Faculty Bibliography

OBJECTIVE: To describe techniques of reconstruction for unclippable and uncoilable middle cerebral artery aneurysms. METHODS: A retrospective review was performed of seven patients who underwent eight operations during a 9-year period to treat complex middle cerebral artery bifurcation aneurysms not amenable to direct clipping or endovascular coiling. All preoperative and postoperative clinical and imaging data were reviewed. Follow-up was obtained for all patients via clinic visit and/or telephone. RESULTS: The operative techniques used included saphenous vein graft bypass (n = 1), radial artery graft interposition (n = 2), radial artery patch (n = 1), superficial temporal artery interposition graft (n = 1), superior thyroid artery interposition graft (n = 1), direct reimplantation of branch (n = 1), and reconstruction of trifurcation (n = 1). There was no mortality. Six patients had excellent outcomes with Glasgow Outcome Scale scores of 5, and one patient had a good outcome with a Glasgow Outcome Scale score of 4. CONCLUSION: Techniques for middle cerebral artery reconstruction may remain important and useful in the age of endovascular aneurysm treatment

OBJECTIVE: To describe the bypass techniques, cranial base approaches, results of treatment, causes of failure, and lessons that are learned in patients with posterior circulation aneurysms requiring revascularization. METHODS: Retrospectively, 19 patients with posterior fossa aneurysms requiring revascularization procedures operated on between 1991 and 2002 were reviewed. Preoperative and postoperative clinical information, neurological examinations, imaging data, and updated follow-ups were reviewed. Patient outcome is reported as the most current Karnofsky Performance Scale score. RESULTS: A total of 22 arterial bypasses were performed in 19 patients for posterior fossa circulation aneurysms between 1991 and 2002. The mean follow-up was 41 months. Total graft patency rate (including patients requiring reoperation) was 86.4% (before) and 100% (after) salvage procedures. Patient outcome was 84.2% with Karnofsky Performance Scale score 80 to 90, and three deaths occurred perioperatively. Only one death could be attributed to the failure of the radial artery graft because of spasm and subsequent rupture during angioplasty. CONCLUSION: Certain graft selection criteria and technical considerations contribute to the success or failure of bypass grafts in the management of posterior circulation aneurysms. Bypass procedures remain an important method of management of complex posterior circulation aneurysms, in addition to endovascular procedures

OBJECTIVE: To discuss the results of endoscope-assisted surgery in microvascular decompression (MVD) of Cranial Nerves (CNs) V, VII, and VIII. METHODS: Neuroendoscopy was used as an adjunct to the surgical microscope in the MVD of the trigeminal (17 patients), facial (10 patients), and vestibulocochlear (1 patient) nerves in a series of 28 consecutive patients. After a standard microsurgical approach to CNs V, VII, and VIII, the endoscope was used to inspect all aspects of neural anatomy, to assess vascular compression, and to check the results of the decompression. Endoscope use was graded in four categories: Grade I, used but no definite role; Grade II, visualization assisted; Grade III, procedure assisted; and Grade IV, primary role. The usefulness of the endoscope was evaluated in each case. RESULTS: The endoscope was useful in visualizing the anatomy in all cases. It was especially useful in establishing trigeminal vein compression of CN V in Meckel's cave; observing multiple sources of vascular compression; ensuring adequate decompression after cauterization of vein, insertion of the Teflon felt, or a pexy procedure; and permitting observation of the compression of CN VII at the root exit zone by small arteries and veins. In six patients with trigeminal neuralgia, the trigeminal vein was cauterized and divided by using endoscopic vision only because the venous compression was not completely visualized with the microscope. During a follow-up period of 6 to 52 months (mean, 29 mo; median, 40 mo), all patients were asymptomatic and receiving no medication. CONCLUSION: The endoscope is a useful adjunct to MVD in the treatment of trigeminal neuralgia, hemifacial spasm, and disabling positional vertigo or tinnitus

OBJECT: Application of sensitive infrared imaging is ideally suited to observe blood vessels and blood flow in exposed organs, including the brain. Temporary vascular occlusion is an important part of neurosurgery, but the capacity to monitor the effects of these occlusions in real time is limited. In surgical procedures that require vascular manipulation, such as those involving aneurysms, arteriovenous malformations (AVMs), or tumors, the ability to visualize blood flow in vessels and their distribution beds would be beneficial. The authors recount their experience in the use of a sensitive (0.02 degrees C), high-resolution (up to 50 microm/pixel) infrared camera with a rapid shutter speed (up to 2 msec/frame) for localizing cortical function intraoperatively. They observed high-resolution images of cerebral arteries and veins. The authors hypothesized that infrared imaging of cerebral arteries, performed using a sensitive, high-resolution camera during surgery, would permit changes in arterial flow to be be seen immediately, thus providing real-time assessment of brain perfusion in the involved vascular territory. METHODS: Cynomolgus monkeys underwent extensive craniectomies, exposing the frontal, parietal, and temporal lobes. Temporary occlusions of the internal carotid artery and middle cerebral artery branches (30 events) were performed serially and were visualized with the aid of an infrared camera. Arteries and veins of the monkey brain were clearly visualized due to cooling of the exposed brain, which contrasted with blood within the vessels that remained at core temperature. Blood flow changes in vessels were seen immediately (< 1 second) in real time during occlusion and reopening of the vessels, regardless of the duration of the occlusion. Areas of decreased cortical blood flow rapidly cooled (-0.3 to 1.3 degrees C) and reheated in response to reperfusion. Rewarming occurred faster in arteries than in the cortex (for a 20-minute occlusion, the change in temperature per second was 2 x 10(-2) degrees C in the artery and 7 x 10(-3) degrees C in the brain). Collateral flow could be evaluated by intraoperative observations and data processing. CONCLUSIONS: Use of high-resolution, digital infrared imaging permits real-time visualization of arterial flow. It has the potential to provide the surgeon with a means to assess collateral flow during temporary vessel occlusion and to visualize directly the flow in parent arteries or persistent filling of an aneurysm after clipping. During surgery for AVMs, the technique may provide a new way to assess arterial inflow, venous outflow, results of embolization, collateral flow, steal, and normal perfusion pressure breakthrough