Surgery For Unruptured Intracranial Aneurysms Research Articles

Association between De Ritis ratio and intraoperative blood transfusion in patients undergoing surgical clipping of unruptured intracranial aneurysms: a single center, retrospective, propensity score-matched study.

Although elective surgery for unruptured intracranial aneurysms (UIA) has increased, few studies have evaluated the risk factors for transfusion during UIA surgery. We evaluated the association between the preoperative De Ritis ratio (aspartate transaminase/alanine transaminase) and the incidence of intraoperative transfusion in patients who had undergone surgical UIA clipping. Patients who underwent surgical clipping of UIA were stratified into two groups according to the preoperative De Ritis ratio cutoff levels (< 1.54 and ≥ 1.54), and the propensity score (PS)-matching analysis was performed to compare the incidence of intraoperative transfusion. Logistic regression analyses were performed to determine the risk factors for intraoperative transfusion. Net reclassification improvement (NRI) and integrated discrimination improvement (IDI) analyses were performed to verify the improvement in the intraoperative transfusion predictive model upon addition of the De Ritis ratio. Intraoperative transfusion incidence was 15.4% (77/502). We observed significant differences in the incidence of intraoperative transfusion (16.2% vs. 39.7%, P = 0.004) between the groups after matching. In the logistic regression analyses, the De Ritis ratio ≥ 1.54 was an independent risk factor for transfusion (odds ratio [OR]: 3.04, 95% CI [1.53, 6.03], P = 0.002). Preoperative hemoglobin (Hb) value was a risk factor for transfusion (OR: 0.33, 95% CI [0.24, 0.47], P < 0.001). NRI and IDI analyses showed that the De Ritis ratio improved the intraoperative blood transfusion predictive models (P = 0.031 and P = 0.049, respectively). De Ritis ratio maybe a significant risk factor for intraoperative transfusion in UIA surgery.

Hyaluronidase Injection to Reduce Periorbital Edema after Surgery for Unruptured Intracranial Aneurysms

Background: In the era of endovascular treatment for intracranial aneurysms, microsurgical treatment might necessitate the minimization of postoperative discomforts such as headache, nausea, vomiting, and edema. The current study aimed to evaluate the effectiveness of hyaluronidase on the reduction of periorbital edema after clipping surgery for unruptured intracranial aneurysms. Methods: From July 2016 to March 2018, the patients who underwent elective surgery for unruptured intracranial aneurysms were included. A mixture of 4500 IU hyaluronidase was injected subcutaneously on the sectional plane of the scalp incision. The photographs of patients’ faces were obtained on postoperative day 1, 3, and 7. The degree of periorbital edema was judged on the grading system based on the vertical palpebral aperture. The thickness of the scalp, temporalis muscle, and soft tissue was measured on a preoperative computed tomography (CT) scan, and other variables (e.g., intraoperative input and output, serum albumin level) were Results: A total of 60 patients were included in this study, and a hyaluronidase mixture was injected in 30 patients. The periorbital edema tended to resolve in 7 days after surgery, but notable differences between the two groups was observed at day three after surgery in this study. On the ordinal logistic regression analysis on the grade of periorbital edema, hyaluronidase injection is significantly associated with the reduction of periorbital edema throughout the postoperative period. (p value &lt; 0.05)Conclusion: Hyaluronidase injection might be helpful in reducing periorbital edema after surgery for unruptured intracranial aneurysms.

