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

A Case of Ruptured Carotid Traumatic Blood Blister-like Aneurysm

Ruptured cerebral aneurysms that occur in the anterior wall of the internal carotid artery (ICA) are known as blood blister-like aneurysms (BBAs); they have been reported to account for 0.3% to 1% of all ruptured ICA aneurysms. In this report, we describe the treatment of an unusual traumatic BBA (tBBA) with high-flow bypass using a radial artery graft, which resulted in a favorable outcome. A 59-year-old female suffered from an acute epidural hematoma, traumatic subarachnoid hemorrhage, and traumatic carotid-cavernous sinus fistula (tCCF) after being involved in a motor vehicle accident. Her angiography results showed tCCF and a tBBA on the anterior wall of the right ICA. On the fourth day after injury, we found rebleeding from the tBBA and performed an emergency high-flow bypass using a radial artery graft with lesion trapping as a curative procedure for the tCCF and tBBA. Postoperatively, right abducens nerve palsy appeared, but no other neurological symptoms were noted; the patient was thereafter transferred to a rehabilitation hospital 49 days after injury. Traumatic ICA aneurysms commonly occur close to the anterior clinoid process, form within 1 to 2 weeks of injury, and often rupture around 2 weeks after trauma. This case was considered rare as the ICA was likely injured and bleeding at the time of injury, resulting in a form of tBBA; this allowed early detection and appropriate treatment that resulted in a good outcome.

Noninvasive Pressure Estimation Based on the Subharmonic Response of SonoVue: Application to Intracranial Blood Pressure Assessment

Intracranial blood pressure can directly reflect the status of blood vessels in real time. However, it can only be estimated invasively using a microcatheter during craniotomy. Subharmonic-aided pressure estimation (SHAPE) is a promising technique for estimating cardiac pressures but mainly uses Sonazoid, whereas SHAPE using SonoVue is still in the early stages of development. The aim of this study was to optimize transcranial SHAPE using SonoVue by investigating the relationship between subharmonic signals and middle cerebral artery pressure (MCAP) (20-160 mmHg) in vitro. We examined the effect of acoustic output levels (peak negative pressures (PNPs) of 238, 346, and 454 kPa), time in suspension (time from reconstituting the suspension to extracting it: 0-30 min), and exposure to gas-equilibrated saline (3 min, 1 h, or original gas completely replaced by air) on the subharmonic-pressure relationship. A mean subharmonic amplitude over a 0.4 MHz bandwidth was extracted using a 5 MHz 12-cycle pulse. A PNP of 346 kPa elicited the best subharmonic sensitivity for assessing hydrostatic pressures up to 0.24 dB/mmHg, possibly because compression-only behavior no longer occurs at this pressure. Moreover, the expansion force is not large enough to offset the effects of hydrostatic pressure. A linear monotonic relationship between the subharmonic amplitude and hydrostatic pressure was only observed for just prepared SonoVue. Excessive exposure to gas-equilibrated saline also affected the subharmonic-pressure relationship. Therefore, just prepared SonoVue should be used, and the duration of the pressure estimation process should be strictly controlled.

Ischemic stroke following STA–MCA double bypass

Objectives

The surgical technique of STA–MCA double bypass is used to improve blood flow supplied by the distal middle cerebral artery (MCA) to the cerebral territory. This retrospective study from a single center aimed to compare the outcomes following STA–MCA double bypass in 12 patients with recurrent ischemic stroke.

Materials and methods

We retrospectively analyzed the data from patients with internal carotid artery occlusion (ICAO) who had undergone STA–MCA double bypass in our center from January 2016 to December 2020. The surgical indications, evaluation of circle of Willis (CoW), changes in cerebral hemodynamic, surgical results, and follow-up results were analyzed.

Results

Post-operative perfusion-weighted imaging showed hemodynamic improvement in all 12 patients. Ten patients (83.33%) showed clinical improvement, and 2 patients (16.67%) had stable disease. No intracranial infections or acute ischemic events occurred. The post-operative National Institutes of Health Stroke Scale score and modified Barther scores were significantly improved after 180 days of follow-up. Twenty three (96%) anastomoses maintain patency of their bypass vessels, and none had recurrent cerebral infarction during a minimum of 36 months follow-up.

