Babak Razavi, MD, PhD

All Publications

• A systematic review on functional electrical stimulation based rehabilitation systems for upper limb post-stroke recovery. Frontiers in neurology Khan, M. A., Fares, H., Ghayvat, H., Brunner, I. C., Puthusserypady, S., Razavi, B., Lansberg, M., Poon, A., Meador, K. J. 2023; 14: 1272992

  Abstract

  Stroke is one of the most common neurological conditions that often leads to upper limb motor impairments, significantly affecting individuals' quality of life. Rehabilitation strategies are crucial in facilitating post-stroke recovery and improving functional independence. Functional Electrical Stimulation (FES) systems have emerged as promising upper limb rehabilitation tools, offering innovative neuromuscular reeducation approaches.The main objective of this paper is to provide a comprehensive systematic review of the start-of-the-art functional electrical stimulation (FES) systems for upper limb neurorehabilitation in post-stroke therapy. More specifically, this paper aims to review different types of FES systems, their feasibility testing, or randomized control trials (RCT) studies.The FES systems classification is based on the involvement of patient feedback within the FES control, which mainly includes "Open-Loop FES Systems" (manually controlled) and "Closed-Loop FES Systems" (brain-computer interface-BCI and electromyography-EMG controlled). Thus, valuable insights are presented into the technological advantages and effectiveness of Manual FES, EEG-FES, and EMG-FES systems.The review analyzed 25 studies and found that the use of FES-based rehabilitation systems resulted in favorable outcomes for the stroke recovery of upper limb functional movements, as measured by the FMA (Fugl-Meyer Assessment) (Manually controlled FES: mean difference = 5.6, 95% CI (3.77, 7.5), P < 0.001; BCI-controlled FES: mean difference = 5.37, 95% CI (4.2, 6.6), P < 0.001; EMG-controlled FES: mean difference = 14.14, 95% CI (11.72, 16.6), P < 0.001) and ARAT (Action Research Arm Test) (EMG-controlled FES: mean difference = 11.9, 95% CI (8.8, 14.9), P < 0.001) scores. Furthermore, the shortcomings, clinical considerations, comparison to non-FES systems, design improvements, and possible future implications are also discussed for improving stroke rehabilitation systems and advancing post-stroke recovery. Thus, summarizing the existing literature, this review paper can help researchers identify areas for further investigation. This can lead to formulating research questions and developing new studies aimed at improving FES systems and their outcomes in upper limb rehabilitation.

  View details for DOI 10.3389/fneur.2023.1272992

  View details for PubMedID 38145118

  View details for PubMedCentralID PMC10739305

• Predicting Sedation Level using Surface and Intracranial EEG with Convolutional Neural Networks during Emergence from Anesthesia Han, L., Purger, D., Eagleman, S., Halpern, C., Buch, V., Razavi, B., Meador, K., Drover, D. LIPPINCOTT WILLIAMS & WILKINS. 2023: 583-585

  View details for Web of Science ID 001058985600203

• Transcranial Direct Current Stimulation for Focal Status Epilepticus or Lateralized Periodic Discharges in Four Patients in a Critical Care Setting. Epilepsia Fisher, R. S., McGinn, R. J., Von Stein, E. L., Wu, T. Q., Qing, K. Y., Fogarty, A., Razavi, B., Venkatasubramanian, C. 2023

  Abstract

  OBJECTIVE: Transcranial direct current stimulation (tDCS) has been advocated for various neurological conditions, including epilepsy. A 1-4 mA cathodal current applied to the scalp over a seizure focus can reduce spikes and seizures. This series of four patients with focal status epilepticus is among the first case series to demonstrate benefit of tDCS in the critical care setting.METHODS: Patients in the intensive care unit were referred for tDCS treatment when focal status or clinically-relevant lateralized periodic discharges did not resolve with conventional anti-seizure medications and anesthetics. Battery-powered direct cathodal current at 2 mA was delivered by an ActivaDose (Caputron) tDCS device via a saline soaked sponge on the scalp over the seizure focus. Anode was on the contralateral forehead or shoulder. Treatment was for 30 minutes, repeated twice in a day, then again 1-4 times more over the next few days.RESULTS: Three females and one male, ages 34-68 were treated. Etiologies of status were PRES in association with immunosuppressants for a liver transplant, perinatal hypoxic-ischemic injury, a prior cardioembolic parietal stroke and CNS lupus. tDCS led to significant reduction of interictal spikes (0.78/s to 0.38/s, p<0.0001) in 3 cases and electrographic seizures (3.83/hr to 0/hr, p<0.001) in two cases. Medication reductions were enabled in all cases subsequent to tDCS. The only side effect of tDCS was transient erythema under the sponge in one case. Two patients died of causes unrelated to tDCS, one was discharged to a nursing home and one became fully responsive as seizures were controlled with tDCS.SIGNIFICANCE: Spikes and electrographic seizure frequency significantly improved within a day of tDCS. Results are potentially confounded by multiple ongoing changes in medications and treatments. These results might encourage further investigation of tDCS in the critical care setting, but verification by controlled studies will be required.

