Role of intraoperative angiography in the surgical treatment of cerebral aneurysms

Current Indications for Aneurysm Surgery

Treatment of cerebral aneurysm has changed greatly over the last several years. Although surgery was the treatment of choice for decades, coiling is coming into more prevalent use now. This article highlights when each modality should be used.

Prospective evaluation of surgical microscope—integrated intraoperative near-infrared indocyanine green videoangiography during aneurysm surgery

Object. The authors prospectively compared a new technique of surgical microscope-based indocyanine green (ICG) videoangiography with intraoperative or postoperative digital subtraction (DS) angiography.

Method. The technique was performed during 187 surgical procedures in which 124 aneurysms in 114 patients were clipped. Using a newly developed setup, the ICG technique has been integrated into an operating microscope (Carl Zeiss Co., Oberkochen, Germany). A microscope-integrated light source containing infrared excitation light illuminates the operating field. The dye is injected intravenously into the patient, and intravascular fluorescence from within the blood vessels is imaged using a video camera attached to the microscope. The patency of parent, branching, and perforating arteries and documentation of clip occlusion of the aneurysm as shown by ICG videoangiography were compared with intraoperative or postoperative findings on DS angiography.

The results of ICG videoangiography corresponded with intra- or postoperative DS angiography in 90% of cases. The ICG technique missed mild but hemodynamically irrelevant stenosis that was evident on DS angiography in 7.3% of cases. The ICG technique missed angiographically relevant findings in three cases (one hemodynamically relevant stenosis and two residual aneurysm necks [2.7% of cases]). In two cases the missed findings were clinically and surgically inconsequential; in the third case, a 4-mm residual neck may require a second procedure. Indocyanine green videoangiography provided significant information for the surgeon in 9% of cases, most of which led to clip correction.

Conclusions. Microscope-based ICG videoangiography is simple and provides real-time information about the patency of vessels of all sizes and about the aneurysm sac. This technique may be useful during routine aneurysm surgery as an independent form of angiography or as an adjunct to intra- or postoperative DS angiography.

Clipping or coiling of cerebral aneurysms

The management of a patient with a cerebral aneurysm is complex, and two accepted treatment modalities are now available. The superiority of either of the treatment options has not been defined, but data are now available with regard to the safety and efficacy of each modality and can be used to decide what is best for individual patients when combined with other important variables, such as the patient's expected longevity, specific aneurysm factors (eg, size, dome-to-neck ratio, location), and operator's experience. This complex decision entertaining all the variables should ensure that patients receive the most appropriate care. New developments in the endovascular management of cerebral aneurysms are likely to alter this algorithm.

Clip readjustment in aneurysm surgery after flow evaluation using the ultrasonic perivascular probe: case report

Occlusion or stenosis of a parent vessel or its distal branches is a major cause of poor patient outcome after cerebral aneurysm surgery. Despite great attempts to preserve patency at the time of clip application, intraoperative visual observation may not reveal arterial compromise or occlusion. Quantitative measurement of blood flow in cerebral vessels during aneurysm surgery can help prevent ischaemia and improve patient outcome. We report a case of a large complex middle cerebral artery (MCA) aneurysm in which perivascular microflow probes were used to measure blood flow quantitatively in MCA and its branches before and after aneurysm clipping. Following aneurysm clipping, blood flow in the MCA branches were significantly reduced to less than its initial baseline value with occlusion of the inferior M2 segment. Prompt detection of compromised blood flow gave the surgeon the opportunity to adjust the clip. This adjustment was performed several times until restore MCA flow to its preclipping values. Intraoperative quantitative vessel-flow measurements were safe and may have prevented cerebral ischaemia and neurological deficit to this patient.

RESULTS OF A PROSPECTIVE PROTOCOL OF COMPUTED TOMOGRAPHIC ANGIOGRAPHY IN PLACE OF CATHETER ANGIOGRAPHY AS THE ONLY DIAGNOSTIC AND PRETREATMENT PLANNING STUDY FOR CEREBRAL ANEURYSMS BY A COMBINED NEUROVASCULAR TEAM

OBJECTIVE

At many centers, patients undergo both computed tomographic angiography (CTA) and digital subtraction angiography (DSA). This practice negates most of the advantages of CTA, and it renders the risks and disadvantages of the two techniques additive. Previous reports in the literature have assessed the sensitivity and specificity of CTA compared with DSA; however, these investigations have not analyzed the clinical implications of a protocol that replaces DSA with CTA as the only diagnostic and pretreatment planning study for patients with cerebral aneurysms.

