Regional cortical blood flow during extra-intracranial bypass surgery in young patients with moyamoya disease

Invasive Neuromonitoring Modalities in the Pediatric Population

Invasive neuromonitoring has become an important part of pediatric neurocritical care, as neuromonitoring devices provide objective data that can guide patient management in real time. New modalities continue to emerge, allowing clinicians to integrate data that reflect different aspects of cerebral function to optimize patient management. Currently, available common invasive neuromonitoring devices that have been studied in the pediatric population include the intracranial pressure monitor, brain tissue oxygenation monitor, jugular venous oximetry, cerebral microdialysis, and thermal diffusion flowmetry. In this review, we describe these neuromonitoring technologies, including their mechanisms of function, indications for use, advantages and disadvantages, and efficacy, in pediatric neurocritical care settings with respect to patient outcomes.

An Alternative Display Could Lead to Earlier Diagnosis of Intracerebral Pathology with a Hemedex Flow Probe In Situ

OBJECTIVE

To report 2 cases of patients who had an ischemic stroke and an intracerebral hematoma after a superficial temporal artery-middle cerebral artery bypass with a thermal diffusion blood flow probe in situ and emphasize how a change in the way the data are presented could have led to an earlier diagnosis.

METHODS

Both patients had flow probes within 2 cm of the graft site and were thus close enough to be representative of local or regional rather than global perfusion. Data smoothening was applied to the raw data that were available and displayed on the monitor. Both the smoothed plots and the raw plots were analyzed.

RESULTS

Good clinical correlation was observed between the flow probe data and the clinical condition of both patients. This was more apparent when viewing the smoothed plots.

CONCLUSIONS

Although there was good clinical correlation, data displayed on the perfusion monitor can be incorrectly interpreted because the signal-to-noise ratio is small. We therefore suggest an alternative presentation of perfusion data for clinicians to recognize hypoperfusion and to take informed action before a stroke or hematoma is clinically manifest.

Neurosurgical Advances in the Treatment of Moyamoya Disease

Background and Purpose—

Moyamoya disease is characterized by chronic stenoocclusive vasculopathy involving the distal supraclinoid internal carotid arteries and presents with ischemic or hemorrhagic symptoms. We review advances in the understanding and management of moyamoya disease.

Summary of Review—

Cerebral revascularization, either direct or indirect, is the cornerstone of treatment for moyamoya disease. Recent advances have been made in understanding the molecular biology and pathophysiology of moyamoya disease, and new genetic mutations and deletions have been identified. Imaging for moyamoya disease is also rapidly improving with new sequences of MRI and better methods of assessing ischemia and cerebrovascular reserve. Positron emission tomography has emerged as an important tool to measure cerebrovascular reserve. Novel surgical techniques assess patency and ischemia during superficial temporal to middle cerebral artery bypass, including indocyanine green videoangiography to evaluate anastomosis patency, and various methods to monitor intraoperative blood flow. Newer methods of indirect revascularization have been described with placement of more tissues supplied by the external carotid artery on the brain surface. Postoperative hyperperfusion to the chronically ischemic brain tissue is a recently identified causative factor of complications. Interestingly, complications from hyperperfusion mimic those caused by ischemia, although they have different treatments, making the role of postoperative blood flow assessment important in distinguishing between the two. Awareness has also increased that even asymptomatic patients can experience significant cognitive decline attributable to chronic ischemia. Whether this reverts after successful revascularization requires investigation.

Conclusions—

Surgical revascularization with direct, indirect, and combined methods remains the preferred procedure for patients with moyamoya disease.

EC-IC bypass using the distal stump of the superficial temporal artery as an additional collateral source of blood flow in patients with Moyamoya disease

BACKGROUND

To establish multiple bypass flow in an adult Moyamoya disease patient, the distal stump of the parietal superficial temporal artery (dsPSTA) was used as an additional donor.

METHODS

Its potential as the donor was first evaluated by measuring the arterial pressure directly in three patients, revealing about 80% in mean arterial pressure of those measured at the proximal stump and radial artery. The anastomosis was performed just as conventionally except an additional anastomosis between the dsPSTA and frontal branch of the middle cerebral artery in 10 hemispheres of 7 patients.

