Confirmation of blood flow in perforating arteries using fluorescein cerebral angiography during aneurysm surgery

Utility and the limit of motor evoked potential monitoring for preventing complications in surgery for cerebral arteriovenous malformation

OBJECTIVE

To evaluate the usefulness of motor evoked potential (MEP) monitoring and mapping in arteriovenous malformation surgery.

METHODS

Intraoperative MEP monitoring was performed in 21 patients whose AVMs were located near the motor area or fed by arteries related to the corticospinal tract to detect blood flow insufficiency and/or direct injury to the corticospinal tract and/or to map the motor area.

RESULTS

In 4 of 16 patients monitored for blood flow insufficiency, the MEP changed intraoperatively. In 2 patients, the changes were attributable to temporary occlusion of the feeding artery (anterior choroidal or lenticulostriate artery): 1 patient had a venous infarction around the internal capsule caused by thrombosis of the draining vein and the other bled intraoperatively from the nidus. In 17 patients, the MEP was monitored to rule out direct injury. In 1 patient, the MEP changed on coagulation of fragile vessels around the nidus in the precentral gyrus; it recovered after coagulation was discontinued. In 1 of 5 patients with MEP changes, the MEP did not recover; permanent hemiparesis developed in this patient because of venous infarction. In 1 of 11 patients subjected to MEP mapping of the motor area, we found translocation to the postcentral sulcus.

CONCLUSION

In arteriovenous malformation surgery, MEP monitoring facilitates the detection of blood flow insufficiency and/or direct injury of the corticospinal tract and mapping of the motor area. It contributes to reducing the incidence of postoperative motor paresis.

Indocyanine green videoangiography to detect aneurysm and related vascular structures buried in subarachnoid clots

This 44-year-old woman presented with a ruptured anterior communicating artery aneurysm. Intraoperative indocyanine green (ICG) videoangiography demonstrated the aneurysm neck and dome, which were buried in subarachnoid clots. Dissection and aspiration of the clots around the neck were safely performed without touching the ruptured points. The aneurysm was successfully clipped. The patient's postoperative course was excellent. This case illustrates the use of intraoperative ICG videoangiography to provide information about the anatomical location of the aneurysm neck and dome despite their being completely obscured by subarachnoid clots. Intraoperative ICG videoangiography allowed safer dissection of the ruptured aneurysm from the blood clots.

Brain Retraction and Thickness of Cerebral Neocortex: An Automated Technique for Detecting Retraction-Induced Anatomic Changes Using Magnetic Resonance Imaging

BACKGROUND:

Treating deep-seated cerebral lesions often requires retracting the brain. Retraction, however, causes clinically significant postoperative neurological deficits in 3% to 9% of intracranial cases.

OBJECTIVE:

This pilot study used automated analysis of postoperative magnetic resonance images (MRIs) to determine whether brain retraction caused local anatomic changes to the cerebral neocortex and whether such changes represented sensitive markers for detecting brain retraction injury.

METHODS:

Pre- and postoperative maps of whole-brain cortical thickness were generated from 3-dimensional MRIs of 6 patients who underwent selective amygdalohippocam-pectomy for temporal lobe epilepsy (5 left hemispheres, 1 right hemisphere). Mean cortical thickness was determined in the inferior temporal gyrus (ITG test), where a retractor was placed during surgery, and in 2 control gyri—the posterior portion of the inferior temporal gyrus (ITG control) and motor cortex control. Regions of cortical thinning were also compared with signs of retraction injury on early postoperative MRIs.

RESULTS:

Postoperative maps of cortical thickness showed thinning in the inferior temporal gyrus where the retractor was placed in 5 patients. Postoperatively, mean cortical thickness declined from 4.1 ± 0.4 mm to 2.9 ± 0.9 mm in ITG test (P = .03) and was unchanged in the control regions. Anatomically, the region of neocortical thinning correlated with postoperative edema on MRIs obtained within 48 hours of surgery.

CONCLUSION:

Postoperative MRIs can be successfully interrogated for information on cortical thickness. Brain retraction is associated with chronic local thinning of the neocortex. This automated technique may be sensitive enough to detect regions at risk for functional impairment during craniotomy that cannot be easily detected on postoperative structural imaging.

Intuitiveness, quality and utility of intraoperative fluorescence videoangiography: Australian Neurosurgical Experience

INTRODUCTION

The authors have undertaken a study of their intraoperative experience with indocyanine green fluorescence videoangiography (ICGFV). In particular, the intuitiveness, image quality and clinical utility of this technology have been assessed.

METHODS

The records of forty-six consecutive craniotomies utilising ICGFV have been retrospectively reviewed: There were 27 aneurysms, 2 extracranial-intracranial (EC-IC) bypasses, 5 arteriovenous malformations (AVM), 1 dural arteriovenous fistula (DAVF), 3 cavernomas, 5 meningiomas, and 3 gliomas. ICGFV was used in 5 awake-craniotomy patients. ICGFV was performed using a Leica OH4 surgical microscope with integrated near-infrared camera and ICG-PULSION.

RESULTS

All attempts of intraoperative ICGFV were intuitive. Image quality and resolution were excellent. Arterial and venous phases were comparable to digital subtraction angiography (DSA) but field of view was relatively limited. In 12 operations (26%) the surgeon was substantially benefited from ICGFV findings. In 22 operations (48%), ICGFV was useful but did not influence surgical management. ICGFV was of no benefit in 11 operations (24%) and was misleading in 1 (2%). In this series, ICGFV was of benefit to 1 of 11 (9%) patients with an intracranial neoplasm or cavernoma.