Necessity of mandatory postoperative intensive care unit management after clipping surgery for unruptured intracranial aneurysms

ObjectiveMany neurosurgeons routinely perform postoperative intensive care unit (ICU) management after clipping of unruptured intracranial aneurysms (UIAs). However, whether routine postoperative ICU care is necessary remains a clinical question. Therefore, we investigated which factors acted as risk factors that actually required ICU care after microsurgical clipping of unruptured aneurysms. MethodsWe included a total of 532 patients who underwent clipping surgery for UIA between January 2020 and December 2020. The patients were divided into two groups: those who really required ICU care (41 patients, 7.7%) and those who did not (491 patients, 92.3%). A backward stepwise logistic regression model was used to identify factors that were independently associated with ICU care requirement. ResultsThe mean hospital stay duration and the operation time were significantly longer in the ICU requirement group than in the no ICU requirement group (9.9 ± 10.7 vs. 6.3 ± 3.7 days, p = 0.041), (259.9 ± 128.4 vs. 210.5 ± 46.1 min, p = 0.019). The transfusion rate was significantly higher (p = 0.024) in the ICU requirement group. Multivariable logistic regression analysis identified male sex (odds ratio [OR], 2.34; 95% confidence interval [CI], 1.15–4.76; p = 0.0195), operation time (OR, 1.01; 95% CI, 1.00–1.01; p = 0.0022), and transfusion (OR, 2.35; 95% CI, 1.00–5.51; p = 0.0500) as independent risk factors for requiring ICU care after clipping. ConclusionsPostoperative ICU management may not be mandatory after clipping surgery for UIAs. Our results suggest that postoperative ICU management may be more required in the male sex, patients with longer operation times, and those who received a transfusion.

Evolution of open surgery for unruptured intracranial aneurysms over a fifteen year period–increased difficulty and morbidity

ObjectiveThe approach to intervention for unruptured intracranial aneurysms (UIAs) remains controversial. Utilization of endovascular techniques for aneurysm repair increased dramatically during the last decade. We sought to analyze recent national trends for electively treated (open and endovascular) UIAs focusing on pre-existing patient disease burden and intervention modality selection. MethodsThe Nationwide Inpatient Sample (NIS) national database was used to identify patients with primary diagnosis codes of unruptured intracranial aneurysm between 1999 and 2014. Patients were dichotomized by intervention into endovascular or open surgical treatment. Analysis of pre-existing disease severity were calculated using the Elixhauser comorbidity index. Complications of combined peri-procedural stroke or death during admission and hospital length of stay were used as primary endpoints for comparison. ResultsThe percent of total UIAs treated electively with open approach decreased from more than 95 % of cases in 1999 to less than 25 % in 2014. Patients undergoing clipping were 3 years younger than those in the endovascular group (p < 0.001). The rate of primary endpoint complications (stroke and death) and length of stay for open cases saw a decrease throughout the study but remained statistically higher when compared to the endovascular group over the study period (p < 0.001). Additionally, non-neurologic complications increased over the time period for open cases. The average preoperative co-morbid disease severity for all groups treated increased over this interval. Conversely, the relative volume of endovascular cases increased but the rate of complications and average group disease remained statistically lower than the surgical clipping group (p < 0.05). ConclusionThe percent of UIAs treated electively with open approach has decreased since 1999 with a concomitant increase in complication rate in particular compared to endovascular cases. However, the health characteristics of patients treated with surgical clipping show an increase in severity of pre-existing co-morbidities. Further research into factors contributing to this finding, including potential socioeconomic differences and changes in surgeon experience are needed.

Correlation of Inflow Velocity Ratio Detected by Phase Contrast Magnetic Resonance Angiography with the Bleb Color of Unruptured Intracranial Aneurysms

