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patients who recover from the treatment of ruptured aneurysms in the frontal basal region , without clinical signs of neurological impairment , may show evidence of cognitive dysfunction upon neuropsychological tests.10)18 ) it has been reported that surgeries in this region , e.g. , in cases of ruptured anterior communicating artery ( acoa ) aneurysms , can lead to post - operative deficits including impairment in memory , language function , executive function , and change in personality.16 ) although considerable importance is attributed to the initial insult caused to the brain by the aneurysm rupture itself and/or consequent vasospasm , other factors , iatrogenic in particular , are expected to affect cognitive outcomes in these patients .
the gyrus rectus ( gr ) is a non - functional and primitive gyrus ; hence , resection of this gyrus is agreed to be a safe surgical procedure , frequently practiced to achieve a better surgical view of the frontal basal region .
this study questioned the safety of this procedure concerning its anatomical proximity of the gr to the limbic system , and collected and analyzed data of the patients who underwent this procedure .
furthermore , since memory and language functions are regulated in the dominant frontotemporal lobes , and surgical approach to the acoa aneurysm involves dissection and manipulation of the frontotemporal lobes , we hypothesized that the direction of surgical approach may have an effect on the cognitive functions of these patients .
the main purpose of this study is to compare the cognitive outcomes following gr resection using mini - mental state examinations ( mmse ) in patients who underwent clipping surgery for ruptured acoa aneurysms .
patients with aneurysmal subarachnoid hemorrhage ( sah ) treated between 2012 and 2015 at our institutions were enrolled in the study . a review of retrospective data of these patients was performed and patients were further selected according to the following inclusion criteria : 1 ) aneurysm location at the acoa origin , 2 ) computed tomography ( ct ) angiography with or without digital subtraction angiography ( dsa ) showing no vascular malformation or other non - aneurysmal sources of hemorrhage , 3 ) early surgery by aneurysm neck clipping , 4 ) not older than 65 years of age , 5 ) clinical state according to hunt and hess scale i - iv on admission , 6 ) clinical state eligible for mmse at least once during the admission period , and 7 ) absence of known prior psychiatric history . among the initial pool of 265 patients with aneurysmal sah , 131 underwent surgical clipping , while 134 underwent endovascular treatment and ; hence , they were excluded . among the surgically treated patients , 43 had aneurysms of an acoa origin .
two patients were excluded since they were at an advanced age , and 2 more were excluded because they were in a grave state and mmse could not be undertaken . in total , 39 patients were selected as final study subjects .
their hospital data on age , sex , initial radiologic and clinical state , operative findings , clinical course , and cognitive functions were reviewed .
the initial neurological status and severity of sah were assessed using the hunt and hess scale and the modified fisher scale , respectively.8)12 ) patients were not randomized according to the direction of craniotomy ; however , right - sided approaches were used when feasible .
a left - sided approach was used when the aneurysmal neck and the feeding arteries were more easily accessible from the left .
partial resection of the gr was performed in patients with high positioned aneurysms or in patients with severe brain swelling and limited surgical view .
the patients were divided into 2 groups based on the type of gr resection during the surgery .
their serial mmse results were recorded , and the 2 groups were compared and statistically analyzed to validate their significance .
another set of analyses was undertaken to investigate whether the direction of the surgical approach had an effect on the mmse results of the 2 groups .
further , subgroup analysis was performed for specific categories of mmse , namely orientation , memory registration , calculation , memory recall , and language .
patients were also grouped according to the direction of the surgical approach , and an association analysis was performed in order to investigate the relationship between the direction of surgery and mmse results .
total number of patients with symptomatic vasospasm was noted , and the effect of vasospasm on the patients ' mmse results was also investigated .
the statistical analysis was generated using the ibm spss statistics version 22 ( ibm corp .
, armonk , ny , usa ) . the data were analyzed with the chi - square test , fisher 's exact test , t - test and the mann - whitney test . for the association analysis , bivariate correlation tests were used . for all analyses ,
the patients were 16 women and 23 men ( ratio 1:1.44 ) , and the mean age was 52.2  8.8 years ( range , 29 - 65 years ) .
the patients ' demographics , initial neurological status , and sah severity at the initial ct scan showed no significant difference between the 2 groups .
the initial mmse was assessed on a mean of 15.2 days after the surgery while the final mmse was assessed on a mean of 44.2 days after the surgery .
the mean initial and final mmse scores were 16.6  9.4 and 21.2  7.3 , respectively . in the gr resection group , the mean initial and final mmse scores were 16.3  9.8 and 20.8  7.3 , respectively . in the non - resection group ,
the mean initial and final mmse scores were 17.1  8.6 and 21.9  4.5 , respectively .
although the values were slightly higher in the non - resection group , there was no significant difference ( p = 0.79 and p = 0.65 , respectively ) .
subgroup analyses concerning each category that constitutes the mmse , namely orientation , memory registration , memory recall , calculation , and language were performed and the results are shown in tables 2 and 3 . in the initial mmse , scores for all 5 categories were lower in the gr resection group than in the non - resection group . among these , only the differences in the memory recall ( 0.29 vs. 0.96 ; p = 0.02 ) and language ( 9.96 vs. 7.14 ; p = 0.02 ) categories were significant .
however , in the final mmse , none of the sub - categories showed a significant difference .
nineteen patients underwent surgery from the right side and 20 from the left . in the association analysis between the direction of surgical approach and mmse
, right - sided craniotomy showed a negative , but not significant (  = -7.86 , se = 4.12 , p = 0.08 ) , relationship with the mmse .
we also analyzed the relationship between the vasospasm and patient cognitive outcome after surgery using mmse .
