Unruptured Anterior Circulation Aneurysms Research Articles

Treatment of Unruptured Distal Anterior Circulation Aneurysms with Flow-Diverter Stents: A Meta-Analysis.

The safety and efficacy of flow diversion among distal anterior circulation aneurysms must be proved. Our aim was to analyze the outcomes after flow diversion among MCA, anterior communicating artery, and distal anterior cerebral artery aneurysms. A systematic search of 3 databases was performed for studies published from 2005 to 2018. According to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we included studies reporting flow diversion of distal anterior circulation aneurysms. Random-effects meta-analysis was used to pool aneurysm occlusion and complication rates. From the individual patient data, univariate and multivariate analyses were used to test predictors of occlusion and complications. We included 27 studies (484 aneurysms). The long-term adequate occlusion rate (O'Kelly-Marotta scale, C-D) was 82.7% (295/364; 95% CI, 77.4%-87.9%; I2 = 52%). Treatment-related complications were 12.5% (63/410; 95% CI, 9%-16%%; I2 = 18.8%), with 5.4% (29/418; 95% CI, 3.2%-7.5%; I2 = 0%) morbidity. MCA location was an independent factor associated with lower occlusion (OR = 0.5, P = .03) and higher complication rates (OR = 1.8, P = .02), compared with anterior communicating artery and distal anterior cerebral artery aneurysms. The Pipeline Embolization Device (versus other stents) gave better occlusion rates (OR = 2.6, P = .002), whereas large/giant aneurysms were associated with higher odds of complications (OR = 2.2, P = .03). The rates of occlusion and narrowing of arteries covered by flow-diverter stents were 6.3% (29/283; 95% CI, 3.5%-9.1%; I2 = 4.2%) and 23.8% (69/283; 95% CI, 15.7%-32%; I2 = 80%), respectively. Symptoms related to occlusion and narrowing of the jailed arteries were 3.5% (6/269; 95% CI, 1.1%-5%; I2 = 0%) and 3% (6/245; 95% CI, 1%-4%; I2 = 0%), respectively. We reviewed small and retrospective series. Flow diversion among distal anterior circulation aneurysms is effective, leading to adequate aneurysm occlusion in 83% of cases. However, this strategy has some limitations among MCA and larger lesions, especially related to the higher rate of complications. Compared with the other devices, the Pipeline Embolization Device seems to be associated with a higher occlusion rate.

Embryological basilar apex disposition as a risk factor of basilar apex aneurysm

The pathogenesis of basilar apex aneurysm (BAA) are still poorly understood. Embryologically, basilar apex anatomical disposition is formed by the fusion of both caudal internal carotid divisions on the midline. To compare basilar apex morphology by embryological classification among patients with BAAs, anterior circulation aneurysms (ACAs), and controls. Prospectively collected data of 47 consecutive patients with unruptured BAAs (42 females and five males), age- and gender-matched 47 patients with unruptured ACAs, and 47 controls without any aneurysms were analyzed. Based on embryology, basilar apex morphology was classified into symmetric cranial fusion (SCrF), symmetric caudal fusion, and asymmetric fusion type. Posterior communicating artery (Pcom) was classified into hypoplastic, adult, or fetal type. The asymmetrical Pcom was defined as bilaterally different type Pcom. The ACAs located at the anterior communicating artery (n = 18), paraclinoid portion (n = 12), middle cerebral artery (n = 8), anterior cerebral artery (n = 5), the top of internal carotid artery (n = 2), and anterior choroidal artery (n = 2). Compared with the ACA group and controls, smoking, asymmetrical Pcom (fetal and adult type), and SCrF type were more prevalent in patients with BAAs by residual analysis. The multinomial logistic regression comparative analysis demonstrated that SCrF type was associated with BAAs (vs. ACA group; odds ratio, 13; 95% confidence interval, 3.8–41 and vs. controls; odds ratio, 25; 95% confidence interval, 5.4–121). The assessment of basilar apex morphology may aid in the understanding of the pathogenesis of BAA and the prediction of BAA formation.

