Michael R. Levitt

Pipeline Embolization Device as primary treatment for blister aneurysms and iatrogenic pseudoaneurysms of the internal carotid artery

Background Blood blister type aneurysms (BBAs) and pseudoaneurysms create a unique treatment challenge. Despite many advances in open surgical and endovascular techniques, this subset of patients retains relatively high rates of morbidity and mortality. Recently, BBAs have been treated with flow-diverting stents such as the Pipeline Embolization Device (PED) with overall positive results. Methods Four patients presented with dissecting internal carotid artery (ICA) aneurysms treated with the PED (two BBAs presenting with subarachnoid hemorrhage (SAH), two pseudoaneurysms after injury during endoscopic trans-sphenoidal tumor surgery). Results Three patients had a successful angiographic and neurological outcome. One patient with a BBA re-ruptured during initial PED placement, again in the postoperative period, and later died. Primary PED treatment involved telescoping stents in two patients and coil embolization supplementation in one patient. Conclusions The PED should be used selectively in the setting of acute SAH. Dual antiplatelet therapy can complicate hydrocephalus management, and the lack of immediate aneurysm occlusion creates the risk of short-term re-rupture. PED treatment for iatrogenic ICA pseudoaneurysms can provide a good angiographic and neurological outcome.

Cerebral Aneurysms Treated with Flow-Diverting Stents: Computational Models with Intravascular Blood Flow Measurements

BACKGROUND AND PURPOSE: Computational fluid dynamics modeling is useful in the study of the hemodynamic environment of cerebral aneurysms, but patient-specific measurements of boundary conditions, such as blood flow velocity and pressure, have not been previously applied to the study of flow-diverting stents. We integrated patient-specific intravascular blood flow velocity and pressure measurements into computational models of aneurysms before and after treatment with flow-diverting stents to determine stent effects on aneurysm hemodynamics. MATERIALS AND METHODS: Blood flow velocity and pressure were measured in peri-aneurysmal locations by use of an intravascular dual-sensor pressure and Doppler velocity guidewire before and after flow-diverting stent treatment of 4 unruptured cerebral aneurysms. These measurements defined inflow and outflow boundary conditions for computational models. Intra-aneurysmal flow rates, wall shear stress, and wall shear stress gradient were calculated. RESULTS: Measurements of inflow velocity and outflow pressure were successful in all 4 patients. Computational models incorporating these measurements demonstrated significant reductions in intra-aneurysmal wall shear stress and wall shear stress gradient and a trend in reduced intra-aneurysmal blood flow. CONCLUSIONS: Integration of intravascular dual-sensor guidewire measurements of blood flow velocity and blood pressure provided patient-specific computational models of cerebral aneurysms. Aneurysm treatment with flow-diverting stents reduces blood flow and hemodynamic shear stress in the aneurysm dome.

Image-guided cerebrospinal fluid shunting in children: catheter accuracy and shunt survival.

OBJECT Cerebrospinal fluid shunt placement has a high failure rate, especially in patients with small ventricles. Frameless stereotactic electromagnetic image guidance can assist ventricular catheter placement. The authors studied the effects of image guidance on catheter accuracy and shunt survival in children. METHODS Pediatric patients who underwent placement or revision of a frontal ventricular CSF shunt were retrospectively evaluated. Catheters were placed using either anatomical landmarks or image guidance. Preoperative ventricular size and postoperative catheter accuracy were quantified. Outcomes of standard and image-guided groups were compared. RESULTS Eighty-nine patients underwent 102 shunt surgeries (58 initial, 44 revision). Image guidance was used in the placement of 56 shunts and the standard technique in 46. Shunt failure rates were not significantly different between the standard (22%) and image-guided (25%) techniques (p = 0.21, log-rank test). Ventricular size was significantly smaller in patients in the image-guided group (p < 0.02, Student t-test) and in the surgery revision group (p < 0.01). Small ventricular size did not affect shunt failure rate, even when controlling for shunt insertion technique. Despite smaller average ventricular size, the accuracy of catheter placement was significantly improved with image guidance (p < 0.01). Shunt accuracy did not affect shunt survival. CONCLUSIONS The use of image guidance improved catheter tip accuracy compared with a standard technique, despite smaller ventricular size. Failure rates were not dependent on shunt insertion technique, but an observed selection bias toward using image guidance for more at-risk catheter placements showed failure rates similar to initial surgeries.

