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Dive into the research topics where Michael C. Dewan is active.

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Featured researches published by Michael C. Dewan.


Journal of NeuroInterventional Surgery | 2014

ADAPT FAST study: a direct aspiration first pass technique for acute stroke thrombectomy.

Aquilla S Turk; Don Frei; David Fiorella; J Mocco; Blaise W. Baxter; Adnan H. Siddiqui; A Spiotta; Maxim Mokin; Michael C. Dewan; Steve Quarfordt; Holly Battenhouse; Raymond D Turner; Imran Chaudry

Background The development of new revascularization devices has improved recanalization rates and time, but not clinical outcomes. We report a prospectively collected clinical experience with a new technique utilizing a direct aspiration first pass technique with large bore aspiration catheter as the primary method for vessel recanalization. Methods 98 prospectively identified acute ischemic stroke patients with 100 occluded large cerebral vessels at six institutions were included in the study. The ADAPT technique was utilized in all patients. Procedural and clinical data were captured for analysis. Results The aspiration component of the ADAPT technique alone was successful in achieving Thrombolysis in Cerebral Infarction (TICI) 2b or 3 revascularization in 78% of cases. The additional use of stent retrievers improved the TICI 2b/3 revascularization rate to 95%. The average time from groin puncture to at least TICI 2b recanalization was 37 min. A 5MAX demonstrated similar success to a 5MAX ACE in achieving TICI 2b/3 revascularization alone (75% vs 82%, p=0.43). Patients presented with an admitting median National Institutes of Health Stroke Scale (NIHSS) score of 17.0 (12.0–21.0) and improved to a median NIHSS score at discharge of 7.3 (1.0–11.0). Ninety day functional outcomes were 40% (modified Rankin Scale (mRS) 0–2) and 20% (mRS 6). There were two procedural complications and no symptomatic intracerebral hemorrhages. Discussion The ADAPT technique is a fast, safe, simple, and effective method that has facilitated our approach to acute ischemic stroke thrombectomy by utilizing the latest generation of large bore aspiration catheters to achieve previously unparalleled angiographic outcomes.


Journal of NeuroInterventional Surgery | 2013

Initial clinical experience with the ADAPT technique: A direct aspiration first pass technique for stroke thrombectomy

Aquilla S Turk; A Spiotta; Don Frei; J Mocco; Blaise W. Baxter; David Fiorella; Adnan H. Siddiqui; Maxim Mokin; Michael C. Dewan; Henry H. Woo; Raymond D Turner; Harris Hawk; Amrendra Miranpuri; Imran Chaudry

Background The development of new revascularization devices has improved recanalization rates and time but not clinical outcomes. We report our initial results with a new technique utilizing a direct aspiration first pass technique with a large bore aspiration catheter as the primary method for vessel recanalization. Methods A retrospective evaluation of a prospectively captured database of 37 patients at six institutions was performed on patients where the ADAPT technique was utilized. The data represent the initial experience with this technique. Results The ADAPT technique alone was successful in 28 of 37 (75%) cases although six cases had large downstream emboli that required additional aspiration. Nine cases required the additional use of a stent retriever and one case required the addition of a Penumbra aspiration separator to achieve recanalization. The average time from groin puncture to at least Thrombolysis in Cerebral Ischemia (TICI) 2b recanalization was 28.1 min, and all cases were successfully revascularized. TICI 3 recanalization was achieved 65% of the time. On average, patients presented with an admitting National Institutes of Health Stroke Scale (NIHSS) score of 16.3 and improved to an NIHSS score of 4.2 by the time of hospital discharge. There was one procedural complication. Discussion This initial experience highlights the fact that the importance of the technique with which new stroke thrombectomy devices are used may be as crucial as the device itself. The ADAPT technique is a simple and effective approach to acute ischemic stroke thrombectomy. Utilizing the latest generation of large bore aspiration catheters in this fashion has allowed us to achieve excellent clinical and angiographic outcomes.


