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Featured researches published by Alvin Y. Chan.


Neurosurgical Focus | 2016

Stereotactic robot-assisted MRI-guided laser thermal ablation of radiation necrosis in the posterior cranial fossa: technical note

Alvin Y. Chan; Diem Kieu Tran; Amandip S. Gill; Frank P.K. Hsu; Sumeet Vadera

Laser interstitial thermal therapy (LITT) is a minimally invasive procedure used to treat a variety of intracranial lesions. Utilization of robotic assistance with stereotactic procedures has gained attention due to potential for advantages over conventional techniques. The authors report the first case in which robot-assisted MRI-guided LITT was used to treat radiation necrosis in the posterior fossa, specifically within the cerebellar peduncle. The use of a stereotactic robot allowed the surgeon to perform LITT using a trajectory that would be extremely difficult with conventional arc-based techniques. A 60-year-old man presented with facial weakness and brainstem symptoms consistent with radiation necrosis. He had a history of anaplastic astrocytoma that was treated with CyberKnife radiosurgery 1 year prior to presentation, and he did well for 11 months until his symptoms recurred. The location and form of the lesion precluded excision but made the patient a suitable candidate for LITT. The location and configuration of the lesion required a trajectory for LITT that was too low for arc-based stereotactic navigation, and thus the ROSA robot (Medtech) was used. Using preoperative MRI acquisitions, the lesion in the posterior fossa was targeted. Bone fiducials were used to improve accuracy in registration, and the authors obtained an intraoperative CT image that was then fused with the MR image by the ROSA robot. They placed the laser applicator and then ablated the lesion under real-time MR thermometry. There were no complications, and the patient tolerated the procedure well. Postoperative 2-month MRI showed complete resolution of the lesion, and the patient had some improvement in symptoms.


Journal of Surgical Education | 2015

National Incidence of Medication Error in Surgical Patients Before and After Accreditation Council for Graduate Medical Education Duty-Hour Reform

Sumeet Vadera; Sandra D. Griffith; Benjamin P. Rosenbaum; Alvin Y. Chan; Nicolas R. Thompson; Varun R. Kshettry; Michael Kelly; Robert J. Weil; William Bingaman; Lara Jehi

OBJECTIVE The Accreditation Council for Graduate Medical Education (ACGME) established duty-hour regulations for accredited residency programs on July 1, 2003. It is unclear what changes occurred in the national incidence of medication errors in surgical patients before and after ACGME regulations. DESIGN Patient and hospital characteristics for pre- and post-duty-hour reform were evaluated, comparing teaching and nonteaching hospitals. A difference-in-differences study design was used to assess the association between duty-hour reform and medication errors in teaching hospitals. SETTING We used the Nationwide Inpatient Sample database, which consists of approximately annual 20% stratified sample of all the United States nonfederal hospital inpatient admissions. PARTICIPANTS A query of the database, including 4 years before (2000-2003) and 8 years after (2003-2011) the ACGME duty-hour reform of July 2003, was performed to extract surgical inpatient hospitalizations (N = 13,933,326). The years 2003 and 2004 were discarded in the analysis to allow for a wash-out period during duty-hour reform (though we still provide medication error rates). RESULTS The Nationwide Inpatient Sample estimated the total national surgical inpatients (N = 135,092,013) in nonfederal hospitals during these time periods with 68,736,863 patients in teaching hospitals and 66,355,150 in nonteaching hospitals. Shortly after duty-hour reform (2004 and 2006), teaching hospitals had a statistically significant increase in rate of medication error (p = 0.019 and 0.006, respectively) when compared with nonteaching hospitals even after accounting for trends across all hospitals during this period. After 2007, no further statistically significant difference was noted. CONCLUSIONS After ACGME duty-hour reform, medication error rates increased in teaching hospitals, which diminished over time. This decrease in errors may be related to changes in training program structure to accommodate duty-hour reform.


Epilepsia | 2017

Rates and predictors of success and failure in repeat epilepsy surgery: A meta‐analysis and systematic review

Max O. Krucoff; Alvin Y. Chan; Stephen C. Harward; Shervin Rahimpour; John D. Rolston; Carrie R. Muh; Dario J. Englot

Medically refractory epilepsy is a debilitating disorder that is particularly challenging to treat in patients who have already failed a surgical resection. Evidence regarding outcomes of further epilepsy surgery is limited to small case series and reviews. Therefore, our group performed the first quantitative meta‐analysis of the literature from the past 30 years to assess for rates and predictors of successful reoperations.


