|Year : 2008 | Volume
| Issue : 1 | Page : 63
Clinical Outcome of Intracranial Aneurysms:A Retrospective Comparison Between Endovascular Coiling and Neurosurgical Clipping
Mukesh M Gupta1, PK Bithal2, HH Dash2, Arvind Chaturvedi3, Hemanshu Prabhakar4
1 Senior Resident, Department of Neuroanaesthesiology, CN Centre, 7th floor, All India Institute of Medical Sciences, New Delhi -110029, India
2 Professor, Department of Neuroanaesthesiology, CN Centre, 7th floor, All India Institute of Medical Sciences, New Delhi -110029, India
3 Additional Professor, Department of Neuroanaesthesiology, CN Centre, 7th floor, All India Institute of Medical Sciences, New Delhi -110029, India
4 Assistant Professor, Department of Neuroanaesthesiology, CN Centre, 7th floor, All India Institute of Medical Sciences, New Delhi -110029, India
|Date of Acceptance||01-Jan-2008|
|Date of Web Publication||19-Mar-2010|
P K Bithal
Department of Neuroanaesthesiology, CN Centre, 7th floor, All India Institute of Medical Sciences, New Delhi -110029
Source of Support: None, Conflict of Interest: None
Endovascular coiling (EC) is being increasingly used as an alternative to surgical clipping (SC) for intracranial aneurysms, although the relative benefits of these two approaches have yet to be established. Purpose of this study was to review the anaesthetic and definitive management of patients with intracranial aneurysms in the interventional neuroradiology suite (INR) and compared with in the operation theatre.
Retrospective review of first 100 consecutive patients in either mode of treatment (endovascular coiling and surgical clipping) was done. Data compared and analyzed included demographic profile, preoperative medical and surgical record, aneurysm characteristics, neurosurgical grading, intra and postoperative complications and clinical outcome at discharge from hospital. P < 0.05 was considered significant.
In INR group, aneurysms were located in both anterior and posterior circulation, but in SC group all they were in anterior circulation. There was no significant difference in Subarachnoid haemorrhage (SAH) grading in regards of Hunt and Hess and World Federation of Neurological Surgeons(WFNS). Clinical outcome at discharge was significantly better in patients treated with endovascular coiling as compared to surgical clipping(P = 0.042).
We conclude that for the anaesthesiologist, one needs to be aware that the patient presenting for endovascular treatment may have more complex aneurysm anatomy and pathophysiology, premorbid systemic disorders (cardiac, respiratory & renal) and may be older. In our study, overall outcome in patients who underwent endovascular coiling (in terms of Glasgow outcome scale) was significantly better then surgical clipping. In most of the time, whatever the complications occurred during the procedure were related to the procedure itself.
Keywords: Subarachnoid haemorrhage; Intracranial aneurysm; Coiling; Clipping
|How to cite this article:|
Gupta MM, Bithal P K, Dash H H, Chaturvedi A, Prabhakar H. Clinical Outcome of Intracranial Aneurysms:A Retrospective Comparison Between Endovascular Coiling and Neurosurgical Clipping. Indian J Anaesth 2008;52:63
|How to cite this URL:|
Gupta MM, Bithal P K, Dash H H, Chaturvedi A, Prabhakar H. Clinical Outcome of Intracranial Aneurysms:A Retrospective Comparison Between Endovascular Coiling and Neurosurgical Clipping. Indian J Anaesth [serial online] 2008 [cited 2017 May 28];52:63. Available from: http://www.ijaweb.org/text.asp?2008/52/1/63/60600
| Introduction|| |
During the past decade, endovascular methods have been developed to treat intracranial aneurysms. Intracranial aneurysms that are surgically difficult to access, such as those situated in the posterior circulation, and patients with high-risk medical conditions may benefit from interventional neuroradiology (INR) technique, as they need not be subjected to more invasive technique of surgery ,, . The recently published randomized controlled International subarachnoid aneurysm trial (ISAT) of neurosurgical clipping versus endovascular coiling in patients with ruptured intracranial aneurysms showed better outcome with endovascular coiling than surgical clipping (SC). There is extensive variation in the routines used for monitoring and management in endovascular technique of treatment for intracranial aneurysm as compared to surgical clipping ,, .