Neurosurgery | 2013

A Multicenter Study of Stent-Assisted Coiling of Cerebral Aneurysms With a Y Configuration

Kyle M. Fargen; J Mocco; Dan Neal; Michael C. Dewan; John F. Reavey-Cantwell; Henry H. Woo; David Fiorella; Maxim Mokin; Adnan H. Siddiqui; Aquilla S Turk; Raymond D Turner; Imran Chaudry; Kalani My; Felipe C. Albuquerque; Brian L. Hoh

BACKGROUND Stent-assisted coiling with 2 stents in a Y configuration is a technique for coiling complex wide-neck bifurcation aneurysms. OBJECTIVE We sought to provide long-term clinical and angiographic outcomes with Y-stent coiling, which are not currently established. METHODS Seven centers provided deidentified, retrospective data on all consecutive patients who underwent stent-assisted coiling for an intracranial aneurysm with a Y-stent configuration. RESULTS Forty-five patients underwent treatment by Y-stent coiling. Their mean age was 57.9 years. Most aneurysms were basilar apex (87%), and 89% of aneurysms were unruptured. Mean size was 9.9 mm. Most aneurysms were treated with 1 open-cell and 1 closed-cell stent (51%), with 29% treated with open-open stents and 16% treated with 2 closed-cell stents. Initial aneurysm occlusion was excellent (84% in Raymond grade I or II). Procedural complications occurred in 11% of patients. Mean clinical follow-up was 7.8 months, and 93% of patients had a modified Rankin Scale score of 0 to 2 at last follow-up. Mean angiographic follow-up was 9.8 months, and 92% of patients had Raymond grade I or II occlusion on follow-up imaging. Of those patients with initial Raymond grade III occlusion and follow-up imaging, all but 1 patient progressed to a better occlusion grade (83%; P < .05). Three aneurysms required retreatment because of recanalization (10%). There was no difference in initial or follow-up angiographic occlusion, clinical outcomes, incidence of aneurysm retreatment, or in-stent stenosis among open-open, open-closed, or closed-closed stent groups. CONCLUSION In a large multicenter series of Y-stent coiling for bifurcation aneurysms, there were low complication rates and excellent clinical and angiographic outcomes.


World Neurosurgery | 2016

Epidemiology of Global Pediatric Traumatic Brain Injury: Qualitative Review

Michael C. Dewan; Nishit Mummareddy; John C. Wellons; Christopher M. Bonfield

BACKGROUND Traumatic brain injury (TBI) is a common condition affecting children all over the world, and it represents a global public health concern. It is unclear how geopolitical, societal, and ethnic differences may influence the nature of TBI among children. METHODS A comprehensive literature search was conducted incorporating studies with hospital-, regional-, or country-specific pediatric TBI epidemiology data published between 1995 and 2015. Incidence, age, severity, mechanism of injury, and other relevant injury characteristics were extracted and compared across diverse geographic regions. RESULTS Thirty articles met inclusion criteria, incorporating TBI data from more than 165,000 children on 5 continents. The worldwide incidence of pediatric TBI ranges broadly and varies greatly by country, with most reporting a range between 47 and 280 per 100,000 children. After the age of 3, male children suffered higher rates of TBI than females. A bimodal age distribution is often described, with very young children (0-2 years) and adolescents (15-18) more commonly injured. Mild TBI (Glasgow Coma Scale ≥13) constitutes more than 80% of injuries, and up to 90% of all injuries are associated with negative imaging. Only a small fraction (<10%) requires surgical intervention. Independent of country or region of origin, the vast majority of children suffering TBI achieve a good clinical outcome. Hospital admission rates vary widely, with U.S. patients more commonly admitted than those from other countries. Falls and motor vehicle collisions (MVCs) represent the majority of injury mechanisms. In Africa and Asia, pedestrians were most commonly injured in MVCs, while vehicle occupants were more likely involved among Australian, European, and U.S. POPULATIONS For children, nonaccidental trauma was prevalent in developing and developed nations alike. CONCLUSIONS TBI is a relatively common entity stretching across traditional geographic and demographic boundaries and affecting pediatric populations worldwide. Continued civil infrastructure development and public health policy reforms may help to reduce the societal burden of pediatric TBI.