  View details for DOI 10.1111/epi.17514

  View details for PubMedID 36661376

• A Robust eLORETA Technique for Localization of Brain Sources in the Presence of Forward Model Uncertainties. IEEE transactions on bio-medical engineering Noroozi, A., Ravan, M., Razavi, B., Fisher, R. S., Law, Y., Hasan, M. S. 2022; PP

  Abstract

  OBJECTIVE: In this paper, we present a robust version of the well-known exact low-resolution electromagnetic tomography (eLORETA) technique, named ReLORETA, to localize brain sources in the presence of different forward model uncertainties.METHODS: We first assume that the true lead field matrix is a transformation of the existing lead field matrix distorted by uncertainties and propose an iterative approach to estimate this transformation accurately. Major sources of the forward model uncertainties, including differences in geometry, conductivity, and source space resolution between the real and simulated head models, and misaligned electrode positions, are then simulated to test the proposed method.RESULTS: ReLORETA and eLORETA are applied to simulated focal sources in different regions of the brain and the presence of various noise levels as well as real data from a patient with focal epilepsy. The results show that ReLORETA is considerably more robust and accurate than eLORETA in all cases.CONCLUSION: Having successfully dealt with the forward model uncertainties, ReLORETA proved to be a promising method for real-world clinical applications.SIGNIFICANCE: eLORETA is one of the localization techniques that could be used to study brain activity for medical applications such as determining the epileptogenic zone in patients with medically refractory epilepsy. However, the major limitation of eLORETA is sensitivity to the uncertainties in the forward model. Since this problem can substantially undermine its performance in real-world applications where the exact lead field matrix is unknown, developing a more robust method capable of dealing with these uncertainties is of significant interest.

  View details for DOI 10.1109/TBME.2022.3202751

  View details for PubMedID 36136923

• High-resolution hippocampal diffusion tensor imaging of mesial temporal sclerosis in refractory epilepsy. Epilepsia Chau Loo Kung, G., Chiu, A., Davey, Z., Mouchawar, N., Carlson, M., Moein Taghavi, H., Martin, D., Graber, K., Razavi, B., McNab, J., Zeineh, M. 2022

  Abstract

  OBJECTIVE: We explore the possibility of using diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) to discern microstructural abnormalities in the hippocampus indicative of mesial temporal sclerosis (MTS) at the subfield level.METHODS: We analyzed data from 57 patients with refractory epilepsy who previously underwent 3.0-T magnetic resonance imaging (MRI) including DTI as a standard part of presurgical workup. We collected information about each subject's seizure semiology, conventional electroencephalography (EEG), high-density EEG, positron emission tomography reports, surgical outcome, and available histopathological findings to assign a final diagnostic category. We also reviewed the radiology MRI report to determine the radiographic category. DTI- and NODDI-based metrics were obtained in the hippocampal subfields.RESULTS: By examining diffusion characteristics among subfields in the final diagnostic categories, we found lower orientation dispersion indices and elevated axial diffusivity in the dentate gyrus in MTS compared to no MTS. By similarly examining among subfields in the different radiographic categories, we found all diffusion metrics were abnormal in the dentate gyrus and CA1. We finally examined whether diffusion imaging would better inform a radiographic diagnosis with respect to the final diagnosis, and found that dentate diffusivity suggested subtle changes that may help confirm a positive radiologic diagnosis.SIGNIFICANCE: The results suggest that diffusion metric analysis at the subfield level, especially in dentate gyrus and CA1, maybe useful for clinical confirmation of MTS.

  View details for DOI 10.1111/epi.17330

  View details for PubMedID 35751514

• Impact of high-density EEG in presurgical evaluation for refractory epilepsy patients. Clinical neurology and neurosurgery Li, Y., Fogarty, A., Razavi, B., Ardestani, P. M., Falco-Walter, J., Werbaneth, K., Graber, K., Meador, K., Fisher, R. S. 2022; 219: 107336

  Abstract

  OBJECTIVE: Electrical source localization (ESI) can help to identify the seizure onset zone or propagation zone, but it is unclear how dipole localization techniques influence surgical planning.METHODS: Patients who received a high density (HD)-EEG from 7/2014-7/2019 at Stanford were included if they met the following inclusion criteria: (1) adequate epileptiform discharges were recorded for source localization analysis, (2) underwent surgical treatment, which was at least 6 months before the survey. Interictal ESI was performed with the LORETA method on age matched MRIs. Six neurophysiologists from the Stanford Epilepsy Program independently reviewed each case through an HIPPA-protected online survey. The same cases were presented again with additional data from the HD-EEG study. Ratings of how much the HD-EEG findings added value and in what way were recorded.RESULTS: Fifty out of 202 patients met the inclusion criteria, providing a total of 276h of HDEEG recordings. All patients had video EEG recordings and at least one brain MRI, 88 % had neuropsychological testing, 78 % had either a PET or SPECT scan. Additional HD-EEG information was rated as helpful in 83.8 %, not useful in 14.4 % and misleading in 1.8 % of cases. In 20.4 % of cases the HD-EEG information altered decision-making in a major way, such as choosing a different surgical procedure, avoidance of invasive recording or suggesting placement of invasive electrodes in a lobe not previously planned. In 21.5 % of cases, HD-EEG changed the plan in a minor way, e.g., extra invasive electrodes near the previously planned sites in the same sub-lobar region. In 42.3 % cases, HD-EEG did not change their plan but provided confirmation. In cases with normal MRI, additional HD-EEG information was more likely to change physicians' decision making during presurgical process when compared to the cases with MRI-visible lesions (53.3 % vs. 34.3 %, p=0.002). Among patients achieving Engel class I/II outcome, the concordance rate of HD-EEG and resection zone was 64.7 % versus 35.3 % with class III/IV (p=0.028).CONCLUSION: HD-EEG assists presurgical planning for refractory epilepsy patients, with a higher yield in patients with non-lesional MRIs. Concordance of HD-EEG dipole analysis localization and resection site is a favorable outcome indicator.