The aim of this retrospective study was to review management and outcome of patients with intracranial aneurysms, in neuroradiology suite and compare it with surgical clipping during the period from January 2001 to June 2004, in our institute.
| Methods|| |
With the approval of our Institutional Ethic's committee, a retrospective record was reviewed of patients treated for intracranial aneurysms by either endovascular coiling or surgical clipping, over a three and a half year period. The first 100 consecutive patients in either mode of treatment (endovascular coiling and surgical clipping) were selected for analysis.
Data were obtained from neurosurgical and anaesthesia records. Data were entered into a master chart after filling a proforma that included, demographic information, signs and symptoms and neurosurgical grades at admission [Modified Hunt & Hess grading, World Federation of Neurological Surgeons' (WFNS) and Fisher's grading], co-existing medical illnesses, interval from ictus to patient admission and definitive treatment, aneurysm characteristics [type, location, size, multiplicity and coexisting arterio-venous malformations (AVM)], intraoperative anaesthesia and surgical records, and the duration of the procedure. Complications relevant to anaesthesia and the procedure, occurred during perioperative period were also recorded. Clinical outcome was assessed with the Glasgow Outcome Scale (GOS)  at discharge from hospital. If the patients were found suitable for surgical clipping (anterior circulation aneurysm, good Hunt and Hess and WFNS grade) and those associated with large parenchymal haematoma, they were taken for the surgery. Patients were referred for endovascular treatment, wherever surgeon assessed surgical difficulty, poor neurological and medical status, multiple aneurysms, AVM associated aneurysms and geriatric age group. We excluded patients with unsuccessful surgical clipping. In those patients who were re-explored or abandoned for any reason and again scheduled or definitive procedure completed in multiple sitting like endovascular coiling for multiple aneurysms, only important events were collected and their whole procedure data were not included for comparison.
Statistical evaluation was performed by using SPSS 11.5 (SPSS Inc., Chicago, IL). Normally distributed continuous variables are expressed as mean (SD) and nonnormally distributed data variables as median (range). Differences between groups were analyzed by Student's unpaired't' test for normally distributed data. Chi-square test was used for categorical variables. The value of P <0.05 was considered significant.
| Results|| |
During the study period, 422 patients were treated by SC and 100 patients by INR. All these cases were planned for definitive procedure at the earliest, but in elective schedule. In INR suite majority of aneurysms were treated with detachable coil occlusion (89%), including balloon or stent-assisted (8%) coiling procedures. Demographic characteristics of all patients are shown in [Table 1].
The most common ECG changes were ST segment depression and T wave inversion. Other changes were left anterior hemiblock, left bundle branch block (rSr pattern), ventricular premature beat, and left ventricular hypertrophy.
Total number of aneurysms in 100 patients of INR group was 120 and in 100 patients of SC group, it was 114 (P = 0.147). Multiple aneurysms were present in 18 patients in INR and 13 patients in SC (P=0.026). Admission CT scan in 74 patients in INR and 92 patients in SC group had radiological evidence of haemorrhage (P = 0.016). SAH grading and time intervals between ictus to definitive procedure are shown in [Table 1] and [Table 2].
The anaesthetic technique for the INR group was general anaesthesia with tracheal intubation in all cases except, four patients who received general anaesthesia with laryngeal mask airway. In SC group, all patients received endotracheal general anaesthesia. Nine patients with poor neurological grades (6 in INR group and 3 in SC group) were on ventilator support in intensive care unit (ICU) before the procedure (P = 0.023) [Table 4]. All patients were monitored with an electrocardiogram, pulse oximetry, non-invasive blood pressure and end-tidal carbon dioxide. Invasive arterial blood pressure was monitored in almost all patients (98/100) for SC group. Patients in SC group were also monitored for CVP via catheter inserted through either arm vein (n = 6) or subclavian vein (n = 48) and internal jugular vein (n = 42). Important intraoperative data is tabulated. [Table 3] Intraarterial nimodipine was used to relieve the cerebral vasospasm in 18 patients during the endovascular coiling. In case of SC, local instillation of papaverine 10 - 20 mg was done in 55 patients for vasospasm following clipping. Temporary clip was applied in 56 patients out of 100 (56%), in SC group. The mean duration of temporary clipping was 7.06 ± 4.54 minutes.
