Neurological Surgeon
17 years of experience
Video profile
Accepting new patients
HW neurological Institute
2011 Church St
Ste 505
Nashville, TN 37203
615-320-0007
Locations and availability (4)

Education ?

Medical School Score Rankings
Vanderbilt University (1993)
Neurological Surgery
  • Currently 3 of 4 apples
Top 50%

Awards & Distinctions ?

Awards  
Patients' Choice Award (2011 - 2013)
Compassionate Doctor Recognition (2011 - 2013)
Top 10 Doctor - State (2014)
Tennessee
Neurological Surgeon
Top 10 Doctor - Metro Area (2014)
Greater Nashville
Neurological Surgeon
Top 10 Doctor - City (2014)
Nashville, TN
Neurological Surgeon
Appointments
Univ Of Fl
ASST PROFNEUROSURGERY
Associations
National Board of Medical Examiners
Congress of Neurological Surgeons
American Board of Neurological Surgery
American Association of Neurological Surgeons

Affiliations ?

Dr. Mericle is affiliated with 13 hospitals.

Hospital Affilations

Score

Rankings

  • St Thomas Hospital
    PO Box 380, Nashville, TN 37202
    • Currently 4 of 4 crosses
    Top 25%
  • Baptist Hospital
    2000 Church St, Nashville, TN 37236
    • Currently 3 of 4 crosses
    Top 50%
  • Hickman Community Health Services
    135 E Swan St, Centerville, TN 37033
    • Currently 2 of 4 crosses
  • Nashville, TN - Saint Thomas Hospital
  • Middle Tennessee Medical Center Inc
  • Shands at The University of FL
  • Nashville, TN - Baptist Hospital
  • Vanderbilt University Hospital
  • Shands Hospital At The Univ Of Fl
  • Vanderbilt Univ Med Ctr
  • Shands at Agh
  • Shands Hospital At Alachual General Hosp
  • Veterans Admin Med Ctr
  • Publications & Research

    Dr. Mericle has contributed to 49 publications.
    Title Rebleeding Risk After Treatment of Ruptured Intracranial Aneurysms.
    Date August 2011
    Journal Journal of Neurosurgery
    Excerpt

    Postprocedural rebleeding is a significant source of morbidity following endovascular treatment of ruptured intracranial aneurysms. Previous large-scale reports include the Cerebral Aneurysm Rerupture After Treatment trial, the International Subarachnoid Aneurysm Trial, and the study on Early Rebleeding after Coiling of Ruptured Cerebral Aneurysms, which reported nonprocedural rebleeding rates within 30 days of treatment of 2.7%, 1.9%, and 1.4%, respectively. However, coiling of intracranial aneurysms is in a state of continual change due to advancing device design and evolving techniques. These studies included only patients initially treated prior to 2004. In the present study the authors assess the most recent short-term results with endovascular treatment of ruptured aneurysms.

    Title Eight-year Follow-up After Palliative Embolization of a Neonatal Intracranial Dural Arteriovenous Fistula with High-output Heart Failure: Management Strategies for Symptomatic Fistula Growth and Bilateral Femoral Occlusions in Pediatric Patients.
    Date January 2011
    Journal Journal of Neurosurgery. Pediatrics
    Excerpt

    The authors report the 8-year follow-up of a patient previously described in the literature who originally presented in high-output cardiac failure secondary to a complex neonatal intracranial dural arteriovenous fistula (DAVF). The earlier case report described palliative treatment with a combination of extracorporeal membrane oxygenation (ECMO) and endovascular embolization for life-threatening high-output cardiac failure secondary to a DAVF. Access was obtained using the ECMO cannula, and embolization was performed while the patient was connected to the ECMO machine. The patient made an excellent recovery following partial embolization of the fistula, but then presented again 7 years later with worsening headaches secondary to significant growth of the known residual portion of the fistula identified on CT angiography. The child also developed bilateral femoral artery (FA) occlusions secondary to multiple previous FA punctures. To achieve complete obliteration of the remaining fistula, the patient required a retroperitoneal approach to the iliac artery and percutaneous puncture of the internal jugular vein. Embolization was performed with a combination of platinum coils and ethylene vinyl alcohol copolymer liquid embolic agent. There were no complications, and the child remains neurologically normal, with no signs of permanent cardiovascular sequelae. In this case report, the authors discuss the long-term management of AVFs treated by endovascular strategies early in life. After neonatal access, sometimes the FAs occlude, requiring more invasive access strategies. The authors also discuss the follow-up method, intervals, and threshold for further treatment for these lesions, and present a review of the literature.

    Title Ultrahigh-dose Intraarterial Infusion of Verapamil Through an Indwelling Microcatheter for Medically Refractory Severe Vasospasm: Initial Experience. Clinical Article.
    Date October 2010
    Journal Journal of Neurosurgery
    Excerpt

    Vasospasm is one of the leading causes of morbidity and death following aneurysmal subarachnoid hemorrhage (SAH). Many patients suffer devastating strokes despite the best medical therapy. Endovascular treatment is the last line of defense for cases of medically refractory vasospasm. The authors present a series of patients who were treated with a prolonged intraarterial infusion of verapamil through an in-dwelling microcatheter.

    Title Use of Intracranial Stenting to Secure Unstable Liquid Embolic Casts in Wide-neck Sidewall Intracranial Aneurysms.
    Date June 2010
    Journal Neurosurgery
    Excerpt

    Onyx HD 500 (eV3, Irvine, CA) is a high-viscosity liquid embolic agent that has recently been approved in the United States as a humanitarian use device for the treatment of wide-neck sidewall intracranial aneurysms. Preliminary evidence suggest that liquid embolic agents can provide improved angiographic results with a lower incidence of recanalization compared to coil embolization.

    Title An Automated Algorithm to Improve the Precision of Basilar Artery Diameter Measurements Before and After Subarachnoid Hemorrhage-induced Vasospasm in an Animal Model.
    Date March 2010
    Journal Neurosurgery
    Excerpt

    Quantifying vasospasm has traditionally been performed manually, a method prone to imprecision and user bias. An alternative approach is to use computerized image analysis techniques to define and quantify the diameter of a vessel. The goal of this article is to demonstrate a novel automated vessel measurement algorithm specific to the needs of vasospasm studies and to compare it with traditional manual measurements in an animal model of vasospasm.

    Title Distal Intracranial Catheterization of Patients with Tortuous Vascular Anatomy Using a New Hybrid Guide Catheter.
    Date January 2010
    Journal Surgical Neurology
    Excerpt

    A hybrid guide catheter mates the traditional strong guide catheter with a thin, soft distal tip, allowing placement further into the distal cervical or proximal cranial circulation.

    Title Training Guidelines for Intra-arterial Catheter-directed Treatment of Acute Ischemic Stroke: a Statement from a Special Writing Group of the Society of Interventional Radiology.
    Date January 2010
    Journal Journal of Vascular and Interventional Radiology : Jvir
    Title Resolution of Trigeminal Neuralgia After Palliative Embolization of a Cerebellopontine Angle Arteriovenous Malformation.
    Date November 2009
    Journal Central European Neurosurgery
    Excerpt

    Trigeminal neuralgia (TN) is a syndrome with debilitating paroxysmal facial pain, one cause of which is thought to be vascular compression of the nerve root entry zone causing ephaptic transmission. Arteriovenous malformations (AVM) have been reported to cause TN, including AVMs in the cerebellopontine (CP) angle. These lesions have been successfully treated with endovascular coiling, ethylene-vinyl alcohol copolymer (Onyx) and surgery for decompression.

