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Davis G. Taylor, Ching-Jen Chen, Thomas J. Buell, Min S. Park, J. Javier Provencio and M. Yashar S. Kalani

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Nam Yoon, Aatman Shah, William T. Couldwell, M. Yashar S. Kalani and Min S. Park

Skull base meningiomas are technically challenging tumors to treat because of their deep vascular supply that can preclude early devascularization during resection. Preoperative embolization of these arterial feeders is thought to decrease blood loss and facilitate resection; however, given the complex and varied anatomy of these skull base lesions, preoperative embolization is not without risk. It is essential for both endovascular and skull base neurosurgeons to understand these risks in light of the potential benefits. The authors review the vascular anatomy of skull base meningiomas, indications for preoperative devascularization, endovascular techniques, and published results regarding embolization of these lesions.

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Corey T. Walker, M. Yashar S. Kalani, Mark E. Oppenlander, Jakub Godzik, Nikolay L. Martirosyan, Robert J. Standerfer and Nicholas Theodore

OBJECTIVE

The authors report a novel paradigm for resection of the disc or dural complex to treat giant calcified transdural herniated thoracic discs, and they describe a technique for the repair of dural defects. These herniated thoracic discs are uncommon, complicated lesions that often require a multidisciplinary team for effective treatment. The intradural component must be removed to effectively decompress the spinal cord. The opening of the friable dura mater, which frequently adheres to the extradural component of the disc, can result in large defects and difficult-to-manage CSF leaks.

METHODS

The authors performed a retrospective study of the technique and outcomes in patients with a transdural herniated disc treated at St. Joseph’s Hospital and Medical Center within a 4-year period between 2012 and 2015.

RESULTS

During the study period, 7 patients (mean age 56.1 years) presented to the department of neurosurgery with clinical symptoms consistent with myeloradiculopathy. In all cases, 2-level corpectomies of the involved levels were combined with circumferential resection of the dura and complete decompression of the spinal cord. The dural defect was repaired with an onlay dural patch, and a large piece of AlloDerm (LifeCell Corp) graft was sewn to close the pleural defect. Every patient had a perioperative lumbar drain placed for CSF diversion. No patient suffered neurological decline related to the surgery, and 3 patients experienced clinically significant improvement in function. Two patients developed an early postoperative CSF leak that required operative revision to oversew the defects.

CONCLUSIONS

This novel technique for decompression of the spinal cord by dural resection for the removal of giant calcified transdural herniated thoracic discs is safe and results in excellent decompression of the spinal cord. The technique becomes necessary when primary repair of the dura is not possible, and it can be used in cases in which the resection of pathology includes the dura.

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Adeel Ilyas, Ching-Jen Chen, Dale Ding, Andrew Romeo, Thomas J. Buell, Tony R. Wang, M. Yashar S. Kalani and Min S. Park

Stroke is one of the leading causes of death worldwide and a significant source of long-term morbidity. Unfortunately, a substantial number of stroke patients either are ineligible or do not significantly benefit from contemporary medical and interventional therapies. To address this void, investigators recently made technological advances to render transcranial MR-guided, high-intensity focused ultrasound (MRg-HIFU) sonolysis a potential therapeutic option for both acute ischemic stroke (AIS)—as an alternative for patients with emergent large-vessel occlusion (ELVO) who are ineligible for endovascular mechanical thrombectomy (EMT) or as salvage therapy for patients in whom EMT fails—and intracerebral hemorrhage (ICH)—as a neoadjuvant means of clot lysis prior to surgical evacuation. Herein, the authors review the technological principles behind MRg-HIFU sonolysis, its results in in vitro and in vivo stroke models, and its potential clinical applications. As a noninvasive transcranial technique that affords rapid clot lysis, MRg-HIFU thrombolysis may develop into a therapeutic option for patients with AIS or ICH. However, additional studies of transcranial MRg-HIFU are necessary to ascertain the merit of this treatment approach for thrombolysis in both AIS and ICH, as well as its technical limitations and risks.