Tracheal extubation was not done in 13 patients in INR group and 23 patients in SC group (P = 0.018). The reason for not extubating trachea was either poor neurological status in preoperative period or intraoperative events like aneurysm rupture and delayed recovery. The duration of procedure was significantly longer in endovascular coiling. [Table 3] In postoperative period, mechanical ventilation was used in 13 patients in INR group and 35 patients in SC group (P =0.013). For prolonged mechanical ventilation, tracheostomy was done in 2 patients in INR group and 4 patients in SC group (P = 0.023). [Table 4]
Various intraoperative complications are tabulated and were managed conservatively [Table 5]. In patients who underwent endovascular coiling, both neurological and systemic complications were significantly less as compared to clipping in postoperative period. [Table 6] Duration of hospital stay after the definitive procedure was also significantly less in patients, who underwent endovascular embolization as compared to surgically treated patients. [Table 4]
An overall good to fair and moderate recovery was better in patients treated with endovascular coiling as compared to surgical clipping( P = 0.042). Poor outcome (major neurological deficits to death) was present in 16 patients in INR group and 24 patients in SC group (P = 0.016). In-hospital mortality was 6% in endovascular group and 8% in surgical group. (P = 0.042)
| Discussion|| |
The two forms of treatment that is, surgical clipping and endovascular coiling for intracranial aneurysm have been compared in many previous studies published in the literature ,,,, . Recently published international multicentre randomised controlled trial (ISAT)  reported that in terms of the proportion of patients dependent or dead at one year was significantly less for patients allocated to endovascular treatment compared with patients allocated to neurosurgical treatment. Therefore the recent trend is to submit more number of patients of intracranial aneurysm for endovascular coiling as a primary treatment modality , .
There is little information in the literature regarding the differences in anaesthetic management and final outcome of patients with intracranial aneurysms following endovascular or surgical treatment. Therefore, we reviewed the anaesthesia records of patients managed in the INR suite and compared this to management of intracranial aneurysm patients in the operating room.
In the demographic data, the mean age of patients in both group was less then that described in the literature , . It may be because of genetic or dietary factors, Indians develop aneurysm at an early age  . Number of patients who underwent INR procedures was more in the age group up to 40 yrs and again in patients older than 60 yrs of age. These observations highlight two important facts, firstly perhaps, it was the difficult location of aneurysm in younger patients for the choice of INR treatment; secondly in older patients preference for INR treatment was perhaps determined more by the surgical risks involved in this group. Elderly patients, because of associated medical diseases are likely to tolerate surgical stress poorly. Females outnumbered males, a finding similar to that described in literature ,, .
In our centre, trend is to go for surgical clipping of aneurysm with no anticipated surgical difficulty and located in anterior circulation. In our study we found, 70% of aneurysm cases were referred for endovascular treatment because of anticipated surgical difficulty and most of them were in posterior circulation. In remainders, were patients with poor neurological grade (10%), systemic disorders (cardiac and respiratory disease), multiple aneurysms (8%), AVM associated aneurysm (4%) and elderly patients. It is an established fact of poor outcome of these patients in presence of multiple aneurysms, posterior circulation aneurysm  and in presence of comorbid diseases , .
Hypertension is considered to be one of the major risk factors for the development of intracranial aneurysm and its rupture, because pressure in aneurysm is directly proportional to systemic pressure , . Incidence of hypertension in the international cooperative study  of intracranial aneurysm was 21%. In our study, 40% patients of endovascular coiling group and 34% patients of surgical clipping group had hypertension at the time of presentation in preoperative period and incidence was significantly higher in the INR group. In them, significantly more patients were known hypertensive (22%) in comparison to surgically treated patients (12%), which was similar to the finding by Lai and Manninen  .
Incidence of benign cardiac arrhythmias and conduction abnormalities in patients with SAH has been recorded from 30 to 90% and 7.5% respectively in previous studies , . When indicated, cardiac troponin-I levels should be drawn to determine the clinical significance of these abnormalities  . These ECG changes are independent of whether the patients have a pre-existing cardiac disease or not. This supports the contention that the ECG changes are a direct consequence of the SAH  . Serious arrhythmias are more likely to occur in patients with advanced age, hypokalemia, and prolonged QT interval. Therefore, continuous ECG monitoring is recommended in all patients with SAH[ 17],, . Despite significantly higher incidence of comorbid illnesses in endovascular treated patients, there were no differences of SAH grades in both the groups in terms of Modified Hunt and Hess, WFNS and Fisher's grading.