    Title Defining the Risk of Retreatment for Aneurysm Recurrence or Residual After Initial Treatment by Endovascular Coiling: a Multicenter Study.
    Date October 2009
    Journal Neurosurgery
    Excerpt

    Endovascular treatment of intracranial aneurysms is less invasive than surgical repair but poses a higher risk for aneurysm recurrence, which may necessitate retreatment, thus adding to the long-term risk. Cerebrovascular neurosurgeons from 8 institutions in the United States and Puerto Rico collaborated to assess the risk of retreatment for residual or recurrent aneurysms after the initial endovascular coiling.

    Title Enhancing Spinal Fusion.
    Date April 2009
    Journal Clinical Neurosurgery
    Excerpt

    The acquisition of bony fusion is a complex task. Attention paid to the details presented here may improve fusion rates and patient outcomes. We have much to learn. We should focus on the details of the present and on the possibilities of the future to guide our surgical decision-making process. Indeed, "traumatized bone, whether disrupted via an overt act of trauma or via surgical intervention, heals best when bone healing enhancing parameters are optimized." Our problem to date is that we do not precisely know when, and under what loading conditions, such an optimization process occurs. It is certain that pressure and load affect this process, as suggested by Wolff. This has been portrayed here. The measurement of these parameters in vivo in humans should provide insight into the process of bone healing and ultimately lead to our ability to positively affect the healing of bone and, hence, patient outcomes.

    Title Dural Arteriovenous Fistulas Masquerading As Dural Sinus Thrombosis.
    Date April 2009
    Journal Journal of Neurosurgery
    Excerpt

    The authors report dural sinus thrombosis diagnosed in 2 patients based on noninvasive imaging results, which were revealed to be dural arteriovenous fistulas (DAVFs) diagnosed using digital subtraction (DS) angiography. The first patient was a 63-year-old man who presented with headaches. Magnetic resonance venography was performed and suggested dural sinus thrombosis of the left transverse sinus and jugular vein. He was administered warfarin anticoagulation therapy but then suffered multiple intracranial hemorrhages. A DS angiogram was requested for a possible dural sinus thrombectomy, but the DS angiogram revealed a DAVF. The patient underwent serial liquid embolization with complete obliteration of the DAVF. The second patient, an 11-year-old boy, also presented with headaches and was diagnosed with dural sinus thrombosis on MR imaging. A DS angiogram was also requested for a possible thrombectomy and revealed a DAVF. This patient underwent serial liquid embolization and eventual operative resection. These reports emphasize that different venous flow abnormalities can appear similar on noninvasive imaging and that proper diagnosis is critical to avoid contraindicated therapies.

    Title Does Angiographic Surveillance Pose a Risk in the Management of Coiled Intracranial Aneurysms? A Multicenter Study of 2243 Patients.
    Date December 2008
    Journal Neurosurgery
    Excerpt

    Endovascular treatment of intracranial aneurysms is a less invasive alternative than surgical repair. However, the higher risk of recurrence after coiling necessitates regular angiographic surveillance, which has associated risks. To date, the risk of surveillance angiography has not been quantified in patients with intracranial aneurysms treated by endovascular embolization.

    Title Microsurgical and Angiographic Anatomy of Middle Cerebral Artery Aneurysms: Prevalence and Significance of Early Branch Aneurysms.
    Date October 2008
    Journal Neurosurgery
    Excerpt

    OBJECTIVE: To determine the prevalence of early branch aneurysms, characterize these lesions angiographically and anatomically, and determine their clinical significance. METHODS: The authors conducted a retrospective review of 125 consecutive patients with a diagnosis of middle cerebral artery (MCA) aneurysm. Eighty-four patients harboring 100 MCA aneurysms were studied; 41 patients were excluded for lack of adequate imaging or for fusiform morphology of the aneurysm. Demographic characteristics including age, side, sex, subarachnoid hemorrhage, intracerebral hematoma, multiple aneurysms, and type of treatment were obtained. RESULTS: The average patient age was 57.3 years (range, 29-79 yr); 69 were women and 15 were men. Fifty-eight were right MCA aneurysms and 42 were left aneurysms. Fourteen patients had multiple MCA aneurysms. Thirty-nine of 100 aneurysms were associated with subarachnoid hemorrhage. Twelve of 100 aneurysms were associated with an intracerebral hematoma. The average aneurysm sizes were 9.1 mm overall (range, 2.0-27.0 mm), 12.3 mm for ruptured aneurysms, and 7.5 mm for unruptured. There were 36 M1 bifurcation aneurysms, 39 early frontal branch aneurysms, 18 early temporal branch aneurysms, four lenticulostriate artery aneurysms, and three trifurcation aneurysms. CONCLUSION: In our retrospective review, the majority of MCA aneurysms arose along the M1 segment proximal to the M1 bifurcation. Early frontal branch aneurysms were more common than typical M1 segment bifurcation aneurysms. M1 segment aneurysms arising from early frontal and early temporal branches have distinct anatomic features that impact surgical management and outcome. Understanding the relationship between the recurrent lenticulostriate arteries arising from the proximal segments of these early branches and the aneurysm neck should allow surgeons to avoid many postoperative ischemic complications when dealing with these challenging lesions.

    Title Improved Image Interpretation with Combined Superselective and Standard Angiography (double Injection Technique) During Embolization of Arteriovenous Malformations.
    Date June 2008
    Journal Neurosurgery
    Excerpt

    OBJECTIVE: Interpretation of angioarchitecture during embolization of intracranial arteriovenous malformations (AVMs) is critical to optimizing results. We describe an adjunctive technique to aid in the interpretation of AVM embolization and improve safety. METHODS: In the past 100 consecutive patients who underwent AVM embolization by a single surgeon (RAM), each AVM nidus was selectively catheterized and microangiography was performed. After the microcatheter contrast exited the AVM, guiding catheter angiography was performed during the same digital run. The microangiogram was digitally superimposed on the guiding catheter angiogram to delineate important landmarks such as the nidus perimeter, draining veins, and microcatheter tip, which were then drawn on the digital subtraction angiographic monitor with a marking pen in two orthogonal views. RESULTS: Important landmarks were continually visualized during the embolization procedure despite subtracted fluoroscopy ("blank" roadmap). These techniques qualitatively helped to: 1) appreciate the overall size and morphology of the nidus, 2) clearly visualize the safe limits of the embolic injection within the nidus perimeter, 3) clearly visualize draining patterns to help avoid premature venous embolization, 4) decipher small draining veins from arteries, 5) continuously monitor the location and status of the microcatheter tip, and 6) increase the confidence of the surgeon during prolonged embolic injections. CONCLUSION: The double injection technique, with marking pen demarcation of the nidus perimeter, venous drainage, and microcatheter tip position, was qualitatively useful in every case.