Clinical Neurophysiology Practice | 2018

Seizure localization by chronic ambulatory electrocorticography

Alvin Y. Chan; Robert C. Knowlton; Edward F. Chang; Vikram Rao

Highlights • Two epilepsy patients did not have seizures during three weeks of intracranial EEG.• They were implanted with a device that enables chronic electrocorticography.• Seizures were localized by ictal recordings at long intervals after implantation.


Operative Neurosurgery | 2018

Accuracy and Efficacy for Robotic Assistance in Implanting Responsive Neurostimulation Device Electrodes in Bilateral Mesial Temporal Lobe Epilepsy

Alvin Y. Chan; Lilit Mnatsakanyan; Mona Sazgar; Indranil Sen-Gupta; Jack J. Lin; Frank P.K. Hsu; Sumeet Vadera

BACKGROUND Responsive neurostimulation (RNS) is a relatively new treatment option that has been shown to be effective for patients with medically refractory focal epilepsy when resection is not possible, especially in bilateral mesial temporal onset. Robotic devices are becoming increasingly popular for use in stereotactic procedures such as stereoelectroencephalography, but have yet to be used when implanting RNS devices. OBJECTIVE To show that these 2 forms of advanced technology were compatible and could be used effectively in patient care. METHODS We implanted RNS devices in 3 patients with bilateral mesial temporal lobe epilepsy. Each patient was placed in the prone position, and electrode trajectories were planned via the robotic navigation system via a transoccipital approach. One lead was placed along each amygdalohippocampal complex. A small craniectomy was then created in the parietal region for RNS generator implantation. Actual and expected target locations and distance were calculated for each depth. There were no complications in this group. RESULTS RNS devices with bilateral leads were successfully implanted in all 3 patients, with bilateral mesial temporal lobe onset. Follow-up ranged from 3 to 6 mo, and there were no complications in this group. The median distance between the estimate and actual targets was 2.18 (range = 1.11-3.27) mm. CONCLUSION We show that implanting RNS devices with robotic assistance is feasible with excellent precision and accuracy. The advantages of using robotic assistance include higher flexibility, accuracy, precision, and consistency.


Neurosurgical Focus | 2018

Strategic hospital partnerships: improved access to care and increased epilepsy surgical volume

Sumeet Vadera; Alvin Y. Chan; Lilit Mnatsankanyan; Mona Sazgar; Indranil Sen-Gupta; Jack J. Lin; Frank P.K. Hsu

OBJECTIVE Surgical treatment of patients with medically refractory focal epilepsy is underutilized. Patients may lack access to surgically proficient centers. The University of California, Irvine (UCI) entered strategic partnerships with 2 epilepsy centers with limited surgical capabilities. A formal memorandum of understanding (MOU) was created to provide epilepsy surgery to patients from these centers. METHODS The authors analyzed UCI surgical and financial data associated with patients undergoing epilepsy surgery between September 2012 and June 2016, before and after institution of the MOU. Variables collected included the length of stay, patient age, seizure semiology, use of invasive monitoring, and site of surgery as well as the monthly number of single-surgery cases, complex cases (i.e., staged surgeries), and overall number of surgery cases. RESULTS Over the 46 months of the study, a total of 104 patients underwent a total of 200 operations; 71 operations were performed in 39 patients during the pre-MOU period (28 months) and 129 operations were performed in 200 patients during the post-MOU period (18 months). There was a significant difference in the use of invasive monitoring, the site of surgery, the final therapy, and the type of insurance. The number of single-surgery cases, complex-surgery cases, and the overall number of cases increased significantly. CONCLUSIONS Partnerships with outside epilepsy centers are a means to increase access to surgical care. These partnerships are likely reproducible, can be mutually beneficial to all centers involved, and ultimately improve patient access to care.