BackgroundIntraoperative rupture is the most fatal and catastrophic complication of surgery for unruptured intracranial aneurysms (UIAs); thus, it is extremely useful to predict reddish and thin-walled regions of the UIA before surgery. Although several studies have reported a relationship between the hemodynamic characteristics and intracranial aneurysm wall thickness, a consistent opinion is lacking. We aimed to investigate the relationship between objectively and quantitatively evaluated bleb wall color and hemodynamic characteristics using phase-contrast magnetic resonance angiography (PC-MRA).MethodsTen patients diagnosed with UIA who underwent surgical clipping and preoperative magnetic resonance imaging along with PC-MRA were included in this study. Bleb wall color was evaluated from an intraoperative video. Based on the Red (R), Green, and Blue values, bleb wall redness (modified R value; mR) was calculated and compared with the hemodynamic characteristics obtained from PC-MRA.ResultsThe wall redness distribution of 18 blebs in 11 UIAs in 10 patients was analyzed. Bleb/neck inflow velocity ratio (Vb/Va: r = 0.66, P = 0.003) strongly correlated with mR, whereas bleb/neck inflow rate ratio (r = 0.58, P = 0.012) correlated moderately. Multivariate regression analysis revealed that only Vb/Va (P = 0.017) significantly correlated with mR. There was no correlation between wall shear stress and mR.ConclusionsThe bleb redness of UIAs and Vb/Va, calculated using PC-MRA, showed a significantly greater correlation. Thus, it is possible to predict bleb thickness noninvasively before surgery. This will facilitate more detailed pre- and intraoperative strategies for clipping and coiling for safe surgery.

Relationship between Deep White Matter Hyperintensities on Magnetic Resonance Imaging and Postoperative Cognitive Function Following Clipping of Unruptured Intracranial Aneurysm.

To evaluate the effects on cognitive function of deep white matter hyperintensities (DWMHs) on magnetic resonance imaging (MRI) in patients treated surgically for unruptured intracranial aneurysms (UIAs). The subjects were 106 patients in whom a Wechsler adult intelligence scale-revised (WAIS-R) examination was performed 1 week before and 1 month after clipping surgery for asymptomatic UIAs. DWMH severity was evaluated on preoperative MR images by Fazekas scale, as follows: none (absence), mild (punctate foci), moderate (beginning confluence of foci), or severe (large confluent areas). A decrease of 7 or more points in intelligence quotient (IQ) postoperatively was considered deterioration. Fazekas score was none in 41 (none group), mild in 42 (mild group), moderate in 21, and severe in 2 patients (moderate/severe group). Patient characteristics, surgical factors, IQ change, and abnormal findings on postoperative MRI were compared among the groups. Although there was no statistically significant deterioration in IQ postoperatively in any group, the percentage of deteriorated patients was significantly higher in the moderate/severe group (34.8%) than in the other groups (4.9% in the none group, 7.1% in the mild group; p <0.01, p <0.05, respectively). Brain injury was observed more frequently on postoperative MR images in the moderate/severe group (17.4%) compared with the none group (2.4%; p = 0.052). The presence of moderate/severe DWMHs was an independent prognostic factor for postoperative cognitive dysfunction. In conclusion, the presence of moderate/severe DWMHs was a prognostic factor for postoperative cognitive dysfunction after surgery for UIAs.

Intraoperative use of transcranial motor/sensory evoked potential monitoring in the clipping of intracranial aneurysms: evaluation of false-positive and false-negative cases.

Somatosensory and motor evoked potentials (SEPs and MEPs) are often used to prevent ischemic complications during aneurysm surgeries. However, surgeons often encounter cases with suspicious false-positive and false-negative results from intraoperative evoked potential (EP) monitoring, but the incidence and possible causes for these results are not well established. The aim of this study was to investigate the efficacy and reliability of EP monitoring in the microsurgical treatment of intracranial aneurysms by evaluating false-positive and false-negative cases. From January 2012 to April 2016, 1514 patients underwent surgery for unruptured intracranial aneurysms (UIAs) with EP monitoring at the authors' institution. An EP amplitude decrease of 50% or greater compared with the baseline amplitude was defined as a significant EP change. Correlations between immediate postoperative motor weakness and EP monitoring results were retrospectively reviewed. The authors calculated the sensitivity, specificity, and positive and negative predictive values of intraoperative MEP monitoring, as well as the incidence of false-positive and false-negative results. Eighteen (1.19%) of the 1514 patients had a symptomatic infarction, and 4 (0.26%) had a symptomatic hemorrhage. A total of 15 patients showed motor weakness, with the weakness detected on the immediate postoperative motor function test in 10 of these cases. Fifteen false-positive cases (0.99%) and 8 false-negative cases (0.53%) were reported. Therefore, MEP during UIA surgery resulted in a sensitivity of 0.10, specificity of 0.94, positive predictive value of 0.01, and negative predictive value of 0.99. Intraoperative EP monitoring has high specificity and negative predictive value. Both false-positive and false-negative findings were present. However, it is likely that a more meticulously designed protocol will make EP monitoring a better surrogate indicator of possible ischemic neurological deficits.

