Kenneth Liu | University of Virginia (original) (raw)

Papers by Kenneth Liu

Research paper thumbnail of A minimally invasive anterior skull base approach for evacuation of a basal ganglia hemorrhage

Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia, Jan 30, 2015

We describe the technical nuances of a minimally invasive anterior skull base approach for micros... more We describe the technical nuances of a minimally invasive anterior skull base approach for microsurgical evacuation of a large basal ganglia hematoma through an endoport. Patients who suffer from large spontaneous intracerebral hemorrhages (ICH) of the basal ganglia have a very poor prognosis. However, the benefit of surgery for the management of ICH is controversial. The development of endoport technology has allowed for minimally invasive access to subcortical lesions, and may offer unique advantages over conventional surgical techniques due to less disruption of the overlying cortex and white matter fiber tracts. A 77-year-old man presented with a hypertensive ICH of the right putamen, measuring 9cm in maximal diameter and 168cm(3) in volume. We planned an endoport trajectory through the long axis of the hematoma using frameless stereotactic neuronavigation. In order to access the optimal cortical entry point at the lateral aspect of the basal frontal lobe, a miniature modified o...

Research paper thumbnail of Stereotactic radiosurgery of meningiomas following resection: Predictors of progression

Journal of Clinical Neuroscience

Residual or recurrent meningiomas after initial surgical resection are commonly treated with ster... more Residual or recurrent meningiomas after initial surgical resection are commonly treated with stereotactic radiosurgery (SRS), but progression of these tumors following radiosurgery is difficult to predict. We performed a retrospective review of 60 consecutive patients who underwent resection and subsequent Gamma Knife (Elekta AB, Stockholm, Sweden) radiosurgery for residual or recurrent meningiomas at our institution from 2001–2012. Patients were subdivided by Simpson resection grade and World Health Organization (WHO) grade. Cox multivariate regression and Kaplan–Meier analyses were performed to assess risk of tumor progression. There were 45 men (75%) and 15 women (25%) with a median age of 56.8 years (range 26.5–82 years). The median follow-up period was 34.9 months (range 6–108.4 months). Simpson grade 1–3 resection was achieved in 17 patients (28.3%) and grade 4 resection in 43 patients (71.7%). Thirty-four tumors (56.7%) were WHO grade 1, and 22 (36.7%) were WHO grade 2–3. Tim...

Research paper thumbnail of Endovascular Treatment of Venous Sinus Stenosis in Idiopathic Intracranial Hypertension: Complications, Neurological Outcomes, and Radiographic Results

The Scientific World Journal, 2015

Introduction. Idiopathic intracranial hypertension (IIH) may result in a chronic debilitating dis... more Introduction. Idiopathic intracranial hypertension (IIH) may result in a chronic debilitating disease. Dural venous sinus stenosis with a physiologic venous pressure gradient has been identified as a potential etiology in a number of IIH patients. Intracranial venous stenting has emerged as a potential treatment alternative. Methods. A systematic review was carried out to identify studies employing venous stenting for IIH. Results. From 2002 to 2014, 17 studies comprising 185 patients who underwent 221 stenting procedures were reported. Mean prestent pressure gradient was 20.1 mmHg (95% CI 19.4-20.7 mmHg) with a mean poststent gradient of 4.4 mmHg (95% CI 3.5-5.2 mmHg). Complications occurred in 10 patients (5.4%; 95% CI 4.7-5.4%) but were major in only 3 (1.6%). At a mean clinical follow-up of 22 months, clinical improvement was noted in 130 of 166 patients with headaches (78.3%; 95% CI 75.8-80.8%), 84 of 89 patients with papilledema (94.4%; 95% CI 92.1-96.6%), and 64 of 74 patients with visual symptoms (86.5%; 95% CI 83.0-89.9%). In-stent stenosis was noted in six patients (3.4%; 95% CI 2.5-4.3%) and stent-adjacent stenosis occurred in 19 patients (11.4%; 95% CI 10.4-12.4), resulting in restenting in 10 patients. Conclusion. In IIH patients with venous sinus stenosis and a physiologic pressure gradient, venous stenting appears to be a safe and effective therapeutic option. Further studies are necessary to determine the long-term outcomes and the optimal management of medically refractory IIH.

Research paper thumbnail of Infundibular dilations of the posterior communicating arteries: pathogenesis, anatomical variants, aneurysm formation, and subarachnoid hemorrhage

Journal of neurointerventional surgery, Jan 18, 2015

Cerebrovascular infundibular dilations (IDs) are triangular-shaped widenings less than 3 mm in di... more Cerebrovascular infundibular dilations (IDs) are triangular-shaped widenings less than 3 mm in diameter, which are most commonly found at the posterior communicating artery (PCoA). The aims of this systematic review are to elucidate the natural histories of IDs, determine their risk of progression to significant pathology, and discuss potential management options. A comprehensive literature search of PubMed was used to find all case reports and series relating to cerebral IDs. IDs were classified into three types: type I IDs do not exhibit morphological change over a long follow-up period, type II IDs evolve into saccular aneurysms, while type III IDs are those that result in subarachnoid hemorrhage without prior aneurysmal progression. Data were extracted from studies that demonstrated type II or III IDs. We reviewed 16 cases of type II and seven cases of type III IDs. For type II IDs, 81.3% of patients were female with a median age at diagnosis of 38. All type II IDs were located ...