  View details for DOI 10.1016/j.clineuro.2022.107336

  View details for PubMedID 35716454

• Magnetic resonance imaging-guided laser interstitial thermal therapy for refractory focal epilepsy in a patient with a fully implanted RNS system: illustrative case. Journal of neurosurgery. Case lessons Buch, V. P., Mirro, E. A., Purger, D. A., Zeineh, M., Wilmer-Fierro, K., Razavi, B., Halpern, C. H. 2022; 3 (21): CASE22117

  Abstract

  BACKGROUND: The resective surgery plus responsive neurostimulation (RNS) system is an effective treatment for patients with refractory focal epilepsy. Furthermore, the long-term intracranial electroencephalography data provided by the system can inform a future resection or ablation procedure. RNS patients may undergo 1.5-T magnetic resonance imaging (MRI) under the conditions specified in the RNS system MRI guidelines; however, it was unknown if the MRI artifact would limit intraoperative laser interstitial thermal therapy (LITT) in a patient with a fully implanted RNS system.OBSERVATIONS: The authors were able to complete a successful awake LITT of epileptogenic tissue in a 1.5-T MRI scanner on the ipsilateral side to an implanted RNS system.LESSONS: If a future LITT procedure is probable, the neurostimulator should be placed contralateral to the side of the potential ablation. Using twist drill holes versus burr holes for depth lead placement may assist in future laser bone anchor seating. Before a LITT procedure in a patient with the neurostimulator ipsilateral to the ablation, 1.5-T MRI thermography scanning should be scheduled preoperatively to assess artifact in the proposed ablation zone. Per the RNS system MRI guidelines, the patient must be positioned supine and awake, with no more than 30 minutes of active scan time before a 30-minute pause.

  View details for DOI 10.3171/CASE22117

  View details for PubMedID 35734233

• Vinpocetine, cognition, and epilepsy. Epilepsy & behavior : E&B Meador, K. J., Leeman-Markowski, B., Medina, A. E., Illamola, S. M., Seliger, J., Novak, G., Lin, C., Ivanisevic, M., Razavi, B., Marino, S., Boyd, A., Loring, D. W. 2021; 119: 107988

  Abstract

  OBJECTIVE: Vinpocetine has been shown to enhance memory in animal models, with possible cognitive benefit in humans. The present study sought to demonstrate if vinpocetine can enhance cognition in healthy volunteers or patients with epilepsy. In addition, we compare blood levels of vinpocetine and its active metabolite (apovincaminic acid; AVA) in humans and animals to further characterize factors related to possible therapeutic benefit.METHODS: The cognitive effects of vinpocetine were assessed in healthy adult volunteers (n = 8) using a double-blind, randomized, crossover design at single doses (placebo, 10, 20, and 60 mg oral). Cognitive effects of vinpocetine in patients with focal epilepsy (n = 8) were tested using a double-blind, randomized, crossover design at single doses (placebo, 20 mg oral) followed by one-month open label at 20 mg oral three times a day. The neuropsychological battery included both computerized and non-computerized tests. Levels of vinpocetine and AVA in the human studies were compared to levels in 45 mice across time dosed at 5-20 mg/kg intraperitoneal of vinpocetine.RESULTS: No significant cognitive benefits were seen in healthy volunteers or patients with epilepsy. No appreciable side effects occurred. Vinpocetine and AVA levels were lower in humans than animals.CONCLUSIONS: Vinpocetine was well tolerated, but was not associated with positive cognitive effects. However, blood levels obtained in humans were substantially less than levels in animals obtained from dosages known to be effective in one model. This suggests that higher dosages are needed in humans to assess vinpocetine's cognitive efficacy.

  View details for DOI 10.1016/j.yebeh.2021.107988

  View details for PubMedID 33957389

• Quantitative EEG during alteration of consciousness in psychogenic non-epileptic seizures Werbaneth, K., Lai, S., Seliger, J., Meador, K., Razavi, B. LIPPINCOTT WILLIAMS & WILKINS. 2021

  View details for Web of Science ID 000729283605065

• Intracranial electroencephalography reveals selective responses to cognitive stimuli in the periventricular heterotopias. The Journal of neuroscience : the official journal of the Society for Neuroscience Akkol, S., Kucyi, A., Hu, W., Zhao, B., Zhang, C., Sava-Segal, C., Liu, S., Razavi, B., Zhang, J., Zhang, K., Parvizi, J. 2021

