Changes in Brain Volume 2 Years after Extracranial-Intracranial Bypass Surgery: A Preliminary Subanalysis of the Japanese EC-IC Trial

Pseudo-continuous arterial spin labeling with short post-labeling delay time sensitively reflects the hemodynamics of symptomatic patients with permanent large vessel occlusion before and after revascularization

BACKGROUND AND PURPOSE

This study evaluated the feasibility of arterial spin labeling (ASL) for diagnosing hemodynamic stroke due to permanent anterior circulation large vessel occlusion.

METHODS

Three-dimensional pseudo-continuous ASL data at two post-labeling delay (PLD) times (1.5 and 2.5 s) in patients with unilateral permanent middle cerebral artery (MCA) segment 1 (M1) or internal cerebral artery (ICA) occlusion were acquired during routine magnetic resonance angiography. Sixty-one patients with symptomatic occlusion (M1, 24; ICA, 37) and 69 patients with asymptomatic occlusion (M1, 21; ICA, 48) were enrolled. Regions of interest were automatically placed in the MCA region using a template. The respective scans were compared with asymptomatic M1 or ICA occlusion scans. The ratio of signal intensity (occlusion side/non-occlusion side) in the perfusion area of MCA (asymmetry index [AI]) was compared between both groups.

RESULTS

In both PLD groups, AI was significantly lower in symptomatic patients than in asymptomatic patients. The receiver operating characteristic curve showed moderate capacity for the prediction of symptomatic AI in both groups (area under the curve, 0.739 and 0.712, respectively). As a result of extracranial-intracranial bypass operation in 28 symptomatic (M1, eight; ICA, 20) patients, AI was significantly higher postoperatively in the PLD 1.5 s group than in the PLD 2.5 s group.

CONCLUSION

In symptomatic patients with permanent large vessel occlusion, the signal intensity ratio of pseudo-continuous ASL with short PLD sensitively reflects the hemodynamics before and after revascularization; therefore, this technique may be an alternative method in situations where PET or SPECT cannot be performed.

Superficial Temporal Artery: Middle Cerebral Artery Bypass, Our Series of 20 Cases, Surgical Technique and Indications with Illustrative Cases

The first extracranial-intracranial (EC-IC) bypass surgery was performed by professor Yasargil in 1967 since then this procedure has been widely used in vascular neurosurgery and sometimes, in tumors excision when a vascular sacrifice is necessary. In this article, we will illustrate the surgical technique of the superficial temporal artery-middle cerebral artery (STA-MCA) bypass with two cases; a 59-year-old male and 64-year-old female who presented with an occlusion of the MCA. The male presented also with a posterior communicating artery-IC aneurysm which was clipped in the same sitting. We also studied in this paper a series of 20 patients operated in Banbuntane Hotokukai Hospital, Fujita Health University, for which a low-flow STA-MCA anastomosis was done for steno-occlusive disease or moyamoya disease. In Banbuntane Hotokukai Hospital, Fujita Health University, 20 patients were operated since 2015, 12 patients were male. Five patients presented with moyamoya disease, while 15 patients presented with vascular steno-occlusive disease. The steno-occlusion was found in internal carotid artery in nine patients. The patients were divided into two categories (steno-occlusive disease and moyamoya). STA-MCA bypass is now one of the basic techniques to master in vascular neurosurgery. It requires to perform the anastomosis correctly within the permissible time. The goal is to have a long-term patency for the anastomosed vessel.

Factors related to improvement of cerebrovascular reserve after superficial temporal artery to middle cerebral artery anastomosis for patients with atherosclerotic steno-occlusive disease

BACKGROUND

This study aimed to investigate factors related to improvement of hemodynamics and evaluated the usefulness of intraoperative Doppler for predicting postoperative hemodynamics in patients with cerebrovascular atherosclerotic steno-occlusive disease (CASD) of the internal carotid artery (ICA) or middle cerebral artery (MCA) who were treated with extracranial-intracranial (EC-IC) bypass surgery.

METHOD

Forty-eight patients with CASD of the ICA or MCA who were treated by superficial temporal artery to middle cerebral artery bypass with a follow-up longer than 12 months were enrolled. Repeated transient ischemic attack or completed ischemic stroke was observed under optimal medical therapy in all patients. Intraoperative blood flow velocity of the MCA was evaluated by a Doppler flowmeter. Cerebral blood flow and cerebrovascular reserve (CVR) were evaluated using N-isopropyl-[¹²³I] p-iodoamphetamine (IMP) single photon emission computed tomography (SPECT) preoperatively and 3 months after surgery. Imaging and clinical data were retrospectively reviewed.