Research paper thumbnail of Direct comparison of Neuroform and Enterprise stents in the treatment of wide-necked intracranial aneurysms

Clinical radiology, 2014

To compare the complications and outcomes of Neuroform and Enterprise stents in the treatment of ... more To compare the complications and outcomes of Neuroform and Enterprise stents in the treatment of unruptured wide-necked aneurysms. Under the auspices of the institutional review board, a review of a prospectively collected patient log identified 130 patients who underwent elective stent-assisted coil embolization of a wide-necked aneurysm, including 53 patients treated with an Enterprise stent and 77 patients treated with a Neuroform stent. Immediate and long-term clinical and radiographic outcomes were recorded for all patients. All patient data were handled in accordance with Health Insurance Portability and Accountability Act of 1996 (HIPAA) regulations. The technical success rate was 94%. Overall morbidity was 15% with Enterprise stents and 3% with Neuroform stents (p = 0.020). However, the type of stent used was not predictive of clinical outcomes as measured by the modified Rankin scale. In a multivariate analysis, the use of a Neuroform stent was one of the predictors of retr...

Research paper thumbnail of E-049 Intraprocedural Diagnosis of Flow-Diverting Stent Malapposition during Endovascular Aneurysm Treatment with DynaCT Imaging

Journal of neurointerventional surgery, 2014

The treatment of large, complex intracranial aneurysms is being increasingly performed using flow... more The treatment of large, complex intracranial aneurysms is being increasingly performed using flow-diverting stents (FDS) such as the Pipeline Embolization Device (PED). Malapposition of a FDS to the parent artery wall decreases the likelihood of aneurysm obliteration and increases the risk of both immediate and delayed complications. DynaCT is a novel imaging modality which uses a flat plane detector to generate computed tomography images using the same C-arm employed for digital subtraction angiography. We present a case of a 40 year-old female with a large, unruptured, cavernous internal carotid artery (ICA) aneurysm who was treated with endovascular obliteration using a PED. A 6 French Chaperon guide catheter was navigated into the left ICA through which subsequent control angiograms could be performed. Cerebral angiography showed a lobular, cavernous ICA aneurysm measuring 11 mm in maximal diameter with a wide 7.5 mm neck. An Excelsior XT-27 microcatheter advanced over an Asahi ...

Research paper thumbnail of E-038 CTA Protocol Optimization for Improved Stent Visualization

Journal of neurointerventional surgery, 2014

Evaluation of stents using noninvasive imaging can be difficult. Artefact from the metallic strut... more Evaluation of stents using noninvasive imaging can be difficult. Artefact from the metallic struts often limits visibility within the stent on computed tomography angiograms (CTA). Special techniques developed for visualization of cardiac stents using CTA can be adapted for cervical and intracranial stent evaluation. All studies were performed on a 64 slice GE Discovery 750HD CT scanner (GE Healthcare, Little Chalfont, Buckinghamshire, United Kingdom). The standard arterial phase imaging protocol is performed with 100 mL of contrast administered at a rate of 5 ml/sec. Scan acquisition is triggered when contrast arrives in the aortic arch. Scan coverage extends from the carina to the vertex of the head. Slice thickness is 0.625. Pitch is 1.375:1. Rotation time is 0.5 sec. Tube voltage is 120 kv with a dynamic tube current ranging from 200-350 mA. The raw images are then reconstructed through the stent using a bone plus algorithm at 0.625 mm x 0.3 mm and a field of view of 20 mm. Thre...

Research paper thumbnail of E-037 single center comparison of ophthalmic aneurysm treatment using pipeline embolization device versus coil embolization

Journal of neurointerventional surgery, 2014

Aneurysms arising from the ophthalmic segment of the internal carotid artery (ICA) account for ap... more Aneurysms arising from the ophthalmic segment of the internal carotid artery (ICA) account for approximately 5% of all intracranial aneurysms. The Pipeline Embolization Device (PED) is a relatively new device available for treatment of these aneurysms. Here, we compare our experience with PED versus coil embolization in the treatment of unruptured ophthalmic artery aneurysms. A review of our prospectively collected patient log identified 106 patients who had undergone endovascular treatment of an unruptured ophthalmic artery aneurysm. Blinded to outcome, PED and coil patients were matched in a 1:2 fashion, respectively, based on aneurysm size. Matched analysis was carried out with marched t-test, Wilcoxon rank sum test, and McNamara's test as appropriate. P-values of ≤ 0.05 were considered statistically significant. Statistical analysis was carried out with Stata 10.0 (College Station, TX). After matching the patients in a 1:2 fashion, there were 20 patients treated with PED and...

Research paper thumbnail of Perforator aneurysms of the posterior circulation: case series and review of the literature

Journal of neurointerventional surgery, 2013

Posterior circulation perforator artery aneurysms are sparsely reported in the literature. The na... more Posterior circulation perforator artery aneurysms are sparsely reported in the literature. The natural history of these rare lesions remains unclear and their diagnosis and management are not well-defined. We reviewed our institution's medical records and performed a comprehensive literature search for cases of posterior circulation perforator aneurysms. Diagnostic imaging, management and clinical outcomes were the primary components of interest. Our first case was a 58-year-old patient who developed an infarct after attempted endovascular treatment of a basilar perforator artery aneurysm, the second case was a 55-year-old patient with a posterior cerebral artery perforator aneurysm who did well with conservative management and the third case was a 68-year-old patient who suffered an infarct after successful Onyx embolization of a superior cerebellar artery perforator aneurysm. From the literature we identified four case reports and four case series, all describing aneurysmal le...