Neurosurgical Focus | 2012

Structural brain injury in sports-related concussion

Scott L. Zuckerman; Andrew W. Kuhn; Michael C. Dewan; Peter J. Morone; Jonathan A. Forbes; Gary S. Solomon; Allen K. Sills

OBJECT Sports-related concussions (SRCs) represent a significant and growing public health concern. The vast majority of SRCs produce mild symptoms that resolve within 1-2 weeks and are not associated with imaging-documented changes. On occasion, however, structural brain injury occurs, and neurosurgical management and intervention is appropriate. METHODS A literature review was performed to address the epidemiology of SRC with a targeted focus on structural brain injury in the last half decade. MEDLINE and PubMed databases were searched to identify all studies pertaining to structural head injury in sports-related head injuries. RESULTS The literature review yielded a variety of case reports, several small series, and no prospective cohort studies. CONCLUSIONS The authors conclude that reliable incidence and prevalence data related to structural brain injuries in SRC cannot be offered at present. A prospective registry collecting incidence, management, and follow-up data after structural brain injuries in the setting of SRC would be of great benefit to the neurosurgical community.


Journal of Neurosurgery | 2016

Prophylactic antiepileptic drug administration following brain tumor resection: results of a recent AANS/CNS Section on Tumors survey

Michael C. Dewan; Reid C. Thompson; Steven N. Kalkanis; Fred G. Barker; Constantinos G. Hadjipanayis

OBJECTIVE Antiepileptic drugs (AEDs) are often administered prophylactically following brain tumor resection. With conflicting evidence and unestablished guidelines, however, the nature of this practice among tumor surgeons is unknown. METHODS On November 24, 2015, a REDCap (Research Electronic Database Capture) survey was sent to members of the AANS/CNS Section on Tumors to query practice patterns. RESULTS Responses were received from 144 individuals, including 18.8% of board-certified neurosurgeons surveyed (across 86 institutions, 16 countries, and 5 continents). The majority reported practicing in an academic setting (85%) as a tumor specialist (71%). Sixty-three percent reported always or almost always prescribing AED prophylaxis postoperatively in patients with a supratentorial brain tumor without a prior seizure history. Meanwhile, 9% prescribed occasionally and 28% rarely prescribed AED prophylaxis. The most common agent was levetiracetam (85%). The duration of seizure prophylaxis varied widely: 25% of surgeons administered prophylaxis for 7 days, 16% for 2 weeks, 21% for 2 to 6 weeks, and 13% for longer than 6 weeks. Most surgeons (61%) believed that tumor pathology influences epileptogenicity, with high-grade glioma (39%), low-grade glioma (31%), and metastases (24%) carrying the greatest seizure risk. While the majority used prophylaxis, 62% did not believe or were unsure if prophylactic AEDs reduced seizures postoperatively. The vast majority (82%) stated that a well-designed randomized trial would help guide their future clinical decision making. CONCLUSIONS Wide knowledge and practice gaps exist regarding the frequency, duration, and setting of AED prophylaxis for seizure-naive patients undergoing brain tumor resection. Acceptance of universal practice guidelines on this topic is unlikely until higher-level evidence supporting or refuting the value of modern seizure prophylaxis is demonstrated.


Journal of Neurosurgery | 2015

Evaluating the relationship of the pB–C2 line to clinical outcomes in a 15-year single-center cohort of pediatric Chiari I malformation

Travis R. Ladner; Michael C. Dewan; Matthew Day; Chevis N. Shannon; Luke Tomycz; Noel Tulipan; John C. Wellons