Distal transsylvian keyhole approach for unruptured anterior circulation small aneurysms

BackgroundTo reduce complications associated with conventional pterional craniotomy, a transsylvian keyhole approach for unruptured small anterior circulation aneurysms is proposed.MethodsA 7-cm linear scalp incision is made along the hairline, beginning at the zygoma, followed by minimal temporal muscle dissection. Two burr holes are drilled out at McCarty’s point and the temporal bone, and a 3-cm equilateral triangle bone flap is made, whose apex is located above the sylvian point. After the sphenoid ridge is drilled off, aneurysms are exposed and clipped with conventional microsurgical instruments.ConclusionsThis approach permits access to aneurysms via the transsylvian corridor with a smaller area of potential injury of superficial structures.

The minipterional approach for ruptured and unruptured anterior circulation aneurysms: Our initial experience.

Objective:To report our experience with the minipterional (MPT) craniotomy approach for anterior circulation aneurysms and to discuss the clinical outcomes as well as to evaluate the advantages of this unique approach.Materials and Methods:Single-center retrospective review of 57 cases involving anterior circulation aneurysms both ruptured and unruptured aneurysms treated with the MPT. We analyzed the clinical and patient demographic data, aneurysm characteristics, surgical outcomes, and complications in these individuals.Results:Between July 2008 and March 2014, of the 57 patients reviewed: 45 had middle cerebral artery (MCA), 6 had internal carotid artery terminus, and 7 had posterior communicating artery aneurysms. 20 of the 57 patients presented with a ruptured aneurysm. The average aneurysm size was 5.8 mm. The length of hospitalization for unruptured aneurysm cases ranged between 3 and 5 days. The average follow-up for all cases was 21.5 months. Successful clipping of the aneurysms was obtained in all patients. None of the cases required additional skin incisions or craniotomy extensions. The overall surgical outcomes were favorable. There was no postoperative facial nerve damage, temporalis muscle wasting, or symptoms of paresthesias around the incision line. Two patients developed a postoperative stroke manifested as symptoms of unilateral arm and facial weakness, receptive aphasia, and dysarthria.Conclusion:The MPT provides a reliable and less invasive alternative to the standard pterional craniotomy. Furthermore, ruptured and unruptured anterior circulation aneurysms can safely and effectively be treated with limited bone removal which provides better cosmetic outcomes and excellent postoperative temporalis muscle function.

Abstract WP88: Relationship Between Aneurysm Size and Distal Cerebral Hemodynamics

Introduction: The impact of aneurysms on distal cerebral hemodynamics is unknown. Here we examine the relationship between aneurysm size and distal hemodynamics prior to treatment. Methods: Patients seen at our institution between 2006-2015 with aneurysms within the cavernous or supraclinoid ICA segment (proximal to ICA terminus) were retrospectively reviewed. Only un-ruptured proximal anterior circulation aneurysms were included, patients with contralateral aneurysms were excluded. Patients were included if they had flow volume rate and flow velocities measured prior to any treatment using Quantitative MRA. Pulsatility index (PI) = [(systolic - diastolic flow velocity)/mean flow velocity] was calculated for ipsilateral and contralateral MCA and ICA. Hemodynamic parameters were analyzed with respect to aneurysm size. Results: 42 patients were included. Mean aneurysm size was 13.5 mm (range 2-40mm). There was significant correlation (Pearson’s) between aneurysm size and ipsilateral MCA PI ( P =0.006; r=0.441), MCA ipsilateral /ICA ipsilateral PI ratio ( P =0.003; r=0.57), and MCA ipsilateral /MCA contralateral PI ratio ( P =0.008; r=0.43). Conclusions: Larger aneurysm size is significantly associated with higher ipsilateral MCA PI, demonstrating that aneurysms change distal cerebral hemodynamics. Aneurysm treatment may thus acutely change those altered hemodynamics.