Factors associated with early seizures after surgery of unruptured intracranial aneurysms

ObjectiveThe aim of the study was to better define the incidence of and risk factors for early seizures after repair of unruptured intracranial aneurysms in modern microsurgical techniques. Patients and methodsThe medical records of 414 consecutive patients who underwent neck clipping of unruptured intracranial aneurysms in our institution over a 5-year period were retrospectively reviewed. Clinical and neuroimaging variables were analyzed to investigate putative predictors of perioperative seizures using multivariate logistic regression analysis. ResultsOverall, 24 patients (5.8%) developed seizures within 14 days of surgery without routine prophylactic use of anticonvulsants. Eleven patients experienced partial seizures, while 13 experienced secondary generalized seizures. The interval between surgery and seizure onset was less than 6 h in 8 patients, 6–24 h in 3, and 1–14 days in 11. History of dialysis (odds ratio [OR] = 77.6, 95% confidence interval [CI] 7.5–1783.4, P < 0.001), and presence of cerebral contusion (OR = 5.1, 95% CI 1.3–16.9, P = 0.02) or infarction (OR = 13.9, 95% CI 3.9–48.5, P < 0.001) detected by postoperative computed tomography were independent and significant risk factors. No patients with early seizures went on to develop refractory epilepsy. ConclusionsDialysis and iatrogenic brain damage were associated with a higher risk of early seizures after aneurysm surgery. Our data support the selective use of anticonvulsants during the perioperative period of elective aneurysm surgery.

未破裂脳動脈瘤治療における「判断と行動」

未破裂脳動脈瘤治療における「判断と行動」

The Risk of Seizure After Surgery for Unruptured Intracranial Aneurysms

We aimed to identify a group of patients with a low risk of seizure after surgery for unruptured intracranial aneurysms (UIA). To determine the risk of seizure after discharge from surgery for UIA. A consecutive prospectively collected cohort database was interrogated for all surgical UIA cases. There were 726 cases of UIA (excluding cases proximal to the superior cerebellar artery on the vertebrobasilar system) identified and analyzed. Cox proportional hazards regression models and Kaplan-Meier life table analyses were generated assessing risk factors. Preoperative seizure history and complication of aneurysm repair were the only risk factors found to be significant. The risk of first seizure after discharge from hospital following surgery for patients with neither preoperative seizure, treated middle cerebral artery aneurysm, nor postoperative complications (leading to a modified Rankin Scale score >1) was <0.1% and 1.1% at 12 months and 7 years, respectively. The risk for those with preoperative seizures was 17.3% and 66% at 12 months and 7 years, respectively. The risk for seizures with either complications (leading to a modified Rankin Scale score >1) from surgery or treated middle cerebral artery aneurysm was 1.4% and 6.8% at 12 months and 7 years, respectively. These differences in the 3 Kaplan-Meier curves were significant (log-rank P < .001). The risk of seizures after discharge from hospital following surgery for UIA is very low when there is no preexisting history of seizures. If this result can be supported by other series, guidelines that restrict returning to driving because of the risk of postoperative seizures should be reconsidered. MCA, middle cerebral arterymRS, modified Rankin ScaleUIA, unruptured intracranial aneurysms.

Effects of preventive surgery for unruptured intracranial aneurysms on attention, executive function, learning and memory: a prospective cohort study.