    Title Real-time Image Guidance for Open Vascular Neurosurgery Using Digital Angiographic Roadmapping.
    Date October 2007
    Journal Neurosurgery
    Excerpt

    OBJECTIVE: Angiographic roadmapping, commonly used for catheter navigation in endovascular procedures, is the superimposition of a live fluoroscopic image on a previously stored digitally subtracted angiogram. We evaluated this technique for the first time as a method for image-guided navigation during surgical resection of intracranial and spinal vascular lesions. METHODS: After obtaining Institutional Review Board approval, we retrospectively reviewed 38 procedures in 35 patients at two centers performed by one neurosurgeon in which intraoperative roadmapping was used as an image-guided navigation tool for surgical resection of cranial and spinal arteriovenous malformations or fistulae. This technique requires femoral or radial artery access and a portable vascular C-arm capable of digitally subtracted angiogram and roadmap angiography in the operating room suite. Once a roadmap identifying the vascular lesion is obtained, a sterile radiopaque instrument is placed over the skin/wound to precisely localize the lesion in multiple dimensions. RESULTS: Angiographic roadmapping was used for resection of seven spinal arteriovenous malformations or fistulae, 23 cranial arteriovenous malformations or fistulae, one aneurysm, two carotid-cavernous fistulae, and transtorcular embolization of five vein of Galen malformations. In all cases, the technique helped us to make precisely localized incisions, avoid unnecessary bone removal, and readily directed us to the vascular lesion. In several cases, it allowed localization of small fistulae not visible on magnetic resonance imaging or computed tomographic angiography scans. Finally, this approach facilitated immediate angiographic confirmation of complete resection at the end of each case. CONCLUSION: Angiographic roadmapping is an effective intraoperative navigation tool for resection of vascular lesions that has not been previously described and offers several advantages to frameless stereotaxy.

    Title Onyx: a Unique Neuroembolic Agent.
    Date March 2007
    Journal Expert Review of Medical Devices
    Excerpt

    Rupture of a cerebral arteriovenous malformation can result in devastating hemorrhage with a possibility of serious neurological injury or death. Endovascular embolization is an important adjunct in the treatment of cerebral arteriovenous malformations, and in a small number of cases may provide definitive treatment. Currently available embolic agents have several shortcomings, including the possibility of recanalization, adhesiveness to the endovascular microcatheter and suboptimal handling at the time of surgical resection. Onyx is an ethylene vinyl alcohol copolymer dissolved in dimethyl sulfoxide that was approved by the US FDA in July 2005 as an embolic agent for brain arteriovenous malformations. Although long-term follow-up is limited, this agent appears to offer several advantages over the other available embolic agents for the endovascular management of arteriovenous malformations and other vascular lesions.

    Title Rapid and Effective Labeling of Brain Tissue Using Tat-conjugated Cds:mn/zns Quantum Dots.
    Date February 2007
    Journal Chemical Communications (cambridge, England)
    Excerpt

    TAT (a cell penetrating peptide)-conjugated CdSratioMn/ZnS quantum dots (Qdots), intra-arterially delivered to a rat brain, rapidly (within a few minutes) labeled the brain tissue without manipulating the blood-brain-barrier (BBB). Qdot loading was sufficiently high that it allowed a gross fluorescent visualization of the whole rat brain using a low power hand-held UV lamp. Histological data clearly showed that TAT-conjugated Qdots migrated beyond the endothelial cell line and reached the brain parenchyma. Qdots without TAT did not label the brain tissue confirming the fact that TAT peptide was necessary to overcome the BBB. The present study clearly demonstrated the possibility of delivering a large amount of Qdot-based imaging agents to the brain tissue.

    Title Endovascular Surgery for Proximal Posterior Inferior Cerebellar Artery Aneurysms: an Analysis of Glasgow Outcome Score by Hunt-hess Grades.
    Date August 2006
    Journal Neurosurgery
    Excerpt

    OBJECTIVE: Proximal posterior inferior cerebellar artery (PICA) aneurysms represent a subset of posterior circulation aneurysms that can be routinely treated with either clipping or coiling. The literature contains limited numbers of patients with proximal PICA aneurysms treated with endovascular surgery. We report our experience with endovascular surgery of proximal PICA aneurysms with emphasis on patients with poor Hunt-Hess grades. METHODS: We reviewed 31 consecutive patients with proximal PICA aneurysms who were treated with endovascular surgery. The following data were analyzed: age, sex, size of aneurysm, Hunt-Hess grade at presentation, Fisher grade at presentation, angiographic result after embolization, complications, number of days hospitalized, duration of follow-up, angiographic follow-up results, and Glasgow Outcome Score at follow-up. RESULTS: Excellent angiographic occlusion was achieved in 30 of 31 (97%) patients. Clinical follow-up with Glasgow Outcome Score was performed on every patient an average of 10 months later. Twenty-one of 31 (68%) patients had good outcomes (Glasgow Outcome Score I or II) at follow-up. Of the patients who presented with a favorable clinical grade (Hunt-Hess 0-III), 13 of 15 (87%) had good outcomes at follow-up. Of the patients who presented with a poor clinical grade (Hunt-Hess Grade IV or higher), 8 of 16 (50%) had good outcomes at follow-up. CONCLUSION: This series demonstrates the safety and efficacy of endovascular surgery for proximal PICA aneurysms. Many patients with poor Hunt-Hess grades from ruptured PICA aneurysms ultimately had a good outcome. This could be secondary to early, aggressive treatment of hydrocephalus and the minimally invasive nature of the endovascular approach.

    Title The Use of Abciximab in the Treatment of Acute Cerebral Thromboembolic Events During Neuroendovascular Procedures.
    Date May 2006
    Journal Surgical Neurology
    Excerpt

    BACKGROUND: Recently, a great interest has emerged regarding the use of abciximab for treatment of stroke. Thromboembolic events that occur during neuroendovascular procedures represent a unique subset of stroke patients because definitive angiographic diagnosis and treatment can be performed immediately. The existing literature on this situation suggests excellent results; however, most publications are case reports, and the largest series is 13 cases. We report our experience using abciximab in the treatment of acute thromboembolic events that occur during neuroendovascular procedures. METHODS: We reviewed the last 1373 consecutive patients who underwent neuroendovascular procedures at the University of Florida from our prospectively maintained clinical database. Of these patients, 29 (2.11%) endovascular cases were complicated by acute cerebral thromboembolic events that were treated with abciximab. Abciximab was administered in less than 1 hour after the onset of the occlusion in every patient. The Thrombolysis In Myocardial Infarction (TIMI) scale was used to measure immediate angiographic outcome, and the Modified Rankin Scale (MRS) was used to measure clinical outcome at the time of follow-up. Independent outcome was defined as an MRS of 3 or less at follow-up. RESULTS: Angiographic improvement in the TIMI grade was achieved in 29 (81%) of 36 arteries. Three intracerebral hemorrhages occurred with abciximab when administered with concurrent mechanical clot disruption; in two of these hemorrhages, recombinant tissue plasminogen activator (r-tPA) was also administered. The mean follow-up time for the living cohort was 7.54 months. Twenty-four (83%) patients were independent at follow-up, 3 (10%) were dependent at follow-up, and 2 (7%) died. CONCLUSION: Abciximab appears to be safe and effective in the treatment of acute cerebral thromboembolic complications during neuroendovascular procedures.