RESULTS

CVR was significantly increased postoperatively (p = 0.03). One year after the operation, two (4.2%) patients developed cerebral infarction. The change in MCA flow velocity just after anastomosis compared with pre-anastomosis proximal and distal of the anastomosis site was a median of 3.0 and 2.6 times, respectively. However, there was no significant association between changes in intraoperative MCA flow velocity and postoperative CVR. Multivariate analysis showed that the presence of a lower estimated glomerular filtration rate (eGFR) was an independent risk factor for a decrease in CVR (p = 0.036).

CONCLUSIONS

A higher eGFR might have prognostic value for improvement in CVR after EC-IC bypass surgery in patients with CASD and misery perfusion.

Intraoperative middle cerebral artery pressure measurements during superficial temporal artery to middle cerebral artery bypass procedures in patients with cerebral atherosclerotic disease

OBJECTIVE

No previous study has monitored middle cerebral artery (MCA) pressure during the superficial temporal artery (STA)-MCA bypass procedure for cerebral atherosclerotic disease. In this paper, the authors describe their method of monitoring MCA pressure and report their initial data on intraoperative MCA pressure and its relationship with hemodynamics prior to and after the bypass procedures.

METHODS

The results from a total of 39 revascularization procedures performed between 2004 and 2014 were analyzed. The patient group included 27 men and 12 women, and their mean age at surgery was 67.6 years (range 39–83 years). The authors investigated the MCA pressure via the STA during STA-MCA bypass procedures. After one branch of the STA was anastomosed to the MCA, the other branch was connected to an arterial line, and a clip was placed temporally on the main STA trunk to monitor the pre-anastomosis MCA pressure. Simultaneously, the radial artery (RA) pressure was determined before removing the temporal clip to measure the post-anastomosis MCA pressure. The relationship between MCA pressures and single photon emission computed tomography findings and the risk factors for hyperperfusion after STA-MCA bypass were analyzed.

RESULTS

The MCA/RA (%) pressure was significantly correlated with that of the resting stenotic/normal side cerebral blood flow (CBF) ratio (%) in the linear regression analysis (slope 1.200, r2 = 0.3564, F = 20.49, p < 0.0001). The intraoperative MCA pressure was 39.3% of RA pressure in patients with Powers' Stage 2 cerebral atherosclerotic disease. After 1 branch of the STA was anastomosed, the intraoperative MCA pressure increased to 75.3% of the RA pressure. The rate of increase in pressure was significantly correlated with the increase in the STA diameter in the linear regression analysis (slope 2.59, r2 = 0.205, F = 9.549, p = 0.0038). Hyperperfusion occurred in 2 cases. When mean values for these 2 patients were compared with those for the 37 patients without hyperperfusion, significant differences were found in the stenotic/normal side CBF ratio (p = 0.0001), pre-anastomosis MCA pressure (p = 0.02), rate of increase in pressure (p = 0.02), pre-anastomotic MCA/RA pressure ratio (p = 0.01), vascular reserve (p = 0.0489), and STA diameter (p = 0.0002).

CONCLUSIONS

The measurement of intraoperative MCA pressure may be a useful technique to assess cerebral perfusion and for predicting the risk of hyperperfusion. Monitoring MCA pressure is recommended during STA-MCA bypass procedures for atherosclerotic disease.