METHODS

Since late 2001/early 2002, the combined neurovascular unit of the Massachusetts General Hospital has adopted a prospective protocol of CTA in place of DSA as the only diagnostic and pretreatment planning study for patients with cerebral aneurysms (ruptured and unruptured). We report the results obtained during the 12-month period from January 2002 to January 2003.

RESULTS

During the study period, 223 patients with cerebral aneurysms underwent initial diagnostic evaluation for cerebral aneurysm by the combined neurovascular team of Massachusetts General Hospital. Of the 223 patients, 109 patients had confirmed subarachnoid hemorrhage (Group A) and 114 patients did not have SAH (Group B). All of these patients were included in the prospective CTA protocol. Cerebral aneurysm treatment was initiated on the basis of CTA alone in 93 Group A patients (86%), in 89 Group B patients (78%), and in 182 patients (82%) overall. Treatment consisted of surgical clipping in 152 patients (68%), endovascular coiling in 56 patients (25%), endovascular parent artery balloon occlusion in 4 patients (2%), and external carotid artery to internal carotid artery bypass and carotid artery surgical occlusion in 2 patients (1%). Nine patients (4%) did not undergo treatment. The cerebral aneurysm detection rate by CTA was 100% for the presenting aneurysm (ruptured aneurysm in Group A or symptomatic/presenting aneurysm in Group B) in both groups. The detection rate by CTA for total cerebral aneurysms, including incidental multiple aneurysms, was 95.3% in Group A, 98.3% in Group B, and 97% overall. The overall morbidity associated with DSA (pretreatment or as intraoperative or postoperative clip evaluation) was one patient (1.3%) with a minor nonneurological complication, one patient (1.3%) with a minor neurological complication, and no patients (0%) with a major neurological complication.

CONCLUSION

We have demonstrated promising results with a prospective protocol of CTA in place of DSA as the only diagnostic and pretreatment planning study for patients with ruptured and unruptured cerebral aneurysms. It seems safe and effective to make decisions regarding treatment on the basis of CTA, without performing DSA, in the majority of patients with ruptured and unruptured cerebral aneurysms.

Intraoperative Cerebral Angiography: Superficial Temporal Artery Method and Results

OBJECTIVE

To report the method for and results of intraoperative cerebral angiography performed via the superficial temporal artery, for assessment of cerebral aneurysm surgery.

METHODS

All patients undergoing craniotomies for treatment of intracranial aneurysms were prospectively entered into a database. A policy of performing angiography via the superficial temporal artery in appropriate cases was instituted. This procedure was performed with retrograde catheterization of the superficial temporal artery, as it coursed over the zygomatic arch, with an 18-gauge, 1.88-inch, intravenous catheter and hand injection of contrast material, with intraoperative digital subtraction fluoroscopic guidance.

RESULTS

Thirty-six patients who underwent 38 craniotomies for clipping of 43 aneurysms underwent intraoperative angiography via the superficial temporal artery. There were six unexpected findings (14%), including four unexpected arterial occlusions and two unexpected residual aneurysms. One aneurysm was observed to be patent when it was punctured, after intraoperative angiography had indicated no filling of the aneurysm. Additional clips were placed. Three patients (8%) developed multiple arterial infarctions in the territory of the injected carotid artery, for which multiple causes were possible. Adequate angiographic images could usually be obtained with this method.

CONCLUSION

Intraoperative angiography via the superficial temporal artery is simple and is not associated with substantial complications. It is a reasonable alternative to transfemoral angiography for detection of adverse consequences of intracranial aneurysm clipping.

Near-infrared indocyanine green video angiography: a new method for intraoperative assessment of vascular flow

OBJECTIVE

We report our initial clinical experience with a new method for intraoperative blood flow assessment. The purposes of the study were to assess the use of indocyanine green (ICG) video angiography in neurovascular cases, to assess the handling and image quality, to compare the findings with postoperative angiographic results, and to evaluate the clinical value of the method in a preliminary feasibility study.