    Title Preoperative Endovascular Brain Mapping for Intraoperative Volumetric Image Guidance: Preliminary Concept and Feasibility in Animal Models.
    Date May 2006
    Journal Journal of Neurosurgery
    Excerpt

    OBJECT: The authors describe a novel concept for brain mapping in which an endovascular approach is used, and they demonstrate its feasibility in animal models. The purpose of endovascular brain mapping is to delineate clearly the nonfunctional brain parenchyma when a craniotomy is performed for resection. The nonfunctional brain will be stained with sharp visual margins, differentiating it from the functional, nonstained brain. The authors list four essential criteria for developing an ideal endovascular mapping agent, and they describe seven potential approaches for accomplishing a successful endovascular brain map. METHODS: Four Sprague-Dawley rats and one New Zealand white rabbit were used to determine initial feasibility of the procedure. The animals were anesthetized, and the internal carotid artery was catheterized. Four potential brain mapping agents were infused into the right hemisphere of the five animals. Afterward, the brains were removed and each was analyzed both grossly and histologically. Fluorescein and FD&C Green No. 3 provided good visual clarity and margins, but required blood-brain barrier (BBB) manipulation. Tantalum particles enabled avoidance of BBB manipulation, but provided inadequate visual clarity, probably because of their size. A Sudan black "cocktail" provided excellent clarity and margins despite remaining in the brain capillaries. CONCLUSIONS: This is a novel application of the endovascular approach, and has broad potential for clinical neurosurgical brain mapping. The animal models in this study establish the feasibility of the procedure. However, further study is required to demonstrate safety, minimize toxicity, investigate stain durability, and improve the characteristics of potential mapping agents. The authors are planning to conduct future studies for identification of mapping agents that do not require BBB manipulation or vascular occlusion.

    Title Tat Conjugated, Fitc Doped Silica Nanoparticles for Bioimaging Applications.
    Date February 2006
    Journal Chemical Communications (cambridge, England)
    Excerpt

    Water-in-oil (w/o) microemulsion synthesis of 70 nm size monodisperse TAT (a cell penetrating peptide, CPP) conjugated, FITC (fluorescein isothiocyanate) doped silica nanoparticles (TAT-FSNPs) is reported; human lung adenocarcinoma (A549) cells (in vitro) and rat brain tissue (in vivo) were successfully labeled using TAT-FSNPs.

    Title Folate Conjugated Fluorescent Silica Nanoparticles for Labeling Neoplastic Cells.
    Date September 2005
    Journal Journal of Nanoscience and Nanotechnology
    Excerpt

    We describe a novel technique of using fluorescent silica nanoparticles (FSNPs) to detect over-expressed folate receptors, as typical for certain malignancies (metastatic adenocarcinoma, pituitary adenoma and others). Using Stöber's method with some modification, 135 nm size FSNPs were synthesized by a hydrolysis and co-condensation reaction of tetraethylorthosilicate (TEOS), fluorescein labeled (3-aminopropyl)triethoxysilane (APTS) and a water-dispersible silane reagent, (3-trihydroxysilyl)propyl methylphosphonate (THPMP) in the presence of ammonium hydroxide catalyst. Folic acid (folate) was covalently attached to the amine modified FSNPs by a carbodiimide coupling reaction. The characterization of folate-FSNPs was performed using a variety of spectroscopic (UV-VIS and fluorescence), microscopic (transmission electron microscopy, TEM) and light scattering techniques. Folate conjugated FSNPs were then targeted to human squamous cancer cells (SCC-9). Laser scanning confocal images successfully demonstrated the labeling of SCC-9 cells and the efficacy of FSNP based detection system.

    Title Finite Element Analysis of Covered Microstents.
    Date August 2005
    Journal Journal of Biomechanics
    Excerpt

    Currently available neuroendovascular devices are inadequate for effective treatment of many wide-necked or fusiform intracranial aneurysms and intracranial carotid-cavernous fistulae (CCF). Placing a covered microstent across the intracranial aneurysm neck and CCF rent could restore normal vessel morphology by preventing blood flow into the aneurysm lumen or CCF rent. To fabricate covered microstents, our research group has developed highly flexible ultra thin (approximately 150 microm) silicone coverings and elastomerically captured them onto commercially available metal stents without stitching. Preliminary in vivo studies were conducted by placing these covered microstents in the common carotid artery of rabbits. The feasibility of using covered stents was demonstrated. However, the cover affected the deployment pressure and the stents failed occasionally during deployment due to tearing of the cover. Appropriate modeling of covered stents will assist in designing suitable coverings, and help to reduce the failure rate of covered microstents. The purpose of this study is to use the finite element method to determine the mechanical properties of the covered microstent and investigate the effects of the covering on the mechanical behavior of the covered microstent. Variations in the mechanical properties of the covered microstent such as deployment pressure, elastic recoil and longitudinal shortening due to change in thickness and material properties of the cover have been investigated. This work is also important for custom design of covered microstents such as adding cutout holes to save adjacent perforating arteries.

    Title Synthesis of Water-dispersible Fluorescent, Radio-opaque, and Paramagnetic Cds:mn/zns Quantum Dots: a Multifunctional Probe for Bioimaging.
    Date March 2005
    Journal Journal of the American Chemical Society
    Excerpt

    Ultra-small (3.1 nm) multifunctional CdS:Mn/ZnS core-shell semiconductor quantum dots (Qdots), which possess fluorescent, radio-opacity, and paramagnetic properties, have been shown here. To demonstrate in vivo bioimaging capability, a rat was administered endovascularly with Qdots conjugated with a TAT peptide. The labeling efficacy of these Qdots was demonstrated on the basis of the histological analysis of the microtome sliced brain tissue, clearly showing that TAT-conjugated Qdots stained brain blood vessels.

    Title Transradial Approach for Neuroendovascular Surgery of Intracranial Vascular Lesions.
    Date December 2004
    Journal Journal of Neurosurgery
    Excerpt

    OBJECT: The authors present their experience in performing a transradial approach for neuroendovascular surgery of intracranial vascular lesions when a transfemoral approach was unfavorable. METHODS: Eight patients ranging in age from 52 to 88 years underwent a total of nine neuroendovascular procedures for intracranial vascular lesions. A transradial approach was used in all patients. The patients had previously undergone a transfemoral approach for the endovascular intervention, but that procedure was unsuccessful. Five patients had intracranial basilar artery (BA) aneurysms, one patient had symptomatic BA stenosis, one patient had a dural arteriovenous fistula in the posterior fossa, and one patient had a high-flow arteriovenous malformation in the frontal lobe. In each case, a transradial approach achieved a stable platform that allowed intracranial microcatheterization for neuroendovascular intervention. None of the patients experienced complications attributed to the transradial artery approach. CONCLUSIONS: During neuroendovascular surgery for the treatment of intracranial lesions, the transradial approach is a viable alternative if the transfemoral approach is unfavorable. This series represents the first known description of neuroendovascular surgery for intracranial lesions via a transradial approach.