Meta-analysis and systematic review of risk factors for shunt dependency after aneurysmal subarachnoid hemorrhage

OBJECTIVE Aneurysmal subarachnoid hemorrhage (aSAH) may be complicated by hydrocephalus in 6.5%-67% of cases. Some patients with aSAH develop shunt dependency, which is often managed by ventriculoperitoneal shunt placement. The objectives of this study were to review published risk factors for shunt dependency in patients with aSAH, determine the level of evidence for each factor, and calculate the magnitude of each risk factor to better guide patient management. METHODS The authors searched PubMed and MEDLINE databases for Level A and Level B articles published through December 31, 2014, that describe factors affecting shunt dependency after aSAH and performed a systematic review and meta-analysis, stratifying the existing data according to level of evidence. RESULTS On the basis of the results of the meta-analysis, risk factors for shunt dependency included high Fisher grade (OR 7.74, 95% CI 4.47-13.41), acute hydrocephalus (OR 5.67, 95% CI 3.96-8.12), in-hospital complications (OR 4.91, 95% CI 2.79-8.64), presence of intraventricular blood (OR 3.93, 95% CI 2.80-5.52), high Hunt and Hess Scale score (OR 3.25, 95% CI 2.51-4.21), rehemorrhage (OR 2.21, 95% CI 1.24-3.95), posterior circulation location of the aneurysm (OR 1.85, 95% CI 1.35-2.53), and age ≥ 60 years (OR 1.81, 95% CI 1.50-2.19). The only risk factor included in the meta-analysis that did not reach statistical significance was female sex (OR 1.13, 95% CI 0.77-1.65). CONCLUSIONS The authors identified several risk factors for shunt dependency in aSAH patients that help predict which patients are likely to require a permanent shunt. Although some of these risk factors are not independent of each other, this information assists clinicians in identifying at-risk patients and managing their treatment.

Insular epilepsy masquerading as multifocal cortical epilepsy as proven by depth electrode.

The insular cortex is an uncommon epileptogenic location from which complex partial seizures may arise. Seizure activity in insular epilepsy may mimic temporal, parietal, or other cortical areas. Semiology, electroencephalography, and even surface electrocorticography recordings may falsely localize other cortical foci, leading to inaccurate diagnosis and treatment. The use of insular depth electrodes allows more precise localization of seizure foci. The authors describe the case of a young girl with seizures falsely localized to the cortex, with foci arising from the insula, as proven by depth electrode recordings. Resection of the insula yielded seizure control.

Accuracy of Computational Cerebral Aneurysm Hemodynamics Using Patient-Specific Endovascular Measurements

Computational hemodynamic simulations of cerebral aneurysms have traditionally relied on stereotypical boundary conditions (such as blood flow velocity and blood pressure) derived from published values as patient-specific measurements are unavailable or difficult to collect. However, controversy persists over the necessity of incorporating such patient-specific conditions into computational analyses. We perform simulations using both endovascularly-derived patient-specific and typical literature-derived inflow and outflow boundary conditions. Detailed three-dimensional anatomical models of the cerebral vasculature are developed from rotational angiography data, and blood flow velocity and pressure are measured in situ by a dual-sensor pressure and velocity endovascular guidewire at multiple peri-aneurysmal locations in 10 unruptured cerebral aneurysms. These measurements are used to define inflow and outflow boundary conditions for computational hemodynamic models of the aneurysms. The additional in situ measurements which are not prescribed in the simulation are then used to assess the accuracy of the simulated flow velocity and pressure drop. Simulated velocities using patient-specific boundary conditions show good agreement with the guidewire measurements at measurement locations inside the domain, with no bias in the agreement and a random scatter of ≈25%. Simulated velocities using the simplified, literature-derived values show a systematic bias and over-predicted velocity by ≈30% with a random scatter of ≈40%. Computational hemodynamics using endovascularly measured patient-specific boundary conditions have the potential to improve treatment predictions as they provide more accurate and precise results of the aneurysmal hemodynamics than those based on commonly accepted reference values for boundary conditions.

Safety and Efficacy of Surgical Resection of Unruptured Low-grade Arteriovenous Malformations From the Modern Decade.

BACKGROUND Recent studies have questioned the utility of surgical resection of unruptured brain arteriovenous malformations (bAVMs). OBJECTIVE We performed an assessment of outcomes and complications of surgical resection of low-grade bAVMs (Spetzler-Martin grade I or II) at a single high-volume neurosurgical center. METHODS We reviewed all unruptured low-grade bAVMs treated with surgery (with or without preoperative embolization) between January 2004 and January 2014. Stroke rate, mortality, and clinical and radiographic outcomes were examined. RESULTS Of 95 patients treated surgically, 85 (25 grade I, 60 grade II) met inclusion criteria, and all achieved radiographic cure postoperatively. Ten patients (11.8%) were lost to follow-up; the mean follow-up of the remaining 85 was 3.3 years. Three patients (3.5%) with grade II bAVMs experienced a stroke; no patients died. Although 20 patients (23.5%) had temporary postoperative neurological deficit, only 3 (3.5%) had new clinical impairment (modified Rankin Scale score ≥2) at last follow-up. Eight of the 13 patients (61.5%) with preexisting clinical impairment had improved modified Rankin Scale scores of 0 or 1; and 17 of 30 patients (56.7%) with preoperative seizures were seizure-free without antiepileptic medication postoperatively. No significant differences existed in stroke rate or clinical outcome between grades I and II patients at follow-up (Fisher exact test, P = .55 and P > .99, respectively). CONCLUSION Surgical resection of low-grade unruptured bAVMs is safe, with a high rate of improvement in functional status and seizure reduction. Although transient postoperative neurological deficit was observed in some patients, permanent treatment-related neurological morbidity was rare. ABBREVIATIONS ARUBA, A Randomized Trial of Unruptured Brain Arteriovenous MalformationsbAVM, brain arteriovenous malformationmRS, modified Rankin Scale.