Prediction of the Long-term Efficacy of STA-MCA Bypass by DSC-PI

Superficial temporal artery-middle cerebral artery (STA-MCA) bypass [1,2] is an important and effective type of surgical revascularization that is widely used in the treatment of ischemic cerebral artery disease. However, a means of predicting its postoperative efficacy has not been established [3,4]. The present study analyzes the correlation between preoperative perfusion parameters (obtained using dynamic susceptibility contrast-enhanced perfusion imaging, DSC-PI) and postoperative long-term prognosis (using modified Rankin Scale, mRS scores). The preoperative perfusion parameters were defined by a combination of perfusion-weighted imaging and the Alberta Stroke Program Early Computerized Tomography Score (PWI-ASPECTS) and included cerebral blood flow (CBF)-ASPECTS, cerebral blood volume (CBV)-ASPECTS, mean transit time (MTT)-ASPECTS, and time to peak (TTP)-ASPECTS. Preoperative and postoperative scores were determined for 33 patients that received a unilateral STA-MCA bypass in order to discover the most reliable imaging predictive index as well as to define the threshold value for a favorable clinical outcome. The results showed that all of the PWI-ASPECTS scores were significantly negatively correlated with clinical prognosis. Receiver operating curve (ROC) analysis of the preoperative parameters in relation to long term prognosis showed the area under curve (AUC) was maximal for the CBF-ASPECTS score (P = 0.002). A preoperative score of less than six indicated a poor postoperative prognosis (sensitivity = 74.1%, specificity = 100%, AUC = 0.843). In conclusion, preoperative PWI-ASPECTS scores have been found useful as predictive indexes for the long-term prognosis of STA-MCA bypass patients, with higher scores indicating better postoperative long-term outcomes. As the most valuable prognostic indicator, the preoperative CBF-ASPECTS score has potential for use as a major index in screening and outcome prediction of patients under consideration for STA-MCA bypass surgery.

Fundamental Basis of Scalp Layering Techniques to Protect Against Wound Infection: A Comparative Study Between Conventional and In-to-Out Dissection of the Superficial Temporal Artery

BACKGROUND

Superficial temporal artery (STA) to middle cerebral artery (MCA) bypass is associated with several surgical problems. Despite the vascular patency and hemodynamic changes after the anastomosis, wound problems can be a major surgical complication.

METHODS

In a review of 41 surgical cases of STA-MCA bypass for moyamoya disease or cerebral occlusive vascular disease, we compared the conventional (out-to-in) dissection method for STA (n = 23) with the in-to-out (ITO) dissection method (n = 18) and evaluated the surgical results with respect to wound problems.

RESULTS

The incidence of skin maceration was significantly higher in the conventional dissection group than the ITO dissection group (34.8% vs. 5.5%; P < 0.01). Skin necrosis also showed a higher incidence in the conventional dissection group (39.1%) than the ITO group (22.2%).

CONCLUSIONS

These data suggest that the simple layering technique of the ITO dissection method can protect against contamination from bacteria and reduce postoperative surgical wound problems. Sealing of the galea aponeurotica (first protective barrier), including fibrous septa and loose areolar tissues, including the periosteal layer (second protective barrier), is an important factor to decrease the rate of scalp wound infection.

Bypass surgery for the prevention of ischemic stroke: current indications and techniques

INTRODUCTION

Although most ischemic strokes are thromboembolic in origin and their management is endovascular or medical, some are haemodynamic in origin and their management may be surgical. We reviewed bypass indications, patient selection and surgical techniques used in our current practice.

METHODS

Extracranial-intracranial (EC-iC) bypass with superior temporal artery-to-middle cerebral artery (STA-MCA) bypass, high-flow interposition grafts and reconstructive techniques were used to treat patients with symptomatic ischemia.

RESULTS

During a 13-year period, 152 bypasses were performed for ischemia in 129 patients. Specific diagnoses included: (1) internal carotid artery (iCA) occlusion (58 bypasses); (2) MCA occlusion and, rarely, high-grade MCA stenosis (22 bypasses); (3) vertebrobasilar atherosclerotic steno-occlusive disease (2 bypasses); (4) moyamoya disease (65 bypasses); and (5) ischemic complications after aneurysm treatment (5 bypasses). of the 152 bypasses, 137 were conventional STA-MCA bypasses. fourteen patients had high-flow bypasses that included 4 "double-barrel" STA-MCA bypasses, 6 bypasses with interposition grafts to the cervical carotid artery, 2 subclavian artery-to-MCA bypasses, 1 MCA-to-posterior cerebral artery (PCA) bypass and 1 aorto-carotid bypass. The bypass patency rate was 96.1%.

CONCLUSIONS

Bypass surgery for the prevention of ischemic stroke is safe and elegant techniques have been developed. Patients with athero-occlusive disease, ischemic symptoms and haemodynamic insufficiency have significant risk of stroke if managed medically or left untreated. However, surgical intervention lacks supporting evidence from the recent Carotid occlusion Surgery Study (CoSS). Patients will be caught in a difficult position between a dismal natural history and an unproven surgical intervention. Clinicians must individualise their management until additional data are published or further consensus develops.

