Superficial Temporal Artery-to-Middle Cerebral Artery Bypass

THE SUPERFICIAL TEMPORAL artery-to-middle cerebral artery bypass represents the mainstay of bypass operations for cerebral revascularization. The role of this operation in the setting of cerebrovascular occlusive disease, with compromised cerebral hemodynamic reserve, is a topic of current investigation. In this report, we describe technical nuances to avert potential pitfalls in the performance of this procedure. The use of intraoperative quantitative blood flow measurements as a reliable method of assessing the success of the bypass is also described.

Reduction of neural and vascular damage by transplantation of VEGF-secreting neural stem cells after cerebral ischemia

We determined the role of VEGF-transfected neural stem cells (NSCs) transplantation in rat brain subjected to ischemia. Fetal NSCs were cultured from E14 days SD rats and transfected with VEGF121 gene by using lipofectamine technique. Temporary middle cerebral artery occlusion (tMCAO) models were established and randomly divided into 1: control group, 2: PBS transplantation group, 3: NSCs transplantation group and 4: VEGF-secreting NSCs transplantation group. Grafts were transplanted into the penumbra zones 3 days after tMCAO model established. Neurological Severity Score (NSS) was checked in all groups 2-12 weeks after transplantation. By using immunofluorescent staining, VEGF expression of transplanted cells, differentiation and migration of transplanted NSCs after transplantation were detected. VEGF gene-transfected neural stem cells expressed gene products during the first 2 weeks. NSS in this group was significantly lower compared with that in other 3 groups 12 weeks after transplantation. VEGF gene-transfected NSCs migrated and expressed VEGF in hosts' brains, some of them differentiated to neurons 12 weeks after transplantation. VEGF-transfected NSCs expressed gene products during the early time after transplantation, which reduce brain injury through protecting the vascular system against ischemic attack.

MERCI 1: a phase 1 study of Mechanical Embolus Removal in Cerebral Ischemia

BACKGROUND AND PURPOSE

To report the result of the Mechanical Embolus Removal in Cerebral Ischemia (MERCI) 1 study, a phase 1 trial to evaluate the safety and efficacy of mechanical embolectomy in the cerebral vasculature.

METHODS

MERCI 1 enrolled 30 patients in 7 US centers. Main inclusion criteria were: National Institutes of Health Stroke Scale score (NIHSS) > or =10; treatment performed within 8 hours from symptoms onset and contra-indication to intravenous thrombolysis; no large hypodensity on computed tomography; and occlusion of a major cerebral artery on the angiogram. Safety was defined by the absence of vascular injury or symptomatic intracranial hemorrhage. Efficacy was assessed by recanalization rate and clinical outcome at 1 month. Significant recovery was defined as 30-day modified Rankin of 0 to 2 in patients with baseline NIHSS 10 to 20 and 30-day modified Rankin of 0 to 3 in patients with baseline NIHSS >20. The procedures were performed with the Merci Retrieval System, a system specially designed for intracranial embolectomy.

RESULTS

Twenty-eight patients were treated. Median NIHSS was 22. Median time from onset to completion of treatment was 6 hours and 15 minutes. Successful recanalization with mechanical embolectomy only was achieved in 12 (43%) patients, and with additional intra-arterial tissue plasminogen activator in 18 (64%) patients. There was one procedure related technical complication, with no clinical consequence. Twelve asymptomatic and no symptomatic intracranial hemorrhages occurred. At 1 month, 9 of 8 revascularized patients and 0 of 10 nonrevascularized patients had achieved significant recovery.

CONCLUSIONS

This phase 1 study shows that cerebral embolectomy with the Merci Retriever was safe and that successful recanalization could benefit a significant number of patients, even when performed in an extended 8-hour time window.

Cerebral hemispherectomy: hospital course, seizure, developmental, language, and motor outcomes

OBJECTIVE

To compare hemispherectomy patients with different pathologic substrates for hospital course, seizure, developmental, language, and motor outcomes.

METHODS

The authors compared hemispherectomy patients (n = 115) with hemimegalencephaly (HME; n = 16), hemispheric cortical dysplasia (hemi CD; n = 39), Rasmussen encephalitis (RE; n = 21), infarct/ischemia (n = 27), and other/miscellaneous (n = 12) for differences in operative management, postsurgery seizure control, and antiepilepsy drug (AED) usage. In addition, Vineland Adaptive Behavior Scale (VABS) developmental quotients (DQ), language, and motor assessments were performed pre- or postsurgery, or both.