    Title Delayed Exacerbation of Third Nerve Palsy Due to Aneurysmal Regrowth After Endovascular Coil Embolization.
    Date July 2004
    Journal Journal of Neuro-ophthalmology : the Official Journal of the North American Neuro-ophthalmology Society
    Excerpt

    A 72-year-old woman with a painful left third cranial nerve palsy due to a basilar artery aneurysm situated between the superior cerebellar and posterior cerebral arteries was treated with Guglielmi detachable coils (GDCs). Despite a good initial angiographic result with a small residual neck and improvement in the ocular motility and pain, the patient experienced worsening of the third cranial nerve palsy 15 months later. Cerebral angiography confirmed coil compaction with aneurysmal regrowth. A second endovascular coil embolization resulted in complete obliteration of the aneurysm. The patient experienced complete resolution of the pain and partial resolution of the third cranial nerve palsy. In some patients, a small residual aneurysm neck after endovascular embolization therapy with GDCs can result in delayed aneurysmal regrowth due to coil compaction. Clinical manifestations may herald this dangerous regrowth.

    Title Use of Gadolinium As an Intraarterial Contrast Agent for Pediatric Neuroendovascular Procedures.
    Date February 2004
    Journal Journal of Neurosurgery
    Excerpt

    OBJECT: The safety and efficacy of Gd as an intraarterial contrast agent for pediatric neuroendovascular procedures were investigated. METHODS: The authors retrospectively reviewed data regarding pediatric neuroendovascular procedures performed during a 1-year period. Seventeen procedures involving the use of gadodiamide in nine pediatric patients were identified. All angiographic images were of diagnostic quality but usually required minimal postimage processing. In time-consuming cases, the use of gadodiamide allowed the procedure to continue when the dosage of iodinated contrast approached a toxicity level and would have otherwise prompted termination of the procedure. This likely reduced the total number of procedures necessary. No adverse events due to the intraarterial use of gadodiamide were identified. CONCLUSIONS: Gadodiamide appears to be a safe and effective contrast agent for pediatric patients.

    Title Extracorporeal Membrane Oxygenation Combined with Endovascular Embolization for Management of Neonatal High-output Cardiac Failure Secondary to Intracranial Arteriovenous Fistula. Case Report.
    Date February 2004
    Journal Journal of Neurosurgery
    Excerpt

    The authors describe a novel approach to the management of high-output heart failure secondary to an intracranial high-flow dural arteriovenous fistula (DAVF) by using extracorporeal membrane oxygenation (ECMO). To the best of the authors' knowledge, this represents the first report of an embolization performed in conjunction with the use of an ECMO circuit and the first report in which an ECMO cannula was used for intraarterial access for cerebral angiography. A 2-day-old girl presented with severe, high-output heart failure secondary to a high-flow intracranial DAVF. The patient was neurologically intact and no brain parenchymal abnormalities were revealed on computerized tomography scanning of the head, but she suffered severe heart failure, pulmonary hypertension, and liver and renal dysfunction. The patient underwent three endovascular embolization procedures involving coils and liquid embolic agents. Despite a decrease in the DAVF flow, the patient had only transient improvement in her pulmonary hypertension, and venoarterial ECMO therapy was instituted. Another embolization was performed while the patient was receiving ECMO therapy. Her cardiovascular status improved, she was weaned from ECMO, and she was eventually discharged home to her family. Extracorporeal membrane oxygenation can be used to sustain severely ill neonates with high-output heart failure secondary to intracranial AVFs. Embolization can be performed while the patient is receiving ECMO therapy.

    Title Microsurgical Anatomy of the Early Branches of the Middle Cerebral Artery: Morphometric Analysis and Classification with Angiographic Correlation.
    Date July 2003
    Journal Journal of Neurosurgery
    Excerpt

    OBJECT: The cortical arteries arising from the main trunk of the middle cerebral artery, proximal to its bifurcation or trifurcation, are called "early branches." The purpose of this study was to characterize these early branches. METHODS: The early branches were characterized according to their sites and patterns of origin, diameters, and relative proximity to the internal carotid artery bifurcation, as well as the course and area of supply of their cortical branches based on an examination of 50 hemispheres. Special attention was directed to the perforating arteries that arose from the early branches and entered the anterior perforated substance. The anatomical findings were compared with data obtained from 109 angiograms. CONCLUSIONS: Early branches directed to the temporal and frontal lobes were found in 90 and 32% of the hemispheres, respectively. The early branches that arose more proximally from the M1 segment were larger than those arising distally. Lenticulostriate arteries arose from 81% of the early frontal branches (EFBs) and from 48% of the early temporal branches (ETBs). An average of two cortical arteries arose from the EFBs and 1.3 from the ETBs, the most common of which supplied the temporopolar and orbitofrontal areas. Although the microsurgical anatomy of the early branches demonstrates abundant diversity, they can be classified into clearly defined patterns based on anatomical features. These patterns can prove helpful in evaluating angiographic data and in planning an operative procedure.

    Title Stent Placement for the Treatment of Occlusive Atherosclerotic Carotid Artery Disease in Patients with Concomitant Coronary Artery Disease.
    Date March 2002
    Journal Journal of Neurosurgery
    Excerpt

    OBJECT: The authors report their experience with carotid artery stent placement (CASP) in patients with concomitant carotid artery (CA) and coronary artery (CorA) diseases. METHODS: In a review of 320 consecutive patients who underwent CASP, the authors identified 49 with severe CorA disease in addition to significant CA stenosis, who had undergone CASP before planned CorA bypass grafting (CorABG). The average age of these 49 patients was 68 years. In 39 patients (80%) the New York Heart Association functional classification grade was IV and in 10 the grade was III. In 26 patients 50% or greater stenosis of the left main CorA was found. Seventeen patients (35%) suffered from either significant hemodynamic contralateral CA stenosis (> 60% stenosis; eight patients) or contralateral CA occlusion (nine patients). Sixteen patients (33%) had symptomatic CA disease. No cerebrovascular events occurred during CorABG. Four patients (8%) died of cardiac arrest and one patient (2%) suffered a major stroke within 30 days after the CorABG procedure. No patient experienced clinically significant recurrent CA stenosis during the study period (average clinical follow-up period 27 months). CONCLUSIONS: Carotid artery stent placement should be considered as an alternative for the management of concomitant CA and CorA diseases. These preliminary results support the feasibility and durability of CASP in the population studied.

    Title A Grading Scale to Predict Outcomes After Intra-arterial Thrombolysis for Stroke Complicated by Contrast Extravasation.
    Date June 2000
    Journal Neurosurgery
    Excerpt

    OBJECTIVE: Contrast extravasation after intra-arterial thrombolysis for stroke occurs frequently and is identifiable on a computed tomographic (CT) scan, but it is often unrecognized or misdiagnosed. Few articles describing this phenomenon have been published. The clinical outcomes of patients after contrast extravasation are poorly understood. We designed a grading system to predict outcomes after contrast extravasation and tested the grading scale prospectively. METHODS: We studied 27 patients who had contrast extravasation exhibited on a CT scan immediately after intra-arterial thrombolysis. The National Institutes of Health Stroke Scale was used to quantify neurological examinations preoperatively, postoperatively, and at follow-up an average of 3 months later. A grading scale from 0 to 10 was developed from a retrospective analysis of the first 18 patients using odds ratios and Fisher's exact test. The grading system was then applied prospectively to the next 9 consecutive patients. RESULTS: Six components of the grading system were weighted approximately proportional to corresponding odds ratios: 1) incomplete recanalization (3 points), 2) prolonged angiographic blush (2 points), 3) hyperdensity greater than 150 Hounsfield units (2 points), 4) lesion volume greater than 50 cc exhibited on a CT scan (1 point), 5) lesion in eloquent parenchyma (1 point), and 6) hypodensity demonstrated on an immediate postoperative CT scan (1 point). The contrast extravasation grades for each outcome category (excellent, fair, poor, died) increased in stepwise fashion. There was a direct linear correlation between the assigned grade and National Institutes of Health Stroke Scale score improvement at follow-up. CONCLUSION: This grading system should prove useful as a preliminary guide for predicting outcomes of patients with contrast extravasation after intra-arterial thrombolysis for stroke. Further analysis in a large cohort of prospective patients is necessary to ensure extensibility.