Journal of Neurosurgery | 2018

Rates and predictors of seizure outcome after corpus callosotomy for drug-resistant epilepsy: a meta-analysis

Alvin Y. Chan; John D. Rolston; Brian Lee; Sumeet Vadera; Dario J. Englot

OBJECTIVECorpus callosotomy is a palliative surgery for drug-resistant epilepsy that reduces the severity and frequency of generalized seizures by disconnecting the two cerebral hemispheres. Unlike with resection, seizure outcomes remain poorly understood. The authors systematically reviewed the literature and performed a meta-analysis to investigate rates and predictors of complete seizure freedom and freedom from drop attacks after corpus callosotomy.METHODSPubMed, Web of Science, and Scopus were queried for primary studies examining seizure outcomes after corpus callosotomy published over 30 years. Rates of complete seizure freedom or drop attack freedom were recorded. Variables showing a potential relationship to seizure outcome on preliminary analysis were subjected to formal meta-analysis.RESULTSThe authors identified 1742 eligible patients from 58 included studies. Overall, the rates of complete seizure freedom and drop attack freedom after corpus callosotomy were 18.8% and 55.3%, respectively. Complete seizure freedom was significantly predicted by the presence of infantile spasms (OR 3.86, 95% CI 1.13-13.23), normal MRI findings (OR 4.63, 95% CI 1.75-12.25), and shorter epilepsy duration (OR 2.57, 95% CI 1.23-5.38). Freedom from drop attacks was predicted by complete over partial callosotomy (OR 2.90, 95% CI 1.07-7.83) and idiopathic over known epilepsy etiology (OR 2.84, 95% CI 1.35-5.99).CONCLUSIONSThe authors report the first systematic review and meta-analysis of seizure outcomes in both adults and children after corpus callosotomy for epilepsy. Approximately one-half of patients become free from drop attacks, and one-fifth achieve complete seizure freedom after surgery. Some predictors of favorable outcome differ from those in resective epilepsy surgery.


Epilepsia Open | 2018

Effect of neurostimulation on cognition and mood in refractory epilepsy

Alvin Y. Chan; John D. Rolston; Vikram Rao; Edward F. Chang

Epilepsy is a common, debilitating neurological disorder characterized by recurrent seizures. Mood disorders and cognitive deficits are common comorbidities in epilepsy that, like seizures, profoundly influence quality of life and can be difficult to treat. For patients with refractory epilepsy who are not candidates for resection, neurostimulation, the electrical modulation of epileptogenic brain tissue, is an emerging treatment alternative. Several forms of neurostimulation are currently available, and therapy selection hinges on relative efficacy for seizure control and amelioration of neuropsychiatric comorbidities. Here, we review the current evidence for how invasive and noninvasive neurostimulation therapies affect mood and cognition in persons with epilepsy. Invasive therapies include vagus nerve stimulation (VNS), deep brain stimulation (DBS), and responsive neurostimulation (RNS). Noninvasive therapies include trigeminal nerve stimulation (TNS), repetitive transcranial magnetic stimulation (rTMS), and transcranial direct current stimulation (tDCS). Overall, current evidence supports stable cognition and mood with all neurostimulation therapies, although there is some evidence that cognition and mood may improve with invasive forms of neurostimulation. More research is required to optimize the effects of neurostimulation for improvements in cognition and mood.


Cureus | 2018

Integrative Medicine as a Vital Component of Patient Care

Richard Gannotta; Shaista Malik; Alvin Y. Chan; Kamran Urgun; Frank P. K. Hsu; Sumeet Vadera

The landscape of medicine in the United States has been slowly progressing toward a more holistic and individualized approach to healing. Part of this progress has been the integration between western and alternative forms of medicine, a concept that has been described as “integrative medicine.” This approach to healthcare incorporates a patient’s mind, spirituality, and sense of community into the healing process. Integrative medicine has been typically well received and the demand has been steadily increasing in primary US hospitals. Here we cover a number of topics that include the definition of integrative medicine, its potential benefits, current examples of successful implementations, and potential barriers to its expansion. The aim was to give a primary on integrative medicine and its current state for healthcare providers.


Pediatric Neurology | 2017

False Localization With Subdural Electroencephalography due to Gyrus Overlap

Alvin Y. Chan; Paul E. Youssef; Sean M. Lew

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Sumeet Vadera

University of California

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Frank P.K. Hsu

University of California

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Jack J. Lin

University of California

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Mona Sazgar

University of California

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Dario J. Englot

Vanderbilt University Medical Center

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