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Al-Wala Awad, Karam Moon, Nam Yoon, Marcus D. Mazur, M. Yashar S. Kalani, Philipp Taussky, Cameron G. McDougall, Felipe C. Albuquerque and Min S. Park

OBJECTIVE

Flow diversion has proven to be an efficacious means of treating cerebral aneurysms that are refractory to other therapeutic means. Patients with tandem aneurysms treated with flow diversion have been included in larger, previously reported series; however, there are no dedicated reports on using this technique during a single session to treat this unique subset of patients. Therefore, the authors analyzed the outcomes of patients who had undergone single-session flow diversion for the treatment of tandem aneurysms.

METHODS

The authors conducted a retrospective review of flow diversion with the Pipeline embolization device (PED) for the treatment of tandem aneurysms in a single session at 2 participating medical centers: University of Utah, Salt Lake City, Utah, and Barrow Neurological Institute, Phoenix, Arizona. Patient demographic data, aneurysm characteristics, treatment strategy and results, complications, and follow-up data were collected from the medical record and analyzed.

RESULTS

Between January 2011 and December 2015, 17 patients (12 female, 5 male) with a total of 38 aneurysms (mean size 4.7 ± 2.7 mm, mean ± SD) were treated. Sixteen patients had aneurysms in the anterior circulation, and 1 patient had tandem aneurysms in the posterior circulation. Twelve patients underwent only placement of a PED, whereas 5 underwent adjunctive coil embolization of at least 1 aneurysm. One PED was used in each of 9 patients, and 2 PEDs were required in each of 8 patients. There were 2 intraprocedural complications; however, in both instances, the patients were asymptomatic at the last follow-up. The follow-up imaging studies were available for 15 patients at a mean of 7 months after treatment (216 days, range 0–540 days). The mean initial Raymond score after treatment was 2.7 ± 0.7, and the mean final score was 1.3 ± 0.7.

CONCLUSIONS

In this series, the use of flow diversion for the treatment of tandem cerebral aneurysms had an acceptable safety profile, indicating that it should be considered as an effective therapy for this complicated subset of patients. Further prospective studies must be performed before more definitive conclusions can be made.

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Craig Kilburg, Philipp Taussky, M. Yashar S. Kalani and Min S. Park

The use of flow-diverting stents for intracranial aneurysms has become more prevalent, and flow diverters are now routinely used beyond their initial scope of approval at the proximal internal carotid artery. Although flow diversion for the treatment of cerebral aneurysms is becoming more commonplace, there have been no reports of its use to treat flow-related cerebral aneurysms associated with arteriovenous malformations (AVMs). The authors report the cases of 2 patients whose AVM-associated aneurysms were managed with flow diversion. A 40-year-old woman presented with a history of headaches that led to the identification of an unruptured Spetzler-Martin Grade V, right parietooccipital AVM associated with 3 aneurysms of the ipsilateral internal carotid artery. Initial attempts at balloon-assisted coil embolization of the aneurysms were unsuccessful. The patient underwent placement of a flow-diverting stent across the diseased vessel; a 6-month follow-up angiogram demonstrated complete occlusion of the aneurysms. In the second case, a 57-year-old man presented with new-onset seizures, and an unruptured Spetzler-Martin Grade V, right frontal AVM associated with an irregular, wide-necked anterior communicating artery aneurysm was identified. The patient underwent placement of a flow-diverting stent, and complete occlusion of the aneurysm was observed on a 7-month follow-up angiogram. These 2 cases illustrate the potential for use of flow diversion as a treatment strategy for feeding artery aneurysms associated with AVMs. Because of the need for dual antiplatelet medications after flow diversion in this patient population, however, this strategy should be used judiciously.

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L. Ian Taylor, James C. Dickerson, Robert J. Dambrino, M. Yashar S. Kalani, Philipp Taussky, Chad W. Washington and Min S. Park

OBJECTIVE

Although the use of dual antiplatelet therapy with flow diversion is recommended and commonplace, the testing of platelet inhibition is more controversial.

METHODS

The authors reviewed the medical literature to establish and describe the physiology of platelet adhesion, the pharmacology of antiplatelet medications, and the mechanisms of the available platelet function tests. Additionally, they present a review of the pertinent neurointerventional and interventional cardiology literature.

