- Clinical Neurophysiology
Clinical Associate Professor, Neurology & Neurological Sciences
Associate Vice Chair, Clinical Operations, Stanford Neuroscience Healthcare Center (2021 - Present)
CELT Co-Executive Director, Stanfordi Healthcare (2021 - Present)
Assistant Clinic Chief, Department of Neurology, Stanford Neuroscience Healthcare Center (2019 - Present)
Physician Director, RITE program, Stanford Healthcare (2019 - 2021)
Co-Director, Advanced Clinical Skills, Stanford School of Medicine (2018 - Present)
Director, Movement Disorder Fellowship, Stanford University (2018 - 2021)
Associate Physician Improvement Leader for Department of Neurology, Stanford University (2017 - Present)
Fellowship: UCLA Dept of Neurology (2015) CA
Residency: University of Southern California Keck School of Medicine (2013) CA
Internship: Loma Linda University Internal Medicine Residency (2010) CA
Board Certification: American Board of Psychiatry and Neurology, Neurology (2013)
Medical Education: University of Vermont College of Medicine (2009) VT
Additional Clinical Info
A Study of LY3154207 in Participants With Dementia Due to Lewy Body Dementia (LBD) Associated With Idiopathic Parkinson's Disease (PD) or Dementia With Lewy Bodies (DLB)
A randomized placebo-controlled trial to evaluate the safety and efficacy of three doses of study drug LY3154207 treated for 12 weeks in participants with mild-to-moderate dementia associated with LBD (PDD or DLB).
Stanford is currently not accepting patients for this trial. For more information, please contact Stephanie Tran, 650-723-6469.
Evaluating the Efficacy, Safety, Pharmacokinetics, and Pharmacodynamics of BIIB054 in Participants With Parkinson's Disease
The primary objective of the study is to evaluate the clinical efficacy of BIIB054 via dose response using the change from baseline in Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Total Score. The secondary objectives of the study are to evaluate the dose-related safety of BIIB054, to evaluate the clinical efficacy of BIIB054 via MDS-UPDRS total score, to assess the pharmacokinetic (PK) profile of BIIB054, to evaluate the clinical efficacy of BIIB054 based on MDS-UPDRS subparts, to evaluate the pharmacodynamic effects of BIIB054 on the integrity of nigrostriatal dopaminergic nerve terminals and to evaluate the immunogenicity of BIIB054.
Stanford is currently not accepting patients for this trial.
- Illusory Responses across the Lewy Body Disease Spectrum ANNALS OF NEUROLOGY 2023
Illusory responses across the Lewy body disease spectrum
WILEY. 2022: S364-S365
To study pareidolias, or perceived meaningful objects in a meaningless stimulus, in patients across the Lewy body (LB) disease spectrum, where most do not report hallucinations or delusions.We studied illusory responses on the Noise Pareidolia Task in 300 participants [38 cognitively-impaired LB, 65 cognitively-unimpaired LB, 51 Alzheimer's disease-spectrum (AD-s), 146 Controls]. Pairwise between-group comparisons examined how diagnosis impacts the number of illusory responses. Ordinal regression analysis compared the number of illusory responses across diagnosis groups, adjusting for age, sex, and education. Analyses were repeated after removing participants with reported hallucinations or delusions.Cognitively-impaired LB participants were 12.3, 4.9, and 4.6 times more likely than Control, cognitively-unimpaired LB, and AD-s participants, respectively, to endorse illusory responses. After adjusting for age, sex and education, the probability of endorsing one or more illusory response was 61% in the cognitively-impaired LB group, compared to 26% in AD-s, 25% in cognitively-unimpaired LB, and 12% in Control participants. All results were similar after repeated analysis only in participants without hallucinations or delusions. In LB without hallucinations or delusions, 52% with mild cognitive impairment and 66.7% with dementia endorsed at least one illusory response.We found illusory responses are common in cognitively impaired LB patients, including those without any reported psychosis. Our data suggest that, prior to the onset of hallucinations and delusions, the Noise Pareidolia Task can easily be used to screen for unobtrusive pareidolias in all LB patients. This article is protected by copyright. All rights reserved.