Conclusion

In this small study, in patients with recurrent ischemic stroke without other types of treatment, STA–MCA double bypass surgery was more effective in the subgroup of patients with ICAO and poor blood supply to the CoW and an area of cerebral hypoperfusion that exceeded the area supplied by the MCA.

Factors Influencing Long-Term Blood Flow in Extracranial-to-Intracranial Bypass for Symptomatic Internal Carotid Artery Occlusive Disease: A Quantitative Study

BACKGROUND

Maintaining the patency of extracranial-to-intracranial (EC-IC) bypass is critical for long-term stroke prevention. However, reports on the factors influencing long-term bypass patency and quantitative assessments of bypass patency are limited.

OBJECTIVE

To quantitatively evaluate blood flow in EC-IC bypass using four-dimensional (4D) flow magnetic resonance imaging (MRI) and investigate factors influencing the long-term patency of EC-IC bypass.

METHODS

Thirty-six adult Japanese patients who underwent EC-IC bypass for symptomatic internal carotid or middle cerebral artery occlusive disease were included. We examined the relationships between decreased superficial temporal artery (STA) blood flow volume and perioperative complications, long-term ischemic complications, patient background, and postoperative antithrombotic medications in patients for whom STA flow could be quantitatively assessed for at least 5 months using 4D flow MRI.

RESULTS

The mean follow-up time was 54.7 ± 6.1 months. One patient presented with a stroke during the acute postoperative period that affected postoperative outcomes. No recurrent strokes were recorded during long-term follow-up. Two patients died of malignant disease. Seven cases of reduced flow occurred in the STA, which were correlated with single bypass (P = .0294) and nonuse of cilostazol (P = .0294). STA occlusion was observed in 1 patient during the follow-up period. Hypertension, age, smoking, dyslipidemia, and diabetes mellitus were not correlated with reduced blood flow in the STA.

CONCLUSION

Double anastomoses and cilostazol resulted in long-term STA blood flow preservation. No recurrence of cerebral infarction was noted in either STA hypoperfusion or occlusion cases.

Cross-Comparison of 4-Dimensional Flow Magnetic Resonance Imaging and Intraoperative Middle Cerebral Artery Pressure Measurements Before and After Superficial Temporal Artery-Middle Cerebral Artery Bypass Surgery

BACKGROUND

The hemodynamic changes after superficial temporal artery (STA) to middle cerebral artery (MCA) bypass surgery are unclear.

OBJECTIVE

To clarify the hemodynamics by comparing flow parameters obtained by 4-dimensional (4D) flow magnetic resonance imaging (MRI) and intraoperative MCA pressure measurement.

METHODS

We recruited 23 patients who underwent STA-MCA bypass surgery for internal carotid artery (ICA) or MCA stenosis. We monitored intraoperative MCA, STA, and radial artery (RA) pressure. All patients underwent 4D flow MRI preoperatively and 3 wk after surgery to quantify the blood flow volume (BFV) of the ipsilateral ICA (BFViICA), contralateral ICA (BFVcICA), basilar artery (BFVBA), ipsilateral STA (BFViSTA), and contralateral STA (BFVcSTA). The sum of intracranial BFV was defined as BFVtotal. We compared BFV parameters and intraoperative pressure.

RESULTS

BFViSTA significantly increased after surgery (P < .001). BFViICA and BFVBA significantly decreased after surgery (BFViICAP = .005; BFVBAP = .02). No significant difference was observed between BFVcICA before and after surgery. As a result, BFVtotal postoperatively increased by 6.8%; however, no significant difference was observed. Flow direction at M1 changed from antegrade to unclear after surgery in 5 patients. Intraoperative MCA pressure and MCA/RA pressure ratio significantly increased after surgery (P < .001). We found a stronger positive correlation between MCA pressure increase ratio and BFVtotal increase ratio in patients with lower pre-MCA pressure (r = 0.907, P < .001).

CONCLUSION

The visual and quantitative assessment of 4D flow MRI revealed that intracranial blood flow changes complementarily after STA-MCA bypass surgery. 4D flow MRI may detect the improvement of cerebral perfusion pressure.