RESULTS

Surgically, HME patients had the greatest perioperative blood loss, and the longest surgery time. Fewer HME patients were seizure free or not taking AEDs 1 to 5 years postsurgery, but the differences between pathologic groups were not significant. Postsurgery, 66% of HME patients had little or no language and worse motor scores in the paretic limbs. By contrast, 40 to 50% of hemi CD children showed near normal language and motor assessments, similar to RE and infarct/ischemia cases. VABS DQ scores showed +5 points or more improvement postsurgery in 57% of patients, and hemi CD (+12.7) and HME (+9.1) children showed the most progress compared with RE (+4.6) and infarct/ischemia (-0.6) cases. Postsurgery VABS DQ scores correlated with seizure duration, seizure control, and presurgery DQ scores.

CONCLUSIONS

The pathologic substrate predicted pre- and postsurgery differences in outcomes, with hemimegalencephaly (but not hemispheric cortical dysplasia) patients doing worse in several domains. Furthermore, shorter seizure durations, seizure control, and greater presurgery developmental quotients predicted better postsurgery developmental quotients in all patients, irrespective of pathology.

Comparison of monitoring techniques for intraoperative cerebral ischemia

OBJECTIVE

To prospectively compare somatosensory evoked potentials, electroencephalography (EEG) and transcranial Doppler ultrasound (TCD) for detection of cerebral ischemia during carotid endarterectomy (CEA).

METHODS

Somatosensory evoked potentials and EEG recordings were attempted in 156 consecutive CEAs and TCD was also attempted in 91 of them. Recordings from all three modalities were obtained for at least 10 minutes before CEA, during CEA and for at least 15 minutes after CEA. Somatosensory evoked potentials peak-to-peak amplitude decrease of >50%, EEG amplitude decrease of >75%, and ipsilateral middle cerebral artery mean blood flow velocity (mean VMCAi) decrease >75% persisting for the entire period of internal carotid artery occlusion were individually considered to be diagnostic of cerebral ischemia. Clinical neurological examination was performed immediately prior to surgery and following recovery from general anaesthesia.

RESULTS

Somatosensory evoked potentials, EEG, and TCD were successfully obtained throughout the entire period of internal carotid artery occlusion in 99%, 95%, and 63% of patients respectively. Two patients (1.3%) suffered intraoperative cerebral infarction detected by clinical neurological examination and subsequent magnetic resonance imaging. Somatosensory evoked potentials accurately predicted intraoperative cerebral infarction in both instances without false negatives or false positives, EEG yielded one false negative result and no false positive results and VMCAi one true positive, four false positive and no false negative results. Transcranial Doppler ultrasound detection of emboli did not correlate with postoperative neurological deficits. Nevertheless the sensitivity and specificity of each test was not significantly different than the others because of the small number of disagreements between tests.

CONCLUSION

A >50% decrease in the cortically generated P25 amplitude of the median somatosensory evoked potentials, which persisted during the entire period of internal carotid artery occlusion, appears to be the most reliable method of monitoring for intraoperative ischemia in our hands because it accurately detected both intraoperative strokes with no false positive or false negative results.

[Surgical procedure improvement to produce rat ischemia-reperfusion injury model with intraluminal suture]

OBJECTIVE

To describe a modified surgical approach to produce rat ischemia-reperfusion injury model with intraluminal suture.

METHODS

After exposure and ligation of the common carotid artery (CCA), the left external carotid artery and pterygopalatine artery were opened in which a 3-0 nylon suture was introduced intraluminally from the distal end of the ligature of the CCA using a scalp needle. Reperfusion injury was induced by withdrawal of the suture.

RESULTS

The length of the suture was about 20.0+/-1.8 mm and the success rate of model establishment was nearly 70%. The rats developed typical symptoms and pathological manifestations after the surgery.

CONCLUSION

This modified surgical approach is simple for model establishment and does not require special microsurgical skills to ensure the high success rate.