According to an international study of unruptured intracranial aneurysms  , in patients with no history of subarachnoid hemorrhage, the five-year cumulative rate of rupture of aneurysms located in the internal carotid artery, anterior communicating artery, anterior cerebral artery, or middle cerebral artery is zero for aneurysms under 7 mm, 2.6 percent for 7 to 12 mm, 14.5 percent for 13 to 24 mm, and 40 percent for 25 mm or more. This rate is lower in contrast to rupture rates for the same sizes of aneurysms in the posterior circulation and posterior communicating artery. In our study, more patients with unruptured aneurysm were treated by INR treatment (26%) as compared to surgical clipping (8%). Justification for the choice to select the endovascular treatment for small, unruptured aneurysm is that it has been proven to be associated with low morbidity and mortality in previous literature  . In our study, patients with unruptured aneurysm had no significant difference in clinical good outcome in terms of GOS in both INR and SC group (P=0.06). This could be misleading as most of unruptured aneurysm patients selected for INR treatment were either because of anticipated surgical difficulty or located in posterior circulation.
In international cooperative study for the timing of aneurysm surgery, outcome was worse when surgery was performed between 7 to 10 days of ictus, but early surgery was found to be neither hazardous nor beneficial as compared to delayed surgery. Data from North American centres show best results with surgery done within three days of SAH  . In our centre the usual practice is to do early definitive treatment of a ruptured aneurysm. In our study, endovascularly treated patients had their procedures performed 22 days after the ictus on an average, as compared to the surgical group (7days). Since our hospital is a referral centre, there could have been delays in the referral and transfer process of these SAH patients. Delay in endovascularly treated patients could be because these patients had more medical problems, which required stabilization. Furthermore, endovascular procedure involves higher expenditure than surgical clipping.
Ability to assess the neurological status of patients immediately at the end of the procedure is desirable following a neurosurgical procedure. In our review, significantly higher numbers of patients were extubated in the endovascular group (87%) compared to the surgical group (77%) (P=0.032). This could either be because of residual effects of anaesthetic agents at the end of procedure, intraoperative events like aneurysm rupture, or because of brain handling. This brain handling is absent in INR group. In addition, incidence of aneurysmal rupture during the procedure is also extremely low in INR group. In several previous studies an unfavourable impact on outcome from intraoperative aneurysm rupture has been documented , . In our study, incidence of intraoperative rupture of aneurysm occurred in one patient during endovascular coiling and sixteen patients during surgical clipping. In the present surgical series, intraoperative aneurysm rupture was (16%) similar to previous studies , . The risk of intra-procedural perforation related to endovascular embolization in our study (1%) was comparable with the findings of a meta-analysis (0.5%)  and a recent study of Qureshi et al (2.3%)  . in which 14% of patients with aneurysm experienced procedure-related complications, which agrees with our finding (17%) These were comparable with the previous reports , . Thromboembolic events are the most common complication during the endovascular treatment of aneurysm and also most important cause of permanent morbidity. In spite of systemic heparinization, this may happen during any part of the procedure, such as when the guide catheter is inserted into the main artery, at microcatheterization, when coils are placed into or withdrawn from the aneurysm sac, and in case of coil protrusion or migration. Predisposing factors for thromboembolic complications are wide neck aneurysm, loose filling of the aneurysm, coil prolapse into the parent artery and various rare coagulation disorders like heparininduced thrombocytopenia and antiphospholipid antibody syndrome  . In our study incidence of thromboembolism was 4%, which is comparable to reported 2.5 to 11% in literature , . Cerebral vasospasm was observed in nine patients during the endovascular procedure. Intra-arterial nimodipine and nitroglycerine were used to relieve the vasospasm. Arterial dissection was seen in one patient, but no morbidity developed and clinical outcome was good (GOS I). The case in which microcatheter broke, there was dense hemiplegia (GOS 3) due to thromboembolism and occlusion of anterior choroidal artery. Two patients in postoperative period developed puncture site hematoma needing surgical evacuation.
In our study postoperative patients in surgical clipping developed significantly more neurological and systemic complications in comparison to those who underwent endovascular coiling. Nine patients deteriorated day after an uneventful surgical clipping compared to only one patient in INR group. These results were similar to that described in Niskanen et al study  . Vast majority of patients experience a systemic complication, which could be severe in 40% of cases  . The most common medical complications include pulmonary edema in 23% (either cardiogenic or neurogenic with the acute respiratory distress syndrome), cardiac arrhythmias in 35%, and electrolyte disturbances in 28% of patients. Hyponatremia can be caused by inappropriate secretion of antidiuretic hormone (normal or increased intravascular volume) or cerebral salt wasting (low intravascular volume) , . In our study, in surgical clipping group significant electrolyte disturbances (14%) and systemic infection (6%) developed, but not in INR group.