Research paper thumbnail of Management strategies for intraprocedural coil migration during endovascular treatment of intracranial aneurysms

Journal of neurointerventional surgery, 2014

Migration of a coil during endovascular treatment of intracranial aneurysm occurs in 2-6% of case... more Migration of a coil during endovascular treatment of intracranial aneurysm occurs in 2-6% of cases. The consequences of coil migration vary significantly from minor flow alterations of the parent artery which are asymptomatic to thromboembolic occlusion of major intracranial vessels resulting in large territory infarcts. We performed a comprehensive literature review and identified 37 reported cases of migrated coil retrieval consisting of 10 case reports and six case series. Most of the aneurysms presented with rupture (65%) and were located in the anterior circulation (70%). The endovascular treatment approaches were coil embolization alone (57%), stent-assisted coiling (26%) and balloon remodeling (17%). Endovascular retrieval was performed with microwires, the Alligator Retrieval device, Merci devices, snares and stentrievers. There was a single report of microsurgical extraction following failed endovascular removal and three cases of coil fracture in which the coil fragments w...

Research paper thumbnail of Microsurgical extraction of a malfunctioned pipeline embolization device following complete deployment

Journal of cerebrovascular and endovascular neurosurgery, 2013

The Pipeline Embolization Device (PED) is an effective treatment approach for complex intracrania... more The Pipeline Embolization Device (PED) is an effective treatment approach for complex intracranial aneurysms. Intraprocedural complications during PED deployment are seldom reported. We report a rare complication of a PED malfunction identified immediately following complete deployment during endovascular treatment of a giant middle cerebral artery (MCA) bifurcation aneurysm. After multiple failed attempts at endovascular retrieval of the malfunctioned PED, the patient was taken for microsurgical extraction due to accumulation of thrombus on the proximal unopened portion of the stent and widespread distal dissemination of emboli. After removing the PED from the vessel lumen and resecting the giant aneurysm, we could not reanastamose the proximal MCA to the distal segment. The management of PED malfunction is poorly understood. While removal of an incompletely deployed PED may be undertaken with limited adverse effects, retrieval of a fully deployed PED is associated with a much high...

Research paper thumbnail of Role of stenting for intracranial atherosclerosis in the post-SAMMPRIS era

BioMed research international, 2013

Introduction. The initial promise of endovascular stenting for the treatment of intracranial athe... more Introduction. The initial promise of endovascular stenting for the treatment of intracranial atherosclerotic disease (ICAD) has been tempered by the results of the SAMMPRIS trial which demonstrated better outcomes with medical management compared to stenting for symptomatic ICAD. We review post-SAMMPRIS ICAD stenting outcomes. Methods. A comprehensive literature search was performed using PubMed to identify all ICAD stenting series published after the SAMMPRIS in September 2011. The type and design of the stent, number of patients and lesions, inclusion criteria, and clinical and angiographic outcomes were noted. Results. From October 2011 to August 2013, 19 ICAD stenting series were identified describing the interventional outcomes for 2,196 patients with 2,314 lesions. Of the 38 different stents used, 87% were balloon-expandable stents (BESs) and 13% were self-expanding stents. The median minimum stenosis was 50%. The median rates of technical success rate, postprocedural ischemic...

Research paper thumbnail of Stenting of symptomatic intracranial stenosis using balloon mounted coronary stents: a single center experience

Journal of neurointerventional surgery, 2015

Intracranial atherosclerotic disease is the cause of up to 10% of ischemic strokes and transient ... more Intracranial atherosclerotic disease is the cause of up to 10% of ischemic strokes and transient ischemic attacks. Intracranial stenting with off-label balloon mounted coronary stents (BMCS) may be a viable alternative for patients with symptomatic intracranial stenosis who fail best medical therapy. Between December 2005 and June 2012, 42 symptomatic intracranial stenoses were treated with a BMCS after failing medical management. Procedural records, clinical outcomes, and imaging follow-up were reviewed. Outcome measurements included technical success rate, morbidity and mortality, long term stent patency, and clinical outcomes, as measured by the modified Rankin Scale. The technical success rate was 98% (41 of 42 lesions). Morbidity within the first 30 days was 7.1% (three of 42 lesions). Overall morbidity, including both periprocedural and long term evaluation, was 9.5% (four of 42 lesions). There were no deaths. Follow-up imaging was available for 30 stents (71%) with an average...

Research paper thumbnail of Endovascular treatment of unruptured wide-necked intracranial aneurysms: comparison of dual microcatheter technique and stent-assisted coil embolization

Journal of neurointerventional surgery, 2015

Endovascular treatment of wide-necked aneurysms is challenging. Stent-assisted coiling (SAC) is a... more Endovascular treatment of wide-necked aneurysms is challenging. Stent-assisted coiling (SAC) is associated with increased complications and requires dual antiplatelet therapy. To compare treatment of unruptured, wide-necked aneurysms with a dual-microcatheter technique (DMT) versus SAC. Between 2006 and 2011, 100 patients with unruptured wide-necked intracranial aneurysms were treated with DMT and 160 with SAC. Over time there was a significant decrease in the use of SAC and a corresponding increase in DMT. The investigators matched 60 patients treated with DMT blinded to outcome in a 1:2 fashion based on maximal aneurysm dome diameter with 120 patients treated with SAC. Outcomes were determined with conditional (matched) multivariate analysis. There were no significant differences in patient or aneurysm characteristics between cohorts, including aneurysm diameter, neck width, or volume. Overall packing density and coil volume achieved was not significantly different between cohorts...