RESULTS

The patency of the dsPSTA bypass was confirmed on postoperative angiography in 5 patients. The comparison of pre- and post-operative single photon emission computed tomography was feasible in 8 hemispheres of 6 patients of which 7 demonstrated improvement of the cerebral blood flow. CONCLUSION; This technique provides a novel source of donor artery in the treatment of Moyamoya disease, in which multiple anastomoses are desirable.

A Novel Minimally Occlusive Microvascular Anastomosis Technique Using a Temporary Intraluminal Shunt: A Prospective Technique to Minimize Brain Ischemia Time during Superficial Temporal Artery-to-Middle Cerebral Artery Bypass

OBJECTIVE:

To describe a new technique of suturing microvessels with persistent perfusion via a temporary intraluminal microshunt.

METHODS:

Experiments were conducted in Wistar rats. Abdominal aorta grafts were explanted from donor rats. A soft silicon microcatheter was introduced into the lumen of this graft. The abdominal aorta of a recipient rat was prepared for end-to-side microvascular anastomosis. Acland clamps (S&T AG, Neuhausen, Switzerland) were applied, and a linear arteriotomy was made. One end of the graft-clad microcatheter was introduced into the lumen and occluded with a fenestrated Acland clamp. At a more distal part, a similar arteriotomy was performed, and the other end of the microcatheter was introduced into the lumen and clamped with a fenestrated Acland clip. This created a temporary shunt through the graft-clad microcatheter. Then, the graft was anastomosed to the arteriotomies at both ends, over the microcatheter, in an end-to-side manner. The microcatheter was explanted from the vessel lumen through an arteriotomy in the middle of the graft. The graft was clipped short to close this arteriotomy. The mean total occlusion time before perfusion was reestablished amounted to 3.7 minutes. This experiment was repeated in 12 animals (6 with and 6 without heparin) without technical complications. As controls, conventional anastomoses were made in 2 animals.

RESULTS:

Suturing microvessels mandates their occlusion during the period of anastomosis. Although ischemia is well tolerated by other tissue types, the brain is quite sensitive to even short windows of ischemia. Nonocclusive anastomotic techniques have been developed recently. These are confined to vessels with luminal diameters greater than 3 mm. We have evolved a novel technique that can be used with microvessels, as pertinent to superficial temporal artery-to-middle cerebral artery bypass.

CONCLUSION:

We have described a new technique for performing microvascular anastomoses over a temporary intraluminal microcatheter shunt.

Evaluation of cerebral blood flow and hemodynamic reserve in symptomatic moyamoya disease using stable Xenon-CT blood flow

Moyamoya disease is a vascular abnormality seen in children and adults characterized by progressive narrowing of the internal carotid, middle, anterior, and posterior cerebral arteries and the development of leptomeningeal and proximal internal carotid artery collaterals, which appear diaphanous on angiogram. Although adults tend to present with subarachnoid hemorrhage and children with ischemic events, the clinical sequelae in these two populations overlap. Expanding upon work done at this institution using stable xenon computer tomographic blood flow determinations with acetazolamide and carbon dioxide challenge to predict which population of patients with severe carotid disease and hemodynamic compromise would benefit from surgical intervention, we used similar rationale to determine which patients with moyamoya disease would likely benefit from revascularization. Data and outcome concerning four such patients make up the body of this report.

Cortical blood flow response to hypercapnia during anaesthesia in Moyamoya disease

Cortical blood flow (CoBF) was measured continuously by the laser-Doppler method to evaluate the effect of hypercapnia on cortical blood flow during ten surgical procedures in ten young patients (mean +/- SD 9.3 +/- 6.4 yr) with Moyamoya disease. The CoBF was 42.8 +/- 13.4 (ml.100 g-1.min-1) during normocapnia (PaCO2 = 39.0 +/- 2.4 mmHg), and 38.7 +/- 14.4 during hypercapnia (PaCO2 = 47.1 +/- 2.5 mmHg). There was a decrease in CoBF with hypercapnia (P < 0.05) so that the normal CoBF response to hypercapnia was impaired during surgery in the patients with Moyamoya disease. He concluded that patients with Moyamoya disease have a precarious cerebral circulation and hypercapnia may be detrimental to the cortical circulation. This suggests that normocapnia is preferable to hypercapnia in patients with Moyamoya disease during anaesthesia.