In endovascular treatment for intracranial aneurysm in most circumstances, 90 to 100% occlusion is required to provide sufficient protection against rebleeding by excluding flow to the aneurysm fundus, which is most common site of rupture. Occlusion of less than 50% of the aneurysm is less likely to be sufficient in terms of rebleeding protection  . In our study, degree of endovascular occlusion was complete (100%) to near complete (90-99%) in 80%, partial (50-90%) in 18 %, failed in two cases. Not a single patient developed rebleeding after endovascular treatment up to the hospital stay. In the surgical group, clipping of the aneurysm was successful in all patients. According to clinical criteria, early results of endovascular treatment are as good as or better than the results reported for neurosurgical clipping. This has been shown in retrospective, as well as prospective series of patients with aneurysms in the anterior and posterior circulation, as well as in patients with unruptured aneurysm ,,,, . In our study too, an overall good to fair outcome at discharge was better in patients treated with endovascular coiling as compared to surgical.
However, there are certain limitations to ours study. It was not a prospective study. Like all retrospectives studies we too feel data available was not comprehensive, that is some data were missing from the patients records. A direct comparison of endovascular treated patients with surgically treated patients may be misleading, because majority of patients in the present study were different in type of aneurysm and way of selection in either group. Some important complications and problems may not have been documented in each group.
To conclude, In our study, patient selection in either group was entirely different, but overall outcome in patients who underwent endovascular coiling (in terms of Glasgow outcome scale) was significantly better then surgical clipping. Most of the time, whatever complications occurred during the procedure were related to the procedure itself. So a more refined research and development is needed in either of technologies for further improvement of patients' outcome.
| References|| |
|1.||Bendo AA. Intracranial vascular surgery. Anesthesiol Clin N Am 2002; 20: 377-88. |
|2.||Molyneux A, Kerr R, Stratton I, Sandercock P, Clarke M, Shrimpton J, Holman R; International Subarachnoid Aneurysm Trial (ISAT) Collaborative Group. International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised trial. Lancet 2002; 360: 1267-74. |
|3.||Young WL, Pile-Spellman J. Anesthetic considerations for interventional neuroradiology. Anesthesiology 1994; 80:427-56. [PUBMED] [FULLTEXT] |
|4.||Lai YC, Manninen PH. Anesthesia for cerebral aneurysms: a comparison between interventional neuroradiology and surgery. Can J Anesth 2001; 48: 391-95. [PUBMED] |
|5.||Lam AM. Cerebral aneurysms: Anesthetic considerations In: Cottrell JE, Smith DS, editors. Anesthesia and neurosurgery. 4th edition. St. Louis: Mosby 2001: 367-97. |
|6.||Jennett B, Bond M. Assessment of outcome after severe brain damage. Lancet 1975; 1: 480-84. [PUBMED] |
|7.||Koivisto T, Vanninen R, Hurskainen H, Saari T, Hernesniemi J, Vapalahti M. Outcomes of early endovascular versus surgical treatment of ruptured cerebral aneurysms. A prospective randomized study. Stroke 2000; 31: 2369-77. [PUBMED] [FULLTEXT] |
|8.||Ogilvy CS. Neurosurgical clipping versus endovascular coiling of patients with ruptured intracranial aneurysms. Stroke. 2003; 34: 2540- 42. [PUBMED] [FULLTEXT] |
|9.||Lusseveld E, Brilstra EH, Nijssen PC, van Rooij WJ, Sluzewski M, Tulleken CA, Wijnalda D, Schellens RL, van der Graaf Y, Rinkel GJ. Endovascular coiling versus neurosurgical clipping in patients with a ruptured basilar tip aneurysm. J Neurol Neurosurg Psychiatry 2002; 73: 591-93. [PUBMED] [FULLTEXT] |