Research paper thumbnail of Predictive Capability of the Spetzler-Martin versus Supplementary Grading Scale for Microsurgical Outcomes of Cerebellar Arteriovenous Malformations

Journal of cerebrovascular and endovascular neurosurgery, 2013

The recently described supplementary grading scale may be superior to the widely used Spetzler-Ma... more The recently described supplementary grading scale may be superior to the widely used Spetzler-Martin grading scale in the prediction of microsurgical outcomes for cerebellar arteriovenous malformations (AVM). We report two cases of ruptured cerebellar AVMs with the same Spetzler-Martin grade but different supplementary grades treated with microsurgical resection. Both patients had symptomatic brainstem compression from cerebellar hematomas and subsequently underwent uncomplicated surgeries; however, their outcomes were significantly different. It has previously been proposed that AVMs distort cerebellar anatomy in a different manner than supratentorial cerebral anatomy thereby potentially resulting in misrepresentation when utilizing the Spetzler-Martin grading scale. However, the components of the supplementary grading scale are independent of cerebellar anatomy, which may explain why it has been shown to be better than the Spetzler-Martin grading scale for prediction of surgical ...

Research paper thumbnail of Microsurgical strategies following failed endovascular treatment with the pipeline embolization device: case of a giant posterior cerebral artery aneurysm

Journal of cerebrovascular and endovascular neurosurgery, 2014

Treatment of giant posterior circulation aneurysms, via endovascular or microsurgical approaches,... more Treatment of giant posterior circulation aneurysms, via endovascular or microsurgical approaches, carries a high risk of morbidity and mortality. While flow-diverting stents (FDSs) represent a potent therapy for endovascular reconstruction of complex aneurysms, they are also associated with novel complications for which effective salvage techniques are lacking. We present a unique complication from failed treatment with a FDS. A 51 year-old male presented with increasing headaches secondary to a giant, fusiform aneurysm of the left posterior cerebral artery, which was largely thrombosed. Due to progressive enlargement of the aneurysm corresponding to worsening clinical symptoms, the lesion was treated with two Pipeline embolization devices (ev3, Plymouth, MN, United States). Three months after Pipeline embolization device treatment, complete posterior cerebral artery occlusion was observed at the origin of the proximal stent. Despite the lack of arterial inflow, the aneurysm dome co...

Research paper thumbnail of Venous stenting with concurrent intracranial pressure monitoring for the treatment of pseudotumor cerebri

Neurosurgical focus, 2014

Increasing evidence supports dural venous sinus stenosis as the patho-etiology of pseudotumor cer... more Increasing evidence supports dural venous sinus stenosis as the patho-etiology of pseudotumor cerebri (PTC) in a subset of affected patients. In this video, we demonstrate our technique for 1) diagnostic venous manometry to identify a flow-limiting stenosis of the transverse sinus in a PTC patient; and 2) successful treatment of the patient with venous stenting across the structural and physiological stricture in the dural sinus. The pressure gradient decreased from 20 mmHg pre-stent to 3 mmHg post-stent. In order to further quantify the effect of our intervention, concurrent intracranial pressure monitoring was performed. The video can be found here: http://youtu.be/auxRg17F8yI .

Research paper thumbnail of Conservative Management or Intervention for Unruptured Brain Arteriovenous Malformations

World Neurosurgery

in an intact brain, Hebbian neuroplasticity seems to be the main player (with its critical role i... more in an intact brain, Hebbian neuroplasticity seems to be the main player (with its critical role in learning and memory). In an injured or diseased brain, metaplasticity seems to play a crucial role in handling the initial injury and guiding the later recovery (with its importance in brain physiologic and possibly anatomic homeostasis). From a neurosurgical prospective, metaplasticity (more precisely, the exact mechanisms underpinning this order of neuroplasticity) should be the focus of investigations that aim to harness neuroplasticity for the treatment of neurosurgical disorders.

Research paper thumbnail of Stereotactic radiosurgery of meningiomas following resection: predictors of progression

Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia, 2015

Residual or recurrent meningiomas after initial surgical resection are commonly treated with ster... more Residual or recurrent meningiomas after initial surgical resection are commonly treated with stereotactic radiosurgery (SRS), but progression of these tumors following radiosurgery is difficult to predict. We performed a retrospective review of 60 consecutive patients who underwent resection and subsequent Gamma Knife (Elekta AB, Stockholm, Sweden) radiosurgery for residual or recurrent meningiomas at our institution from 2001-2012. Patients were subdivided by Simpson resection grade and World Health Organization (WHO) grade. Cox multivariate regression and Kaplan-Meier analyses were performed to assess risk of tumor progression. There were 45 men (75%) and 15 women (25%) with a median age of 56.8 years (range 26.5-82 years). The median follow-up period was 34.9 months (range 6-108.4 months). Simpson grade 1-3 resection was achieved in 17 patients (28.3%) and grade 4 resection in 43 patients (71.7%). Thirty-four tumors (56.7%) were WHO grade 1, and 22 (36.7%) were WHO grade 2-3. Tim...

Research paper thumbnail of Combined microsurgical PICA-PICA bypass and endovascular parent artery occlusion for a ruptured dissecting vertebral artery aneurysm

Neurosurgical FOCUS

Dissecting vertebral artery (VA) aneurysms are difficult to obliterate when the parent artery can... more Dissecting vertebral artery (VA) aneurysms are difficult to obliterate when the parent artery cannot be safely occluded. In this video, we demonstrate a combined microsurgical and endovascular treatment technique for a ruptured, dissecting VA aneurysm incorporating the origin of the posterior inferior cerebellar artery (PICA). We first performed a PICA-PICA side-to-side bypass to preserve flow through the right PICA. An endovascular approach was then utilized to embolize the proximal portion of the aneurysm from the right VA and the distal portion of the aneurysm from the left VA. The video can be found here: http://youtu.be/dkkKsX2BiJI .