  Abstract

  Our recent work suggests that non-lesional epileptic brain tissue is capable of generating normal neurophysiological responses during cognitive tasks, which are then seized by ongoing pathological epileptic activity. Here, we aim to extend the scope of our work to epileptic periventricular heterotopias (PVH) and examine if the PVH tissue also exhibits normal neurophysiological responses and network-level integration with other non-lesional cortical regions. As part of routine clinical assessment, three adult patients with PVH underwent implantation of intracranial electrodes and participated in experimental cognitive tasks. We obtained simultaneous recordings from PVH and remote cortical sites during rest as well as controlled experimental conditions. In all three subjects (2 female), cognitive experimental conditions evoked significant electrophysiological responses in discrete locations within the PVH tissue that were correlated with responses seen in non-epileptic cortical sites. Moreover, the responsive PVH sites exhibited correlated electrophysiological activity with responsive, non-lesional cortical sites during rest conditions. Taken together, our work clearly demonstrates that the PVH tissue may be functionally organized and it may be functionally integrated within cognitively engaged cortical networks despite its anatomical displacement during neurodevelopment.SIGNIFICANCE STATEMENT:Periventricular heterotopias (PVH) are developmentally abnormal brain tissues that frequently cause epileptic seizures. In a rare opportunity to obtain direct electrophysiological recordings from PVH, we were able to show that, contrary to common assumptions, PVH functional activity is similar to healthy cortical sites during a well-established cognitive task and exhibits clear resting state connectivity with the responsive cortical regions.

  View details for DOI 10.1523/JNEUROSCI.2785-20.2021

  View details for PubMedID 33727335

• Real-world experience with direct brain-responsive neurostimulation for focal onset seizures. Epilepsia Razavi, B., Rao, V. R., Lin, C., Bujarski, K. A., Patra, S. E., Burdette, D. E., Geller, E. B., Brown, M. M., Johnson, E. A., Drees, C., Chang, E. F., Greenwood, J. E., Heck, C. N., Jobst, B. C., Gwinn, R. P., Warner, N. M., Halpern, C. H. 2020

  Abstract

  OBJECTIVE: The RNS System is a direct brain-responsive neurostimulation system that is US Food and Drug Administration-approved for adults with medically intractable focal onset seizures based on safety and effectiveness data from controlled clinical trials. The purpose of this study was to retrospectively evaluate the real-world safety and effectiveness of the RNS System.METHODS: Eight comprehensive epilepsy centers conducted a chart review of patients treated with the RNS System for at least 1year, in accordance with the indication for use. Data included device-related serious adverse events and the median percent change in disabling seizure frequency from baseline at years 1, 2, and 3 of treatment and at the most recent follow-up.RESULTS: One hundred fifty patients met the criteria for analysis. The median reduction in seizures was 67% (interquartile range [IQR] = 33%-93%, n=149) at 1 year, 75% (IQR = 50%-94%, n=93) at 2 years, 82% (IQR = 50%-96%, n=38) at ≥3years, and 74% (IQR = 50%-96%, n=150) at last follow-up (mean=2.3years). Thirty-five percent of patients had a ≥90% seizure frequency reduction, and 18% of patients reported being clinically seizure-free at last follow-up. Seizure frequency reductions were similar regardless of patient age, age at epilepsy onset, duration of epilepsy, seizure onset in mesial temporal or neocortical foci, magnetic resonance imaging findings, prior intracranial monitoring, prior epilepsy surgery, or prior vagus nerve stimulation treatment. The infection rate per procedure was 2.9% (6/150 patients); five of the six patients had an implant site infection, and one had osteomyelitis. Lead revisions were required in 2.7% (4/150), and 2.0% (3/150) of patients had a subdural hemorrhage, none of which had long-lasting neurological consequences.SIGNIFICANCE: In this real-world experience, safety was similar and clinical seizure outcomes exceeded those of the prospective clinical trials, corroborating effectiveness of this therapy and suggesting that clinical experience has informed more effective programming.

  View details for DOI 10.1111/epi.16593

  View details for PubMedID 32658325

• 3D Printed Models of Brain and Intracranial Electrodes for Epilepsy Education and Surgical Planning Ardestani, P., Gifford, K., Bogart, K., Walters, S., Zeineh, M., Fleischmann, D., Razavi, B. LIPPINCOTT WILLIAMS & WILKINS. 2020

  View details for Web of Science ID 000536058005042

• Diagnostic Utility of Reduced Electroencephalography for Seizure Detection: A Systematic Review Gururangan, K., Razavi, B., Popat, R. LIPPINCOTT WILLIAMS & WILKINS. 2020

  View details for Web of Science ID 000536058004172

• Epileptogenic network of focal epilepsies mapped with cortico-cortical evoked potentials. Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology Guo, Z. H., Zhao, B. T., Toprani, S. n., Hu, W. H., Zhang, C. n., Wang, X. n., Sang, L. n., Ma, Y. S., Shao, X. Q., Razavi, B. n., Parvizi, J. n., Fisher, R. n., Zhang, J. G., Zhang, K. n. 2020; 131 (11): 2657–66

  Abstract

  The goal of this study was to investigate the spatial extent and functional organization of the epileptogenic network through cortico-cortical evoked potentials (CCEPs) in patients being evaluated with intracranial stereoelectroencephalography.We retrospectively included 25 patients. We divided the recorded sites into three regions: epileptogenic zone (EZ); propagation zone (PZ); and noninvolved zone (NIZ). The root mean square of the amplitudes was calculated to reconstruct effective connectivity network. We also analyzed the N1/N2 amplitudes to explore the responsiveness influenced by epileptogenicity. Prognostic analysis was performed by comparing intra-region and inter-region connectivity between seizure-free and non-seizure-free groups.Our results confirmed that stimulation of the EZ caused the strongest responses on other sites within and outside the EZ. Moreover, we found a hierarchical connectivity pattern showing the highest connectivity strength within EZ, and decreasing connectivity gradient from EZ, PZ to NIZ. Prognostic analysis indicated a stronger intra-EZ connection in the seizure-free group.The EZ showed highest excitability and dominantly influenced other regions. Quantitative CCEPs can be useful in mapping epileptic networks and predicting surgical outcome.The generated computational connectivity model may enhance our understanding of epileptogenic networks and provide useful information for surgical planning and prognosis prediction.