|10.||Schievink WI. Intracranial aneurysms. N Engl J Med 1997; 336: 28-40. [PUBMED] [FULLTEXT] |
|11.||Webb ST, Farling PA. Survey of arrangements for anaesthesia for interventional neuroradiology for aneurysmal subarachnoid haemorrhage. Anaesthesia 2005; 60: 560- 64 |
|12.||Kapoor K, Kak VK. Incidence of intracranial aneurysms in north-west Indian population. Neurol Ind 2003; 51: 22-6. |
|13.||Hanel RA, Lopes DK, Wehman JC, Sauvageau E, Levy EI, Guterman LR, Hopkins LN. Endovascular treatment of intracranial aneurysms and vasospasm after aneurysmal subarachnoid hemorrhage. Neurosurg Clin N Am 2005; 16: 317-53. |
|14.||Teunissen LL, Rinkel GJ, Algra A, van Gijn J. Risk factors for subarachnoid hemorrhage: a systematic review. Stroke 1996; 27: 544-49. [PUBMED] [FULLTEXT] |
|15.||Feigin V, Parag V, Lawes CM, Rodgers A, Suh I, Woodward M, Jamrozik K, Ueshima H. Asia Pacific Cohort Studies Collaboration. Smoking and elevated blood pressure are the most important risk factors for subarachnoid hemorrhage in the AsiaPacific region: an overview of 26 cohorts involving 306,620 participants. Stroke 2005; 36: 1360- 65. |
|16.||Haley EC Jr, Kassell NF, Torner JC. The International Cooperative Study on the Timing of Aneurysm Surgery. The North American experience. Stroke 1992; 23: 205-14. [PUBMED] [FULLTEXT] |
|17.||Khechinashvili G, Asplund K. Electrocardiographic changes in patients with acute stroke: a systematic review. Cerebrovasc Dis 2002; 14: 67-76. [PUBMED] [FULLTEXT] |
|18.||Kawasaki T, Azuma A, Sawada T, Sugihara H, Kuribayashi T, Satoh M, Shimizu Y, Nakagawa M. Electrocardiographic score as a predictor of mortality after subarachnoid hemorrhage. Circ J 2002 ; 66: 567-70. [PUBMED] [FULLTEXT] |
|19.||Naidech AM, Kreiter KT, Janjua N, Ostapkovich ND, Parra A, Commichau C, Fitzsimmons BF, Connolly ES, Mayer SA. Cardiac troponin elevation, cardiovascular morbidity, and outcome after subarachnoid hemorrhage. Circulation 2005 ; 112: 2851-56. [PUBMED] [FULLTEXT] |
|20.||Banki NM, Kopelnik A, Dae MW, Miss J, Tung P, Lawton MT, Drew BJ, Foster E, Smith W, Parmley WW, Zaroff JG. Acute neurocardiogenic injury after subarachnoid hemorrhage. Circulation 2005; 112: 3314-19. [PUBMED] [FULLTEXT] |
|21.||Niskanen M, Koivisto T, Rinne J, Ronkainen A, Pirskanen S, Saari T, Vanninen R. Complications and postoperative care in patients undergoing treatment for unruptured intracranial aneurysms. J Neurosurg Anesthesiol 2005; 17:100-5. [PUBMED] [FULLTEXT] |
|22.||Whitfield PC, Kirkpatrick PJ. Timing of surgery for aneurysmal subarachnoid hemorrhage. Cochrane Database Syst Rev 2001; 2:CD001697. [PUBMED] [FULLTEXT] |
|23.||Liu AY, Lopez JR, Do HM, Steinberg GK, Cockroft K, Marks MP. Neurophysiological monitoring in the endovascular therapy of aneurysms. Am J Neuroradiol 2003; 24:1520-27. [PUBMED] [FULLTEXT] |
|24.||Raaymakers TW, Rinkel GJ, Limburg M, Algra A. Mortality and morbidity of surgery for unruptured intracranial aneurysms: a meta-analysis. Stroke 1998; 29:1531-38. [PUBMED] [FULLTEXT] |
|25.||Qureshi AI, Suri MF, Khan J, Kim SH, Fessler RD, Ringer AJ, Guterman LR, Hopkins LN. Endovascular treatment of intracranial aneurysms by using Guglielmi detachable coils in awake patients: safety and feasibility. J Neurosurg 2001; 94:880-85. [PUBMED] [FULLTEXT] |
|26.||Solenski NJ, Haley EC Jr, Kassell NF, et al. Medical complications of aneurysmal subarachnoid hemorrhage: a report of the multicenter, cooperative aneurysm study. Crit Care Med 1995; 23:1007-17. [PUBMED] [FULLTEXT] |
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]