Surgical experience of minipterional craniotomy with 102 ruptured and unruptured anterior circulation aneurysms

The pterional approach was described in the 1970s and has become the most utilized cranial approach with many variations described, including the minipterional technique. Although described recently as an alternative to the pterional approach for anterior circulation aneurysms, to our knowledge a large series of cases using the minipterional approach in both ruptured and unruptured aneurysms has not been described. We present our clinical experience with the minipterional craniotomy in more than 100 ruptured and unruptured anterior circulation aneurysms. The results of 86 consecutive patients with 102 ruptured non-giant, anterior circulation aneurysms treated with early surgery utilizing the minipterional craniotomy were analyzed. Postoperative angiography was carried out in all cases. Outcome results were classified as excellent in 67 (77.9%), and good in seven (8.1%), while 16 (13.9%) patients died. The minipterional technique provides adequate surgical exposure and excellent outcomes for both ruptured and unruptured anterior circulation aneurysm clipping. It constitutes a safe and effective alternative to the pterional approach, with equivalent or potentially better aesthetic and functional outcomes.

Minimally Invasive Thumb-sized Pterional Craniotomy for Surgical Clip Ligation of Unruptured Anterior Circulation Aneurysms.

Less invasive surgical approaches for intracranial aneurysm clipping may reduce length of hospital stay, surgical morbidity, treatment cost, and improve patient outcomes. We present our experience with a minimally invasive pterional approach for anterior circulation aneurysms performed in a major tertiary cerebrovascular center and compare the results with an aged matched dataset from the Nationwide Inpatient Sample (NIS). From August 2008 to December 2012, 22 elective aneurysm clippings on patients ≤55 years of age were performed by the same dual fellowship-trained cerebrovascular/endovascular neurosurgeon. One patient (4.5%) experienced transient post-operative complications. 18 of 22 patients returned for follow-up imaging and there were no recurrences through an average duration of 22 months. A search in the NIS database from 2008 to 2010, also for patients aged ≤55 years of age, yielded 1,341 hospitalizations for surgical clip ligation of unruptured cerebral aneurysms. Inpatient length of stay and hospital charges at our institution using the minimally invasive thumb-sized pterional technique were nearly half that of NIS (length of stay: 3.2 vs 5.7 days; hospital charges: $52,779 vs. $101,882). The minimally invasive thumb-sized pterional craniotomy allows good exposure of unruptured small and medium-sized supraclinoid anterior circulation aneurysms. Cerebrospinal fluid drainage from key subarachnoid cisterns and constant bimanual microsurgical techniques avoid the need for retractors which can cause contusions, localized venous infarctions, and post-operative cerebral edema at the retractor sites. Utilizing this set of techniques has afforded our patients with a shorter hospital stay at a lower cost compared to the national average.

Minimally Invasive Thumb-sized Pterional Craniotomy for Surgical Clip Ligation of Unruptured Anterior Circulation Aneurysms

Minimally Invasive Thumb-sized Pterional Craniotomy for Surgical Clip Ligation of Unruptured Anterior Circulation Aneurysms

Incidence and risk factors of chronic subdural hematoma after surgical clipping for unruptured anterior circulation aneurysms.

ObjectiveChronic subdural hematoma (CSDH) is a rare complication of unruptured aneurysm clipping surgery. The purpose of this study was to identify the incidence and risk factors of postoperative CSDH after surgical clipping for unruptured anterior circulation aneurysms.MethodsThis retrospective study included 518 patients from a single tertiary institute from January 2008 to December 2013. CSDH was defined as subdural hemorrhage which needed surgical treatment. The degree of brain atrophy was estimated using the bicaudate ratio (BCR) index. We used uni- and multivariate analyses to identify risk factors correlated with CSDH.ResultsSixteen (3.1%) patients experienced postoperative CSDH that required burr hole drainage surgery. In univariate analyses, male gender (p<0.001), size of aneurysm (p=0.030), higher BCR index (p=0.004), and the use of antithrombotic medication (p=0.006) were associated with postoperative CSDH. In multivariate analyses using logistic regression test, male gender [odds ratio (OR) 4.037, range 1.287-12.688], high BCR index (OR 5.376, range 1.170-25.000), and the use of antithrombotic medication (OR 4.854, range 1.658-14.085) were associated with postoperative CSDH (p<0.05). Postoperative subdural fluid collection and arachnoid plasty were not showed statistically significant difference in this study.ConclusionThe incidence of CSDH was 3.1% in unruptured anterior circulation aneurysm surgery. This study shows that male gender, degree of brain atrophy, and the use of antithrombotic medication were associated with postoperative CSDH.