  View details for DOI 10.1016/j.clinph.2020.08.012

  View details for PubMedID 32957038

• Comparative neuropsychological effects of carbamazepine and eslicarbazepine acetate EPILEPSY & BEHAVIOR Meador, K. J., Seliger, J., Boyd, A., Razavi, B., Falco-Walter, J., Le, S., Loring, D. W. 2019; 94: 151–57

  View details for DOI 10.1016/j.yebeh.2019.02.034

  View details for Web of Science ID 000467913700025

• Comparative Neuropsychological Effects of Carbamazepine and Eslicarbazepine Acetate Meador, K., Seliger, J., Razavi, B., Falco-Walter, J., Le, S., Loring, D. LIPPINCOTT WILLIAMS & WILKINS. 2019

  View details for Web of Science ID 000475965905239

• Assessment of Resident Opinions and Knowledge of Neurology Subspecialty Fellowship Application Ahmad, S. R., Razavi, B. LIPPINCOTT WILLIAMS & WILKINS. 2019

  View details for Web of Science ID 000475965902102

• Comparative neuropsychological effects of carbamazepine and eslicarbazepine acetate. Epilepsy & behavior : E&B Meador, K. J., Seliger, J., Boyd, A., Razavi, B., Falco-Walter, J., Le, S., Loring, D. W. 2019; 94: 151–57

  Abstract

  People with epilepsy are at increased risk for neuropsychological dysfunction due to multiple factors, of which the most amendable are antiseizure medications (ASMs). Antiseizure medication effectiveness is frequently determined by tolerability. In this study, we compared the neuropsychological effects of eslicarbazepine acetate (ESL) and carbamazepine immediate-release (CBZ) using a randomized, double-blind, crossover design in healthy volunteers with a 2-week titration and 4-week maintenance phase in each treatment arm (CBZ = 400 mg BID and ESL = 800 mg qAM). Neuropsychological testing was performed at the initial visit, repeated at 1st baseline nondrug condition, end treatment #1, 2nd nondrug condition one month after treatment #1, end treatment #2, and 3rd nondrug condition one month after treatment #2. Neuropsychological testing was conducted 2 h after morning dose and included computer (i.e., dual task test, selective attention test, symbol digit, verbal memory, visuospatial memory, and 1- & 2-back continuous performance) and noncomputer tasks (i.e., Medical College of Georgia (MCG) paragraph memory, Stroop, Symbol Digit Modalities Test, Profile of Mood States). z-Scores calculated from nondrug conditions were used to compare ESL and CBZ for the 23 completers. Follow-up analyses included individual test scores and distribution of individual raw means. Mean blood levels on test day were CBZ = 8.9 mug/ml and ESL = 15.3 mug/ml. Omnibus z-score was significantly better for ESL (p = .0001). For individual measures, executive function and selective attention tests were statistically significantly better for ESL. Individual test raw means favored ESL over CBZ on 22 of 30 measures (p = .016, 2-tailed sign test). Eslicarbazepine acetate demonstrated less adverse neuropsychological effects than CBZ.

  View details for PubMedID 30939410

• Treatment of drug-resistant epilepsy in patients with periventricular nodular heterotopia using RNS® System: Efficacy and description of chronic electrophysiological recordings. Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology Nune, G. n., Arcot Desai, S. n., Razavi, B. n., Agostini, M. A., Bergey, G. K., Herekar, A. A., Hirsch, L. J., Lee, R. W., Rutecki, P. A., Srinivasan, S. n., Van Ness, P. C., Tcheng, T. K., Morrell, M. J. 2019; 130 (8): 1196–1207

  Abstract

  Describe changes in clinical seizure frequency and electrophysiological data recorded in patients with medically-intractable seizures and periventricular nodular heterotopias (PVNH) treated with the RNS® System (NeuroPace, Inc., Mountain View, CA).Clinical seizures from eight patients (mean follow-up of 10.1 years) were analyzed pre- and post-treatment. Chronic ambulatory electrocorticograms (ECoGs) recorded from PVNHs, hippocampus and neocortex were evaluated to identify the earliest electrographic seizure onset type, pattern of spread, and interictal characteristics.Mean reduction in disabling seizures was 85.7 % (n = 8); seven patients had >50% seizure reduction and two were seizure-free in the final year of analysis. Seizure rate showed a progressive reduction over the course of the study with the highest rate of improvement in the first two to three years after implantation. Four of seven patients with one PVNH lead and a second lead in the hippocampus or neocortex had some electrographic seizures first recorded at either lead location, suggesting two foci or seizure propagation patterns. Low voltage fast type activity was the prominent seizure onset pattern. Interictal ECoG power was lower in PVNH than hippocampus.RNS® System treatment substantially reduced clinical seizure frequency in patients with PVNH. Analysis of ictal ECoG records suggests PVNH may be involved in seizure generation.Chronic ECoG recordings suggest PVNH tissue can actively participate in epileptogenic networks. Direct brain-responsive neurostimulation is a safe and effective treatment option in such patients, progressively reducing seizure rate over a period of years.