Whole-Field Indocyanine Green Intensity Analysis to Intraoperatively Predict Cerebral Hyperperfusion Syndrome Following Superficial Temporal Artery-Middle Cerebral Artery Bypass: A Retrospective Case-Control Study in 7-Year Experience With 112 Cases

BACKGROUND

Intraoperative prediction of postoperative cerebral hyperperfusion syndrome (CHS) after cerebrovascular bypass surgery is challenging.

OBJECTIVE

To conduct a retrospective case-control study with indocyanine green (ICG) intensity analysis of the superficial temporal artery-middle cerebral artery (STA-MCA) bypass and investigate whether its washout pattern might be a marker for intraoperative prediction of CHS.

METHODS

Between 2012 and 2018, 6 of 112 patients (5.4%) that underwent STA-MCA bypass exhibited CHS. We selected 5 patients with CHS (3 with atherosclerotic cerebrovascular disease [ASCVD] and 2 with moyamoya) and 15 patients without CHS (60% ASCVD and 40% moyamoya) as a matched control group. During prebypass and postbypass, washout times (WTs) for the first 10%, 25%, 50%, and 75% of maximum ICG intensity measured in the whole-camera field were compared between groups. The changes in WT (ΔWT) from prebypass to postbypass for each ICG intensity level were compared between groups. The cutoff ΔWTs, sensitivities, and specificities were also calculated.

RESULTS

Postbypass WTs were significantly longer in the CHS group than the control group at all ICG intensities (P < .05). ΔWT was significantly greater in the CHS group than the control group for the first 10%, 25%, and 50% ICG intensities (P < .001). A cutoff ΔWT of ≥2.66 s for the first 50% ICG intensity showed a sensitivity of 100% and specificity of 100%.

CONCLUSION

We found that a ΔWT ≥2.66 s for the first 50% ICG intensity could be an intraoperative predictive factor for CHS.

[The use of high-flow extracranial-intracranial artery bypass in pathology of the cerebral and brachiocephalic arteries: technical features and surgical outcomes]

BACKGROUND

Poor outcomes of surgical treatment for complex cerebral aneurysms due to the development of cerebral ischemia were the cause to use cerebral revascularization surgery for this pathology.

OBJECTIVE

the study objective was to master a high-flow extracranial-intracranial (EC-IC) artery bypass technique and evaluate its application in surgical treatment of complex and giant cerebral aneurysms as well as complex lesions of the brachiocephalic arteries.

MATERIAL AND METHODS

Fifty two patients underwent high-flow IC-EC bypass surgery; of these, 34 patients had complex cerebral aneurysms, and 18 patients had complex stenotic occlusive lesions of the brachiocephalic arteries. After bypass placement, the patients with aneurysms underwent different variants of aneurysm exclusion (trapping or proximal clipping/ligation of the parent artery). All patients underwent follow-up studies of the bypass function and clinical condition in the early postoperative period and 6 and 12 months after surgery.

RESULTS

High-flow IC-EC bypass surgery is routinely used in clinical practice of the Novosibirsk Federal Center of Neurosurgery. Fifty one out of the 52 patients were followed-up in a range of 4 to 56 months. According to the direct or CT angiography data, bypasses functioned in 51 (98.1%) patients in the early and long-term postoperative periods. The clinical efficacy (no ischemic changes and improved cerebral perfusion) of high-flow IC-EC bypasses was demonstrated in 31 (91.2%) of 34 patients with aneurysms and in 17 (94.4%) of 18 patients with complex lesions of the brachiocephalic arteries. The total number of surgical complications was 8 (15.4%) cases: 7 complications occurred in patients with aneurysms, and 1 complication developed in a patient with bilateral ICA occlusion. Of these, ischemic complications developed in 4 (7.7%) cases, hemorrhagic complications occurred in 2 (3.8%) cases, and cranial nerve complications were found in 2 (3.8%) cases. One (1.9%) female patient with a giant aneurysm died from hemispheric stroke due to insufficient blood flow through the bypass.