The Minipterional Craniotomy for Anterior Circulation Aneurysms

The pterional craniotomy is well established for microsurgical clipping of most anterior circulation aneurysms. The incision and temporalis muscle dissection impacts postoperative recovery and cosmetic outcomes. The minipterional (MPT) craniotomy offers similar microsurgical corridors, with a substantially shorter incision, less muscle dissection, and a smaller craniotomy flap. To report our experience with the MPT craniotomy in select unruptured anterior circulation aneurysms. From January 2009 to July 2013, 82 unruptured aneurysms were treated in 72 patients, with 74 MPT craniotomies. Seven patients had multiple aneurysms treated with a single MPT craniotomy. The average patient age was 56 years (range: 24-87). Aneurysms were located along the middle cerebral artery (n = 36), posterior communicating (n = 22), paraophthalmic (n = 22), choroidal (n = 1), and dorsal ICA segments (n = 1). The MPT craniotomy utilized an incision just posterior to the hairline and a single myocutaneous flap. The average aneurysm size was 5.45 mm (range: 1-14). There were no instances of compromised operative corridors requiring craniotomy extension. Three significant early postoperative complications included epidural and subdural hematomas requiring evacuation, and a middle cerebral artery infarction. Average length of hospitalization was 3.96 days (range: 2-20). Two patients required reoperation for wound infections. Average follow-up was 421 days (range: 5-1618). Minimal to no temporalis muscle wasting was noted in 96% of patients. The MPT craniotomy is a worthwhile alternative to the standard pterional craniotomy. There were no instances of suboptimal operative corridors and clip applications when the MPT craniotomy was utilized in the treatment of unruptured middle cerebral artery and supraclinoid internal carotid artery aneurysms proximal to the terminal internal carotid artery bifurcation.

A safety, length of stay, and cost analysis of minimally invasive microsurgery for anterior circulation aneurysms

The aim of our study was to evaluate minimally invasive techniques for the treatment of anterior circulation aneurysms versus standard surgery, and to calculate the impact of these techniques on health resources, length of stay, and treatment costs. A consecutive series of 24 patients with ruptured and 30 with unruptured anterior circulation aneurysms treated with minimally invasive microsurgery (MIM) by the same surgeon was compared with a matched series of standard microsurgeries (SM) conducted for 23 ruptured and 22 unruptured aneurysms. Complication rates, aneurysm obliteration, modified Rankin Scale (mRS) outcomes, length of stay, and treatment costs were assessed. Surgical complications, aneurysm obliteration rates and mRS outcomes were comparable between MIM and SM groups in ruptured and unruptured aneurysm cohorts. MIM resulted in shorter operative times both in unruptured (102.7 ± 4.35 vs 194.7 ± 10.26 min, p < 0.0001) and ruptured aneurysms (124.3 ± 827 vs 209 ± 13.84 min, p < 0.0001). Length of stay was reduced in patients with MIM for unruptured aneurysms (1.55 ± 24 vs 4.28 ± 0.71 days, p < 0.000,1) but not in those with ruptured aneurysms. MIM reduced treatment costs of unruptured aneurysm patients, mainly through reduced utilization of inpatient resources (non-acute bed costs in CAD: 371.2 ± 80.99 vs 1440 ± 224.1, p < 0.0001), whereas costs were comparable in patients with ruptured aneurysms. Minimally invasive surgery is a safe and effective approach for the treatment of ruptured and unruptured aneurysms of the anterior circulation. In patients with unruptured aneurysms, reduced invasiveness and shorter operative times decreased length of stay, which reflects improved patient postoperative recovery. Overall, this translated into bed resource economy and cost reduction.

Superciliary keyhole approach for unruptured anterior circulation aneurysms: surgical technique, indications, and contraindications.