Usefulness of laser speckle flowgraphy for the assessment of ocular blood flow in extracranial-intracranial bypass

Laser speckle flowgraphy (LSFG) is a noninvasive technique that can measure relative blood flow velocity in the optic fundus. The authors present a case of symptomatic internal carotid artery occlusion treated with superficial temporal artery (STA)-middle cerebral artery (MCA) bypass in which an improvement of ocular circulation was confirmed by LSFG. A 47-year-old man presented with a 1-month history of repeated left blurred vision and motor weakness of the right leg. Diffusion-weighted magnetic resonance imaging revealed a small infarction in the left frontal lobe. Carotid angiography revealed that the left internal carotid artery was occluded at the C4 portion. Single-photon emission computed tomography indicated that the cerebral blood flow in the left MCA territory was markedly impaired. Ophthalmologic examination revealed ischemic change of the left optic fundi, and LSFG revealed decreased blood flow around the left optic disc. Left STA-MCA bypass was successfully performed. Both ischemic ocular symptoms and the ischemic symptoms of the right leg were completely recovered after surgery. Postoperative ophthalmologic examination revealed improvement of both ischemic changes of the left optic fundi. Moreover, LSFG revealed improvement of the blood flow around the left optic disc. LSFG can be a promising clinical tool for the assessment of ocular circulation before and after bypass surgery for occlusive cerebrovascular disease.

Bypass using V2-V3 segment of the vertebral artery as donor or recipient: technical nuances and results

OBJECTIVE

Surgical revascularization (bypass) technique has been used to treat vascular diseases of the posterior circulation, including ischemia, aneurysms, and tumors encasing a major artery. We focused on procedures using the V2-V3 segment of the vertebral artery (VA) as either the donor or recipient of the bypass. We have described technical nuances developed over time and evaluated the surgical results of those cases.

METHODS

Data on all patients who underwent bypasses using the V2-V3 segment were collected retrospectively from a prospectively maintained database.

RESULTS

Twenty patients had bypasses using V2-V3 distal VA as either the donor (13) or recipient (7); 19 patients had an intervening graft and in 1 patient, the VA was used for reimplantation of the posterior inferior cerebellar artery. Except for 1 patient, who died during the perioperative period, the mean follow-up time for the rest of the patients was 24.7 months (range 1-72 months). One patient developed postoperative stroke. One radial artery graft occluded, and a redo saphenous vein graft also occluded in the same patient. All the other bypasses were patent without flow limitation at the latest follow-up. Fourteen patients had a modified Rankin Scale score of 2 or better at the latest follow-up, and 2 died of unrelated causes as the result of their tumors.

CONCLUSIONS

The V2-V3 segment of the VA can be used both as a donor and a recipient for bypass surgery. Using the technical steps perfected over time, we are able to achieve surgical results with high rate of graft patency and good functional outcome in patients.

Bypass for the prevention of ischemic stroke

OBJECTIVE

Although most ischemic strokes are thromboembolic in origin and their management is endovascular or medical, some are hemodynamic in origin and their management may be surgical. Extracranial-intracranial bypass with superficial temporal artery-to-middle cerebral artery (MCA) bypass, high-flow interposition grafts, and reconstructive techniques have been developed. Clinical indications and efficacy are controversial, and this review examines current practices.

METHODS

Bypass surgery is indicated for patients with athero-occlusive disease that results in chronic, low cerebral blood flow accompanied by episodes of ischemic symptoms. Specific diagnoses include: (1) internal carotid artery occlusion; (2) MCA occlusion and, rarely, high-grade MCA stenosis; (3) vertebrobasilar atherosclerotic steno-occlusive disease; (4) vasculitis resulting in severe occlusive disease; and (5) moyamoya disease.

RESULTS

Discouraging results from the Extracranial-Intracranial Bypass Trial demonstrated the importance of selecting surgical patients based on objective measures of hemodynamic insufficiency. Two such tests are xenon-enhanced computed tomography with acetazolamide challenge and positron emission tomography with measurement of oxygen extraction fraction. Perfusion computed tomography may be another, more practical test. Surgical series, systematic reviews of the literature, and two new randomized clinical trials that use these diagnostic techniques reveal contradictory results. Although they demonstrate that bypass surgery has a morbidity rate of less than 5% and a patency rate of more than 95%, they have not proven a clear benefit.

CONCLUSIONS

Patients with athero-occlusive disease and symptoms of hemodynamic insufficiency have significant risk of stroke if left untreated or managed medically. On the other hand, surgical intervention lacks supporting evidence. Clinicians must individualize their management recommendations until additional data are published or further consensus develops.