Human neural stem cells improve sensorimotor deficits in the adult rat brain with experimental focal ischemia

Ischemic stroke is caused by the interruption of cerebral blood flow that leads to brain damage with long-term sensorimotor deficits. Stem cell transplantation may recover functional deficit by replacing damaged brain. In this study, we attempted to test whether the human neural stem cells (NSCs) can improve the outcome in the rat brain with intravenous injection and also determine the migration, differentiation and the long-term viabilities of human NSCs in the rat brain. Focal cerebral ischemia was induced by intraluminal thread occlusion of middle cerebral artery (MCA). One day after surgery, the rats were randomly divided into two groups: NSCs-ischemia vs. Ischemia-only. Human NSCs infected with retroviral vector encoding beta galactosidase were intravenously injected in NSCs-ischemia group (5 x 10(6) cells) and the same amount of saline was injected in Ischemia-only group for control. The animals were evaluated for 4 weeks using turning in an alley (TIA) test, modified limb placing test (MLPT) and rotarod test. Transplanted cells were detected by X gal cytohistochemistry or beta gal immunohistochemistry with double labeling of other cell markers. The NSCs-ischemia group showed better performance on TIA test at 2 weeks, and MLPT and rotarod test from 3 weeks after ischemia compared with the Ischemia-only group. Human NSCs were detected in the lesion side and labeled with marker for neurons or astrocytes. Postischemic hemispheric atrophy was noted but reduced in NSCs-ischemia group. X gal+ cells were detected in the rat brain as long as 540 days after transplantation. Our data suggest intravenously transplanted human NSCs can migrate and differentiate in the rat brain with focal ischemia and improve functional recovery.

Superficial Temporal Artery-to-Middle Cerebral Artery Bypass Grafting for Cerebral Revascularization

SUPERFICIAL TEMPORAL ARTERY-to-middle cerebral artery bypass procedures are an important tool in the armamentarium of cerebrovascular surgeons for the treatment of carotid occlusion and revascularization for complex aneurysms and brain tumors. This article enumerates the essential steps in performing superficial temporal artery-to-middle cerebral artery bypass procedures. The nuances of this technique reflect the extensive experience of the senior authors (RFS, JMZ).

[Extra-intracranial arterial bypass for treatment of patient with clinical refractory cerebral ischemia]

The extra-intracranial bypass may be used in selected cases of brain vascular insufficiency refractory to clinical treatment. We report a case of encephalic ischemia in the territory of the right middle cerebral artery due to occlusion of the ipsilateral internal carotid artery, with consequent reduction of the perfusion and vascular reserve in the parietal and frontal regions. Despite the clinical treatment, motor deficit improvement was directly related to the maintenance of high systemic arterial tension levels due to the use of vasopressor agent. After lateral-terminal extra-intracranial bypass between the superficial temporal and right middle cerebral artery, there was significant improvement of cerebral perfusion with remission of the motor deficit.

Quality of life after decompressive craniectomy in patients suffering from supratentorial brain ischemia

BACKGROUND

Decompressive craniectomy in patients suffering from severe ischemic stroke in the middle cerebral artery territory (MCA) decreases mortality to near 30%. Additionally functional outcome in patients after early craniectomy seems to be better than in patients without surgery. The aim of this study was to investigate the quality of life of patients who were treated with a decompressive craniectomy for severe ischemic stroke.

METHODS

We retrospectively investigated the patient records of 48 patients (26 men, mean age 48 years) suffering from ischemic strokes who underwent craniectomy since 1993. We registrated the preoperative neurological status, the diagnostic data as well as the operative procedure. The outcome was assessed using the Barthel Index, the Glasgow outcome score and a questionnaire to assess the quality of life according to Blau consisting of eleven items at follow-up.

FINDINGS

The mortality rate was 26%, age correlated to mortality (44.5 versus 60.3 years GOS 1, mean, p<0.0006). Craniectomy without dura patch correlated to mortality (58% versus 14% GOS 1 with dura patch, p<0.005). The quality of life index was 6 points mean. The quality of life index did neither differ significantly between patients with left or right sided lesions nor in patients with and without aphasia. 83% of the surviving patients and/or dependents would agree to surgery in the future.

CONCLUSION

Despite the fact that some patients remain in a poor neurological condition, quality of life after decompressive surgery for ischemic stroke seems to be acceptable to the patients.