View details for Web of Science ID 000859942301355
View details for PubMedID 36511519
- Viewpoint on Milestones for Fellowship Training in Movement Disorders. Movement disorders : official journal of the Movement Disorder Society 2022
Dopaminergic medication normalizes aberrant cognitive control circuit signalling in Parkinson's disease.
Brain : a journal of neurology
Dopaminergic medication is widely used to alleviate motor symptoms of Parkinson's disease (PD), but these medications also impact cognition with significant variability across patients. It is hypothesized that dopaminergic medication impacts cognition and working memory in PD by modulating frontoparietal-basal ganglia cognitive control circuits, but little is known about the underlying causal signalling mechanisms and their relation to individual differences in response to dopaminergic medication. Here we use a novel state-space computational model with ultra-fast (490 msec resolution) fMRI to investigate dynamic causal signalling in frontoparietal-basal ganglia circuits associated with working memory in 44 PD patients ON and OFF dopaminergic medication, as well as matched 36 healthy controls. Our analysis revealed aberrant causal signaling in frontoparietal-basal ganglia circuits in PD patients OFF medication. Importantly, aberrant signaling was normalized by dopaminergic medication and a novel quantitative distance measure predicted individual differences in cognitive change associated with medication in PD patients. These findings were specific to causal signaling measures, as no such effects were detected with conventional non-causal connectivity measures. Our analysis also identified a specific frontoparietal causal signaling pathway from right middle frontal gyrus to right posterior parietal cortex that is impaired in PD. Unlike in healthy controls, the strength of causal interactions in this pathway did not increase with working memory load and the strength of load-dependent causal weights was not related to individual differences in working memory task performance in PD patients OFF medication. However, dopaminergic medication in PD patients reinstated the relation with working memory performance. Our findings provide new insights into aberrant causal brain circuit dynamics during working memory and identify mechanisms by which dopaminergic medication normalizes cognitive control circuits.
View details for DOI 10.1093/brain/awac007
View details for PubMedID 35357463
Patient and Clinician Perspectives of New and Return Ambulatory Teleneurology Visits.
Neurology. Clinical practice
1800; 11 (6): 472-483
Background and Objectives: To evaluate the adoption and perceived utility of video visits for new and return patient encounters in ambulatory neurology subspecialties.Methods: Video visits were launched in an academic, multi-subspecialty, ambulatory neurology clinic in March 2020. Adoption of video visits for new and return patient visits was assessed using clinician-level scheduling data from March 22 to May 16, 2020. Perceived utility of video visits was explored via a clinician survey and semistructured interviews with clinicians and patients/caregivers. Findings were compared across 5 subspecialties and 2 visit types (new vs return).Results: Video visits were adopted rapidly; all clinicians (n = 65) integrated video visits into their workflow within the first 6 weeks, and 92% of visits were conducted via video, although this varied by subspecialty. Utility of video visits was higher for return than new patient visits, as indicated by surveyed (n = 48) and interviewed clinicians (n = 30), aligning with adoption patterns. Compared with in-person visits, clinicians believed that it was easier to achieve a similar physical examination, patient-clinician rapport, and perceived quality of care over video for return rather than new patient visits. Of the 25 patients/caregivers interviewed, most were satisfied with the care provided via video, regardless of visit type, with the main limitation being the physical examination.Discussion: Teleneurology was robustly adopted for both new and return ambulatory neurology patients during the COVID-19 pandemic. Return patient visits were preferred over new patient visits, but both were feasible. These results provide a foundation for developing targeted guidelines for sustaining teleneurology in ambulatory care.
View details for DOI 10.1212/CPJ.0000000000001065
View details for PubMedID 34992955
Semantic fluency and processing speed are reduced in non-cognitively impaired participants with Parkinson's disease.