Dissection of both frontal and parietal branches of the superficial temporal artery for bypass surgery through a single linear skin incision

BACKGROUND

Double superficial temporal artery (STA) to middle cerebral artery (MCA) bypass surgery has typically involved more than one linear incision. In this report, we demonstrate how the procedure can be performed through a single linear skin incision over the parietal branch of the STA.

METHODS

Initial dissection of the parietal branch and creation of a subcutaneous cavity along the frontal branch were performed using the conventional microscopic method. Detailed additional dissection and isolation of the frontal branch were accomplished with the aid of an endoscopic retractor.

RESULTS

This procedure was performed in five patients for harvesting of approximately 8- and 5-cm lengths of the parietal and frontal branches, respectively. The resultant lengths of the harvested vessels were sufficient for anastomotic revascularization of MCA recipient arteries in both the frontal and temporal lobes.

CONCLUSION

This method can be safely performed with achievement of a less invasive dissection of the STA and an overall improved cosmetic outcome.

Cognitive outcome after EC-IC bypass surgery in hemodynamic cerebral ischemia

OBJECTIVE

The purpose of this study was to evaluate cognitive functions in patients undergoing extracranial-intracranial (EC-IC) bypass surgery for cerebral ischemia.

POPULATION AND METHODS

From August 2003 to January 2009, 276 patients with occluded internal carotid arteries (ICA) were screened. Forty of these met the criteria for a low-flow EC-IC bypass. These patients were identified based on evidence of exhausted vasomotor reactivity (VMR) using the Doppler CO(2) test and CT perfusion. These patients were invited to have a complete battery of neuropsychological tests preoperatively and 12 months after surgery. Complete neurocognitive testing was finished in 20 patients.

RESULTS

This group of 20 patients showed preoperative cognitive impairment ranging from mild to medium-severe. There were no cases of stroke ipsilateral to the operated side during the follow-up period. VMR improvement was seen in all patients within 6 months of surgery. A comparison using a paired t-test demonstrated significant improvement 12 months after surgery in the following neuropsychological tests: WAIS-R (p = 0.01), Number Collection Test (p = 0.02), Trail Making Test (p = 0.03), and Benton Visual Retention Test (p = 0.05). Repeat analysis of variance (ANOVA) suggested the following predictors associated with cognitive improvement:the presence of ophthalmic collateral flow (p = 0.04), preoperative amaurosis fugax (p = 0.02), and external watershed infarction detected by MRI (p = 0.04).

CONCLUSION

Patients with occlusion of the ICA and exhausted VMR have cognitive impairment prior to EC-IC bypass surgery. Twelve months after surgery, there is significant improvement in various areas of cognition.

Surgical revascularization reverses cerebral cortical thinning in patients with severe cerebrovascular steno-occlusive disease

BACKGROUND AND PURPOSE

Chronic deficiencies in regional blood flow lead to cerebral cortical thinning without evidence of gross tissue loss at the same time as potentially negatively impacting on neurological and cognitive performance. This is most pronounced in patients with severe occlusive cerebrovascular disease in whom affected brain areas exhibit "steal physiology," a paradoxical reduction of cerebral blood flow in response to a global vasodilatory stimulus intended to increase blood flow. We tested whether surgical brain revascularization that eliminates steal physiology can reverse cortical thinning.

METHODS

We identified 29 patients from our database who had undergone brain revascularization with pre- and postoperative studies of cerebrovascular reactivity using blood oxygen(ation) level-dependent MRI and whose preoperative study exhibited steal physiology without MRI-evident structural abnormalities. Cortical thickness in regions corresponding to steal physiology, and where applicable corresponding areas in the normal hemisphere, were measured using Freesurfer software.

RESULTS

At an average of 11 months after surgery, cortical thickness increased in every successfully revascularized hemisphere (n=30). Mean cortical thickness in the revascularized regions increased by 5.1% (from 2.40 ± 0.03 to 2.53 ± 0.03; P<0.0001).

CONCLUSIONS

Successful regional revascularization and reversal of steal physiology is followed by restoration of cortical thickness.

Incidence and Predictive Factors of Cerebral Hyperperfusion After Extracranial-Intracranial Bypass for Occlusive Cerebrovascular Diseases

BACKGROUND:

Although many studies of postoperative cerebral hyperperfusion syndrome (CHS) after carotid endarterectomy have been reported, there are few reports related to extracranial-intracranial (EC-IC) bypass for atherosclerotic occlusive cerebrovascular diseases.

OBJECTIVE:

To examine the incidence of cerebral hyperperfusion and CHS after EC-IC bypass and to investigate predictive factors.