    Title Vein of Galen Malformation.
    Date May 2000
    Journal Pediatric Neurosurgery
    Title Carotid Artery Angioplasty and Use of Stents in High-risk Patients with Contralateral Occlusions.
    Date June 1999
    Journal Journal of Neurosurgery
    Excerpt

    OBJECT: The risks associated with carotid endarterectomy (CEA) are increased in the presence of contralateral carotid artery (CA) occlusion. The 30-day stroke and death rate for patients in the North American Symptomatic Carotid Endarterectomy Trial (NASCET) who had contralateral CA occlusion was 14.3%. The authors analyze their experience with angioplasty and/or stent placement in patients with contralateral CA occlusion to determine the safety and efficacy of endoluminal revascularization in this subgroup. METHODS: Twenty-six procedures were evaluated in 23 patients with high-grade CA stenosis and contralateral CA occlusion. The first 15 procedures were evaluated retrospectively, and the next 11 prospectively. All patients had severe medical comorbidities and were considered too high risk for CEA, even without considering the contralateral occlusion. Clinical follow-up review was performed an average of 18 months later (median 15 months). CONCLUSIONS: The average ipsilateral CA stenosis according to NASCET criteria was 78% preprocedure and 5% postprocedure. There were no changes in neurological or functional outcome immediately postoperatively in any patient. The 30-day postoperative stroke and death rates were zero. However, there was one symptomatic femoral hematoma that resolved without surgery. At follow up, there were three patients who had suffered stroke or death. One patient died secondary to respiratory arrest at 2 months; one died secondary to prostate carcinoma at 12 months; and one patient experienced a minor stroke contralateral to the treated artery at 41 months. Despite the substantial preoperative risk factors in patients in this series, the 30-day stroke and death rate for angioplasty and/or stent placement appears to be lower than that of CEA in patients with contralateral occlusions.

    Title Percutaneous Transluminal Angioplasty and Stent Placement for Recurrent Carotid Artery Stenosis.
    Date April 1999
    Journal Journal of Neurosurgery
    Excerpt

    OBJECT: Treatment consisting of percutaneous transluminal angioplasty (PTA) and stent placement has recently been proposed as an alternative to surgical reexploration in patients with recurrent carotid artery stenosis following endarterectomy. The authors retrospectively reviewed their experience after performing 25 procedures in 21 patients to assess the safety and efficacy of PTA with or without stent placement for carotid artery restenosis. METHODS: The mean interval between endarterectomy and the endovascular procedures was 57 months (range 8-220 months). Seven arteries in five patients were treated by PTA alone (including bilateral procedures in one patient and repeated angioplasty in the same vessel in another). Early suboptimum results and recurrent stenosis in some of these initial cases prompted the authors to combine PTA with stent placement in the treatment of 18 arteries over the past 3 years. No major periprocedural deficits (neurological or cardiac complications) or death occurred. There was one periprocedural transient neurological event, and in one patient a pseudoaneurysm of the femoral artery (at the access site) required surgical repair. In the 16 patients who each underwent at least 6 months of follow-up review, no neurological events ipsilateral to the treated artery had occurred after a mean follow-up period of 27 months (range 6-57 months). Three of five patients who underwent PTA alone developed significant (>50%) asymptomatic restenoses that required repeated angioplasty in one and PTA with stent placement in two patients. Significant restenosis (55%) was observed in only one of the vessels treated by combined angioplasty and stent placement. CONCLUSIONS: Endovascular PTA and stenting of recurrent carotid artery stenosis is both technically feasible and safe and has a satisfactory midterm patency. This procedure can be considered a viable alternative to surgical reexploration in patients with recurrent carotid artery stenosis.

    Title Stenting and Secondary Coiling of Intracranial Internal Carotid Artery Aneurysm: Technical Case Report.
    Date February 1999
    Journal Neurosurgery
    Excerpt

    OBJECTIVE AND IMPORTANCE: Endovascular stents have been successfully used in the treatment of fusiform and dissecting aneurysms of the peripheral circulation and extracranial carotid and vertebral arteries. Technical limitations related to the inability to navigate the stent and the delivery system through tortuous vascular segments has limited their application with intracranial lesions. Availability of new flexible and pliable stent systems might overcome these difficulties. CLINICAL PRESENTATION: A 49-year-old woman presented with a dissecting pseudoaneurysm of the horizontal portion of the petrous internal carotid artery that increased in size, as revealed by serial angiographic studies. INTERVENTION: The aneurysm was treated by deploying a new flexible stent across the aneurysm neck and by then packing the aneurysm sac with Guglielmi detachable coils that were delivered by a microcatheter positioned through the stent struts into the aneurysm lumen. CONCLUSION: New flexible stents can be used to treat intracranial internal carotid artery aneurysms in difficult-to-access areas, such as the horizontal petrous segment. The stent may disrupt the aneurysm inflow tract, thereby inducing stasis and facilitating intra-aneurysmal thrombosis. In addition, the stent acts as an endoluminal scaffold to prevent coil herniation into the parent artery, which allows tight packing of even wide-necked and irregularly shaped aneurysms. The stent may also serve as a matrix for endothelial growth. We think this new generation of flexible stents and the use of this described technique will usher in the next era of endovascular management of intracranial aneurysms.

    Title Cavernous Sinus Syndrome During Balloon Test Occlusion of the Cervical Internal Carotid Artery. Report of Two Cases.
    Date October 1998
    Journal Journal of Neurosurgery
    Excerpt

    The authors report the occurrence of ipsilateral transient cavernous sinus syndrome during balloon test occlusion (BTO) of the cervical internal carotid artery (ICA) and discuss the involved pathomechanisms. The authors reviewed their series of 129 BTOs of the ICA performed between 1989 and 1996. Two patients developed facial paresthesias and transient palsies of the third through sixth cranial nerves during test occlusion of the cervical ICA. The tests were performed prior to planned permanent carotid artery occlusion for the treatment of a neck sarcoma in one patient and a giant cavernous carotid artery aneurysm in the other. The patients' symptoms resolved with deflation of the balloon. When the balloon was subsequently inflated above the inferior cavernous sinus artery (ICSA), one of the patients complained of mild facial discomfort. There was no contralateral weakness or mental status change during test occlusion in either patient. Angiography demonstrated good filling of the ipsilateral intracranial circulation via collateral vessels of the circle of Willis. In these two cases, the cranial nerves in the cavernous sinus were likely supplied by the ICA via the meningohypophyseal trunk and the ICSA. In each case, there was excellent blood supply to the ipsilateral cerebral hemisphere; however, there was probably inadequate retrograde filling of the cranial nerve collateral vessels located where the meningohypophyseal trunk and ICSA originated. These cases emphasize the importance of a patent external carotid artery-ICA connection for successful cervical carotid artery occlusion. Neurological examination during BTO was critical to interpret the clinical manifestations caused by the hemodynamic changes.