METHODS

Fourteen patients with aneurysms (n = 12) or spinal (n = 1) or intracranial (n = 1) dural fistulae were included. Before and/or after aneurysm or dural fistula occlusion, ICG (25 mg) was injected intravenously. A near-infrared laser excitation light source (lambda = 780 nm) illuminated the operating field. The intravascular fluorescence of ICG (maximal lambda = 835 nm) was recorded by a nonintensified video camera, with optical filtering to block ambient and laser light for collection of only ICG-induced fluorescence.

RESULTS

A total of 21 investigations were performed for 14 patients. For the 17 successful ICG video angiographic investigations, image quality and resolution were excellent, allowing intraoperative real-time assessment of the cerebral circulation. ICG angiographic results could be divided into arterial, capillary, and venous phases, comparable to those observed with digital subtraction angiography. In all cases, the postoperative angiographic results corresponded to the intraoperative ICG video angiographic findings. In three cases, the information provided by intraoperative ICG angiography significantly changed the surgical procedure.

CONCLUSION

ICG video angiography is simple and provides real-time information on the patency of arterial and venous vessels of all relevant diameters, including small and perforating arteries (<0.5 mm), and the visible aneurysm sac. It may be a useful adjunct to improve the quality of neurovascular procedures and to document the intraoperative vascular flow.

Selective intraoperative angiography in intracranial aneurysm surgery: intraoperative factors associated with aneurysmal remnants and vessel occlusions

BACKGROUND

The objective of this study was to assess the role of selective intraoperative angiography and to analyze the factors associated with faulty clip application.

METHODS

Two hundred thirty-eight patients undergoing surgery for intracranial aneurysms were studied consecutively for intraoperative angiography (IOA)-related events. The procedure was performed in 155 operations. Demographic details, clinical grade of the patient, location and size of the aneurysm, intraoperative rupture, application of the temporary clip, IOA findings, and final outcome were analyzed.

RESULTS

In the 155 patients in the series, there were 125 anterior circulation aneurysms and 30 on the vertebrobasilar system. Aneurysms were smaller than 10 mm in 63% of the patients, and 19 were giant aneurysms. Thirty-eight percent were unruptured, 36% were Hunt and Hess Grades I and II, 21% were Grade III, and 5% were Grades IV and V. An intraoperative rupture occurred in 18 operations. Intraoperative angiography was normal in 88%; in 11 cases (7%) there was a residual neck, and in 8 (5%), occlusion of the artery was observed. An incomplete clipping was significantly related to intraoperative rupture of the aneurysm (p < 0.008) and anterior location of the aneurysm (p = 0.05), whereas vessel occlusion had a significant association with posterior location of the aneurysm (p < 0.0005). An eventful IOA had significant association with poor outcome (p < 0.003).

CONCLUSION

Intraoperative rupture and a posterior location of the aneurysm had a significant correlation with residual aneurysm and vessel occlusion, respectively. The use of IOA is justified in aneurysms associated with these factors.

Modified, multipurpose, radiolucent sugita head frame for intraoperative cerebral angiography

OBJECTIVE

Although several radiolucent head-fixation devices have been developed to allow intraoperative cerebral angiography, no device provides satisfactory freedom to obtain the most suitable head position. We recently designed a multipurpose radiolucent Sugita head frame (modified radiolucent Sugita frame) with satisfactory degrees of freedom and rigidity for intraoperative head positioning and head holding, respectively.

DESCRIPTION OF INSTRUMENTATION

A short arm and a ring joint, made of engineering plastic, were added to the prototype radiolucent Sugita frame, to permit side-tilting movements of the frame. The shape of all handles at the joints was also changed and the size was enlarged, to facilitate adjustment of the head position.

EXPERIENCE AND RESULTS

We used this modified radiolucent Sugita frame in 20 cases involving aneurysms or arteriovenous malformations. The frame performed satisfactorily in all cases, in terms of firm head fixation and unrestrained freedom of head positioning at the surgeon's request. The modified radiolucent Sugita frame was evaluated with respect to its resistance to physical forces. The physical strength of the modified radiolucent Sugita frame is almost equivalent to that of the metallic Sugita frame and is considered sufficient for clinical usage.