Research paper thumbnail of A minimally invasive anterior skull base approach for evacuation of a basal ganglia hemorrhage

Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia, Jan 30, 2015

We describe the technical nuances of a minimally invasive anterior skull base approach for micros... more We describe the technical nuances of a minimally invasive anterior skull base approach for microsurgical evacuation of a large basal ganglia hematoma through an endoport. Patients who suffer from large spontaneous intracerebral hemorrhages (ICH) of the basal ganglia have a very poor prognosis. However, the benefit of surgery for the management of ICH is controversial. The development of endoport technology has allowed for minimally invasive access to subcortical lesions, and may offer unique advantages over conventional surgical techniques due to less disruption of the overlying cortex and white matter fiber tracts. A 77-year-old man presented with a hypertensive ICH of the right putamen, measuring 9cm in maximal diameter and 168cm(3) in volume. We planned an endoport trajectory through the long axis of the hematoma using frameless stereotactic neuronavigation. In order to access the optimal cortical entry point at the lateral aspect of the basal frontal lobe, a miniature modified o...

Research paper thumbnail of Stereotactic radiosurgery of meningiomas following resection: Predictors of progression

Journal of Clinical Neuroscience

Residual or recurrent meningiomas after initial surgical resection are commonly treated with ster... more Residual or recurrent meningiomas after initial surgical resection are commonly treated with stereotactic radiosurgery (SRS), but progression of these tumors following radiosurgery is difficult to predict. We performed a retrospective review of 60 consecutive patients who underwent resection and subsequent Gamma Knife (Elekta AB, Stockholm, Sweden) radiosurgery for residual or recurrent meningiomas at our institution from 2001–2012. Patients were subdivided by Simpson resection grade and World Health Organization (WHO) grade. Cox multivariate regression and Kaplan–Meier analyses were performed to assess risk of tumor progression. There were 45 men (75%) and 15 women (25%) with a median age of 56.8 years (range 26.5–82 years). The median follow-up period was 34.9 months (range 6–108.4 months). Simpson grade 1–3 resection was achieved in 17 patients (28.3%) and grade 4 resection in 43 patients (71.7%). Thirty-four tumors (56.7%) were WHO grade 1, and 22 (36.7%) were WHO grade 2–3. Tim...

Research paper thumbnail of Endovascular Treatment of Venous Sinus Stenosis in Idiopathic Intracranial Hypertension: Complications, Neurological Outcomes, and Radiographic Results

The Scientific World Journal, 2015

Introduction. Idiopathic intracranial hypertension (IIH) may result in a chronic debilitating dis... more Introduction. Idiopathic intracranial hypertension (IIH) may result in a chronic debilitating disease. Dural venous sinus stenosis with a physiologic venous pressure gradient has been identified as a potential etiology in a number of IIH patients. Intracranial venous stenting has emerged as a potential treatment alternative. Methods. A systematic review was carried out to identify studies employing venous stenting for IIH. Results. From 2002 to 2014, 17 studies comprising 185 patients who underwent 221 stenting procedures were reported. Mean prestent pressure gradient was 20.1 mmHg (95% CI 19.4-20.7 mmHg) with a mean poststent gradient of 4.4 mmHg (95% CI 3.5-5.2 mmHg). Complications occurred in 10 patients (5.4%; 95% CI 4.7-5.4%) but were major in only 3 (1.6%). At a mean clinical follow-up of 22 months, clinical improvement was noted in 130 of 166 patients with headaches (78.3%; 95% CI 75.8-80.8%), 84 of 89 patients with papilledema (94.4%; 95% CI 92.1-96.6%), and 64 of 74 patients with visual symptoms (86.5%; 95% CI 83.0-89.9%). In-stent stenosis was noted in six patients (3.4%; 95% CI 2.5-4.3%) and stent-adjacent stenosis occurred in 19 patients (11.4%; 95% CI 10.4-12.4), resulting in restenting in 10 patients. Conclusion. In IIH patients with venous sinus stenosis and a physiologic pressure gradient, venous stenting appears to be a safe and effective therapeutic option. Further studies are necessary to determine the long-term outcomes and the optimal management of medically refractory IIH.

Research paper thumbnail of Infundibular dilations of the posterior communicating arteries: pathogenesis, anatomical variants, aneurysm formation, and subarachnoid hemorrhage

Journal of neurointerventional surgery, Jan 18, 2015

Cerebrovascular infundibular dilations (IDs) are triangular-shaped widenings less than 3 mm in di... more Cerebrovascular infundibular dilations (IDs) are triangular-shaped widenings less than 3 mm in diameter, which are most commonly found at the posterior communicating artery (PCoA). The aims of this systematic review are to elucidate the natural histories of IDs, determine their risk of progression to significant pathology, and discuss potential management options. A comprehensive literature search of PubMed was used to find all case reports and series relating to cerebral IDs. IDs were classified into three types: type I IDs do not exhibit morphological change over a long follow-up period, type II IDs evolve into saccular aneurysms, while type III IDs are those that result in subarachnoid hemorrhage without prior aneurysmal progression. Data were extracted from studies that demonstrated type II or III IDs. We reviewed 16 cases of type II and seven cases of type III IDs. For type II IDs, 81.3% of patients were female with a median age at diagnosis of 38. All type II IDs were located ...