    Title A Novel Approach to Flow Quantification in Brain Arteriovenous Malformations Prior to Enbucrilate Embolization: Use of Insoluble Contrast (ethiodol Droplet) Angiography.
    Date September 1998
    Journal Journal of Neurosurgery
    Excerpt

    OBJECT: Successful therapeutic embolization of arteriovenous malformations (AVMs) of the brain with liquid polymers (glues) requires precise knowledge of highly variable AVM structure and flow velocities and transit times of blood through the AVM nidus. The goal of this study was to improve AVM flow measurement and visualization by the substitution of the insoluble Ethiodol (ethiodized oil) contrast agent for the soluble contrast media normally used in angiographic studies. METHODS: Before enbucrilate embolization of 24 AVM feeding pedicles in 13 patients, standard contrast medium was superselectively injected into each target pedicle, followed by infusion of 20 microl of Ethiodol microdroplets. Transport of contrast material was assessed using high-speed biplane pulsed digital subtraction angiography (DSA) operating at 15 frames per second. The mean blood flow transit times through AVMs after administration of Ethiodol were found to be approximately half as long as in those measured after injection of soluble contrast materials (0.22 +/- 0.10 seconds compared with 0.46 +/- 0.19 seconds [mean +/- standard deviation]; p < 0.0001). The discrete Ethiodol microdroplets travel with the core flow, more closely approximating the dynamic behavior of enbucrilate, allowing the AVM structure to be traced with high spatial and temporal resolution. There were no inadvertent vessel occlusions or pulmonary complications related to the use of Ethiodol for DSA. CONCLUSIONS: Because of diffusion and convection, forces that decrease concentration, visualization of the contrast front is reduced, often resulting in deceptively long transit times when soluble contrast materials are used. Overestimation may prove dangerous when planning embolizations. The Ethiodol droplet DSA method provides accurate transit time measurements and precise, detailed, and dynamic AVM visualization. Further development of this method will improve the safety and precision of AVM treatments.

    Title Delayed Aneurysm Regrowth and Recanalization After Guglielmi Detachable Coil Treatment. Case Report.
    Date July 1998
    Journal Journal of Neurosurgery
    Excerpt

    Guglielmi detachable coil (GDC) treatment for complicated cerebral aneurysms is an attractive option that has become widely accepted in recent years. This technique is usually considered only if the patient harbors an aneurysm that is not a good candidate for surgical clipping. However, the definition of "surgical candidate" varies among institutions, and many patients worldwide are being treated with GDCs as primary therapy. Although most centers currently perform follow-up angiography at 6 months to 1 year, others do not routinely perform it after an initially good result. The authors present a case that indicates longer follow up may be necessary and illustrates some of the pitfalls of GDC treatment. This 56-year-old man presented to the emergency room with a Hunt and Hess Grade II subarachnoid hemorrhage and was found to have a wide-necked basilar apex aneurysm. Because of associated medical comorbidities, it was decided to treat the aneurysm with endovascular techniques. The patient did well on follow-up angiography at 1 year postprocedure. However, at approximately 2 years follow up, the aneurysm was demonstrated to have dramatically recanalized and regrown, requiring open surgical intervention. Endovascular coiling was insufficient to treat this aneurysm and complicated definitive surgical management because a large coil mass had been placed in the operative field. It can be inferred from this case that angiographic follow up of these types of lesions may be beneficial up to 2 years after GDC treatment.

    Title Temporary Balloon Protection As an Adjunct to Endosaccular Coiling of Wide-necked Cerebral Aneurysms: Technical Note.
    Date November 1997
    Journal Neurosurgery
    Excerpt

    OBJECTIVE: We present an endovascular technique for treating wide-necked cerebral aneurysms using Guglielmi detachable coils (Target Therapeutics, Fremont, CA) and simultaneous temporary balloon protection. The temporary balloon serves as a mechanical external force to mold the microcoils away from the parent artery. METHODS: Two illustrative cases of wide-necked cerebral aneurysms treated with Guglielmi detachable coils and a temporary balloon are presented. Emphasis is placed on the technical aspects of the approach, with several variations. The first case involves a left posterior cerebral artery aneurysm at the P1/P2 segment, and the second case involves a left paraclinoid internal carotid artery aneurysm. Both patients suffered from subarachnoid hemorrhage, but neither was a candidate for craniotomy. In each case, the coils, when used alone, protruded into the parent artery and were therefore removed. Then a temporary balloon was inflated for mechanical protection during coil deployment. RESULTS: The use of simultaneous temporary balloon protection allowed more dense intra-aneurysmal coil packing, especially in the neck, without parent artery compromise, than did the use of Guglielmi detachable coils alone. CONCLUSION: Endovascular treatment of wide-necked cerebral aneurysms can be facilitated by simultaneous temporary balloon protection.

    Title Treatment of Acute Pandysautonomia with Intravenous Immunoglobulin.
    Date June 1997
    Journal Journal of Neurology, Neurosurgery, and Psychiatry
    Excerpt

    Acute pandysautonomia has been suggested to be an uncommon variant of Guillain-Barre syndrome. Acute pandysautonomia does not seem to have been treated with intravenous immunoglobulin or other therapies proved efficacious in Guillain-Barre syndrome. A patient is reported with severe acute pandysautonomia who responded dramatically to intravenous immunoglobulin. The findings are consistent with a dysimmune pathogenesis for this syndrome and suggest a possible treatment for future cases.

    Title Determination of the Lethal Dose of Dexamethasone for Early Passage in Vitro Human Glioblastoma Cell Cultures.
    Date November 1993
    Journal Neurosurgery
    Excerpt

    Previous investigators have supported the idea that glucocorticoids may be oncolytic. In this study, the percentage of cell death in two human glioblastoma cell cultures was related to the concentration of dexamethasone that was administered. It was determined that for Cell line 1, the median lethal dose was approximately 500-800 micrograms/ml and the completely lethal dose was about 900-1000 micrograms/ml; the 3H-thymidine uptake to approximate the mitotic rate was 16,607 cpm, and the dexamethasone receptor activity was 228 fmol/mg protein. The median lethal dose and completely lethal dose for Cell line 2 was approximately 500-600 micrograms/ml and 700-1000 micrograms/ml, respectively; the 3H-thymidine uptake was 8402 cpm, and the dexamethasone receptor activity was 137 fmol/mg protein. These lethal concentrations of dexamethasone are probably higher than can be tolerated by systemic delivery. However, it remains to be seen whether the interstitial administration of dexamethasone could achieve local concentrations resulting in the oncolysis of malignant gliomas. The clinical significance of these findings will depend on the local tolerance of normal brain parenchyma to very high doses of dexamethasone. A review of some of the literature is included.