Assessment of cerebral hemodynamics in childhood moyamoya disease using a quantitative and a semiquantitative IMP-SPECT study

BACKGROUND

We evaluated the cerebral hemodynamics in childhood moyamoya disease patients before and after surgery to assess both surgical indication and the effect of revascularization using single photon emission computed tomography (SPECT) study with N-isopropyl-p-123I-iodoamphetamine (IMP). We compared results of quantitative and semi-quantitative SPECT studies to determine parameters by the semi-quantitative method to define severe hemodynamic ischemia.

METHODS

There were 14 pediatric patients with moyamoya disease who suffered transient ischemic attacks (TIAs) in the anterior circulation. Before and after surgical revascularization by STA-MCA bypass and encephalomyosynangiosis (EMS), quantitative IMP-SPECT studies using the autoradiographic method (IMP-ARG method) were performed. Resting regional cerebral blood flow (rCBF) and regional vascular reserve (rVR) were measured in bilateral cortical territories (ROI) and cerebellum. Semi-quantitative parameters were calculated from the ratio of ROI counts to the dominant cerebellar counts (ROI/Ce ratio) at resting and acetazolamide-activated conditions.

RESULTS

Before surgery, the mean resting rCBF and rVR in bilateral ACA and MCA territories were less than 40 ml/100 g/min and less than 10%, respectively, indicating severe hemodynamic ischemia. Except for the ACA territories, both the mean resting rCBF and mean rVR values in the entire cortex increased significantly after surgery (p < 0.05). By semi-quantitative studies, before surgery, the mean resting and acetazolamide-activated ROI/Ce ratios in bilateral ACA and MCA territories were less than 0.90 and 0.80, respectively. The mean resting and acetazolamide-activated ROI/Ce ratios increased significantly in the MCA territory after surgery. Severe hemodynamic ischemia, which categorized by the quantitative thresholds (resting rCBF < 40 ml/100 g/min and rVR < 10%) was diagnosed by the semi-quantitative thresholds (resting ROI/ Ce ratio < 0.90 and acetazolamide-activated ROI/Ce ratio < 0.85), the sensitivity and specificity of which were 87.5% and 90.9%, respectively.

CONCLUSIONS

The cerebral hemodynamics in childhood moyamoya disease was improved entirely after surgery. Severe hemodynamic cerebral ischemia was diagnosed by not only quantitative but also semi-quantitative IMP-SPECT studies.

Three-dimensional display in staging hemodynamic brain ischemia for JET study: objective evaluation using SEE analysis and 3D-SSP display

The Japanese EC-IC bypass trial (JET study) was established to evaluate the validity of MCA-STA anastomosis in intracranial arterial occlusive disease aiming at stroke prevention. This study must use an objective method to reliably estimate hemodynamic brain ischemia. We devised a method of objectively classifying the severity of hemodynamic ischemia using quantitatively analytical and display software, stereotactic extraction estimation for stereotactic brain coordinates and three-dimensional stereotactic surface projections (3D-SSP). We analyzed data from 16 patients registered in the JET study. Our method offers quantitative information and 3-dimensional displays of the CBF at rest and after Diamox challenge, vascular reserve and the severity of the hemodynamic brain ischemia. We compared the maximal projection counts with ROI data from tomographic images in the anterior commissure-posterior commissure plane. The maximal counts data correlated closely with the ROI data of rest and with Diamox SPECT images (both p < 0.0001). The slopes of the linear regression line were 1.15 and 1.12, respectively. The results of this study indicated that our method could simply and objectively evaluate the severity of impaired brain circulation. This procedure should support the evaluation of hemodynamic ischemia in the JET study although validation is required by several institutions using more study subjects.

Monitoring and preventing blood flow insufficiency due to clip rotation after the treatment of internal carotid artery aneurysms

✓ The authors report a case in which anterior choroidal artery (AChA) blood flow insufficiency due to aneurysm clip rotation was detected intraoperatively by motor evoked potential (MEP) monitoring and ischemia was successfully avoided.

The patient had an incidentally discovered aneurysm for which occlusion of its neck was performed through a standard frontotemporal craniotomy without changing the MEP amplitude. After it was confirmed that the surrounding arteries were not stenotic, the brain retractor on the frontal lobe was released; MEP amplitude subsequently decreased. Rotation of the clip toward the frontal base by repositioning of the frontal lobe caused the AChA stenosis at the origin of its branches. On reorienting the clip toward the frontal lobe, the AChA stenosis was released and MEP amplitude recovered. To prevent repeated clip rotation, a large amount of gelatin (Spongel) was inserted between the frontal base and the clip. The authors confirmed that clip rotation did not occur after repositioning of the frontal lobe. Motor evoked potential amplitude was maintained until dural closure. Postoperatively, the patient demonstrated no neurological deficit and there was no newly developed low-density area on computerized tomography scans.