Research paper thumbnail of Direct comparison of Neuroform and Enterprise stents in the treatment of wide-necked intracranial aneurysms

Clinical radiology, 2014

To compare the complications and outcomes of Neuroform and Enterprise stents in the treatment of ... more To compare the complications and outcomes of Neuroform and Enterprise stents in the treatment of unruptured wide-necked aneurysms. Under the auspices of the institutional review board, a review of a prospectively collected patient log identified 130 patients who underwent elective stent-assisted coil embolization of a wide-necked aneurysm, including 53 patients treated with an Enterprise stent and 77 patients treated with a Neuroform stent. Immediate and long-term clinical and radiographic outcomes were recorded for all patients. All patient data were handled in accordance with Health Insurance Portability and Accountability Act of 1996 (HIPAA) regulations. The technical success rate was 94%. Overall morbidity was 15% with Enterprise stents and 3% with Neuroform stents (p = 0.020). However, the type of stent used was not predictive of clinical outcomes as measured by the modified Rankin scale. In a multivariate analysis, the use of a Neuroform stent was one of the predictors of retr...

Research paper thumbnail of E-049 Intraprocedural Diagnosis of Flow-Diverting Stent Malapposition during Endovascular Aneurysm Treatment with DynaCT Imaging

Journal of neurointerventional surgery, 2014

The treatment of large, complex intracranial aneurysms is being increasingly performed using flow... more The treatment of large, complex intracranial aneurysms is being increasingly performed using flow-diverting stents (FDS) such as the Pipeline Embolization Device (PED). Malapposition of a FDS to the parent artery wall decreases the likelihood of aneurysm obliteration and increases the risk of both immediate and delayed complications. DynaCT is a novel imaging modality which uses a flat plane detector to generate computed tomography images using the same C-arm employed for digital subtraction angiography. We present a case of a 40 year-old female with a large, unruptured, cavernous internal carotid artery (ICA) aneurysm who was treated with endovascular obliteration using a PED. A 6 French Chaperon guide catheter was navigated into the left ICA through which subsequent control angiograms could be performed. Cerebral angiography showed a lobular, cavernous ICA aneurysm measuring 11 mm in maximal diameter with a wide 7.5 mm neck. An Excelsior XT-27 microcatheter advanced over an Asahi ...

Research paper thumbnail of E-038 CTA Protocol Optimization for Improved Stent Visualization

Journal of neurointerventional surgery, 2014

Evaluation of stents using noninvasive imaging can be difficult. Artefact from the metallic strut... more Evaluation of stents using noninvasive imaging can be difficult. Artefact from the metallic struts often limits visibility within the stent on computed tomography angiograms (CTA). Special techniques developed for visualization of cardiac stents using CTA can be adapted for cervical and intracranial stent evaluation. All studies were performed on a 64 slice GE Discovery 750HD CT scanner (GE Healthcare, Little Chalfont, Buckinghamshire, United Kingdom). The standard arterial phase imaging protocol is performed with 100 mL of contrast administered at a rate of 5 ml/sec. Scan acquisition is triggered when contrast arrives in the aortic arch. Scan coverage extends from the carina to the vertex of the head. Slice thickness is 0.625. Pitch is 1.375:1. Rotation time is 0.5 sec. Tube voltage is 120 kv with a dynamic tube current ranging from 200-350 mA. The raw images are then reconstructed through the stent using a bone plus algorithm at 0.625 mm x 0.3 mm and a field of view of 20 mm. Thre...

Research paper thumbnail of E-037 single center comparison of ophthalmic aneurysm treatment using pipeline embolization device versus coil embolization

Journal of neurointerventional surgery, 2014

Aneurysms arising from the ophthalmic segment of the internal carotid artery (ICA) account for ap... more Aneurysms arising from the ophthalmic segment of the internal carotid artery (ICA) account for approximately 5% of all intracranial aneurysms. The Pipeline Embolization Device (PED) is a relatively new device available for treatment of these aneurysms. Here, we compare our experience with PED versus coil embolization in the treatment of unruptured ophthalmic artery aneurysms. A review of our prospectively collected patient log identified 106 patients who had undergone endovascular treatment of an unruptured ophthalmic artery aneurysm. Blinded to outcome, PED and coil patients were matched in a 1:2 fashion, respectively, based on aneurysm size. Matched analysis was carried out with marched t-test, Wilcoxon rank sum test, and McNamara's test as appropriate. P-values of ≤ 0.05 were considered statistically significant. Statistical analysis was carried out with Stata 10.0 (College Station, TX). After matching the patients in a 1:2 fashion, there were 20 patients treated with PED and...

Research paper thumbnail of Perforator aneurysms of the posterior circulation: case series and review of the literature

Journal of neurointerventional surgery, 2013

Posterior circulation perforator artery aneurysms are sparsely reported in the literature. The na... more Posterior circulation perforator artery aneurysms are sparsely reported in the literature. The natural history of these rare lesions remains unclear and their diagnosis and management are not well-defined. We reviewed our institution's medical records and performed a comprehensive literature search for cases of posterior circulation perforator aneurysms. Diagnostic imaging, management and clinical outcomes were the primary components of interest. Our first case was a 58-year-old patient who developed an infarct after attempted endovascular treatment of a basilar perforator artery aneurysm, the second case was a 55-year-old patient with a posterior cerebral artery perforator aneurysm who did well with conservative management and the third case was a 68-year-old patient who suffered an infarct after successful Onyx embolization of a superior cerebellar artery perforator aneurysm. From the literature we identified four case reports and four case series, all describing aneurysmal le...