  View details for DOI 10.1016/j.clinph.2019.04.706

  View details for PubMedID 31163364

• Tripolar concentric EEG electrodes reduce noise. Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology Aghaei-Lasboo, A. n., Inoyama, K. n., Fogarty, A. S., Kuo, J. n., Meador, K. J., Walter, J. J., Le, S. T., Graber, K. D., Razavi, B. n., Fisher, R. S. 2019; 131 (1): 193–98

  Abstract

  To assay EEG signal quality recorded with tripolar concentric ring electrodes (TCREs) compared to regular EEG electrodes.EEG segments were recorded simultaneously by TCREs and regular electrodes, low-pass filtered at 35 Hz (REG35) and 70 Hz (REG70). Clips were rated blindly by nine electroencephalographers for presence or absence of key EEG features, relative to the "gold-standard" of the clinical report.TCRE showed less EMG artifact (F = 15.4, p < 0.0001). Overall quality rankings were not significantly different. Focal slowing was better detected by TCRE and spikes were better detected by regular electrodes. Seizures (n = 85) were detected by TCRE in 64 cases (75.3%), by REG70 in 75 (88.2%) and REG35 in 69 (81.2%) electrodes. TCRE detected 9 (10.6%) seizures not detected by one of the other 2 methods. In contrast, 14 seizures (16.5%) were not detected by TCRE, but were by REG35 electrodes. Each electrode detected interictal spikes when the other did not.TCRE produced similar overall quality and confidence ratings versus regular electrodes, but less muscle artifact. TCRE recordings detected seizures in 7% of instances where regular electrodes did not.The combination of the two types increased detection of epileptiform events compared to either alone.

  View details for DOI 10.1016/j.clinph.2019.10.022

  View details for PubMedID 31809982

• Reply to "Syncope is associated with electroencephalography changes" and to "Video-EEG during tilt-table testing is an invaluable aid for understanding syncope". Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology Muppidi, S., Miglis, M. G., Razavi, B. 2018; 129 (7): 1500–1501

  View details for DOI 10.1016/j.clinph.2018.04.601

  View details for PubMedID 29729888

• The clinical utility of qualitative electroencephalography during tilt table testing - A retrospective study CLINICAL NEUROPHYSIOLOGY Muppidi, S., Razavi, B., Miglis, M. G., Jaradeh, S. 2018; 129 (4): 783–86

  Abstract

  To assess electroencephalography (EEG) changes during tilt table testing in syncope and other orthostatic syndromes.We retrospectively reviewed consecutive tilt table studies with simultaneous EEG from April 2014 to May 2016 at our center. All patients had video EEG during tilt table. All patients had at least 10 min of head up tilt unless they had syncope or did not tolerate the study. Video EEG was interpreted by epileptologists.Eighty-seven patients met the inclusion criteria. Mean age was 45 years, and 55 were women. Seven patients (∼8%) had syncope during tilt table, 11 patients (∼12%) had significant neurogenic orthostatic hypotension and a separate group of 11 patients (∼12%) had significant orthostatic tachycardia. Valsalva responses were abnormal in 7 of the 11 patients with orthostatic hypotension, suggesting an underlying neurogenic orthostatic hypotension. Visually discernable EEG changes were seen in only 3 patients (∼43%) who had syncope and in 1 patient (∼9%) with orthostatic tachycardia.Qualitative EEG analysis based on visual inspection during tilt table study revealed abnormalities in less than half the patients with syncope and a very small fraction with orthostatic tachycardia.Routine qualitative EEG recording might not be clinically useful during tilt table studies.

  View details for DOI 10.1016/j.clinph.2018.01.058

  View details for Web of Science ID 000427485900010

  View details for PubMedID 29448152

• Diagnostic utility of eight-channel EEG for detecting generalized or hemispheric seizures and rhythmic periodic patterns. Clinical neurophysiology practice Gururangan, K., Razavi, B., Parvizi, J. 2018; 3: 65-73

  Abstract

  To compare the diagnostic utility of electroencephalography (EEG) using reduced, 8-channel montage (rm-EEG) to full, 18-channel montage (fm-EEG) for detection of generalized or hemispheric seizures and rhythmic periodic patterns (RPPs) by neurologists with extensive EEG training, neurology residents with minimal EEG exposure, and medical students without EEG experience.We presented EEG samples in both fm-EEG (bipolar montage) and rm-EEG (lateral leads of bipolar montage) to 20 neurologists, 20 residents, and 42 medical students. Unanimous agreement of three senior epileptologists defined samples as seizures (n = 7), RPPs (n = 10), and normal or slowing (n = 20). Differences in median accuracy, sensitivity, and specificity were assessed using Wilcoxon signed-rank tests.Full and reduced EEG demonstrated similar accuracy when read by neurologists (fm-EEG: 95%, rm-EEG: 95%, p = 0.29), residents (fm-EEG: 80%, rm-EEG: 80%, p = 0.05), and students (fm-EEG: 60%, rm-EEG: 51%, p = 0.68). Moreover, neurologists' sensitivity for detecting seizure activity was comparable between fm-EEG (100%) and rm-EEG (98%) (p = 0.17). Furthermore, the specificity of rm-EEG for seizures and RPP (neurologists: 100%, residents: 90%, students: 86%) was significantly greater than that of fm-EEG (neurologists: 93%, p = 0.03; residents: 80%, p = 0.01; students: 69%, p < 0.001).The reduction of the number of EEG channels from 18 to 8 does not compromise neurologists' sensitivity for detecting seizures that are often a core reason for performing urgent EEG. It may also increase their specificity for detecting rhythmic and periodic patterns, and thereby providing important diagnostic information to guide patient's management.Our study is the first to document the utility of a reduced channel EEG above the hairline compared to full montage EEG in aiding medical staff with varying degrees of EEG training to detect generalized or hemispheric seizures.