Neurosurgeons have been trying to reduce surgical invasiveness by applying minimally invasive keyhole approaches. Therefore, this paper clarifies the detailed surgical technique, its limitations, proper indications, and contraindications for a superciliary keyhole approach as a minimally invasive modification of a pterional approach. Successful superciliary keyhole surgery for unruptured aneurysms requires an understanding of the limitations and the use of special surgical techniques. Essentially, this means the effective selection of surgical indications, usage of the appropriate surgical instruments with a tubular shaft, and refined surgical techniques, including straightforward access to the aneurysm, clean surgical dissection, and the application of clips with an appropriate configuration. A superciliary keyhole approach allows unruptured anterior circulation aneurysms to be clipped safely, rapidly, and less invasively on the basis of appropriate surgical indications.

Clinical characteristics and risk factors of chronic subdural haematoma associated with clipping of unruptured cerebral aneurysms

Chronic subdural haematoma (CSDH) is an uncommon but potentially serious complication of clipping unruptured cerebral aneurysms. We conducted a study to identify the patients who are at risk of developing postoperative CSDH. The data from 713 consecutive patients who underwent clipping of unruptured anterior circulation aneurysms were reviewed, and risk factors correlated with CSDH were identified by multivariate regression analysis of demographic variables. Fifteen patients (2.1%) developed CSDH after the surgery. Advanced age (odds ratio [OR] 1.151, 95% confidence interval [CI] 1.051–1.261) and male gender (OR 3.167, 95% CI 1.028–9.751) were correlated with CSDH. Subsequently, all 713 patients were quadrichotomized on the basis of gender and age, with 70years as the cut-off value for age. The frequency of CSDH in men <70years of age was 1.3% and that in men ⩾70years of age was 15.1%, with risk of CSDH was significantly higher in the older men (OR 13.39; 95% CI: 3.42–52.44). The frequency of CSDH in women <70years of age was 0.6% and that in women ⩾70years of age was 3.7%. As in men, the risk of CSDH was significantly higher in the older women (OR 6.69, 95% CI 1.10–40.73). The interval between the aneurysm clipping and CSDH development was 0.5–6months, suggesting that clinical observation should be continued up to 6months after surgery. Although prognosis for patients with a postoperative CSDH complication is generally favourable, the risk of CSDH should be taken into account when considering elective clipping of unruptured aneurysms in patients ⩾70years of age.

Early seizures after clipping of unruptured aneurysms of the anterior circulation: analysis on consecutive 1,000 cases

Seizures occurring after clipping of unruptured cerebral aneurysms have rarely been documented in the literature. The objective of this retrospective study is to clarify whether the frequency of early seizures, i.e., seizures occurring within 14days of surgery, is influenced by patient- or aneurysm-specific characteristics. Data on 1,000 consecutive patients who underwent clipping of unruptured anterior circulation aneurysms were reviewed. They consisted of 387 men and 613 women with mean age of 59.8 ± 9.7years. Fifty-one patients (5.1%) developed early seizures. Interestingly, the frequency was similar to that occurring after clipping of unruptured posterior circulation aneurysms (n = 20, 5.0%). Multivariate regression analysis revealed that younger age was correlated with early seizures (odds ratio (OR) 0.902; 95% confidence interval (CI) 0.891-0.989). However, other variables, including aneurysm size and operation length, were not correlated. Although patients with history of epilepsy exhibited relatively high frequency of early seizures, the difference was not statistically significant. The frequency was unaffected by location or multiplicity of aneurysms. Thirty-one patients (61%) developed seizures within 24h of clipping. Regarding seizure types, 34 (67%) developed generalized seizures and the other 17 (33%) experienced partial seizures. Patients with generalized seizures were significantly more likely to harbor an iatrogenic brain lesion than those with partial seizures (47 vs. 18%; OR 4.148; 95% CI 1.005-17.113). Among 40 patients with follow-up period >12months, seizures were temporary without recurrence in 38 (95%). Although early seizures are mostly benign, a small possibility of them becoming a permanent morbidity needs to be explained to patients undergoing elective clipping.