Research paper thumbnail of Management strategies for intraprocedural coil migration during endovascular treatment of intracranial aneurysms

Journal of neurointerventional surgery, 2014

Migration of a coil during endovascular treatment of intracranial aneurysm occurs in 2-6% of case... more Migration of a coil during endovascular treatment of intracranial aneurysm occurs in 2-6% of cases. The consequences of coil migration vary significantly from minor flow alterations of the parent artery which are asymptomatic to thromboembolic occlusion of major intracranial vessels resulting in large territory infarcts. We performed a comprehensive literature review and identified 37 reported cases of migrated coil retrieval consisting of 10 case reports and six case series. Most of the aneurysms presented with rupture (65%) and were located in the anterior circulation (70%). The endovascular treatment approaches were coil embolization alone (57%), stent-assisted coiling (26%) and balloon remodeling (17%). Endovascular retrieval was performed with microwires, the Alligator Retrieval device, Merci devices, snares and stentrievers. There was a single report of microsurgical extraction following failed endovascular removal and three cases of coil fracture in which the coil fragments w...

Research paper thumbnail of Microsurgical extraction of a malfunctioned pipeline embolization device following complete deployment

Journal of cerebrovascular and endovascular neurosurgery, 2013

The Pipeline Embolization Device (PED) is an effective treatment approach for complex intracrania... more The Pipeline Embolization Device (PED) is an effective treatment approach for complex intracranial aneurysms. Intraprocedural complications during PED deployment are seldom reported. We report a rare complication of a PED malfunction identified immediately following complete deployment during endovascular treatment of a giant middle cerebral artery (MCA) bifurcation aneurysm. After multiple failed attempts at endovascular retrieval of the malfunctioned PED, the patient was taken for microsurgical extraction due to accumulation of thrombus on the proximal unopened portion of the stent and widespread distal dissemination of emboli. After removing the PED from the vessel lumen and resecting the giant aneurysm, we could not reanastamose the proximal MCA to the distal segment. The management of PED malfunction is poorly understood. While removal of an incompletely deployed PED may be undertaken with limited adverse effects, retrieval of a fully deployed PED is associated with a much high...

Research paper thumbnail of Role of stenting for intracranial atherosclerosis in the post-SAMMPRIS era

BioMed research international, 2013

Introduction. The initial promise of endovascular stenting for the treatment of intracranial athe... more Introduction. The initial promise of endovascular stenting for the treatment of intracranial atherosclerotic disease (ICAD) has been tempered by the results of the SAMMPRIS trial which demonstrated better outcomes with medical management compared to stenting for symptomatic ICAD. We review post-SAMMPRIS ICAD stenting outcomes. Methods. A comprehensive literature search was performed using PubMed to identify all ICAD stenting series published after the SAMMPRIS in September 2011. The type and design of the stent, number of patients and lesions, inclusion criteria, and clinical and angiographic outcomes were noted. Results. From October 2011 to August 2013, 19 ICAD stenting series were identified describing the interventional outcomes for 2,196 patients with 2,314 lesions. Of the 38 different stents used, 87% were balloon-expandable stents (BESs) and 13% were self-expanding stents. The median minimum stenosis was 50%. The median rates of technical success rate, postprocedural ischemic...

Research paper thumbnail of Stenting of symptomatic intracranial stenosis using balloon mounted coronary stents: a single center experience

Journal of neurointerventional surgery, 2015

Intracranial atherosclerotic disease is the cause of up to 10% of ischemic strokes and transient ... more Intracranial atherosclerotic disease is the cause of up to 10% of ischemic strokes and transient ischemic attacks. Intracranial stenting with off-label balloon mounted coronary stents (BMCS) may be a viable alternative for patients with symptomatic intracranial stenosis who fail best medical therapy. Between December 2005 and June 2012, 42 symptomatic intracranial stenoses were treated with a BMCS after failing medical management. Procedural records, clinical outcomes, and imaging follow-up were reviewed. Outcome measurements included technical success rate, morbidity and mortality, long term stent patency, and clinical outcomes, as measured by the modified Rankin Scale. The technical success rate was 98% (41 of 42 lesions). Morbidity within the first 30 days was 7.1% (three of 42 lesions). Overall morbidity, including both periprocedural and long term evaluation, was 9.5% (four of 42 lesions). There were no deaths. Follow-up imaging was available for 30 stents (71%) with an average...

Research paper thumbnail of Endovascular treatment of unruptured wide-necked intracranial aneurysms: comparison of dual microcatheter technique and stent-assisted coil embolization

Journal of neurointerventional surgery, 2015

Endovascular treatment of wide-necked aneurysms is challenging. Stent-assisted coiling (SAC) is a... more Endovascular treatment of wide-necked aneurysms is challenging. Stent-assisted coiling (SAC) is associated with increased complications and requires dual antiplatelet therapy. To compare treatment of unruptured, wide-necked aneurysms with a dual-microcatheter technique (DMT) versus SAC. Between 2006 and 2011, 100 patients with unruptured wide-necked intracranial aneurysms were treated with DMT and 160 with SAC. Over time there was a significant decrease in the use of SAC and a corresponding increase in DMT. The investigators matched 60 patients treated with DMT blinded to outcome in a 1:2 fashion based on maximal aneurysm dome diameter with 120 patients treated with SAC. Outcomes were determined with conditional (matched) multivariate analysis. There were no significant differences in patient or aneurysm characteristics between cohorts, including aneurysm diameter, neck width, or volume. Overall packing density and coil volume achieved was not significantly different between cohorts...