OBJECT The clinical significance of radiological measurements of the craniocervical junction in pediatric Chiari I malformation (CM-I) is yet to be fully established across the field. The authors examined their institutional experience with the pB-C2 line (drawn perpendicular to a line drawn between the basion and the posterior aspect of the C-2 vertebral body, at the most posterior extent of the odontoid process at the dural interface). The pB-C2 line is a measure of ventral canal encroachment, and its relationship with symptomatology and syringomyelia in pediatric CM-I was assessed. METHODS The authors performed a retrospective review of 119 patients at the Monroe Carell Jr. Childrens Hospital at Vanderbilt University who underwent posterior fossa decompression with duraplasty, 78 of whom had imaging for review. A neuroradiologist retrospectively evaluated preoperative and postoperative MRI examinations performed in these 78 patients, measuring the pB-C2 line length and documenting syringomyelia. The pB-C2 line length was divided into Grade 0 (<3 mm) and Grade I (≥3 mm). Statistical analysis was performed using the t-test for continuous variables and Fishers exact test analysis for categorical variables. Multivariate logistic and linear regression analyses were performed to assess the relationship between pB-C2 line grade and clinical variables found significant on univariate analysis, controlling for age and sex. RESULTS The mean patient age was 8.5 years, and the mean follow-up duration was 2.4 years. The mean pB-C2 line length was 3.5 mm (SD 2 mm), ranging from 0 to 10 mm. Overall, 65.4% of patients had a Grade I pB-C2 line. Patients with Grade I pB-C2 lines were 51% more likely to have a syrinx than those with Grade 0 pB-C2 lines (RR 1.513 [95% CI 1.024-2.90], p=0.021) and, when present, had greater syrinx reduction (3.6 mm vs 0.2 mm, p=0.002). Although there was no preoperative difference in headache incidence, postoperatively patients with Grade I pB-C2 lines were 69% more likely to have headache reduction than those with Grade 0 pB-C2 lines (RR 1.686 [95% CI 1.035-2.747], p=0.009). After controlling for age and sex, pB-C2 line grade remained an independent correlate of headache improvement and syrinx reduction. CONCLUSIONS Ventral canal encroachment may explain the symptomatology of select patients with CM-I. The clinical findings presented suggest that patients with Grade I pB-C lines2, with increased ventral canal obstruction, may experience a higher likelihood of syrinx reduction and headache resolution from decompressive surgery with duraplasty than those with Grade 0 pB-C2 lines.


Journal of NeuroInterventional Surgery | 2015

Current practice regarding seizure prophylaxis in aneurysmal subarachnoid hemorrhage across academic centers

Michael C. Dewan; J Mocco

Object The objective of this study was to determine current practices regarding seizure prophylaxis in aneurysmal subarachnoid hemorrhage (aSAH). Methods An eight question survey was sent to 25 US centers with high volume aSAH cases (>100 annually). Respondents were asked about institutional practices regarding use, duration, and type of seizure prophylaxis. Results 13 (52%) respondents endorsed the utility of seizure prophylaxis while 10 (40%) did not, and two (8%) were unsure. Among respondents using prophylaxis, levetiracetam was the firstline medication for the majority (94%) while phenytoin was used as a primary agent at one (4%) center and as a secondary agent at four (16%) centers. Duration of levetiracetam prophylaxis ranged from 1 day to 6 weeks following SAH (mean 13.2; median 11). Only a single center employed EEG routinely in all aSAH patients but most supported EEG use when the neurologic examination was unreliable or inexplicably declining. 24 (96%) respondents agreed that a trial randomizing patients to levetiracetam or no antiseizure medication is warranted at this time, and all 25 (100%) believed that such a trial would be appropriate or ethically sound. Conclusions The routine use of seizure prophylaxis following aSAH is controversial. Among a sampling of 25 major academic centers, most administer prophylaxis, while a significant proportion does not. The majority believes a trial randomizing patients to receive seizure prophylaxis is both timely and ethical.


Neurosurgical Focus | 2012

Neurosurgical checklists: a review

Scott L. Zuckerman; Cain S. Green; Kevin Carr; Michael C. Dewan; Peter J. Morone; J Mocco

Morbidity due to avoidable medical errors is a crippling reality intrinsic to health care. In particular, iatrogenic surgical errors lead to significant morbidity, decreased quality of life, and attendant costs. In recent decades there has been an increased focus on health care quality improvement, with a concomitant focus on mitigating avoidable medical errors. The most notable tool developed to this end is the surgical checklist. Checklists have been implemented in various operating rooms internationally, with overwhelmingly positive results. Comparatively, the field of neurosurgery has only minimally addressed the utility of checklists as a health care improvement measure. Literature on the use of checklists in this field has been sparse. Considering the widespread efficacy of this tool in other fields, the authors seek to raise neurosurgical awareness regarding checklists by reviewing the current literature.