We prospectively evaluated the effects of preventive surgery for unruptured intracranial aneurysms on attention, executive function, learning and memory. Between March 2012 and June 2013, 56 patients were recruited for this study. Fifty-one patients met the inclusion criteria and were enrolled. Inclusion criteria were as follows: (1) age ≤65years and (2) planned microsurgery or endovascular surgery for unruptured intracranial aneurysm. Exclusion criteria were as follows: (1) preoperative intelligence quotient <80 (n = 3); (2) initial modified Rankin scale ≥1 (n = 1); (3) loss to follow-up (n = 1). An auditory controlled continuous performance test (ACCPT), word-color test (WCT) and verbal learning test (VLT) were performed before and after (6months) preventive surgery. ACCPT (attention), WCT (executive function) and VLT (learning and memory) scores did not change significantly between the pre- and postoperative evaluations. The ACCPT, WCT, total VLT scores (verbal learning) and delayed VLT scores (memory) did not differ significantly between patients undergoing microsurgery and those undergoing endovascular surgery. However, ACCPT, WCT and delayed VLT scores decreased postoperatively in patients with leukoaraiosis on preoperative FLAIR images (OR 9.899, p = 0.041; OR 11.421, p = 0.006; OR 2.952, p = 0.024, respectively). Preventive surgery for unruptured intracranial aneurysms did not affect attention, executive function, learning or memory. However, patients with leukoaraiosis on FLAIR images might be prone to deficits in attention, executive function and memory postoperatively, whereas learning might not be affected.

Surgery for Unruptured Intracranial Aneurysms in the ISAT and ISUIA Era

The ISAT and ISUIA studies, along with the improvement of endovascular treatment (EVT) have strongly influenced the management of intracranial aneurysms (IAs). We present our experience in the microsurgical treatment of unruptured IAs (UIAs) in this context. We retrospectively reviewed a consecutive series of non-giant UIAs selected for surgery during a five-year period. Patients and aneurysms characteristics, surgical results and outcome assessed by the Glascow Outcome Scale (GOS) at three month follow-up were studied. Eighty-five patients underwent 93 surgical procedures to obliterate 113 UIAs. Those were incidental in 89% of the cases and mainly located on the middle cerebral artery (65%). Patients were assigned to surgery according to their medical history (young, previous subarachnoid haemorrhage), aneurysm characteristics (wide neck, branch at the neck, "small" size, associated "surgical" aneurysm) or failure of EVT (5%). Operatively, 48% of UIAs had thin wall or blebs and 71% were occluded with one titanium clip. Thrombectomy or temporary clipping were necessary in 4% and 11% of the cases, three aneurysms peroperatively ruptured, four were deemed unclippable, three paraclinoid UIAs had an intracavernous residue and 16% were wrapped because of a small neck remnant (class 2). The mortality rate was 0% and 4% of the patients experienced a definitive major neurological deterioration. Final GOS was unchanged in 96% of the patients. Despite reduction in operative cases and in appropriately selected patients ineligible to EVT, microsurgical clipping of non-giant anterior circulation UIAs can still achieve good outcome with very low mortality and neurological morbidity.