Entry Point to the Sylvian Fissure for the Pterional Transsylvian Approach

Although the anatomy of the Sylvian fissure is understood, there is little information on where to start its dissection in the pterional transsylvian (PT-TS) approach. At small craniotomy using the PT-TS approach, we set the entry point to the Sylvian fissure at 15 mm behind the anterior edge of the craniotomy along the Sylvian fissure and designated this site "point 15." Here we compared the utility of "point 15" with the Sylvian point (point on the Sylvian fissure giving rise to the horizontal and anterior ascending rami) that had been recommended earlier as the entry site for opening the Sylvian fissure. This study includes 16 patients with 7 ruptured and 9 unruptured anterior circulation aneurysms. We evaluated the usefulness of "point 15" in the PT-TS approach for aneurysmal neck clipping with respect to the adequacy of anatomical exposure and low invasiveness. In 12 patients "point 15" provided for excellent anatomical exposure of the Sylvian fissure; complete neck clipping was possible with minimal brain retraction and damage. In two patients with ruptured aneurysms and thick subarachnoid hemorrhage and in two patients with unruptured aneurysms, the dissection had to be enlarged 3 to 4 mm distally without reaching the Sylvian point. In the latter two patients the Sylvian veins were tethered to frontal and temporal lobes. The "point 15" was an easily set entry point to the Sylvian fissure. It provided for sufficient anatomical exposure at surgery for anterior circulation aneurysms; additional posterior dissection was required in rare cases. We found that "point 15" was useful in small craniotomies using the PT-TS approach.

Reduced Length of Stay and Hospital Cost for Unruptured Anterior Circulation Aneurysms Treated with Endovascular Coiling or a Minimally Invasive Thumb-Sized Pterional Craniotomy: Single Center Experience and Nationwide Inpatient Sample Data Analysis

Cost-benefit analysis of endovascular treatment compared to open-surgical treatment of cerebral aneurysms in the setting of global economic restrictions is of growing importance. We present our experience with coil embolization and a modified thumb-sized pterional craniotomy for clip ligation of unruptured anterior circulation cerebral aneurysms performed in a major tertiary cerebrovascular center; our experience is then compared to a matched dataset from the Nationwide Inpatient Sample (NIS). In our institutional analysis, all patients were aged ≤55 years and treated electively for unruptured anterior circulation aneurysms. A matched dataset from the NIS was constructed using patients ≤55 years with unruptured aneurysms. At our institution, length of stay was half that of NIS for both the surgical clipping group and the endovascular group. Additionally, hospital charges were reduced by one-third for surgical clipping and by approximately one-fourth for endovascular coiling. The cost of clipping vs coiling for unruptured cerebral aneurysms should not undermine the ethics of decision making, but rather should be used as a guide in allocation of hospital resources, manpower and funds. Thumb-sized craniotomies without use of cerebral retractors for clipping provide excellent recovery and show a significant decrease in the postoperative hospital stay as well as a lower cost of hospitalization compared to the national average. High volume centers for treatment of cerebral aneurysms, like ours which is managed by the same neurovascular staff for both treatment options, is an important factor in lowering the length of stay and hospitalization cost. Keywords: Craniotomy, cerebral aneurysm, clip ligation, endovascular coiling, health care costs, length of stay, minimally invasive, retractorless, surgery. Read more →

Reduced Length of Stay and Hospital Cost for Unruptured Anterior Circulation Aneurysms Treated with Endovascular Coiling or a Minimally Invasive Thumb-Sized Pterional Craniotomy: Single Center Experience and Nationwide Inpatient Sample Data Analysis

Cost-benefit analysis of endovascular treatment compared to open-surgical treatment of cerebral aneurysms in the setting of global economic restrictions is of growing importance. We present our experience with coil embolization and a modified thumb-sized pterional craniotomy for clip ligation of unruptured anterior circulation cerebral aneurysms performed in a major tertiary cerebrovascular center; our experience is then compared to a matched dataset from the Nationwide Inpatient Sample (NIS). In our institutional analysis, all patients were aged � 55 years and treated electively for unruptured anterior circulation aneurysms. A matched dataset from the NIS was constructed using patients � 55 years with unruptured aneurysms. At our institution, length of stay was half that of NIS for both the surgical clipping group and the endovascular group. Additionally, hospital charges were reduced by one-third for surgical clipping and by approximately one-fourth for endovascular coiling. The cost of clipping vs coiling for unruptured cerebral aneurysms should not undermine the ethics of decision making, but rather should be used as a guide in allocation of hospital resources, manpower and funds. Thumb-sized craniotomies without use of cerebral retractors for clipping provide excellent recovery and show a significant decrease in the postoperative hospital stay as well as a lower cost of hospitalization compared to the national average. High volume centers for treatment of cerebral aneurysms, like ours which is managed by the same neurovascular staff for both treatment options, is an important factor in lowering the length of stay and hospitalization cost.

