Surgical Endovascular Neuroradiology in the 21st Century: What Lies Ahead?

Comparison of tertiary-center aneurysm location frequencies in 400 consecutive cases: Decreasing incidence of posterior communicating artery region aneurysms

Background:

The growing number of community hospitals with neurointerventional services over the past decade has changed the type and complexity of cerebral aneurysms referred to tertiary centers. The authors hypothesized that this would be reflected in changes in the location frequencies of aneurysms treated now compared to before the widespread institution of endovascular coiling.

Methods:

Using a prospectively collected aneurysm database, aneurysm location frequencies were retrospectively reviewed for the last 200 consecutively treated aneurysms (2009–2010) and 200 consecutive aneurysms treated starting from May 1999 to December 2000. International Subarachnoid Aneurysm Trial (ISAT) aneurysm location nomenclature was utilized. Two-tailed Student's t-tests were used to compare means and Fisher exact tests were used to compare proportions.

Results:

The location frequencies of all aneurysms (ruptured and unruptured) treated in the 2000 epoch as compared to the modern epoch showed significant changes for middle cerebral aneurysms (12.0% vs. 21.0%, P = 0.014), posterior communicating (21.0% vs. 13.0%, P = 0.0001), and para-ophthalmic aneurysms (10.0% vs. 25.5%, P = 0.0002). For unruptured/elective aneurysms, the change in posterior communicating aneurysms was even more pronounced (27.8% vs 3.6%, P = 0.0001). The rate of aneurysm coiling at the center rose from 26% to 37% (P = 0.02).

Conclusions:

The significant reduction in the referrals to our tertiary center of less technically complex aneurysms (posterior communicating segment) and increased referrals of aneurysms not as amenable to coil embolization (middle cerebral artery) is likely attributable to the growth of neurointerventional services at community hospitals over the past 10 years.

Imaging of acute ischemic stroke

In this article the individual components of multimodal computed tomography and multimodal magnetic resonance imaging are discussed, the current status of neuroimaging for the evaluation of the acute ischemic stroke is presented, and the potential role of a combined multimodal stroke protocol is addressed.

The role of CT and MRI in the emergency evaluation of persons with suspected stroke

As a growing number of therapeutic treatment options for acute stroke are being introduced, multimodal acute neuroimaging is assuming a growing role in the initial evaluation and management of patients. Multimodal neuroimaging, using either a CT or MRI approach, can identify the type, location, and severity of the lesion (ischemia or hemorrhage); the status of the cerebral vasculature; the status of cerebral perfusion; and the existence and extent of the ischemic penumbra. Both acute and long-term treatment decisions for stroke patients can then be optimally guided by this information.

Computer simulation of vertebral artery occlusion in endovascular procedures

OBJECTIVE

The aim of this work is to establish a computational pipeline for the simulation of blood flow in vasculatures and apply this pipeline to endovascular interventional scenarios, e.g. angioplasty in vertebral arteries.

METHODS

A patient-specific supra-aortal vasculature is digitized from a 3D CT angiography image. By coupling a reduced formulation of the governing Navier-Stokes equations with a wall constitutive equation we are able to solve the transient flow in elastic vessels. By further incorporating a bifurcation model the blood flow across vascular branches can be evaluated, thus flow in a large vasculature can be modeled. Vascular diseases are simulated by modifying the arterial tree configurations, e.g. the effective diameters, schematic connectivity, etc. Occlusion in an artery is simulated by removing that artery from the arterial tree.

RESULTS

It takes about 2 min per cardiac cycle to compute blood flow in an arterial tree consisting of 38 vessels and 18 bifurcations on a laptop PC. The simulation results show that blood supply in the posterior region is compensated from the contralateral vertebral artery and the anterior cerebral arteries if one of the vertebral arteries is occluded.

CONCLUSION

The computational pipeline is computationally efficient and can capture main flow patterns at any point in the arterial tree. With further improvement it can serve as a powerful tool for the haemodynamic analysis in patient-specific vascular structures.

The combined approach to intracranial aneurysm treatment

BACKGROUND

A consecutive series of patients with intracranial aneurysms in the practice of one neurovascular surgeon was retrospectively reviewed to illustrate that one physician can become proficient in microneurosurgery as well as endovascular surgery and achieve favorable outcomes in both disciplines. This supports one model of training for cerebrovascular surgeons that includes the complimentary practice of open microneurovascular surgery with endovascular surgery.

METHODS

The senior author (HAR) treated 351 patients with 413 aneurysms between July 2001 and March 2007. Of these, 172 patients (216 aneurysms) were treated with open microneurosurgical techniques and 179 patients (197 aneurysms) were treated using endovascular techniques.

RESULTS

Complete obliteration was attained in 94.3% of clipped aneurysms, and 61.9% and 65.9% of coiled aneurysms immediately and after at least 6 months of follow-up, respectively. At latest evaluation, 93% of endovascular patients and 90% of microneurosurgical patients had good clinical outcomes (GOS, 4 or 5; mean follow-up, 23 months; combines ruptured and unruptured cohorts). Procedure-related mortality included 1 surgical patient and 2 endovascular patients.

CONCLUSIONS

Because the fields of microvascular and endovascular surgeries are both technically complex, there has been concern that hybrid cerebrovascular surgeons cannot perform each technique with the skill necessary to achieve good outcomes. When compared to clipping and coiling reviews in the neurosurgical literature, we illustrate that one hybrid neurovascular surgeon is capable of attaining great facility in both techniques and that this type of physician will represent one practice model of cerebrovascular specialist in the future. This has potential implications for the training of hybrid cerebrovascular surgeons.

Multimodal CT in stroke imaging: new concepts

A multimodal CT protocol provides a comprehensive noninvasive survey of acute stroke patients with accurate demonstration of the site of arterial occlusion and its hemodynamic tissue status. It combines widespread availability with the ability to provide functional characterization of cerebral ischemia, and could potentially allow more accurate selection of candidates for acute stroke reperfusion therapy. This article discusses the individual components of multimodal CT and addresses the potential role of a combined multimodal CT stroke protocol in acute stroke therapy.