Response

HomeStrokeVol. 36, No. 6Cognitive Function After Surgical Repair of Unruptured Intracranial Aneurysms Free AccessLetterPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyRedditDiggEmail Jump toFree AccessLetterPDF/EPUBCognitive Function After Surgical Repair of Unruptured Intracranial Aneurysms Mauro Bergui, MD, Marco Fontanella, MD and Gianni Boris Bradac, MD Mauro BerguiMauro Bergui Università Di Torino, Torino, Italy Search for more papers by this author , Marco FontanellaMarco Fontanella Università Di Torino, Torino, Italy Search for more papers by this author and Gianni Boris BradacGianni Boris Bradac Università Di Torino, Torino, Italy Search for more papers by this author Originally published1 Jun 2005https://doi.org/10.1161/01.STR.0000167420.43668.adStroke. 2005;36:1112To the Editor:Otawara et al1 found no cognitive impairment or cerebral blood flow reduction in 42 patients submitted to surgical clipping of unruptured cerebral aneurysms. Two further patients of the series—supposed to be consecutive—were excluded from cognitive evaluation because of brain injuries caused by surgery, with Rankin Scale decrease >1. In other words, they had 0% mortality, 4.5% morbidity, and no cognitive impairment in the remaining 95.5%. These data favorably compare with 2.7% mortality and 9.9% morbidity resulting from the ISUIA study,2 as usually happens, for a series of reasons for single-center series in comparison with multicenter trials. The authors conclude that unruptured aneurysm surgery does not affect cognitive function, provided that the patient does not have brain damage sustained from the surgery. I wonder about the meaning of this statement for 2 reasons: first, it does not make sense to exclude patients with brain damage sustained from surgery; second, even uncomplicated surgery always requires a series of invasive maneuvers on the brain, making brain damage unavoidable. Clinical symptoms may appear or not, depending on the extent of the damage, on the region of the brain involved, and on the sensitivity of the applied tests. Neuropsycological and brain flow measurements are simply not sensitive enough to reveal subtle damages of the brain function.1 Otawara Y, Ogasawara K, Ogawa A, and Yamadate K. Cognitive function before and after surgery in patients with unruptured intracranial aneurysm. Stroke. 2005; 36: 142–143.LinkGoogle Scholar2 The International Study of Unruptured Intracranial Aneurysms Investigators. Unruptured intracranial aneurysms: natural history, clinical outcome, and risks of surgical and endovascular treatment. Lancet. 2003; 362: 103–110.CrossrefMedlineGoogle ScholarstrokeahaStrokeStrokeStroke0039-24991524-4628Lippincott Williams & WilkinsResponse:Otawara Yasunari, , MD, Ogasawara Kuniaki, , MD, and Ogawa Akira, , MD01062005We appreciate the interest of Dr Bergui and colleagues in our article on safe surgery for unruptured intracranial aneurysms in patients without restrictions in postoperative lifestyle.1 Dr Bergui focuses our attention on the exclusion of two patients with surgical complications. We certainly agree with them that clinical symptoms may or may not appear, depending on the extent of the brain damage, the region of the brain damage involved, and the sensitivity of the tests applied. However, we maintain our conclusions for the following reasons.The cognitive tests we applied can detect general intellectual function, visuospatial construction, and memory function. Although this test battery is not perfect, it can detect cognitive dysfunction if trans-Sylvian surgery affected the frontal and/or temporal lobes of the patient.I do not agree that even uncomplicated surgery always requires invasive maneuvers in the brain, resulting in unavoidable brain damage. Surgery for unruptured intracranial aneurysm should not cause brain damage, although brain retraction is essential for this procedure. Our surgical procedure involved wide opening of the Sylvian fissure, intermittent use of self-retractors, and careful preservation of the cerebral veins. We believe that these surgical manipulations will preserve the cerebral blood flow and cognitive functions. Previous literature also supports the safety of unruptured aneurysm surgery based on cognitive tests2 and positron emission tomography.3We believe that surgery for unruptured intracranial aneurysm is safe if we exclude patients with restrictions in postoperative lifestyle. However, we must continue to improve our surgical results.We thank Dr Bergui and colleagues for their insightful comments. Previous Back to top Next FiguresReferencesRelatedDetails June 2005Vol 36, Issue 6Article InformationMetrics https://doi.org/10.1161/01.STR.0000167420.43668.adPMID: 15914766 Originally publishedJune 1, 2005 PDF download Advertisement

Cognitive Function Before and After Surgery in Patients With Unruptured Intracranial Aneurysm

This prospective study investigated whether surgery for unruptured intracranial aneurysms (UIAs) affects cognitive function and cerebral blood flow (CBF). Cognitive tests using the Wechsler Adult Intelligence Scale-Revised, Wechsler Memory Scale, Rey-Osterrieth Complex Figure test, and CBF measurements using single-photon emission computed tomography were performed before and after surgery for UIAs in 44 patients < or =70 years of age. Group-rate analysis showed the verbal intelligence quotient (IQ), performance IQ, full-scale IQ, and recall trial scores of the Rey-Osterrieth Complex Figure test all increased significantly after surgery, whereas the Wechsler Memory Scale and copy trial scores of the Rey-Osterrieth Complex Figure test were not significantly different. Event-rate analysis demonstrated that no patient showed impaired cognition. There was no significant difference between CBF before and after surgery. Surgical repair for UIAs does not impair cognition or CBF in patients without postoperative restrictions in lifestyle.

