Therapeutic Occlusion of Major Vessels, Test Occlusion and Techniques

Temporary Balloon Occlusion Test of the Left Vertebral Artery Using Parenchymography as Tolerance Predictor

Temporary balloon occlusion is used as tolerance predictor in patients undergoing vascular occlusion with the aid of clinical assessment during a 30–40 minute temporary occlusion. Several other techniques have been used to help predict each patient's tolerance. Digital cerebral parenchymography (DCP) was originally described to improve our analysis of brain perfusion during ischemic events. We report a case using DCP as tolerance predictor in a patient undergoing sacrifice of the left vertebral artery.

Cerebral Perfusion Imaging

There are multiple imaging techniques available to assess cerebral perfusion, including positron emission tomography (PET), xenon computed tomography (XeCT), single photon emission computed tomography (SPECT), perfusion-weighted MRI (PWI), and perfusion computed tomography (PCT). Current interest has focused mainly on their use in the setting of acute brain ischemia. Perfusion imaging may be able to distinguish infarcted from salvageable ischemic tissue as a guide to treatment. Perfusion techniques may also be helpful in cases of chronic ischemia, post-subarachnoid hemorrhage vasospasm, trauma, and contemplated therapeutic carotid artery occlusion.

The magnetic resonance Matas test: Feasibility and comparison with the conventional intraarterial balloon test occlusion with SPECT perfusion imaging

PURPOSE

To evaluate a new MR Matas test that uses a form of contrast-enhanced MR angiography (MRA) with temporary manual occlusion of the common carotid artery whose internal carotid artery (ICA) is to be permanently sacrificed.

MATERIALS AND METHODS

The MR Matas test was performed on eight patients using an open type MR imager (Signa Profile 0.2 Tesla ver. 7.5, GE-YMS, Tokyo, Japan). Conventional balloon occlusion Matas test and single-photon emission computed tomography (SPECT) of the brain were performed in all cases within a week before or after the MR Matas test.

RESULTS

The MR Matas test was successful in all eight patients without any complications. The image quality of the MR Matas test was generally sufficient to confirm cross-flow from the patent side to the occluded side in comparison with selective intraarterial digital subtraction angiography (IADSA) except in one case.

CONCLUSION

Brain perfusion information using MR Matas test is comparable to brain SPECT.

Cerebral perfusion CT: technique and clinical applications

Perfusion computed tomography (CT) is a relatively new technique that allows rapid qualitative and quantitative evaluation of cerebral perfusion by generating maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT). The technique is based on the central volume principle (CBF = CBV/MTT) and requires the use of commercially available software employing complex deconvolution algorithms to produce the perfusion maps. Some controversies exist regarding this technique, including which artery to use as input vessel, the accuracy of quantitative results, and the reproducibility of results. Despite these controversies, perfusion CT has been found to be useful for noninvasive diagnosis of cerebral ischemia and infarction and for evaluation of vasospasm after subarachnoid hemorrhage. Perfusion CT has also been used for assessment of cerebrovascular reserve by using acetazolamide challenge in patients with intracranial vascular stenoses who are potential candidates for bypass surgery or neuroendovascular treatment, for the evaluation of patients undergoing temporary balloon occlusion to assess collateral flow and cerebrovascular reserve, and for the assessment of microvascular permeability in patients with intracranial neoplasms. This article is a review of the technique, clinical applications, and controversies surrounding perfusion CT.

A protocol for management of a catastrophic complication of functional endoscopic sinus surgery: internal carotid artery injury

Injury to the cavernous portion of the internal carotid artery is a well recognized and dreaded complication of functional endoscopic sinus surgery. Little information, however, has been presented in the Otolaryngology literature regarding the etiology, prevention, or treatment of this complication. The purpose of this study is to present a case report of a cavernous carotid artery injury during functional endoscopic sinus surgery. Relevant anatomy, preventive measures, and treatment approaches are discussed for this difficult problem.

Minimally invasive neurosurgery

BACKGROUND

The philosophy and practice of minimally invasive surgery have fundamentally altered the practice of general and gynaecological surgery, and are currently transforming the practice of neurosurgery. The goal of minimally invasive surgery is to reduce tissue disruption and thus morbidity. This is a review of the development, applications, and benefits of minimally invasive neurosurgery, and its wider surgical implications.

METHODS

A synthesis of the literature is presented.

RESULTS

Interactive computer imaging with frame-based and frameless stereotaxy, ultrasonographic and endoscopic techniques are increasingly being used independently and in combination in order to execute minimally invasive approaches and to navigate a safe path within the cranium or spine. Interaction using an interlinking stereotactic instrument or robot between the surgeon, a graphic interface (such as a computer workstation) and the patient, enables precise planning and execution of surgery with exact correspondence of imaging data and the living pathology. The direct influence of virtual reality, cybernetics, robotics, and telepresence will further revolutionize the practice of neurosurgery and will impact increasingly on other surgical disciplines. Safety and precision are further enhanced by intra-operative physiological monitoring techniques. Interventional neuroradiology and stereotactic radiosurgery add further dimensions to the minimally invasive approach and may not only diminish the need for open surgery, but in selected cases obviate the need altogether.

CONCLUSIONS

Minimally invasive neurosurgery is a major force in contemporary neurosurgery and many of the current neurosurgical applications will have far-reaching effects on the practice of surgery in general.

Medical management in the endovascular treatment of carotid-cavernous aneurysms

Carotid-cavernous aneurysms account for between 1.9% and 9.0% of intracranial aneurysms. Entirely intercavernous aneurysms are believed to have a relatively benign course, with cranial nerve findings or headache being the usual initial symptomatology; however, subarachnoid hemorrhage or carotid-cavernous fistula formation can result from rupture. Over the past 15 years endovascular parent artery occlusion has essentially replaced surgical carotid occlusion as the treatment of choice. The authors describe a series of 39 consecutive patients at the University of Virginia Health Sciences Center who underwent endovascular treatment of a carotid-cavernous aneurysm. Aggressive invasive hemodynamic monitoring and maintenance of a state of normo- to mild hypervolemia in the asymptomatic patient was used throughout the periprocedural period. Rapid institution of hypervolemic-hypertensive therapy can reverse early neurological deficits related to hypoperfusion in these patients. Only one individual managed with this protocol developed neurological deficits not reversible with hypertensive-hypervolemic therapy. Heparin therapy was administered for 48 hours after occlusion, with patients receiving subsequent aspirin therapy for 6 months to combat distal embolism secondary to thrombosis. Long-term complications were not seen in patients receiving aneurysm trapping; however, two individuals with proximal carotid occlusion developed late optic neuropathy and one had recurrent transient ischemic attacks that ceased with supraclinoidal carotid clipping.

Acute subdural hematoma caused by a ruptured giant intracavernous aneurysm: case report

A case of a giant intracavernous carotid artery aneurysm that presented as an acute subdural hematoma is reported. The patient was initially treated unsuccessfully with endovascular aneurysmal embolization and subsequently underwent attempted microsurgical clipping with preservation of the parent artery. At operation, an angiogram showed occlusion of the parent vessel, and the aneurysm was trapped by occlusion of the internal carotid artery. The patient did well for 2 days postoperatively but then developed contralateral progressive hemiplegia and aphasia. Emergent subsequent exploration and middle cerebral artery embolectomy were performed, and the hemiplegia and aphasia resolved rapidly. At 2-year follow-up, the patient continues to do well. To our knowledge, this is the first reported case of a patient who survived an acute subdural hematoma caused by an intracavernous carotid artery aneurysm.