Journal of Neurosurgery | 2016

Perioperative seizure in patients with glioma is associated with longer hospitalization, higher readmission, and decreased overall survival

Michael C. Dewan; Gabrielle A. White-Dzuro; Philip R. Brinson; Reid C. Thompson; Lola B. Chambless

OBJECTIVE Seizures are among the most common perioperative complications in patients undergoing craniotomy for brain tumor resection and have been associated with increased disease progression and decreased survival. Little evidence exists regarding the relationship between postoperative seizures and hospital quality measures, including length of stay (LOS), disposition, and readmission. The authors sought to address these questions by analyzing a glioma population over 15 years. METHODS A retrospective cohort study was used to evaluate the outcomes of patients who experienced a postoperative seizure. Patients with glioma who underwent craniotomy for resection between 1998 and 2013 were enrolled in the institutional tumor registry. Basic data, including demographics and comorbidities, were recorded in addition to hospitalization details and complications. Seizures were diagnosed by clinical examination, observation, and electroencephalography. The Student t-test and chi-square test were used to analyze differences in the means between continuous and categorical variables, respectively. Multivariate logistic and linear regression was used to compare multiple clinical variables against hospital quality metrics and survival figures, respectively. RESULTS In total, 342 patients with glioma underwent craniotomy for first-time resection. The mean age was 51.0 ± 17.3 years, 192 (56.1%) patients were male, and the median survival time for all grades was 15.4 months (range 6.2-24.0 months). High-grade glioma (Grade III or IV) was seen in 71.9% of patients. Perioperative antiepileptic drugs were administered to 88% of patients. Eighteen (5.3%) patients experienced a seizure within 14 days postoperatively, and 9 (50%) of these patients experienced first-time seizures. The mean time to the first postoperative seizure was 4.3 days (range 0-13 days). There was no significant association between tumor grade and the rate of perioperative seizure (Grade I, 0%; II, 7.0%; III, 6.1%; IV, 5.2%; p = 0.665). A single ictal episode occurred in 11 patients, while 3 patients experienced 2 seizures and 4 patients developed 3 or more seizures. Compared with their seizure-free counterparts, patients who experienced a perioperative seizure had an increased average hospital (6.8 vs 3.6 days, p = 0.032) and ICU LOS (5.4 vs 2.3 days; p < 0.041). Seventy-five percent of seizure-free patients were discharged home in comparison with 55.6% of seizure patients (p = 0.068). Patients with a postoperative seizure were significantly more likely to visit the emergency department within 90 days (44.4% vs 19.0%; OR 3.41 [95% CI 1.29-9.02], p = 0.009) and more likely to be readmitted within 90 days (50.0% vs 18.4%; OR 4.45 [95% CI 1.69-11.70], p = 0.001). In addition, seizure-free patients had a longer median overall survival (15.6 months [interquartile range 6.6-24.4 months] vs 3.0 months [interquartile range 1.0-25.0 months]; p = 0.013). CONCLUSIONS Patients with perioperative seizures following glioma resection required longer hospital and ICU LOS, were readmitted at higher rates than seizure-free patients, and experienced shorter overall survival. Biological and clinical factors that predispose to the development of seizures after glioma surgery portend a worse outcome. Efforts to identify these factors and reduce the risk of postoperative seizure should remain a priority among neurosurgical oncologists.

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Peter J. Morone

Vanderbilt University Medical Center

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J Mocco

Vanderbilt University

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Chevis N. Shannon

Vanderbilt University Medical Center

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Reid C. Thompson

Vanderbilt University Medical Center

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J Mocco

Vanderbilt University

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Aquilla S Turk

Medical University of South Carolina

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