Surgery for unruptured intracranial aneurysms in a low-volume neurosurgical unit.

To evaluate outcomes after surgical treatment for unruptured intracranial aneurysms in a low-volume neurosurgical unit. Consecutive patients operated during the years 1988-98 at the Department of Neurosurgery, University Hospital of North Norway, were studied retrospectively. Procedure-related complications were registered. The modified Rankin Scale and the Glasgow Outcome Scale, Extended version (GOS-E), were used for assessment of outcome. Thirty-six aneurysms were repaired in 32 patients during 34 surgical procedures. Surgery-related central nervous system complications occurred in eight (25%) patients. The complication rate was 35% for the first 17 procedures, and 12% for the last 17. The latter group of procedures were performed during a period of 3 years, whereas the former group was spread over a period of 8 years. A favourable outcome (GOS-E score 6-8) was reached in 27 (84%) patients. Decision-making in patients with unruptured intracranial aneurysms must be based on knowledge about institution-specific complication rates, preferably followed on a prospective basis.

Treatment options of unruptured intracranial aneurysms.

Aneurysmal subarachnoid hemorrhage (SAH), despite improvements in surgical and medical treatment, is still a serious disease with high rates of case fatality (40% to 50%) and morbidity.1–3 Incidence rates of SAH have not changed during the CT era, and outcome of SAH has only modestly improved during the past few decades. Outcome is still determined mainly by severity of initial bleeding or early rebleeding.1–4 It seems that identification of preventive treatment methods for aneurysm rupture and of modifiable risk factors for SAH are important as means to influence incidence and outcome of this serious disease. Unruptured aneurysms, when incidentally discovered or found in connection with diagnosis of ruptured aneurysm (multiple aneurysm cases), have been operated on for 2 to 3 decades in western countries. In this way, the high case fatality and morbidity associated with a possible severe initial bleed can be eliminated by preventive surgical intervention. However, the natural history as well as risks of surgery of unruptured intracranial aneurysms are poorly known as are the risk factors for rupture because of lack of studies with sufficient number of patients and follow-up years. The Table shows cohorts of largest studies of rupture risk of unruptured intracranial aneurysms.4–8 The recently published prospective part of The International Study of Unruptured Intracranial Aneurysms (ISUIA; patient enrollment in 61 centers between 1991 and 1998)5 shows somewhat different results as compared with those of the retrospective part of ISUIA (in 53 centers between 1970 and 1991).7 In the prospective study,5 overall incidence of aneurysm rupture was higher (0.8% versus 0.3% per year); risk for rupture of vertebrobasilar aneurysms was lower (relative risk 2.3 versus 5.1 to 13.8 as compared with other aneurysms); mean follow-up time per patient was shorter (3.9 versus 8.3 years); there was a lower limit …

未破裂脳動脈りゅう術後の虚血性合併症

We treated a series of 125 patients with unruptured intracranial aneurysms (UIAs) over a period of 6 years and 5 months (1995.12.1-2002.4.30). Ninety-seven patients were operated on, 1 was endovascularly embolized, and 27 were observed. Of the 97 patients who were operated on, 4 had postoperative ischemic complications; 2 had a new cerebral infarction, 1 experienced deterioration of the known infarction and 1 had delayed symptomatic vasospasm. The etiologies of the new cerebral infarction were a subclinical pre-existing stenosis of the parent artery around the aneurysmal neck and stenosis of the parent artery induced by inappropriate neck clipping. Worsening of the known cerebral infarction was seen in a recent case of infarction that developed 2 months before surgery. Pathogeneses of the delayed symptomatic vasospasm after surgery for UIAs are unclear, but the important point is that symptomatic vasospasm does occur after surgery for UIAs. These results suggest that asymptomatic stenotic lesions of the parent artery around the aneurysmal neck have a potential to become symptomatic postoperatively and cause cerebral infarction, that a recent infarction is a risk factor of postoperative ischemic complication as is already known and that a delayed spasm can occur even after uneventful surgery for UIAs.