RESULTS

Competing reports in the neurointerventional literature argue for and against the use of routine platelet function testing, with adjustments to the dosage or medications based on the results. The interventional cardiology literature has also wrestled with this dilemma after percutaneous coronary interventions, with conflicting reports of the benefits of platelet function testing.

CONCLUSIONS

Despite its prevalence, the benefits of platelet function testing prior to flow diversion are unproven. This practice will likely remain controversial until the level of evidence improves through more rigorous testing and reporting.

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M. Yashar S. Kalani, John E. Wanebo, Nikolay L. Martirosyan, Peter Nakaji, Joseph M. Zabramski and Robert F. Spetzler

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David S. Xu, Michael R. Levitt, M. Yashar S. Kalani, Leonardo Rangel-Castilla, Celene B. Mulholland, Isaac J. Abecassis, Ryan P. Morton, John D. Nerva, Adnan H. Siddiqui, Elad I. Levy, Robert F. Spetzler, Felipe C. Albuquerque and Cameron G. McDougall

OBJECTIVE

Fusiform dolichoectatic vertebrobasilar aneurysms are rare, challenging lesions. The natural history of these lesions and medium- and long-term patient outcomes are poorly understood. The authors sought to evaluate patient prognosis after diagnosis of fusiform dolichoectatic vertebrobasilar aneurysms and to identify clinical and radiographic predictors of neurological deterioration.

METHODS

The authors reviewed multiple, prospectively maintained, single-provider databases at 3 large-volume cerebrovascular centers to obtain data on patients with unruptured, fusiform, basilar artery dolichoectatic aneurysms diagnosed between January 1, 2000, and January 1, 2015.

RESULTS

A total of 50 patients (33 men, 17 women) were identified; mean clinical follow-up was 50.1 months and mean radiographic follow-up was 32.4 months. At last follow-up, 42% (n = 21) of aneurysms had progressed and 44% (n = 22) of patients had deterioration of their modified Rankin Scale scores. When patients were dichotomized into 2 groups— those who worsened and those who did not—univariate analysis showed 5 variables to be statistically significantly different: sex (p = 0.007), radiographic brainstem compression (p = 0.03), clinical posterior fossa compression (p < 0.001), aneurysmal growth on subsequent imaging (p = 0.001), and surgical therapy (p = 0.006). A binary logistic regression was then created to evaluate these variables. The only variable found to be a statistically significant predictor of clinical worsening was clinical symptoms of posterior fossa compression at presentation (p = 0.01).

CONCLUSIONS

Fusiform dolichoectatic vertebrobasilar aneurysms carry a poor prognosis, with approximately one-half of the patients deteriorating or experiencing progression of their aneurysm within 5 years. Despite being high risk, intervention—when carefully timed (before neurological decline)—may be beneficial in select patients.

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Craig Kilburg, J. Scott McNally, Adam de Havenon, Philipp Taussky, M. Yashar S. Kalani and Min S. Park

The evaluation and management of acute ischemic stroke has primarily relied on the use of conventional CT and MRI techniques as well as lumen imaging sequences such as CT angiography (CTA) and MR angiography (MRA). Several newer or less-established imaging modalities, including vessel wall MRI, transcranial Doppler ultrasonography, and 4D CTA and MRA, are being developed to complement conventional CT and MRI techniques. Vessel wall MRI provides high-resolution analysis of both extracranial and intracranial vasculature to help identify previously occult lesions or characteristics of lesions that may portend a worse natural history. Transcranial Doppler ultrasonography can be used in the acute setting as a minimally invasive way of identifying large vessel occlusions or monitoring the response to stroke treatment. It can also be used to assist in the workup for cryptogenic stroke or to diagnose a patent foramen ovale. Four-dimensional CTA and MRA provide a less invasive alternative to digital subtraction angiography to determine the extent of the clot burden and the degree of collateral blood flow in large vessel occlusions. Along with technological advances, these new imaging modalities are improving the diagnosis, workup, and management of acute ischemic stroke— roles that will continue to expand in the future.