  View details for DOI 10.1016/j.cnp.2018.03.001

  View details for PubMedID 30215011

  View details for PubMedCentralID PMC6133909

• Detecting silent seizures by their sound. Epilepsia Parvizi, J., Gururangan, K., Razavi, B., Chafe, C. 2018

  Abstract

  The traditional approach to interpreting electroencephalograms (EEGs) requires physicians with formal training to visually assess the waveforms. This approach can be less practical in critical settings where a trained EEG specialist is not readily available to review the EEG and diagnose ongoing subclinical seizures, such as nonconvulsive status epilepticus.We have developed a novel method by which EEG data are converted to sound in real time by letting the underlying electrophysiological signal modulate a voice tone that is in the audible range. Here, we explored whether individuals without any prior EEG training could listen to 15-second sonified EEG and determine whether the EEG represents seizures or nonseizure conditions. We selected 84 EEG samples to represent seizures (n = 7), seizure-like activity (n = 25), or nonperiodic, nonrhythmic activity (normal or focal/generalized slowing, n = 52). EEGs from single channels in the left and right hemispheres were then converted to sound files. After a 4-minute training video, medical students (n = 34) and nurses (n = 30) were asked to designate each audio sample as "seizure" or "nonseizure." We then compared their performance with that of EEG-trained neurologists (n = 12) and medical students (n = 29) who also diagnosed the same EEGs on visual display.Nonexperts listening to single-channel sonified EEGs detected seizures with remarkable sensitivity (students, 98% ± 5%; nurses, 95% ± 14%) compared to experts or nonexperts reviewing the same EEGs on visual display (neurologists, 88% ± 11%; students, 76% ± 19%). If the EEGs contained seizures or seizure-like activity, nonexperts listening to sonified EEGs rated them as seizures with high specificity (students, 85% ± 9%; nurses, 82% ± 12%) compared to experts or nonexperts viewing the EEGs visually (neurologists, 90% ± 7%; students, 65% ± 20%).Our study confirms that individuals without EEG training can detect ongoing seizures or seizure-like rhythmic periodic patterns by listening to sonified EEG. Although sonification of EEG cannot replace the traditional approaches to EEG interpretation, it provides a meaningful triage tool for fast assessment of patients with suspected subclinical seizures.

  View details for DOI 10.1111/epi.14043

  View details for PubMedID 29558565

• Quantitative EEG Metrics Differ Between Outcome Groups and Change Over the First 72 h in Comatose Cardiac Arrest Patients NEUROCRITICAL CARE Wiley, S., Razavi, B., Krishnamohan, P., Mlynash, M., Eyngorn, I., Meador, K. J., Hirsch, K. G. 2018; 28 (1): 51–59

  Abstract

  Forty to sixty-six percent of patients resuscitated from cardiac arrest remain comatose, and historic outcome predictors are unreliable. Quantitative spectral analysis of continuous electroencephalography (cEEG) may differ between patients with good and poor outcomes.Consecutive patients with post-cardiac arrest hypoxic-ischemic coma undergoing cEEG were enrolled. Spectral analysis was conducted on artifact-free contiguous 5-min cEEG epochs from each hour. Whole band (1-30 Hz), delta (δ, 1-4 Hz), theta (θ, 4-8 Hz), alpha (α, 8-13 Hz), beta (β, 13-30 Hz), α/δ power ratio, percent suppression, and variability were calculated and correlated with outcome. Graphical patterns of quantitative EEG (qEEG) were described and categorized as correlating with outcome. Clinical outcome was dichotomized, with good neurologic outcome being consciousness recovery.Ten subjects with a mean age = 50 yrs (range = 18-65) were analyzed. There were significant differences in total power (3.50 [3.30-4.06] vs. 0.68 [0.52-1.02], p = 0.01), alpha power (1.39 [0.66-1.79] vs 0.27 [0.17-0.48], p < 0.05), delta power (2.78 [2.21-3.01] vs 0.55 [0.38-0.83], p = 0.01), percent suppression (0.66 [0.02-2.42] vs 73.4 [48.0-97.5], p = 0.01), and multiple measures of variability between good and poor outcome patients (all values median [IQR], good vs. poor). qEEG patterns with high or increasing power or large power variability were associated with good outcome (n = 6). Patterns with consistently low or decreasing power or minimal power variability were associated with poor outcome (n = 4).These preliminary results suggest qEEG metrics correlate with outcome. In some patients, qEEG patterns change over the first three days post-arrest.

