcome analysis is lacking for post-aneurysmal subarachnoid haemorrhage patients. Cognitive, intellectual, and behavioural deficits are grossly under-reported 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 method, 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 aneurysmal subarachnoid haemorrhage. However, neither the neurological outcome nor the cognitive outcome scores have been standardised for assessment in post-aneurysmal subarachnoid haemorrhage patients. In addition, several missing links exist between the outcome assessment tools for neurological outcome and the ones 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 (NIMHANS) Neuropsychology Test Battery, and Glasgow Outcome Scale – Extended (GOSE), respectively. The results were compared with fifty-one healthy volunteers who simultaneously underwent neurological examination and neuropsychological assessment. The authors observed that at six 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 the premotor, prefrontal, and medial inferior frontal lobes. At six months, both neurological and cognitive impairment equally contributed to the functional outcome, as assessed by the GOSE scale. 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 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 assess if the outcome varies between a bled aneurysm and an unruptured incidental aneurysm (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 an increased risk of cognitive deficits due to their medial basifrontal location. Studies have also attempted to compare outcome following clipping with that following coiling. Apart from the neuropsychological outcomes obtained from the International Subarachnoid Aneurysm Trial (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 post-treatment impairment, and visual memory tasks a trend toward post-treatment 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 unruptured incidental aneurysms in the anterior circulation do not affect the overall neurocognitive processing in the short-term period. However, the subtest analyses showed a significant impairment in several domains like the psychomotor and executive functioning, as well as the auditory-verbal memory after surgery. In general, on neuropsychological assessment at one-year post-treatment duration, the patients with clipped aneurysms were found to be significantly more impaired than the ones in the coiled group on measures of verbal intelligence quotient (IQ) and memory in most of the published studies. Surgery under anaesthesia with its associated factors like the use of retractors, temporary clipping time, gyrus rectus resection, etc., may explain this disparity in outcome.
Available studies have unequivocally reaffirmed the fact that the routine use of cognitive outcome scales improves the sensitivity of aSAH outcome assessment, and their inclusion in future clinical aSAH studies cannot be overemphasised. The Swiss Study on Aneurysmal Subarachnoid Haemorrhage (SOS) study group have already established a standardised 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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