Microsurgical clipping in forty patients with unruptured anterior cerebral circulation aneurysms: an investigation into cognitive outcome

It is a consensus that most unruptured intracranial aneurysms (UIA) can be treated with acceptably low morbidity. However, some studies recently reported postoperative cognitive impairment, suggesting that it could be attributable to surgical damage. Our goal is to evaluate cognitive function before and after microsurgical clipping in patients with UIA. A consecutive series of 40 patients who underwent microsurgical clipping for UIA were studied. The cognitive assessment (Mini Mental State Examination, MMSE) was performed immediately before and at least one month after surgery. Paired Student's "t" test and analysis of variance (ANOVA) were used for statistical purposes. The mean MMSE score in the preoperative analysis was 28.12 (SD, 1.34). In the postoperative period the mean MMSE score was 28.40 (SD, 1.46). Paired Student's "t" test was applied to the scores and no significant difference was found (p = 0.315). ANOVA did not find independent associations between MMSE scores and age, hypertension, smoking, dyslipidemia, education, aneurysm location, number, laterality or size. The present study suggests that microsurgical clipping for UIA does not result in major cognitive dysfunction as determined by the MMSE.

Application of the FlexiForce Contact Surface Force Sensor to Continuous Extraocular Compression Monitoring During Craniotomy for Cerebral Aneurysms

The aims of this study were to introduce our newly developed device equipped with a contact surface force sensor (FlexiForce) for monitoring extraocular compression continuously, and to illustrate its potential clinical application using this device in patients undergoing uncomplicated frontotemporal or bifrontal craniotomy for surgical clipping of unruptured anterior circulation aneurysms. In a pilot study with volunteers, we determined the critical force of 100 gf to cause painful ocular sensation. Then we performed the bilateral extraocular force measurements in 15 patients undergoing uncomplicated frontotemporal or bifrontal craniotomy for surgical clipping of unruptured anterior circulation aneurysms. Extraocular force increased immediately after retraction of the flap, increased to 144+/-26 gf (mean+/-SD) during lower craniotomy close to the orbit, was maintained at 91+/-18 gf during microsurgery, and returned close to baseline at 24+/-14 gf after restoration of skin flap retraction. Such changes were observed only on the surgical side in frontotemporal craniotomy. Abnormal increase in extraocular force was effectively reduced by placing a real-time digital panel meter to warn surgeons to avoid excessive skin flap retraction during the surgical procedure. In conclusion, this new tool may allow us to monitor the external forces that can be applied intraoperatively to the ocular globe in the supine position.

未破裂脳動脈瘤に対するＯｖｅｒｎｉｇｈｔ手術を目標としたＫｅｙｈｏｌｅ ｃｌｉｐｐｉｎｇ術の開発

Forty-eight patients with 52 unruptured aneurysms were treated by 50 keyhole clipping procedures. The 32 middle cerebral artery aneurysms were treated through the pterional keyhole approach using an outer canthal skin incision. The 16 internal carotid artery aneurysms and 4 anterior communicating artery aneurysms were treated through supraorbital keyhole craniotomy via an eyebrow skin incision (Perneczky method). Preoperative three-dimensional computed tomography angiography with the osteotomy technique was used to determine the best location and size for the keyhole in each patient. No scalp hair shaving, drainage placement, or anti-convulsant medication were needed. The mean sizes of the pterional and supraorbital keyholes were 25×23 mm and 29×21 mm, respectively. The outcomes on the modified Rankin Scale were Grade 0 in 46 cases, Grade 1 in 3 cases with frontalis muscle weakness, and Grade 3 in 1 case with lacunar infarction. Most of the patients were discharged on the 2nd or 3rd postoperative day. Keyhole clipping surgery is another treatment option for relatively small unruptured anterior circulation aneurysms and may require only overnight hospitalization.