Switching state-space modeling of neural signal dynamics.

Linear parametric state-space models are a ubiquitous tool for analyzing neural time series data, providing a way to characterize the underlying brain dynamics with much greater statistical efficiency than non-parametric data analysis approaches. However, neural time series data are frequently time-varying, exhibiting rapid changes in dynamics, with transient activity that is often the key feature of interest in the data. Stationary methods can be adapted to time-varying scenarios by employing fixed-duration windows under an assumption of quasi-stationarity. But time-varying dynamics can be explicitly modeled by switching state-space models, i.e., by using a pool of state-space models with different dynamics selected by a probabilistic switching process. Unfortunately, exact solutions for state inference and parameter learning with switching state-space models are intractable. Here we revisit a switching state-space model inference approach first proposed by Ghahramani and Hinton. We provide explicit derivations for solving the inference problem iteratively after applying a variational approximation on the joint posterior of the hidden states and the switching process. We introduce a novel initialization procedure using an efficient leave-one-out strategy to compare among candidate models, which significantly improves performance compared to the existing method that relies on deterministic annealing. We then utilize this state inference solution within a generalized expectation-maximization algorithm to estimate model parameters of the switching process and the linear state-space models with dynamics potentially shared among candidate models. We perform extensive simulations under different settings to benchmark performance against existing switching inference methods and further validate the robustness of our switching inference solution outside the generative switching model class. Finally, we demonstrate the utility of our method for sleep spindle detection in real recordings, showing how switching state-space models can be used to detect and extract transient spindles from human sleep electroencephalograms in an unsupervised manner.

Disease modifying therapy management of multiple sclerosis after stem cell therapies: A retrospective case series.

BACKGROUND: Stem cell therapies (SCT) have not received formal regulatory approval for the treatment of people with multiple sclerosis (PwMS), but PwMS may seek various options on their own accord. The current literature largely focuses on the efficacy and safety of SCT in PwMS in clinical trials, in particular autologous hematopoietic stem cell transplantation (aHSCT), in carefully selected participants. There is little reported on the MS disease modifying therapy (DMT) management of PwMS who choose to undergo SCT outside of these trials. METHODS: We identified PwMS from two academic centers who had MS diagnosis fulfilling 2017 McDonald criteria and received SCT (methodologies permitted: aHSCT, umbilical-derived mesenchymal stem cells and/or adipose-derived mesenchymal stem cells (AdMSC)), with the goal to treat MS, between 1/1/2015 and 11/30/2021. RESULTS: Nine PwMS (five females; age range at SCT treatment 25-69 years old; MS disease duration 1-12 years; six relapsing-remitting, three secondary progressive, one primary progressive) underwent a total of eleven SCTs (nine aHSCT, two AdMSC, one umbilical-derived MSC) with the goal to treat MS. Two of six PwMS who underwent SCT <10 years from MS diagnosis, and one of three PwMS who underwent stem cell therapies >10 years from MS diagnosis were clinically stable thereafter. An MS DMT was resumed in five PwMS afterwards, including rituximab, ocrelizumab, siponimod, and glatiramer acetate: one remained clinically stable, whereas four clinically progressed. Four PwMS remained off of a DMT: three were clinically stable, whereas one clinically progressed. All nine patients demonstrated radiographic stability by MRI after SCT. Only one met formal criteria to consider aHSCT for MS. CONCLUSIONS: We demonstrate the heterogeneous real-world experience of treating MS after patient-chosen experimental SCTs, detailing the range of DMT management in various patient circumstances. Limitations of our study include its small sample size and the variety of stem cell therapies received.

Electronic pill bottles to monitor and promote medication adherence for people with multiple sclerosis: A randomized, virtual clinical trial.

OBJECTIVE: We perform a randomized trial to test the impact of electronic pill bottles with audiovisual reminders on oral disease modifying therapy (DMT) adherence in people with MS (PwMS). METHODS: Adults with multiple sclerosis (MS) taking an oral DMT were randomized 1:1 for 90 days to remote smartphone app- and pill bottle-based (a) adherence monitoring, or (b) adherence monitoring with audiovisual medication reminders. Optimal adherence was defined as the proportion of doses taken ±3 h of the scheduled time. Numbers of missed pills and pills taken early, on time, late, and extra were recorded. A multivariable regression model tested possible associations between optimal adherence and age, MS duration, cognitive functioning, and number of daily prescription pills. RESULTS: 85 participants (66 female; mean age 44.9 years) took dimethyl/diroximel fumarate (n = 49), fingolimod (n = 26), or teriflunomide (n = 10). Optimal adherence was on average higher in the monitoring with reminders arm (71.4%) than the monitoring only arm (61.6%; p = 0.033). In a multivariable model, optimal adherence was less likely in younger participants (p < 0.001) and those taking more daily prescription pills (p < 0.001). In the monitoring only arm, 4.0% of doses were taken early, 61.6% on time, 5.6% late, 4.4% in excess, and 24.4% were missed. In the reminders arm, these proportions were 3.4%, 71.4%, 3.7%, 8.7%, and 12.8%, respectively. CONCLUSION: We map real-world oral DMT adherence patterns using mHealth technology. PwMS who received medication reminders had higher optimal adherence. Nonadherence was more nuanced than simply missing pills. Developing strategies to improve adherence remains important in longitudinal MS care.