METHODS:

Fifty consecutive patients undergoing EC-IC bypass for atherosclerotic occlusive cerebrovascular diseases were studied. Immediately after bypass surgery, resting regional cerebral blood flow was determined under continuous sedation, and postoperative hyperperfusion was evaluated according to the definitions as follows: &gt; 50% increase in regional cerebral blood flow compared with the contralateral side (method 1) and &gt; 100% increase in corrected regional cerebral blood flow compared with preoperative values (method 2). Logistic regression analysis was conducted to determine the effect of multiple variables on postoperative hyperperfusion.

RESULTS:

Transient symptoms of CHS were observed in 3 patients. Cerebral hyperperfusion was detected in 12 patients (24%) as defined by method 1 and in 9 patients (18%) by method 2. Postoperative hyperperfusion occurred significantly more frequently in patients with the steal phenomenon (regional cerebral vasoreactivity ≤ 0%; P = .001 by method 1 and P = .001 by method 2) and correlated with impaired preoperative regional cerebral vasoreactivity (P &lt; .001). Logistic regression analysis revealed that the steal phenomenon was a significant risk factor for hyperperfusion as defined by both methods 1 (P = .009) and 2 (P = .03).

CONCLUSION:

The incidence of cerebral blood flow-assessed postoperative hyperperfusion after EC-IC bypass for atherosclerotic occlusive cerebrovascular diseases was not rare. Post EC-IC bypass CHS could be reduced by continuous, strict blood pressure control under sedation.

Improvement of exhausted cerebral vasoreactivity in carotid occlusion: benefit of statins?

In internal carotid artery occlusion (ICAO), a spontaneous increase of cerebral vasoreactivity (CVR) may occur over time. Statins are known to increase CVR. We analyzed the influence of statin treatment and other cofactors on CVR improvement in patients with ICAO. Sixty-six patients with ICAO were reexamined after 15 ± 6 months. CVR in both middle cerebral arteries was assessed by transcranial Doppler and inhalation of 7% CO(2). Pre-defined cut-off values were used to define exhausted CVR. Cofactors analyzed were: age, sex, hypertension, diabetes, statin treatment, degree of contralateral stenosis, quality of intracranial collateral flow, duration of ICAO. Mean CVR did not differ between the two studies. Twenty patients had exhausted CVR at baseline, 11 of them improved above the cut-off at follow-up (55%). Factors significantly associated with this improvement were good collateral pattern at baseline (p = 0.0065) and statin treatment (p = 0.0179). Odds ratios for improving CVR were 36.0 [95% CI 2.7-476.3] for good collateral flow and 20.0 [95% CI 1.7-238.6] for statin treatment. In conclusion, exhausted CVR frequently improves during the course of ICAO. Good collateral function and statin treatment are significantly associated with improving CVR.

Perfusion CT scanning and CT angiography in the evaluation of extracranial-intracranial bypass grafts

OBJECT

Extracranial-intracranial (EC-IC) bypass surgery remains an important treatment alternative for patients with occlusive cerebrovascular disease. The aim of the present study was to use perfusion CT and CT angiography (CTA) to evaluate cerebral hemodynamics and bypass patency in patients with occlusive cerebrovascular disease before and after EC-IC bypass surgery.

METHODS

Ten patients underwent perfusion CT and CTA before and after bypass surgery. Preoperative and postoperative digital subtraction angiography served as the diagnostic gold standard. An artery bypass was established from the superficial temporal artery to a cortical branch of the middle cerebral artery. Perfusion CT scanning was performed at the level of the basal ganglia. Color-coded perfusion maps of cerebral blood volume, cerebral blood flow, and time to peak were calculated.

RESULTS

Preoperative perfusion CT showed significant prolonged time to peak and reduced cerebral blood flow of the affected hemisphere. Postoperative neurological deterioration did not develop in any patient. Computed tomography angiography provided adequate evaluation of the anastomoses as well as the course and caliber of the bypass and confirmed bypass patency in all patients. Postoperative perfusion CT showed improved cerebral hemodynamics with a return to nearly normal perfusion parameters.

CONCLUSIONS

Computed tomography angiography is a noninvasive and reliable tool for evaluating patients with EC-IC bypass. Perfusion CT allows monitoring of hemodynamic changes after bypass surgery. The combination of both modalities enables noninvasive anatomical and functional analysis of superficial temporal artery-middle cerebral artery anastomoses using a single CT protocol. Hemodynamic evaluation of patients with occlusive cerebrovascular disease before and after surgery may improve the prediction of outcome and may help identify patients in whom a bypass procedure can be performed.