Research paper thumbnail of Predictive Capability of the Spetzler-Martin versus Supplementary Grading Scale for Microsurgical Outcomes of Cerebellar Arteriovenous Malformations

Journal of cerebrovascular and endovascular neurosurgery, 2013

The recently described supplementary grading scale may be superior to the widely used Spetzler-Ma... more The recently described supplementary grading scale may be superior to the widely used Spetzler-Martin grading scale in the prediction of microsurgical outcomes for cerebellar arteriovenous malformations (AVM). We report two cases of ruptured cerebellar AVMs with the same Spetzler-Martin grade but different supplementary grades treated with microsurgical resection. Both patients had symptomatic brainstem compression from cerebellar hematomas and subsequently underwent uncomplicated surgeries; however, their outcomes were significantly different. It has previously been proposed that AVMs distort cerebellar anatomy in a different manner than supratentorial cerebral anatomy thereby potentially resulting in misrepresentation when utilizing the Spetzler-Martin grading scale. However, the components of the supplementary grading scale are independent of cerebellar anatomy, which may explain why it has been shown to be better than the Spetzler-Martin grading scale for prediction of surgical ...

Research paper thumbnail of Microsurgical strategies following failed endovascular treatment with the pipeline embolization device: case of a giant posterior cerebral artery aneurysm

Journal of cerebrovascular and endovascular neurosurgery, 2014

Treatment of giant posterior circulation aneurysms, via endovascular or microsurgical approaches,... more Treatment of giant posterior circulation aneurysms, via endovascular or microsurgical approaches, carries a high risk of morbidity and mortality. While flow-diverting stents (FDSs) represent a potent therapy for endovascular reconstruction of complex aneurysms, they are also associated with novel complications for which effective salvage techniques are lacking. We present a unique complication from failed treatment with a FDS. A 51 year-old male presented with increasing headaches secondary to a giant, fusiform aneurysm of the left posterior cerebral artery, which was largely thrombosed. Due to progressive enlargement of the aneurysm corresponding to worsening clinical symptoms, the lesion was treated with two Pipeline embolization devices (ev3, Plymouth, MN, United States). Three months after Pipeline embolization device treatment, complete posterior cerebral artery occlusion was observed at the origin of the proximal stent. Despite the lack of arterial inflow, the aneurysm dome co...

Research paper thumbnail of Venous stenting with concurrent intracranial pressure monitoring for the treatment of pseudotumor cerebri

Neurosurgical focus, 2014

Increasing evidence supports dural venous sinus stenosis as the patho-etiology of pseudotumor cer... more Increasing evidence supports dural venous sinus stenosis as the patho-etiology of pseudotumor cerebri (PTC) in a subset of affected patients. In this video, we demonstrate our technique for 1) diagnostic venous manometry to identify a flow-limiting stenosis of the transverse sinus in a PTC patient; and 2) successful treatment of the patient with venous stenting across the structural and physiological stricture in the dural sinus. The pressure gradient decreased from 20 mmHg pre-stent to 3 mmHg post-stent. In order to further quantify the effect of our intervention, concurrent intracranial pressure monitoring was performed. The video can be found here: http://youtu.be/auxRg17F8yI .

Research paper thumbnail of Conservative Management or Intervention for Unruptured Brain Arteriovenous Malformations

World Neurosurgery

in an intact brain, Hebbian neuroplasticity seems to be the main player (with its critical role i... more in an intact brain, Hebbian neuroplasticity seems to be the main player (with its critical role in learning and memory). In an injured or diseased brain, metaplasticity seems to play a crucial role in handling the initial injury and guiding the later recovery (with its importance in brain physiologic and possibly anatomic homeostasis). From a neurosurgical prospective, metaplasticity (more precisely, the exact mechanisms underpinning this order of neuroplasticity) should be the focus of investigations that aim to harness neuroplasticity for the treatment of neurosurgical disorders.

Research paper thumbnail of Stereotactic radiosurgery of meningiomas following resection: predictors of progression

Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia, 2015

Residual or recurrent meningiomas after initial surgical resection are commonly treated with ster... more Residual or recurrent meningiomas after initial surgical resection are commonly treated with stereotactic radiosurgery (SRS), but progression of these tumors following radiosurgery is difficult to predict. We performed a retrospective review of 60 consecutive patients who underwent resection and subsequent Gamma Knife (Elekta AB, Stockholm, Sweden) radiosurgery for residual or recurrent meningiomas at our institution from 2001-2012. Patients were subdivided by Simpson resection grade and World Health Organization (WHO) grade. Cox multivariate regression and Kaplan-Meier analyses were performed to assess risk of tumor progression. There were 45 men (75%) and 15 women (25%) with a median age of 56.8 years (range 26.5-82 years). The median follow-up period was 34.9 months (range 6-108.4 months). Simpson grade 1-3 resection was achieved in 17 patients (28.3%) and grade 4 resection in 43 patients (71.7%). Thirty-four tumors (56.7%) were WHO grade 1, and 22 (36.7%) were WHO grade 2-3. Tim...

Research paper thumbnail of Combined microsurgical PICA-PICA bypass and endovascular parent artery occlusion for a ruptured dissecting vertebral artery aneurysm

Neurosurgical FOCUS

Dissecting vertebral artery (VA) aneurysms are difficult to obliterate when the parent artery can... more Dissecting vertebral artery (VA) aneurysms are difficult to obliterate when the parent artery cannot be safely occluded. In this video, we demonstrate a combined microsurgical and endovascular treatment technique for a ruptured, dissecting VA aneurysm incorporating the origin of the posterior inferior cerebellar artery (PICA). We first performed a PICA-PICA side-to-side bypass to preserve flow through the right PICA. An endovascular approach was then utilized to embolize the proximal portion of the aneurysm from the right VA and the distal portion of the aneurysm from the left VA. The video can be found here: http://youtu.be/dkkKsX2BiJI .