Journal of clinical and experimental neuropsychology
Introduction: Parkinson's disease (PD) is associated with a range of cognitive deficits. Few studies have carefully examined the subtle impacts of PD on cognition among patients who do not meet formal criteria for MCI or dementia. The aim of the current study was thus to describe the impact of PD on cognition in those without cognitive impairment in a well-characterized cohort.Methods: Non-cognitively impaired participants (122 with PD, 122 age- and sex-matched healthy volunteers) underwent extensive cognitive testing. Linear regression analyses compared diagnostic group performance across cognitive measures. For cognitive tasks that were significantly different between groups, additional analyses examined group differences restricting the group inclusion to PD participants with mild motor symptoms or disease duration less than 10years.Results: Processing speed and semantic verbal fluency were significantly lower in the PD group (B =-3.77, 95% CIs [-5.76 to -1.77], p <.001, and B =-2.02, 95% CIs [-3.12, -0.92], p <.001, respectively), even after excluding those with moderate to severe motor symptoms (B =-2.73, 95% CIs [-4.94 to -0.53], p =.015 and B =-2.11, 95% CIs [-3.32 to -0.91], p <.001, respectively) or longer disease duration (B =-3.89, 95% CIs [-6.14 to -1.63], p <.001 and B =-1.58, 95% CIs [-2.78 to -0.37], p =.010, respectively). Semantic verbal fluency remained significantly negatively associated with PD diagnosis after controlling for processing speed (B =-1.66, 95% CIs [-2.79 to -0.53], p =.004).Conclusions: Subtle decline in specific cognitive domains may be present among people diagnosed with PD but without evidence to support a formal cognitive diagnosis. These results suggest the importance of early awareness of the potential for diminishing aspects of cognition in PD even among those without mild cognitive impairment or dementia.
View details for DOI 10.1080/13803395.2021.1927995
View details for PubMedID 34355669
- Quality Improvement in Neurology: 2020 Parkinson Disease Quality Measurement Set Update. Neurology 2021; 97 (5): 239-245
Evaluation of Patient and Clinician Perspectives for New and Return Ambulatory Teleneurology Visits, with special attention to subspecialty differences
LIPPINCOTT WILLIAMS & WILKINS. 2021
View details for Web of Science ID 000729283600146
Resident-driven strategies to improve the educational experience of teleneurology
LIPPINCOTT WILLIAMS & WILKINS. 2021
View details for Web of Science ID 000729283605320
Hallucinations and Development of Dementia in Parkinson's Disease.
Journal of Parkinson's disease
Neuropsychiatric symptoms are common in Parkinson's disease (PD). We investigated the relationship between neuropsychiatric symptoms and current and future diagnosis of PD dementia (PDD). Individuals with PD who had a study partner were enrolled (n = 696). Study partners were administered the Neuropsychiatric Inventory or Neuropsychiatric Inventory Questionnaire at baseline. Participants were assigned a cognitive diagnosis at baseline and follow up visits. Hallucinations were significantly associated with a diagnosis of PDD cross-sectionally (p < 0.001) and with shortened time to dementia longitudinally among initially nondemented participants (n = 444; p = 0.005). Screening for hallucinations may be useful for assessing risk of dementia in participants with PD.
View details for DOI 10.3233/JPD-202116
View details for PubMedID 32741842
Accelerated launch of video visits in ambulatory neurology during COVID-19: Key lessons from the Stanford experience.
The COVID-19 pandemic has rapidly moved telemedicine from discretionary to necessary. Here we describe how the Stanford Neurology Department: 1) rapidly adapted to the COVID-19 pandemic, resulting in over 1000 video visits within four weeks and 2) accelerated an existing quality improvement plan of a tiered roll out of video visits for ambulatory neurology to a full-scale roll out. Key issues we encountered and addressed were related to: equipment/software, provider engagement, workflow/triage, and training. Upon reflection, the key drivers of our success were provider engagement and a supportive physician champion. The physician champion played a critical role understanding stakeholder needs, including staff and physicians' needs, and creating workflows to coordinate both stakeholder groups. Prior to COVID-19, physician interest in telemedicine was mixed. However, in response to county and state stay-at-home orders related to COVID-19, physician engagement changed completely; all providers wanted to convert a majority of visits to video visits as quickly as possible. Rapid deployment of neurology video visits across all its subspecialties is feasible. Our experience and lessons learned can facilitate broader utilization, acceptance, and normalization of video visits for neurology patients in the present as well as the much anticipated post-pandemic era.