CONCLUSION

With its rigidity, satisfactory degrees of freedom, and ease of handling, the clinical applicability of the dramatically improved radiolucent head frame enables us to obtain satisfactory intraoperative angiograms.

Routine intraoperative angiography during aneurysm surgery

OBJECT

The routine use of intraoperative angiography as an aid in the surgical treatment of aneurysms is uncommon. The advantages of the ability to visualize residual aneurysm or unintended occlusion of parent vessels intraoperatively must be weighed against the complications associated with repeated angiography and prolonged vascular access. The authors reviewed the results of their routine use of intraoperative angiography to determine its safety and efficacy.

METHODS

Prospectively gathered data from all aneurysm cases treated surgically between January 1996 and June 2000 were reviewed. A total of 303 operations were performed in 284 patients with aneurysms; 24 patients also underwent postoperative angiography. Findings on intraoperative angiographic studies prompted reexploration and clip readjustment in 37 (11%) of the 337 aneurysms clipped. Angiography revealed parent vessel occlusion in 10 cases (3%), residual aneurysm in 22 cases (6.5%), and both residual lesion and parent vessel occlusion in five cases (1.5%). When compared with subsequent postoperative imaging, false-negative results were found on two intraoperative angiograms (8.3%) and a false-positive result was found on one (4.2%). Postoperative angiograms obtained in both false-negative cases revealed residual anterior communicating artery aneurysms. Both of these aneurysms also subsequently rebled, requiring reoperation. In the group that underwent intraoperative angiography, in 303 operations eight patients (2.6%) suffered complications, of which only one was neurological.

CONCLUSIONS

In the surgical treatment of intracranial aneurysms, the use of routine intraoperative angiography is safe and helpful in a significant number of cases, although it does not replace careful intraoperative inspection of the surgical field.

Intraoperative angiography during aneurysm surgery: a prospective evaluation of efficacy

OBJECT

Indications for intraoperative angiography during aneurysm surgery remain unclear. To define its use, the authors report the results of a prospective study in which this modality was used in all patients undergoing surgery for intracranial aneurysms.

METHODS

Intraoperative angiography was performed prospectively in the surgical treatment of 517 consecutive aneurysms regardless of the lesion's location, size, or complexity. In 64 (12.4%) of 517 aneurysms intraoperative angiography findings prompted a change in surgical treatment. Residual aneurysm (47%) was the most frequent finding leading to clip revision. In 44% of cases, intraoperative angiography revealed vessel compromise. Surgery for aneurysms of the proximal internal carotid artery (ICA) was the most frequently altered, with lesions located at the superior hypophyseal artery (SHA) and clinoidal region having the highest revision rates, eight (40%) of 20 and eight (44%) of 18, respectively. Aneurysm size predicted the need for revision; giant aneurysms (> 24 mm) underwent revision in nine (29%) of 31 cases, whereas large aneurysms (15-24 mm) were revised in 12 (22%) of 54 cases. In a multivariate logistic regression model, factors related to increased revision rates included the SHA and clinoidal locations, as well as giant and large size. Ninety-five patients underwent both intraoperative and postoperative angiography. Five discrepancies were noted (95% accuracy); four were flow-related and one involved a previously unrecognized residual aneurysm. Complications attributable to intraoperative angiography occurred in 0.4% of cases.

CONCLUSIONS

Proximal ICA location and large aneurysm size significantly predicted revision of surgery following intraoperative angiography. Unexpected findings, even in less complex locations, are frequently identified on intraoperative angiography. Low complication rates, high accuracy, and the unexpected need for clip readjustments favor a more widespread use of intraoperative angiography.

Intraoperative angiography evaluation of the microsurgical clipping of unruptured cerebral aneurysms

Intraoperative angiography evaluation of the clippings of cerebral aneurysms was investigated in a series of 38 consecutive patients with unruptured cerebral aneurysms to determine any favorable impact on the outcome. Unexpected findings including major arterial occlusion or residual aneurysm were identified. Specific variables such as the size and site of aneurysm were analyzed to determine the impact on clinical outcome and the incidence of clip modification. There were 11 large and 27 small aneurysms in this series. Mortality and permanent morbidity after microsurgical clipping were 0.0% and 2.6%, respectively. Unexpected angiographic findings necessitating clip repositioning consisted of residual aneurysm in two cases and distal branch occlusion or parent vessel stenosis in four. The need for clip modification was significantly higher for large than for small aneurysms (p = 0.007), and the rate of clip adjustment increased with increasing aneurysm size (p = 0.008). Intraoperative assessment prior to wound closure allows for the recognition and correction of defects and decreases the risk of postoperative complications. Intraoperative angiography may become important in the microsurgical clipping of unruptured cerebral aneurysms, especially large aneurysms.

