Faculty Bibliography

Myelin is a modified cell membrane that forms a multilayer sheath around the axon. It retains the main characteristics of biological membranes, such as lipid bilayer, but differs from them in several important respects. In this review, we focus on aspects of myelin composition that are peculiar to this structure and differentiate it from the more conventional cell membranes, with special attention to its constituent lipid components and several of the most common and important myelin proteins: myelin basic protein, proteolipid protein, and myelin protein zero. We also discuss the many-fold functions of myelin, which include reliable electrical insulation of axons to ensure rapid propagation of nerve impulses, provision of trophic support along the axon and organization of the unmyelinated nodes of Ranvier, as well as the relationship between myelin biology and neurologic disease such as multiple sclerosis. We conclude with a brief history of discovery in the field and outline questions for future research.

Background: Remotely-supervised transcranial direct current stimulation (RS-tDCS) is a telerehabilitation protocol that provides access to tDCS treatment to participants with aphasia in their homes using real-time monitoring via videoconference and overcomes barriers associated with in-person tDCS treatment of neurological disease. Aims: Two feasibility studies for participants with aphasia are presented herein that investigate (1) RS-tDCS procedural implementation, acceptability, and demand, and (2) acceptability of ten repeated consecutive RS-tDCS sessions. Methods & Procedures: Thirteen participants with aphasia were enrolled in Study 1: (1) seven participants with stroke-induced latent aphasia, (2) four participants with stroke-induced clinically diagnosed aphasia, and (3) two participants with logopenic variant primary progressive aphasia (lvPPA). Four supervisors (1 certified speech-language pathologist [SLP], 3 graduate SLPs-in-training) were trained to supervise RS-tDCS and also provided survey responses. All participants participated in RS-tDCS training and a virtual simulation of home delivery. Two participants with stroke-induced aphasia (1 latent aphasia, 1 clinically diagnosed aphasia) were enrolled in 10 consecutive sessions of RS-tDCS alongside computerized treatment in their home for Study 2. Outcomes & Results: This work provides preliminary evidence for the feasibility of RS-tDCS for people with stable and progressive aphasia of varying severity and typology and includes both participant and clinician perspectives. Importantly, no major barriers to use of RS-tDCS were revealed for people with aphasia, though eHelpers were required for two participants. Conclusions: This work confirms that remotely supervised at-home tDCS studies can be used to enable much-needed efficacy trials, with sufficient sample size, power, and dosing considerations, that will determine the clinical efficacy of tDCS as a treatment adjuvant to aphasia treatment.

Advanced wearable devices are increasingly incorporating high-resolution multi-camera systems. As state-of-the-art neural networks for processing the resulting image data are computationally demanding, there has been a growing interest in leveraging fifth generation (5G) wireless connectivity and mobile edge computing for offloading this processing closer to end-users. To assess this possibility, this paper presents a detailed simulation and evaluation of 5G wireless offloading for object detection in the case of a powerful, new smart wearable called VIS4ION, for the Blind-and-Visually Impaired (BVI). The current VIS4ION system is an instrumented book-bag with high-resolution cameras, vision processing, and haptic and audio feedback. The paper considers uploading the camera data to a mobile edge server to perform real-time object detection and transmitting the detection results back to the wearable. To determine the video requirements, the paper evaluates the impact of video bit rate and resolution on object detection accuracy and range. A new street scene dataset with labeled objects relevant to BVI navigation is leveraged for analysis. The vision evaluation is combined with a full-stack wireless network simulation to determine the distribution of throughputs and delays with real navigation paths and ray-tracing from new high-resolution 3D models in an urban environment. For comparison, the wireless simulation considers both a standard 4G-Long Term Evolution (LTE) sub-6-GHz carrier and high-rate 5G millimeter-wave (mmWave) carrier. The work thus provides a thorough and detailed assessment of edge computing for object detection with mmWave and sub-6-GHz connectivity in an application with both high bandwidth and low latency requirements.