View details for DOI 10.1212/WNL.0000000000010015
View details for PubMedID 32611634
APOE epsilon 4-related differences in visuospatial impairment in female Parkinson's Disease patients
LIPPINCOTT WILLIAMS & WILKINS. 2020
View details for Web of Science ID 000536058001085
Rapid implementation of video visits in neurology during COVID-19: a mixed methods evaluation.
Journal of medical Internet research
Telemedicine has been used for decades; yet, despite its many advantages, its uptake and rigorous evaluation of feasibility across neurology's ambulatory subspecialties has been sparse. The SARS-CoV-2 (COVID-19) pandemic however, prompted healthcare systems worldwide to reconsider traditional healthcare delivery. To safeguard healthcare workers and patients many healthcare systems quickly transitioned to telemedicine, including across neurology subspecialties, providing a new opportunity to evaluate this modality of care.To evaluate the accelerated implementation of video visits in ambulatory neurology during the COVID-19 pandemic, we used mixed methods to assess the adoption, acceptability, appropriateness, and perceptions of potential sustainability.Video visits were launched rapidly in ambulatory neurology clinics of a large academic medical center. To assess adoption, we analyzed clinician-level scheduling data collected between March 22 and May 16, 2020. We assessed acceptability, appropriateness, and sustainability via a clinician survey (n=48) and semi-structured interviews with providers (n=30) completed between March and May 2020.Video visits were adopted rapidly; 65 (98%) clinicians integrated video visits into their workflow within the first 6 implementation weeks and 92% of all visits were conducted via video. Video visits were largely considered acceptable by clinicians, although various technological issues impacted satisfaction. Video visits were reported to be more convenient for patients, families, and/or caregivers than in-person visits; however, access to technology, the patient's technological capacity, and language difficulties were considered barriers. Many clinicians expressed optimism about future utilization of video visits in neurology. They believed that video visits promote continuity of care and can be incorporated into their practice long-term, although several insisted that they can never replace the in-person examination.Video visits are an important addition to clinical care in ambulatory neurology and are anticipated to remain a permanent supplement to in-person visits, promoting patient care continuity, and flexibility for patients and clinicians alike.
View details for DOI 10.2196/24328
View details for PubMedID 33245699
A Medical Legal Curriculum for Residents to Increase Physician Comfort in Patient Interactions
LIPPINCOTT WILLIAMS & WILKINS. 2019
View details for Web of Science ID 000475965902090
Quantifying the burden of unfilled clinic appointment slots created by late-notice cancellations
LIPPINCOTT WILLIAMS & WILKINS. 2019
View details for Web of Science ID 000475965903284
Cognitive associations with comprehensive gait and static balance measures in Parkinson's disease.
Parkinsonism & related disorders
2019; 69: 104–10
Gait and balance impairments are cardinal features of Parkinson's disease (PD) that require cognitive input. However, the extent to which specific gait and balance characteristics relate to cognition in PD is unclear. In addition, independent models of gait and balance have not been developed from the same cohort. We aimed to i) develop models of gait and balance in a large PD cohort and ii) determine which gait and balance characteristics best related to cognition.One hundred and ninety-eight people with PD were recruited to the Pacific Udall Center. Using six inertial sensors (APDM, Inc.), comprehensive gait measurements were collected over a 2-min continuous walk and comprehensive static balance measures were collected during a 60-second standing task. Six domains of cognition were assessed: global cognition, attention, executive function, language, memory, and visuospatial function. Correlations and hierarchical linear regression determined independent associations.Principal components analysis identified a gait model containing four domains accounting for 80.1% of total variance: pace/turning, rhythm, variability, and trunk. The balance model contained four independent domains accounting for 84.5% of total variance: sway area/jerkiness, sway velocity, sway frequency anteroposterior, and sway frequency mediolateral. Gait domains of pace/turning and variability were strongly associated with attention and executive function. Sway area and jerkiness of balance associated with attention and visuospatial function.Gait and balance characteristics were associated with specific types of cognition. The specific relationships between gait or balance with cognitive functions suggests shared cerebral cortical circuitry for mobility and cognitive functions.