initial and final mean mmse scores were 16.7  10.4 and 21.8  5.2 , respectively . in the non - vasospasm group ,
mean initial and final mmse scores were 16.5  9.4 and 21.0  6.8 , respectively .
no significant difference was observed between patients in both groups ( p = 0.97 and p = 0.77 , respectively ) .
post - surgical cognitive impairment in acoa aneurysms may be caused by multiple factors that involve the orbital prefrontal cortex lesions or a disconnection in the ventromedial circuits.1)5)6)13 ) the close proximity of these structures to the paraolfactory area , the nucleus accumbens septi and the diagonal band of broca , makes this zone delicate during acoa dissection procedures .
ramos et al . reported that in their study , the nucleus accumbens septi was damaged if the dissection was performed over 5 mm in depth from the basal surface.16 ) another anatomical risk may be an injury to the small perforating vessels , originating from the acoa , that supply the frontal basal region.17 ) it has been suggested that in patients with acoa aneurysmal rupture , the cerebral areas traditionally associated with memory functioning are spared , and damage to the basal forebrain and frontal lobes is responsible for memory impairment.3)4)15 ) there are other several potential causes of cerebral damage after surgery for acoa aneurysmal rupture .
these include generalized vasospasm with ischemia or infarction , cerebral edema and subsequent mesial temporal lobe herniation , hydrocephalus , and hemorrhagic infarction of the frontotemporal lobes following retraction.11)18 ) since language , intellectual , and cognitive functions are controlled in the dominant hemisphere , which is the left hemisphere in most cases , we presumed that the direction of surgical dissection and gr resection may have an effect on patients ' cognitive outcomes .
however , our results did not show a significant relationship between the direction of surgical approach and the mmse results .
, where the side of the lesion did not influence the severity of post - surgical neuropsychological dysfunctions.1)14 ) they commented that the lack of lateralization , in the case of frontal basal regions , might be explained by the projection of the main output fibers from the fornix to both ipsilateral and contralateral hippocampus.1 ) stenhouse et al .
reported that the most frequent mechanism of cerebral damage in their patients that underwent surgery for acoa aneurysms , was ischemia that presumably resulted from vasospasm.18 ) we checked the vasospasm using a transcranial doppler daily and additionally evaluated the patients ' clinical symptoms . if the vasospasm was confirmed , we conducted angioplasty , using nimodipine . in our study , the relationship between vasospasm and cognitive outcome was not significant . moreover , the study sample was too small to comment on the effects of such potential mechanisms with certainty .
the sub - categories of memory recall and language being lower in the gr resection group in the initial , but not the final , mmse may be explained by short - term neuroplasticity of the brain .
many studies have reported substantial changes in frontal white matter and increased cognitive function after exposure to repeated training or experience , in brains of patients with pathologic conditions and in elderly patients with age - related changes.7)19 ) moreover , takeuchi et al .
reported in their recent studies the positive impact of working - memory training on the frontoparietal gray matter.20 ) similarly , repeated exposure to auditory , verbal , and visual stimulation and repeated neurocognitive examinations during admission may have accelerated neuroplasticity and resulted in such a change in mmse results .
. there may have been a selection bias and gr may have been resected in cases of severe brain swelling , suggesting poorer baseline cognitive functions in these patients .
second , a small sample size limited the significance of the results . further larger sampled , anterograde , and randomized studies are needed to prove a stronger correlation between gr resection and postsurgical cognitive outcomes .
third , mmse may be a simple and handy questionnaire that can be done anywhere in a short period ; however , it might be insufficient to interpret a patient 's detailed cognitive status .
moreover , a learning effect after repeated tests may have masked the patients ' true cognitive status.2)9 ) a more focused and complex neuropsychiatric test may need to be applied in future studies to overcome such limitations .
in general , there was no significant correlation between the gr resection and cognitive outcomes in terms of total mmse scores after surgery for ruptured acoa aneurysm .
however , subgroup analysis showed a negative effect of gr resection on categories of language and memory recall .
although limited by a small sample size , this study suggests contemplating to perform the gr resection superficially , considering its close anatomical proximity to the limbic system .
objectivethe gyrus rectus ( gr ) is known as a non - functional gyrus ; hence , its resection is agreed to be a safe procedure frequently practiced to achieve a better surgical view during specific surgeries . 
 this study aimed at comparing the cognitive outcomes following gr resection in patients who underwent surgery for ruptured anterior communicating artery ( acoa ) aneurysms.materials and methodsfrom 2012 to 2015 , 39 patients underwent surgical clipping for ruptured acoa aneurysms . 
 mini - mental state examinations ( mmse ) were performed in 2 different periods . the statistical relationship between gr resection and mmse results was evaluated , and further analysis of mmse subgroup was performed.resultstwenty-five out of the 39 patients ( 64.19% ) underwent gr resection . 
 mean initial and final mmse scores in the gr resection group were 16.3  9.8 and 20.8  7.3 , respectively . 
 in the non - resection group , the mean initial and final mmse scores were 17.1  8.6 and 21.9  4.5 , respectively . 
 neither group 's scores showed a significant change . 
 subgroup analysis of initial mmse showed a significant difference in memory recall and language ( p = 0.02 ) but not in the final mmse scores.conclusionthere was no significant relationship between the gr resection and cognitive outcomes in terms of total mmse scores after surgery for ruptured acoa aneurysm . however , subgroup analysis revealed a temporary negative effect of gr resection in the categories of language and memory recall . 
 this study suggests that gr resection should be executed superficially , owing to its close anatomical relationship with the limbic system .