CONCLUSIONS

ICGFV is safe, intuitive and provides neurosurgeons with high quality, valuable, real-time imaging of cerebrovascular anatomy. It can assist in intraoperative surgical management and/or stroke prevention particularly during aneurysm clipping, EC-IC bypass and AVM/DAVF surgery.

Surgical management of aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a common and often devastating condition that requires prompt neurosurgical evaluation and intervention. Modern management of aSAH involves a multidisciplinary team of subspecialists, including vascular neurosurgeons, neurocritical care specialists and, frequently, neurointerventional radiologists. This team is responsible for stabilizing the patient on presentation, diagnosing the offending ruptured aneurysm, securing the aneurysm, and managing the patient through a typically prolonged and complicated hospital course. Surgical intervention has remained a definitive treatment for ruptured cerebral aneurysms since the early 1900s. Over the subsequent decades, many innovations in microsurgical technique, adjuvant maneuvers, and intraoperative and perioperative medical therapies have advanced the care of patients with aSAH. This report focuses on the modern surgical management of patients with aSAH. Following a brief historical perspective on the origin of aneurysm surgery, the topics discussed include the timing of surgical intervention after aSAH, commonly used surgical approaches and craniotomies, fenestration of the lamina terminalis, intraoperative neurophysiological monitoring, intraoperative digital subtraction and fluorescent angiography, temporary clipping, deep hypothermic cardiopulmonary bypass, management of acute hydrocephalus, cerebral revascularization, and novel clip configurations and microsurgical techniques. Many of the topics highlighted in this report represent some of the more debated techniques in vascular neurosurgery. The popularity of such techniques is constantly evolving as new studies are performed and data about their utility become available.

Intraoperative indocyanine green angiography for obliteration of a spinal dural arteriovenous fistula

Spinal dural arteriovenous fistulas (DAVFs) are the most common type of spinal arteriovenous malformation and are an important, underdiagnosed cause of progressive myelopathy and morbidity in patients with spine disorders. Successful microsurgical management of these lesions is dependent on the surgeon's ability to identify vessels of the fistula and to confirm its successful obliteration postintervention. Indocyanine green (ICG) fluorescent angiography is an emerging tool for delineating intraoperative vascular anatomy, and it has significant potential utility in the treatment of vascular disease in the spine. The authors present the case of a 76-year-old man with progressive and debilitating bilateral lower-extremity weakness and numbness on exertion, in whom a left T-8 spinal DAVF was diagnosed based on results of conventional spinal angiography. Unfavorable anatomy based on angiographic findings precluded endovascular embolization of the fistula, and the patient subsequently underwent T7-9 bilateral laminectomies for microsurgical clip occlusion. Intraoperative ICG fluorescent angiography was used before clip placement to identify the arterialized veins of the fistula, and after clip placement to confirm obliteration of the fistulous connection and restoration of normal blood flow. Intraoperative ICG angiography serves an important role in the microsurgical treatment of DAVF. It can be used to map the anatomy of the fistula in real time during surgery and to verify fistula obliteration rapidly after clip placement. This report adds to the growing body of literature demonstrating the importance of ICG angiography in vascular neurosurgery of the spine.

Role of pre- and intraoperative imaging and neuronavigation in neurosurgery

Advances in neuroimaging acquisition, computing and image processing have enabled neurosurgeons to use radiological imaging to guide both preoperative planning and intraoperative guidance. In preoperative planning, imaging may be used to evaluate surgical risks, choose the best method of intervention and select the safest surgical approach. Neuronavigation may be useful in designing the surgical flap and alerting the surgeon of surrounding anatomy. Finally, intraoperative imaging may be used to define brain shift associated with the resection of intracranial lesions, assist in more complete lesion resection, and monitor for certain intraoperative complications. In the following review, we briefly examine the history of neuroradiology for neurosurgery, neuronavigation and intraoperative imaging and trace their advances to current systems in use. We will also highlight new experimental applications of neuroimaging that are currently being refined.

Fluorophore-conjugated anti-CEA antibody for the intraoperative imaging of pancreatic and colorectal cancer

INTRODUCTION

Colorectal and pancreatic cancers together comprise the third and fourth most common causes of cancer-related death in the United States. In both of these cancers, complete detection of primary and metastatic lesions at the time of surgery is critical to optimal surgical resection and appropriate patient treatment.

MATERIALS AND METHODS

We have investigated the use of fluorophore-labeled anti-carcinoembryonic antigen (CEA) monoclonal antibody to aid in cancer visualization in nude mouse models of human colorectal and pancreatic cancer. Anti-CEA was conjugated with a green fluorophore. Subcutaneous, orthotopic primary and metastatic human pancreatic and colorectal tumors were easily visualized with fluorescence imaging after administration of conjugated anti-CEA. The fluorescence signal was detectable 30 min after systemic antibody delivery and remained present for 2 weeks, with minimal in vivo photobleaching after exposure to standard operating room lighting. Tumor resection techniques revealed improved ability to resect labeled tumor tissue under fluorescence guidance. Comparison of two different fluorophores revealed differences in dose-response and photobleaching in vivo.

CONCLUSION

These results indicate that fluorophore-labeled anti-CEA offers a novel intraoperative imaging technique for enhanced visualization of tumors in colorectal and pancreatic cancer when CEA expression is present, and that the choice of fluorophore significantly affects the signal intensity in the labeled tumor.