View details for DOI 10.1016/j.parkreldis.2019.06.014
View details for PubMedID 31731260
Expert Patient Tutors: The Eradication of Neurophobia
LIPPINCOTT WILLIAMS & WILKINS. 2018
View details for Web of Science ID 000453090801010
Feature visualization and classification for the discrimination between individuals with Parkinson's disease under levodopa and DBS treatments
BIOMEDICAL ENGINEERING ONLINE
Over the years, a number of distinct treatments have been adopted for the management of the motor symptoms of Parkinson's disease (PD), including pharmacologic therapies and deep brain stimulation (DBS). Efficacy is most often evaluated by subjective assessments, which are prone to error and dependent on the experience of the examiner. Our goal was to identify an objective means of assessing response to therapy.In this study, we employed objective analyses in order to visualize and identify differences between three groups: healthy control (N = 10), subjects with PD treated with DBS (N = 12), and subjects with PD treated with levodopa (N = 16). Subjects were assessed during execution of three dynamic tasks (finger taps, finger to nose, supination and pronation) and a static task (extended arm with no active movement). Measurements were acquired with two pairs of inertial and electromyographic sensors. Feature extraction was applied to estimate the relevant information from the data after which the high-dimensional feature space was reduced to a two-dimensional space using the nonlinear Sammon's map. Non-parametric analysis of variance was employed for the verification of relevant statistical differences among the groups (p < 0.05). In addition, K-fold cross-validation for discriminant analysis based on Gaussian Finite Mixture Modeling was employed for data classification.The results showed visual and statistical differences for all groups and conditions (i.e., static and dynamic tasks). The employed methods were successful for the discrimination of the groups. Classification accuracy was 81 ± 6% (mean ± standard deviation) and 71 ± 8%, for training and test groups respectively.This research showed the discrimination between healthy and diseased groups conditions. The methods were also able to discriminate individuals with PD treated with DBS and levodopa. These methods enable objective characterization and visualization of features extracted from inertial and electromyographic sensors for different groups.
View details for DOI 10.1186/s12938-016-0290-y
View details for Web of Science ID 000391062100001
View details for PubMedID 28038673
View details for PubMedCentralID PMC5203727
Platelet mitochondrial activity and pesticide exposure in early Parkinson's disease
2015; 30 (6): 862-866
Mitochondrial dysfunction has been implicated in the pathogenesis of Parkinson's disease (PD), but the cause of this dysfunction is unclear.Platelet mitochondrial complex I and I/III (nicotinamide adenine dinucleotide cytochrome c reductase, NCCR) activities were measured in early PD patients and matched controls enrolled in a population-based case-control study. Ambient agricultural pesticide exposures were assessed with a geographic information system and California Pesticide Use Registry.In contrast to some previous reports, we found no differences in complex I and I/III activities in subjects with PD and controls. We did find that NCCR activity correlated with subjects' exposure to pesticides known to inhibit mitochondrial activity regardless of their diagnosis.Electron transport chain (ETC) activity is not altered in PD in this well-characterized cohort when compared with community-matched controls but appears to be affected by environmental toxins, such as mitochondria-inhibiting pesticides.
View details for DOI 10.1002/mds.26164
View details for Web of Science ID 000354731500021
View details for PubMedID 25757798
View details for PubMedCentralID PMC4439327