Broadband slow-wave modulation in posterior and anterior cortex tracks distinct states of propofol-induced unconsciousness.

A controversy has developed in recent years over the roles of frontal and posterior cortices in mediating consciousness and unconsciousness. Disruption of posterior cortex during sleep appears to suppress the contents of dreaming, yet activation of frontal cortex appears necessary for perception and can reverse unconsciousness under anesthesia. We used anesthesia to study how regional cortical disruption, mediated by slow wave modulation of broadband activity, changes during unconsciousness in humans. We found that broadband slow-wave modulation enveloped posterior cortex when subjects initially became unconscious, but later encompassed both frontal and posterior cortex when subjects were more deeply anesthetized and likely unarousable. Our results suggest that unconsciousness under anesthesia comprises several distinct shifts in brain state that disrupt the contents of consciousness distinct from arousal and awareness of those contents.

Light therapy for multiple sclerosis-associated fatigue: a randomized, controlled phase II trial.

BACKGROUND: Bright white light therapy (LT) can improve fatigue in several disease states but has not been studied in multiple sclerosis (MS). OBJECTIVE: To determine whether controlled home-based LT is feasible, tolerable, and well-adhered to in MS-associated fatigue. METHODS: A randomized, controlled trial of twice-daily 1-h bright white LT (BWLT) (10,000 lx, active arm) versus dim red LT (DRLT) (< 300 lx, control arm) was performed. Adults with MS-associated fatigue were enrolled for 10 weeks: 2-week baseline, 4-week intervention, 4-week washout. RESULTS: 41 participants were enrolled; 35 were randomized (average age 42 years, 80% female; BWLT n = 20; DRLT n = 15). 31 were in the intention to treat analysis. The average duration of LT sessions was similar between groups (BWLT 60.9 min, DRLT 61.5 min, p = 0.70). The most commonly reported adverse event was headache. There were no events that led to discontinuation. Baseline fatigue was severe in both arms (each 53/63 points on the Fatigue Severity Scale (FSS), p = 0.92). FSS was lower following BWLT (FSS 45.8 post-LT, p = 0.04; 44.9 post-washout, p = 0.02 intra-group compared to baseline FSS) and DRLT (FSS 46.7 post-LT, p = 0.03; 43.9 post-washout, p = 0.002 intragroup compared to baseline FSS). There was no difference between BWLT and DRLT groups in the magnitude of reduction of FSS scores (p = 0.81 after LT; p = 0.77 after washout for between group comparisons). Similarly, MS quality of life metrics improved in both arms but were not significantly different between groups after LT (p = 0.22) or washout. CONCLUSIONS: LT is safe, feasible, and well-tolerated in people with MS-associated fatigue. Improvement in both light spectra likely indicates a strong placebo effect for the DRLT group.

Progressive multifocal leukoencephalopathy: A 25-year retrospective cohort study.

OBJECTIVE: To characterize the risk factors, clinical course, and treatment of patients with progressive multifocal leukoencephalopathy (PML) diagnosed and followed over a 25-year epoch at 2 academic hospitals. METHODS: Patients with a definite diagnosis of PML were identified by positive CSF PCR for JC virus or histopathology between January 1, 1994, and January 1, 2019. Demographic and PML-specific variables were recorded on symptomatic presentation and at follow-up, including risk factors, clinical outcome, neuroimaging findings, and modified Rankin Scale (mRS) score at last follow-up. RESULTS: There were 91 patients with confirmed PML. HIV infection was the most common risk factor, identified in 49% (n = 45). Other frequent risk factors included lymphoma, leukemia, or myelodysplasia, identified in 31% of patients (n = 28); exposure to chemotherapeutic medications (30%, n = 27); and exposure to monoclonal antibody therapies (19%, n = 17). Thirty percent of the cohort was alive at the time of censoring, with a median mRS of 2 points, indicating slight disability at last follow-up. Median survival following PML diagnosis in HIV-infected patients was longer than in HIV-uninfected patients (1,992 vs 101 days, p = 0.024). Forty patients survived more than 1 year after PML symptom onset, of whom 24 were HIV infected (60%). Thirteen patients survived more than 10 years after PML symptom onset, all HIV infected, of the 59 patients diagnosed before June 1, 2009, and eligible for 10-year survivor status (22%). CONCLUSIONS: We add to the limited literature on PML by reporting its epidemiology in a large observational cohort. These parameters may be useful for future clinical trials that measure survival and clinical outcomes.