ABSTRACT/UNASSIGNED:Opioids relieve acute pain, but there is little evidence to support the stability of the benefit over long-term treatment of chronic noncancer pain. Previous systematic reviews consider only group level published data which did not provide adequate detail. Our goal was to use patient-level data to explore the stability of pain, opioid dose, and either physical function or pain interference in patients treated for 12 months with abuse deterrent formulations of oxycodone and hydrocodone. All available studies in the Food and Drug Administration Document Archiving, Reporting, and Regulatory Tracking System were included. Patient-level demographics, baseline data, exposure, and outcomes were harmonized. Individual patient slopes were calculated from a linear model of pain, physical function, and pain interference to determine response over time. Opioid dose was summarized by change between baseline and the final month of observation. Patients with stable or less pain, stable or lower opioid dose, and stable or better physical function (where available) met our prespecified criteria for maintaining long-term benefit from chronic opioids. Of the complete data set of 3192 patients, 1422 (44.5%) maintained their pain level and opioid dose. In a secondary analysis of 985 patients with a measured physical function, 338 (34.3%) maintained their physical function in addition to pain and opioid dose. Of 2040 patients with pain interference measured, 788 (38.6%) met criteria in addition. In a carefully controlled environment, about one-third of patients successfully titrated on opioids to treat chronic noncancer pain demonstrated continued benefit for up to 12 months.

Background/UNASSIGNED:Treatment with aspirin plus clopidogrel, dual antiplatelet therapy (DAPT), within 24 hours of high-risk transient ischemic attack (TIA) or minor stroke symptoms to eligible patients is recommended by national guidelines. Whether or not this treatment has been adopted by emergency medicine (EM) physicians is uncertain. Methods/UNASSIGNED:We conducted an online survey of EM physicians in the United States. The survey consisted of 13 multiple choice questions regarding physician characteristics, practice settings, and usual approach to TIA and minor stroke treatment. We report participant characteristics and use chi-squared tests to compare between groups. Results/UNASSIGNED:We included 162 participants in the final study analysis. 103 participants (64%) were in practice for >5 years and 96 (59%) were at nonacademic centers; all were EM board-certified or board-eligible. Only 9 (6%) participants reported that they would start DAPT for minor stroke and 8 (5%) reported that they would start DAPT after high-risk TIA. Aspirin alone was the selected treatment by 81 (50%) participants for minor stroke patients who presented within 24 hours of symptom onset and were not candidates for thrombolysis. For minor stroke, 69 (43%) participants indicated that they would defer medical management to consultants or another team. Similarly, 75 (46%) of participants chose aspirin alone to treat high-risk TIA; 74 (46%) reported they would defer medical management after TIA to consultants or another team. Conclusion/UNASSIGNED:In a survey of EM physicians, we found that the reported rate of DAPT treatment for eligible patients with high-risk TIA and minor stroke was low.

OBJECTIVE:We sought to determine which combination of clinical and electroencephalography (EEG) characteristics differentiate between an antiseizure medication (ASM)-resistant vs ASM-responsive outcome for patients with idiopathic generalized epilepsy (IGE). METHODS:This was a case-control study of ASM-resistant cases and ASM-responsive controls with IGE treated at five epilepsy centers in the United States and Australia between 2002 and 2018. We recorded clinical characteristics and findings from the first available EEG study for each patient. We then compared characteristics of cases vs controls using multivariable logistic regression to develop a predictive model of ASM-resistant IGE. RESULTS:We identified 118 ASM-resistant cases and 114 ASM-responsive controls with IGE. First, we confirmed our recent finding that catamenial epilepsy is associated with ASM-resistant IGE (odds ratio [OR] 3.53, 95% confidence interval [CI] 1.32-10.41, for all study subjects) after covariate adjustment. Other independent factors seen with ASM resistance include certain seizure-type combinations (absence, myoclonic, and generalized tonic-clonic seizures [OR 7.06, 95% CI 2.55-20.96]; absence and generalized tonic-clonic seizures [OR 4.45, 95% CI 1.84-11.34]), as well as EEG markers of increased generalized spike-wave discharges (GSWs) in sleep (OR 3.43, 95% CI 1.12-11.36 for frequent and OR 7.21, 95% CI 1.50-54.07 for abundant discharges in sleep) and the presence of generalized polyspike trains (GPTs; OR 5.49, 95% CI 1.27-38.69). The discriminative ability of our final multivariable model, as measured by area under the receiver-operating characteristic curve, was 0.80. SIGNIFICANCE:Multiple clinical and EEG characteristics independently predict ASM resistance in IGE. To improve understanding of a patient's prognosis, clinicians could consider asking about specific seizure-type combinations and track whether they experience catamenial epilepsy. Obtaining prolonged EEG studies to record the burden of GSWs in sleep and assessing for the presence of GPTs may provide additional predictive value.