CONCLUSION

Implementation of a large number of surgeries enabled improvement of the technique and clarification of the prerequisites for preoperative examination, intraoperative control, and postoperative management of patients. A low mortalits rate suggests this technique for use in clinical practice. The surgery is indicated for the treatment of giant aneurysms of the petrous, cavernous, and clinoid segments of the ICA. In the case of giant supraclinoid aneurysms, the surgery may be combined with removal of thrombotic masses from the aneurysm sac for rapid decompression of the cranial nerves. Application of this surgery for treatment of giant aneurysms of the trunk and bifurcation of the basilar artery is promising but requires further investigation. The surgery is also recommended for improving cerebral perfusion in the setting of complex stenotic occlusive lesions of the BCA: prolonged BCA stenoses, tandem ICA stenoses located in both the extracranial and intracranial segments, nonspecific vasculitis and arteriitis, subcranial aneurysms, kinking etc.

Cerebral Hyperperfusion Syndrome by the Numbers: Transient Focal Neurological Deficit, Imaging-Proven Focal Hyperperfusion, and High Graft Flow Rate Following Superficial Temporal Artery-Middle Cerebral Artery bypass in a Patient With Symptomatic Carotid Occlusion—Case Report

BACKGROUND AND IMPORTANCE

Cerebral hyperperfusion syndrome (CHS) is a well-known complication of superficial temporal artery (STA) to middle cerebral artery (MCA) bypass for ischemic cerebrovascular disease. While this argues against “low flow” in the bypass construct, flow rates in the graft have not been previously quantified in the setting of CHS.

CLINICAL PRESENTATION

A 58-yr-old man presented with recurrent left hemispheric ischemic strokes and fluctuating right hemiparesis and aphasia. Vascular imaging revealed left cervical internal carotid artery occlusion and perfusion imaging confirmed left hemispheric hypoperfusion. After failing to respond to maximal medical therapy, the patient underwent single-barrel STA-MCA bypass. Postoperatively, his symptoms resolved and blood pressure (BP) was strictly controlled within normal range. However, 2 d later, he developed severe expressive aphasia. CTA demonstrated a patent bypass graft and SPECT showed focal hyperperfusion in Broca's speech area. Seizure activity was ruled out. A high graft flow rate of 52 mL/min was documented by quantitative magnetic resonance angiography (MRA). Thus, the diagnosis of CHS was made and managed with strict BP control. The patient exhibited complete recovery of speech over a period of days and was discharged home. Repeat SPECT at 4 mo showed resolution of hyperperfusion and quantitative MRA demonstrated reduction of graft flow rate to 34 mL/min.

CONCLUSION

This is the first case of perfusion imaging-proven CHS after STA-MCA bypass, where high graft flow rates are objectively documented. Our observations constitute irrefutable evidence challenging the classic belief that the STA-MCA bypass is a low-flow construct.

Double-Barrel Superficial Temporal Artery-Middle Cerebral Artery Bypass: Can It Be Considered “High-Flow?”

BACKGROUND

Traditionally, superficial temporal artery-middle cerebral artery (STA-MCA) bypass uses one STA branch. Its augmentation of flow has classically been described as “low flow.” In a double-barrel STA-MCA bypass, however, both branches of the STA are utilized. Here we hypothesize that this should not be considered “low flow.”

OBJECTIVE

To review quantitative flow data from our cases and investigate the impact of double-barrel STA-MCA bypass on total flow augmentation, and to assess whether double-barrel STA-MCA bypass might be useful in situations that traditionally demand more complex bypass strategies.

METHODS

Intraoperative flow probe measurements from STA-MCA bypass cases were retrospectively tabulated and compared. Cut flow and bypass flow measurements were, respectively, taken before and after completion of anastomoses. The higher value was labeled best observed flow (BOF).

RESULTS

We identified 21 STA-MCA bypass cases with available intraoperative flow probe measurements, of which 17 utilized double-barrel technique. Only 1 STA branch was available in 4 cases. Significantly higher average BOF was seen when utilizing 2 STA branches (69 vs 39 cc/min, P &lt; .001). A majority (9/17) of double-barrel bypasses provided BOF ≥ 65 cc/min (120 cc/min maximum). The single branch bypass maximum BOF was 40 cc/min.

CONCLUSION

Double-barrel bypass technique significantly enhances STA-MCA flow capacity and may be useful in situations in which a high-flow bypass is needed. The 2 efferent limbs allow flexibility in distributing flow across separate at-risk territories. The method compares favorably to other descriptions of high-flow bypass without the morbidity of graft harvest or an additional cervical incision.