Smartphone EEG and remote online interpretation for children with epilepsy in the Republic of Guinea: Quality, characteristics, and practice implications.

PURPOSE: Children with epilepsy in low-income countries often go undiagnosed and untreated. We examine a portable, low-cost smartphone-based EEG technology in a heterogeneous pediatric epilepsy cohort in the West African Republic of Guinea. METHODS: Children with epilepsy were recruited at the Ignace Deen Hospital in Conakry, 2017. Participants underwent sequential EEG recordings with an app-based EEG, the Smartphone Brain Scanner-2 (SBS2) and a standard Xltek EEG. Raw EEG data were transmitted via Bluetooth™ connection to an Android™ tablet and uploaded for remote EEG specialist review and reporting via a new, secure web-based reading platform, crowdEEG. The results were compared to same-visit Xltek 10-20 EEG recordings for identification of epileptiform and non-epileptiform abnormalities. RESULTS: 97 children meeting the International League Against Epilepsy's definition of epilepsy (49 male; mean age 10.3 years, 29 untreated with an antiepileptic drug; 0 with a prior EEG) were enrolled. Epileptiform discharges were detected on 21 (25.3%) SBS2 and 31 (37.3%) standard EEG recordings. The SBS2 had a sensitivity of 51.6% (95%CI 32.4%, 70.8%) and a specificity of 90.4% (95%CI 81.4%, 94.4%) for all types of epileptiform discharges, with positive and negative predictive values of 76.2% and 75.8% respectively. For generalized discharges, the SBS2 had a sensitivity of 43.5% with a specificity of 96.2%. CONCLUSIONS: The SBS2 has a moderate sensitivity and high specificity for the detection of epileptiform abnormalities in children with epilepsy in this low-income setting. Use of the SBS2+crowdEEG platform permits specialist input for patients with previously poor access to clinical neurophysiology expertise.

Light therapy for multiple sclerosis-associated fatigue: Study protocol for a randomized controlled trial.

BACKGROUND: Fatigue is the most commonly reported symptom among multiple sclerosis (MS) patients, more than a quarter of whom consider fatigue to be their most disabling symptom. However, there are few effective treatment options for fatigue. We aim to investigate whether supplemental exposure to bright white light will reduce MS-associated fatigue. METHODS: Eligible participants will have clinically confirmed multiple sclerosis based on the revised McDonald criteria (2010) and a score ≥36 on the Fatigue Severity Scale (FSS). Participants will be randomized 1:1 to bright white light (10,000 lux; active condition) or dim red light (<300 lux; control condition) self-administered for 1 hour twice daily. The study will include a 2-week baseline period, a 4-week treatment period, and a 4-week washout period. Participants will record their sleep duration, exercise, caffeine, and medication intake daily. Participants will record their fatigue using the Visual Analogue Fatigue Scale (VAFS) 4 times every third day, providing snapshots of their fatigue level at different times of day. Participants will self-report their fatigue severity using FSS on 3 separate visits: at baseline (week 0), following completion of the treatment phase (week 6), and at study completion (week 10). The primary outcome will be the change in the average FSS score after light therapy. We will perform an intention-to-treat analysis, comparing the active and control groups to assess the postintervention difference in fatigue levels reported on FSS. Secondary outcome measures include change in global VAFS scores during the light therapy and self-reported quality of life in the Multiple Sclerosis Quality of Life-54. DISCUSSION: We present a study design and rationale for randomizing a nonpharmacological intervention for MS-associated fatigue, using bright light therapy. The study limitations relate to the logistical issues of a self-administered intervention requiring frequent participant self-report in a relapsing condition. Ultimately, light therapy for the treatment of MS-associated fatigue may provide a low-cost, noninvasive, self-administered treatment for one of the most prevalent and burdensome symptoms experienced by people with MS.