Involuntary movement induced by cerebral ischemia: pathogenesis and surgical outcome

Object. Involuntary movement is an uncommon manifestation of a transient ischemic attack. It may be induced by cerebral hemodynamic insufficiency, which is associated with several cerebral ischemic diseases. The authors present three cases of limb shaking due to moyamoya disease (MMD) or radiation-induced middle cerebral artery stenosis, and three additional cases of choreic movement due to MMD. Neuroimaging studies and surgical outcomes in these patients were retrospectively analyzed to investigate the pathological mechanism underlying the symptoms and to provide guidance for the management of involuntary movement disorders in cases of ischemic cerebral disease.

Methods. The patient population included two children and four adults with ages at presentation ranging between 7 and 50 years. The initial presenting symptoms were involuntary movements in all six cases. A magnetic resonance imaging finding common in all cases was a small infarct in the frontal corona radiata, which did not extend to the cortex or basal ganglia. A perfusion defect in the frontoparietal cortical and subcortical regions was demonstrated by singlephoton emission computerized tomography in all patients. Improved hemodynamic circulation in the frontoparietal cortical and subcortical regions occurred in parallel with clinical improvement following indirect or direct bypass surgery.

Conclusions. Ischemic dysfunction of the frontal cortical and subcortical motor pathways rather than that of the basal ganglia was suspected to be the cause of the observed contralateral involuntary movements. Direct and indirect bypass surgery can be used effectively to treat involuntary movements in patients with cerebral ischemic diseases such as MMD and in those with stenosis of an intracranial major artery.

Continuous arterial spin labeled perfusion magnetic resonance imaging in patients before and after carotid endarterectomy

Continuous arterial spin labeling perfusion magnetic resonance imaging (CASL-pMRI) uses magnetically labeled arterial blood water as a tracer to obtain quantifiable measurements of cerebral blood flow (CBF) (mL/100 g-1/min-1). CASL-pMRI was used to assess CBF changes in major vascular distributions in patients (n = 10) prior to and 3 months after carotid endarterectomy (CEA). No significant change in the global baseline CBF before and after CEA was observed in the group as a whole (P = .81). In patients with reduced CBF prior to CEA (< 50 ml/100 g/min), a significant increase in global CBF following CEA was observed. An inverse relationship existed between percent change in CBF after CEA versus baseline CBF within the anterior circulation (r = -.78, P < .05) but not in the posterior distribution (r = .25, P = .63). CASL-pMRI may provide a convenient, inexpensive, noninvasive method for identifying CEA patients at risk for hyperperfusion following carotid revascularization.

Clinical outcome of standard extracranial-intracranial bypass surgery in patients with symptomatic atherosclerotic occlusion of the internal carotid artery

OBJECTIVE

In this retrospective study we wanted to determine the role of cerebral revascularization in patients with symptomatic occlusive cerebrovascular disease. Special emphasis was put on subsequent cerebrovascular events, benefit in neurological functioning and bypass patency, as evaluated during the follow-up period.

METHODS

A total of 73 superficial temporal artery to the middle cerebral artery bypasses were performed on 67 patients from 1986-2000. All patients exhibited a symptomatic occlusion of the internal carotid artery verified by angiography. All patients in our group were refractory to medical treatment. 65 patients (69 bypasses) with a mean age of 61 years (range: 38-79 years) were followed up over an average time of 44 months (range: 1.5-150 months).

RESULTS

The peri-operative morbidity rate was 3% with no mortality. 55 patients (85%) had no further cerebrovascular events after surgery, and only 7 (11%) patients experienced another cerebrovascular event. 57 (88%) patients showed an improvement of symptoms after surgery and only 1 patient fared worse during the follow-up period due to a stroke he suffered two years after bypass surgery. 90% of all bypasses remained patent during the follow-up.

CONCLUSIONS

Although bypass surgery for occlusive cerebrovascular disease is still controversial, our retrospective study suggests both an improvement of symptoms and signs and a risk-reduction for future cerebrovascular events after surgery.