Endovascular therapy for intracranial aneurysms: a historical and present status review

Beginning in the 1960s, neurosurgeons and radiologists have made attempts to treat intracranial aneurysms using nonclip techniques. The evolution of such therapy has included acrylics, metallic particles, balloons, electric current, and nondetachable and detachable coils. This article will chronologically review these various techniques and the papers that reported their results so that the reader can understand how endovascular therapy developed and the position it currently holds in the treatment of intracranial aneurysms.

Intraoperative angiography for emergency cerebrovascular surgery using an exclusively developed radiolucent Sugita head frame and fixation

Intraoperative angiography during emergency cerebrovascular surgery, clipping operation for acute aneurysmal subarachnoid hemorrhage, is reported. For acquisition of intraoperative angiography, an exclusively developed radiolucent version of a Sugita head frame, made of engineering plastics for angiography, and an ordinary fluoroscopic unit were installed. In a radiolucent head frame, all the parts of the ordinary metallic Sugita multipurpose head frame, fixation and its accessories were made of high-molecular polymer plastics in the same size. In emergency cerebrovascular surgery, the radiolucent Sugita frame enabled us to carry out meticulous dissection and precise retraction control as the ordinary metallic system and to perform the intraoperative angiography if needed.

Quantitative assessment of vessel flow integrity for aneurysm surgery. Technical note

Quantitative measurement of blood flow in cerebral vessels during aneurysm surgery can help prevent ischemic injury and improve patient outcome. The authors report a case of a superior cerebellar artery (SCA) aneurysm in which perivascular microflow probes were used to measure blood flow quantitatively in both the SCA and the posterior cerebral artery before and after aneurysm clipping. Following aneurysm clipping, blood flow in the SCA was reduced to less than 25% of its initial baseline value. Prompt detection of compromised blood flow gave the surgeon the opportunity to adjust the clip and restore SCA flow to its preclipping value within 5 minutes of initial clip placement. Quantitative vessel-flow measurements were integral to the safe progression of the operation and may have prevented an adverse neurological outcome in this patient. The recommended surgical technique and the principle of operation are described.

Aneurysmal intracerebral hemorrhage: Clinical outcome after emergent surgical treatment

BACKGROUND

Management guidelines and recovery potentials for individuals presenting with poor clinical condition owing to an aneurysmal intracerebral hemorrhage are not well established.

METHODS

We assessed the outcome of a consecutive series of 6 patients with aneurysmal intracerebral hemorrhages presenting with Hunt and Hess clinical grade IV or V selected to undergo emergent hematoma evacuation and aneurysm clip obliteration. Their presenting clinical condition and neuroradiology were assessed, as well as early surgical results and follow-up outcome.

RESULTS

The 2 women and 4 men were 30 to 59 years old. All 6 patients had profound neurological deficits on admission, with Glasgow Coma Scale scores of 4 to 9. Aneurysmal intracerebral hemorrhage diameters measured from 6 to 8 cm and were associated with 5 to 15 mm of midline shift. Surgical intervention was initiated within 3 hours of ictus in 5 patients and within 7 hours in one patient. All 6 patients survived, demonstrated clinical improvement postoperatively, and were transferred to rehabilitation centers 19 to 30 days after presentation. The Glasgow Outcome Scores were 2 to 3 with a minimum follow-up interval of 12 months. Four patients returned home and resumed independent activities of daily living; one required partial supervision. One patient remained in a chronic care facility.

CONCLUSION

An acute management protocol, including aggressive neurosurgical intervention, with craniotomy for hematoma evacuation and aneurysm clip obliteration, can result in good neurological outcome in carefully selected, poor-grade patients with aneurysmal intracerebral hemorrhage.