    Title Serum Angiotensin Converting Enzyme in Diabetic Patients.
    Date June 1993
    Journal The American Journal of the Medical Sciences
    Excerpt

    Serum angiotensin converting enzyme (ACE) levels are higher in patients with diabetes mellitus than in many others. Techniques are available to grade different degrees of diabetic retinopathy, which can demonstrate a relationship between ACE and diabetic retinopathy. In this study, patients with diabetic retinopathy had higher serum ACE levels (6.3 +/- 0.2) than nondiabetic patients (4.3 +/- 0.5) (p < 0.001). In addition, the mean serum ACE level in diabetic patients with nonproliferative retinopathy (5.55 +/- 0.4) was less than that in diabetic patients with proliferative retinopathy (6.63 +/- 0.25) (p = 0.02). Due to the variability in individual serum ACE levels and the frequent use of ACE inhibitors by hypertensive diabetics, these techniques are not suitable for retinopathy screening programs. However, the graded relationship demonstrated by these data may have relevance for the pathophysiology of diabetic retinopathy.

    Title Carotid Intervention: A NeurosurgeonÕs Perspective.
    Date
    Journal The Journal of Invasive Cardiology
    Title Angioplasty and Stenting for Carotid Artery Stenosis: Indications, Techniques, Results, and Complications.
    Date
    Journal Neurosurgical Focus
    Excerpt

    Following the favorable results obtained in the treatment of coronary artery disease, combined angioplasty and stenting has been advocated for the treatment of carotid artery stenosis as well. Although widespread application of angioplasty and stenting for carotid artery disease is neither indicated nor recommended, it may be a viable alternative therapy for select patients who are high-risk patients for surgery. The results of early series have suggested that endoluminal revascularization in these high-risk patients can be performed with an acceptable degree of safety. Although the incidence of death and major stroke rates following angioplasty and stenting procedures compares favorably with surgery, results of more recent clinical series have suggested that the incidence of perioperative transient neurological events and minor strokes may be higher than suggested by earlier reports, especially in patients with recent neurological symptoms and "unstable" plaques. In this article, the authors review the current potential indications for and preliminary results of angioplasty and stenting and describe their procedural technique. In addition, potential applications of stenting to intracranial thromboocclusive carotid artery disease are reviewed.

    Title Comparison of N-butyl Cyanoacrylate and Onyx for the Embolization of Intracranial Arteriovenous Malformations: Analysis of Fluoroscopy and Procedure Times.
    Date
    Journal Neurosurgery
    Excerpt

    OBJECTIVE: Intracranial arteriovenous malformations (AVM) may be managed through staged preoperative embolization and resection. Two commonly used liquid embolics are N-butyl cyanoacrylate (nBCA; Cordis Microvascular, Inc., New Brunswick, NJ) and Onyx (ev3, Inc., Irvine, CA). We sought to compare the utility of these agents in terms of fluoroscopy and procedure times. METHODS: All intracranial AVMs embolized from 2002 to 2006 at the University of Florida were included in this study. Patients were stratified into three treatment groups: nBCA, Onyx, and patients who received both nBCA and Onyx during separate embolizations. Cohorts were compared by sex, age, Spetzler-Martin grade, AVM volume, fluoroscopy time, procedure time, surgical blood loss, and complications. RESULTS: A total of 182 embolizations were performed on 88 patients (nBCA, 60 patients and 106 procedures; Onyx, 20 patients and 43 procedures; and nBCA/Onyx, eight patients and 16 nBCA and 17 Onyx procedures). There were no significant differences in patient demographics, AVM volumes, and Spetzler-Martin grades. Mean fluoroscopy and procedure times were increased for Onyx (57 min; 2.6 h) compared with nBCA (37 min; 2.1 h) embolizations (P < 0.0001 and P = 0.001, respectively). Cumulative mean fluoroscopy time was increased for Onyx (135 min) and nBCA/Onyx (180 min) cohorts relative to nBCA (64 min; P < 0.0001). Cumulative mean procedure time was increased in the nBCA/Onyx group (10.4 h) compared with nBCA (3.7 h) and Onyx (5.4 h; P < 0.0001). Seventy patients (80%) underwent AVM resection. No significant differences in surgical blood loss or complication rates were observed among the cohorts. CONCLUSION: Onyx AVM embolization requires increased fluoroscopy and procedure times compared with nBCA. Further investigation is necessary to justify increased radiation exposure and procedure time associated with Onyx.

    Title Endovascular Treatment of Side Wall Aneurysms Using a Liquid Embolic Agent: a Us Single-center Prospective Trial.
    Date
    Journal Neurosurgery
    Excerpt

    Onyx HD-500 is a liquid embolic agent consisting of ethylene vinyl alcohol copolymer dissolved in dimethylsulfoxide and mixed with tantalum. This viscous embolic agent was designed to treat intracranial side wall aneurysms, but there have been no prospective published series from the United States. From this early experience, we developed several protocol revisions, technical details, and clinical pearls that have not been published for liquid embolic embolization of aneurysms.

    Title Erratum.
    Date
    Journal Neurosurgery
    Title Biomechanical Attributes of Microcatheters Used in Liquid Embolization of Intracranial Aneurysms.
    Date
    Journal Journal of Neurointerventional Surgery
    Excerpt

    Objective A steel-reinforced and a nitanol-reinforced microcatheter are both approved for use with Onyx HD-500 embolization of intracranial aneurysms. The biomechanical behavior of these catheters when used with high viscosity embolic liquids is poorly understood. We performed biomechanical laboratory testing and examined our clinical experience to identify situations where one catheter might have an advantage over the other. Methods The catheters were tested for detachment force from aneurysm cast, burst pressure, burst location, and pressure under dynamic delivery pressure. The results were compared using ANOVA. Results The average detachment forces for the Echelon 10, 14, and Rebar 14 catheters were 97.6, 76.825, and 62.6 g, respectively (p=0.023). The average burst pressures for the Echelon 10, 14, and Rebar 14 were 1108, 1213, and 1365 psi, respectively (p=0.003). The average burst location was 26.0, 20.0, and 4.5 mm, respectively, from the tip (p=0.035). There was no significant difference regarding burst location (p=0.39). The delivery pressures of the catheters were not significant (p=0.98). Two cases are presented that illustrate the importance of these findings and how they can be incorporated into practice. Conclusion The lower detachment force of the Rebar 14 makes it ideal for liquid embolization, but its stiffness makes it less desirable for accessing smaller aneurysms or navigating tortuous anatomy. The Echelon 10 should be avoided unless it is the only catheter that can access an aneurysm because of small size or tortuous anatomy. In such cases, the higher detachment force suggests a stent should be in place to prevent the cast from being destabilized.

    Title Relative Cost Comparison of Embolic Materials Used for Treatment of Wide-necked Intracranial Aneurysms.
    Date
    Journal Journal of Neurointerventional Surgery
    Excerpt

    Embolization of wide-necked intracranial aneurysms can be associated with excessive expense, especially for large/giant aneurysms. Depending on the material used, endovascular treatment may be cost prohibitive. The goal of this study was to evaluate the relative cost of various embolic agents.

    Similar doctors nearby

    Dr. Arthur Ulm

    Neurological Surgery
    11 years experience
    Nashville, TN

    Dr. Robbi Franklin

    Neurological Surgery
    6 years experience
    Nashville, TN

    Dr. Arthur Ulm

    Neurological Surgery
    11 years experience
    Nashville, TN

    Dr. Harold Smith

    Neurological Surgery
    35 years experience
    Nashville, TN

    Dr. Gregory Lanford

    Neurological Surgery
    26 years experience
    Nashville, TN

    Dr. Douglas Mathews

    Neurological Surgery
    19 years experience
    Nashville, TN
    Search All Similar Doctors