Usefulness of an ultrasonic scalpel to harvest and skeletonize the superficial temporal artery for extracranial-intracranial bypass surgery

OBJECTIVE

A new method to harvest and skeletonize the superficial temporal artery (STA) using an ultrasonic scalpel is presented. The technique is simple and safe, and reduces bleeding. We also investigated histopathological changes in donor vessels and whether it is possible to shorten the time needed for STA harvesting using the ultrasonic scalpel.

METHODS

Between January 1, 2005, and December 31, 2007, 31 consecutive patients underwent STA and middle cerebral artery anastomosis surgery in our hospital. All patients underwent harvesting of both the frontal and parietal branches of the STA. STA harvesting using an ultrasonic scalpel was performed in 18 of the 31 patients. We compared the time needed for STA harvesting by dividing patients into 2 groups: a non-ultrasonic scalpel group and an ultrasonic scalpel group. We also examined the histopathological changes by application of ultrasonic waves on the STA in the 6 most recent patients.

RESULTS

The mean time needed for STA harvesting was 84.2 +/- 14.1 minutes for the non-ultrasonic scalpel group and 55.1 +/- 15.2 minutes for the ultrasonic scalpel group. The ultrasonic scalpel group showed a significantly shorter harvesting time than the non-ultrasonic scalpel group (P < 0.01). No histopathological change was observed in any layers of the STA.

CONCLUSION

Our data suggest that STA harvesting with the ultrasonic scalpel may be useful for STA-middle cerebral artery anastomosis surgery.

Computed tomography angiography, perfusion computed tomography, and a drug-eluting stent for the treatment of in-stent restenosis of the middle cerebral artery

The authors report a case of in-stent restenosis (ISR) of the middle cerebral artery (MCA) following bare-metal stent (BMS) deployment and subsequent treatment using a drug-eluting stent (DES). This 65-year-old woman presented with frequent transient ischemic attacks. Initial studies revealed occlusion of the left internal carotid artery and severe stenosis of the right MCA with decreased cerebral perfusion in the bilateral MCA territories. Stent-assisted angioplasty of the right MCA was performed using a BMS, and satisfactory results were obtained with no complications. Six months after the procedure the patient presented with recurrent symptoms, and workups revealed ISR with decreased cerebral perfusion. A DES was successfully placed without complications. Follow-up studies at 3 and 8 months after retreatment showed sustained luminal integrity and cerebral perfusion. A combination of CT angiography and perfusion CT exhibited the anatomical results and hemodynamic status of the stenotic lesion, and these findings coincided with the patient's clinical symptoms and the results of conventional cerebral angiography. In-stent restenosis of the MCA after placement of a BMS can be treated using a DES. A combination of CT angiography and perfusion CT can be an alternative to conventional angiography. Low-profile devices with an amelioration of trackability are essential for the further incorporation of the DES into the field of endovascular neurosurgery. More clinical experiences and long-term follow-ups are mandatory to evaluate the safety, efficacy, and durability of the DES.

The evolution of cerebral revascularization surgery

Among the relatively few surgeons to be awarded the Nobel Prize was Alexis Carrel, a French surgeon and pioneer in revascularization surgery at the turn of the 20th century. The authors trace the humble beginnings of cerebral revascularization surgery through to the major developments that helped shape the modern practice of cerebral bypass surgery. They discuss the cornerstone studies in the development of this technique, including the Extracranial/Intracranial Bypass Study initiated in 1977. Recent innovations, including modern techniques to monitor cerebral blood flow, microanastomosis techniques, and ongoing trials that play an important role in the evolution of this field are also evaluated.

The extracranial-intracranial bypass trial: implications for future investigations

The 1985 International Extracranial-Intracranial (EC-IC) Bypass Trial failed to show a surgical benefit of EC-IC bypass in patients with varying degrees of angiographic stenosis. This study was limited by the technology available at the time it was conducted. In the 20 years since, there has been considerable progress in imaging techniques that now enable the identification of a subset of stroke patients with hemodynamic ischemia. In the present study, the authors review the relevant literature and propose a reevaluation of the benefits of the EC-IC bypass procedure using these new imaging techniques. The authors reviewed the admission criteria for the EC-IC Bypass Trial in the light of more recently discovered neurovascular physiology and showed that the imaging criteria used in that trial are not physiologically adequate. A MED-LINE (1985-2007) database search for EC-IC case studies was conducted, and additional studies were identified manually by scrutinizing references from identified manuscripts, major neurosurgical journals and texts, and personal files.