Publication bias in neurosurgery: lessons from series of unruptured aneurysms.

Bias favouring publication of research with "positive" results over studies with "negative" results is widely suspected. The present investigation addressed this problem in the field of neurosurgery through a review of recent literature concerning outcome of surgery for unruptured intracranial aneurysms. A Medline search was performed seeking case series of surgical treatment for unruptured intracranial aneurysms that analyzed 50 or more patients. Ten type I studies (retrospective studies from a single institution; 1457 patients) met these entry criteria. In general, type I studies reported excellent surgical outcome, with mean combined mortality and morbidity of 7.8% (95% confidence interval (CI), 6.4% to 9.2%). We found 4 multicenter or community-based studies (type II studies; 5401 patients). Mean combined mortality and morbidity in the type II studies was 20.3% (95% CI, 19.2% to 21.4%), much higher than in type I studies. Relative risk was 2.6 (95% CI, 2.2 to 3.1) for patients in type II studies compared with those in type I studies. Two meta-analyses (type III studies) described combined mortality and morbidity of 5.0% and 12.7%, essentially corresponding to results of type I studies. Publication bias is present in the neurosurgical literature. Studies with an excellent surgical outcome are more likely to be published than those with an average outcome. Conclusions of literature reviews or meta-analyses based on published work therefore may be misleading. The solution to the problem would be community-based prospective registration of all patients who underwent surgery, providing a sampling frame free from publication bias.

Mortality and morbidity of surgery for unruptured intracranial aneurysms: a meta-analysis.

Greater availability and improvement of neuroradiological techniques have resulted in more frequent detection of unruptured aneurysms. Because prognosis of subarachnoid hemorrhage is still poor, preventive surgery is increasingly considered as a therapeutic option. Elective surgery requires reliable data on its risks. Therefore, we performed a meta-analysis on the mortality and morbidity of surgery for unruptured intracranial aneurysms. Through Medline and additional searches by hand, we retrieved studies on clipping of unruptured (additional, symptomatic, or incidental) aneurysms published from 1966 through June 1996. Two authors independently extracted data. We used weighted linear regression for data analysis. We included 61 studies that involved 2460 patients (57% female; mean age, 50 years) and at least 2568 unruptured aneurysms (27% >25 mm, 30% located in the posterior circulation). Mortality was 2.6% (95% confidence interval [CI], 2.0% to 3.3%). Permanent morbidity occurred in 10.9% (95% CI, 9.6% to 12.2%) of patients. Postoperative mortality was significantly lower in more recent years for nongiant aneurysms and aneurysms with an anterior location; the last 2 characteristics were also associated with a significantly lower morbidity. In studies published between 1966 and 1996 on clipping of unruptured aneurysms, mortality was 2.6% and morbidity was 10.9%. In calculating the pros and cons of preventive surgery, these proportions should be taken into account.

Risks of surgery for unruptured intracranial aneurysms.

A series is presented of 43 patients with multiple aneurysms and subarachnoid hemorrhage in whom a second operation was necessary in order to clip all the aneurysms. There was one surgical death due to coronary thrombosis and infarction which occurred 3 weeks after surgery, for a surgical mortality rate of 2.3%. One patient developed a permanent neurological deficit (hemiparesis and dysphasia). Thus, the surgical risks are smaller than the natural risk of bleeding and death from hemorrhage. Patients with any other serious illness increasing the surgical risk should not be subjected to an operation for an unruptured aneurysm; a second operation is indicated in all low-risk patients with multiple aneurysms or with incidentally identified aneurysms.