Angiographic perfusion imaging: real-time assessment of endovascular treatment for cerebral vasospasm.

Cerebral perfusion analysis is useful in the diagnosis and treatment of cerebral vasospasm. A new modality of real‐time cerebral perfusion imaging and analysis has been developed using standard 2‐dimensional angiography. We report our initial experience with this technique to assess response to therapy during endovascular vasospasm procedures.

Low-dose head computed tomography in children: a single institutional experience in pediatric radiation risk reduction

OBJECT In this study, the authors describe their experience with a low-dose head CT protocol for a preselected neurosurgical population at a dedicated pediatric hospital (Seattle Childrens Hospital), the largest number of patients with this protocol reported to date. METHODS All low-dose head CT scans between October 2011 and November 2012 were reviewed. Two different low-dose radiation dosages were used, at one-half or one-quarter the dose of a standard head CT scan, based on patient characteristics agreed upon by the neurosurgery and radiology departments. Patient information was also recorded, including diagnosis and indication for CT scan. RESULTS Six hundred twenty-four low-dose head CT procedures were performed within the 12-month study period. Although indications for the CT scans varied, the most common reason was to evaluate the ventricles and catheter placement in hydrocephalic patients with shunts (70%), followed by postoperative craniosynostosis imaging (12%). These scans provided adequate diagnostic imaging, and no patient required a follow-up full-dose CT scan as a result of poor image quality on a low-dose CT scan. Overall physician comfort and satisfaction with interpretation of the images was high. An additional 2150 full-dose head CT scans were performed during the same 12-month time period, making the total number of CT scans 2774. This value compares to 3730 full-dose head CT scans obtained during the year prior to the study when low-dose CT and rapid-sequence MRI was not a reliable option at Seattle Childrens Hospital. Thus, over a 1-year period, 22% of the total CT scans were able to be converted to low-dose scans, and full-dose CT scans were able to be reduced by 42%. CONCLUSIONS The implementation of a low-dose head CT protocol substantially reduced the amount of ionizing radiation exposure in a preselected population of pediatric neurosurgical patients. Image quality and diagnostic utility were not significantly compromised.

Multimodality treatment of complex unruptured cavernous and paraclinoid aneurysms.

BACKGROUND Unruptured aneurysms of the cavernous and paraclinoid internal carotid artery can be approached via microsurgical and endovascular approaches. Trends in treatment reflect a steady shift toward endovascular techniques. OBJECTIVE To analyze our results with multimodal treatment. METHODS We reviewed patients with unruptured cavernous and paraclinoid internal carotid artery aneurysms proximal to the posterior communicating artery treated at a single center from 2007 to 2012. Treatment included 4 groups: (1) stent-assisted coiling, (2) pipeline endovascular device (PED) flow diverter, (3) clipping, and (4) trapping/bypass. Follow-up was 2 to 60 months. RESULTS The 109 aneurysms in 102 patients were studied with the following treatment groupings: 41 were done with stent-assisted coiling, 24 with Pipeline endovascular device, 24 by microsurgical clipping, and 20 by trap/bypass. Group: (1) two percent had delayed significant intraparenchymal hemorrhage; (2) thirteen percent had central nerve palsies, 8% had small asymptomatic infarcts, and 4% had small, asymptomatic remote-site hemorrhages; (3) twenty-nine percent of patients suffered from transient central nerve palsies, 4% experienced major stroke, and 8% had small intracerebral hemorrhages; (4) thirty-five percent had transient central nerve palsies, 10% had strokes, and 10% had intracerebral hemorrhages. In terms of follow-up obliteration, 83% had complete/nearly complete obliteration at last follow-up, 17% had residual aneurysms, and 10% required retreatment. Ninety-six percent of group 1 (35/38), 100% of group 2 (23/23), 100% of group 3 (21/21), and 95% of group 4 had modified Rankin Scale scores of 0 to 1. CONCLUSION Treatment of these aneurysms can be carried out with acceptable rates of morbidity. Careful patient selection is crucial for optimal outcome. Endovascular treatment volumes likely will continue to predominate over microsurgical techniques as changing skill sets evolve in neurosurgery, but individualized application of all available treatment options will continue.