Risk of intraoperative ischemia due to temporary vessel occlusion during standard extracranial–intracranial arterial bypass surgery

Object

Standard extracranial–intracranial (EC–IC) arterial bypass surgery represents a well-recognized procedure in which the aim is to augment distal cerebral circulation. The creation of the bypass requires temporary occlusion of the recipient vessel. Thus, there exists controversy about the risk of standard EC–IC arterial bypass surgery causing ischemic complications due to temporary vessel occlusion. In this prospective study, the incidence of intraoperative ischemia was investigated in symptomatic patients with steno-occlusive cerebrovascular disease and existing hemodynamic insufficiency.

Methods

Twenty consecutive patients (14 women and 6 men; mean age 46 ± 11 years) suffering from recurrent transient ischemic attacks due to occlusive cerebrovascular disease and proven hemodynamic compromise in functional blood flow studies were enrolled in this study. The underlying pathological condition was internal carotid artery (ICA) or middle cerebral artery (MCA) occlusion in 6 cases and ICA or MCA stenosis in 3 cases, whereas 11 patients presented with moyamoya syndrome or moyamoya disease. The surgical procedure consisted of the establishment of a standard superficial temporal artery (STA)–MCA bypass, and was performed while a strict intraoperative management protocol was applied. Patients underwent clinical examination and magnetic resonance (MR) imaging within 48 hours before and after surgery.

Results

The incidence of reversible clinical signs of ischemia was 2 (10%) of 20 patients. Postoperative MR imaging revealed signs of diffusion disturbances in 2 (10%) of 20 cases. The observed diffusion-weighted imaging changes, however, were situated within the dependent vascular territory at risk for ischemia in 1 patient only. No permanent neurological deficit occurred. The temporary vessel occlusion time ranged between 25 and 42 minutes (mean 33 ± 7 minutes). All means are expressed ± the standard deviation.

Conclusions

Temporary vessel occlusion during standard STA–MCA arterial bypass surgery carries a low risk of intraoperative ischemia when a strict perioperative management protocol is applied.

Treatment of hemodynamic insufficiency in chronic CCA occlusion using a short saphenous vein interposition graft: diagnostic and technical considerations

Extracranial-intracranial bypass surgery has been shown to reverse hemodynamic insufficiency on the basis of steno-occlusive disease of the internal carotid artery (ICA) or middle cerebral artery. In contrast, chronic occlusion of the common carotid artery (CCA) without extracranial donor vessels affords alternative revascularization procedures as well as a more elaborate preoperative workup. This case is intended to illustrate the specific diagnostic approach and considerations as well as a beneficial treatment modality in the setting of pronounced hemodynamic insufficiency as a consequence of a CCA occlusion, in conjunction with contralateral CCA and ICA stenoses. A 61-year-old man complaining of new onset aphasia underwent vascular imaging that revealed a proximal occlusion of the left CCA with a concomitant patent proximal ICA on ultrasound. Functional cerebral blood flow measurement including Xenon-enhanced computer tomography showed corresponding chronic hemodynamic insufficiency of the left hemisphere. The patient received a modified revascularization procedure, where a saphenous vein was used as interposition graft between the subclavian artery and the left proximal ICA. Postoperatively, both clinical and morphological improvement were noted. Successful treatment of hemodynamic insufficiency because of chronic CCA occlusion necessitates a thorough preoperative workup and application of alternative revascularization strategies.

EC-IC bypass: The failure of a clinical trial? Applicability to PFO closure trials

Extracranial-to-intracranial (EC-IC) bypass surgery was used to prevent stroke in patients with carotid occlusion and inadequate collateral flow. Because of inappropriate proliferation of EC-IC bypass, a randomized clinical trial was carried out. The failure of the trial may have been related to inappropriate patient selection and all eligible patients not being randomized. Subsequent study has identified criteria for patient selection and new trials are underway. The present patent foramen ovale closure trials share many of the same difficulties, including overuse of the procedure and interventionalists reluctant to randomize patients. If these trials are not properly done we will be in the same situation in 20 years that the EC-IC trialists are facing today. Improvements in patient selection criteria, randomization of all eligible patients, and better statistical parameters will increase the likelihood of future trials getting the correct answer the first time. The importance of carefully done observational trials should not be overlooked.