  View details for PubMedID 28646267

• Detecting silent seizures by their sound Epilepsia Parvizi, J., Gururangan, K., Razavi, B., Chafe, C. 2018; 59 (4): 877-884

  Abstract

  The traditional approach to interpreting electroencephalograms (EEGs) requires physicians with formal training to visually assess the waveforms. This approach can be less practical in critical settings where a trained EEG specialist is not readily available to review the EEG and diagnose ongoing subclinical seizures, such as nonconvulsive status epilepticus.We have developed a novel method by which EEG data are converted to sound in real time by letting the underlying electrophysiological signal modulate a voice tone that is in the audible range. Here, we explored whether individuals without any prior EEG training could listen to 15-second sonified EEG and determine whether the EEG represents seizures or nonseizure conditions. We selected 84 EEG samples to represent seizures (n = 7), seizure-like activity (n = 25), or nonperiodic, nonrhythmic activity (normal or focal/generalized slowing, n = 52). EEGs from single channels in the left and right hemispheres were then converted to sound files. After a 4-minute training video, medical students (n = 34) and nurses (n = 30) were asked to designate each audio sample as "seizure" or "nonseizure." We then compared their performance with that of EEG-trained neurologists (n = 12) and medical students (n = 29) who also diagnosed the same EEGs on visual display.Nonexperts listening to single-channel sonified EEGs detected seizures with remarkable sensitivity (students, 98% ± 5%; nurses, 95% ± 14%) compared to experts or nonexperts reviewing the same EEGs on visual display (neurologists, 88% ± 11%; students, 76% ± 19%). If the EEGs contained seizures or seizure-like activity, nonexperts listening to sonified EEGs rated them as seizures with high specificity (students, 85% ± 9%; nurses, 82% ± 12%) compared to experts or nonexperts viewing the EEGs visually (neurologists, 90% ± 7%; students, 65% ± 20%).Our study confirms that individuals without EEG training can detect ongoing seizures or seizure-like rhythmic periodic patterns by listening to sonified EEG. Although sonification of EEG cannot replace the traditional approaches to EEG interpretation, it provides a meaningful triage tool for fast assessment of patients with suspected subclinical seizures.

  View details for DOI 10.1111/epi.14043

• Diagnostic utility of eight-channel EEG for detecting generalized seizures Clinical Neurophysiology Practice Gururangan, K., Razavi, B., Parvizi, J. 2018; 3

  View details for DOI 10.1016/j.cnp.2018.03.001

• EEG with Fewer Electrodes Is More Specific for Detecting Seizures and Seizure-Like Activity Gururangan, K., Razavi, B., Parvizi, J. WILEY. 2017: S158

  View details for Web of Science ID 000413198700326

• Utility of electroencephalography: Experience from a U.S. tertiary care medical center. Clinical neurophysiology Gururangan, K., Razavi, B., Parvizi, J. 2016; 127 (10): 3335-3340

  Abstract

  To investigate the utility of electroencephalography (EEG) for evaluation of patients with altered mental status (AMS).We retrospectively reviewed 200 continuous EEGs (cEEGs) obtained in ICU and non-ICU wards and 100 spot EEGs (sEEGs) obtained from the emergency department (ED) of a large tertiary medical center. Main outcomes were access time (from study request to hookup), and diagnostic yield (percentage of studies revealing significant abnormality).Access time, mean±SD (maximum), was 3.5±3.2 (20.8) hours in ICU, 4.8±5.0 (25.6) hours in non-ICU, and 2.7±3.6 (23.9) hours in ED. Access time was not significantly different for stat requests or EEGs with seizure activity. While the primary indication for EEG monitoring was to evaluate for seizures as the cause of AMS, only 8% of cEEGs and 1% of sEEGs revealed seizures. Epileptiform discharges were detected in 45% of ICU, 24% of non-ICU, and 9% of ED cases, while 2% of ICU, 15% of non-ICU, and 45% of ED cases were normal.Access to EEG is hampered by significant delays, and in emergency settings, the conventional EEG system detects seizures only in a minority of cases.Our findings underscore the inefficiencies of current EEG infrastructure for accessing diagnostically important information, as well as the need for more prospective data describing the relationship between EEG access time and EEG findings, clinical outcomes, and cost considerations.

  View details for DOI 10.1016/j.clinph.2016.08.013

  View details for PubMedID 27611442

• Dynamics of Quantitative EEG Changes During Cerebral Hypoperfusion Razavi, B., Meador, K. LIPPINCOTT WILLIAMS & WILKINS. 2016

  View details for Web of Science ID 000411328606016

• Quantitative (Spectral) Analysis of Continuous EEG for Prognostication in Post Cardiac Arrest Coma Wiley, S., Razavi, B., Hirsch, K., Meador, K. LIPPINCOTT WILLIAMS & WILKINS. 2016

  View details for Web of Science ID 000411328602100

• Quantitative (Spectral) Analysis of Continuous EEG for Prognostication in Post Cardiac Arrest Coma Wiley, S., Razavi, B., Hirsch, K., Meador, K. LIPPINCOTT WILLIAMS & WILKINS. 2016

  View details for Web of Science ID 000411328602190

• Dynamics of Quantitative EEG Changes During Cerebral Hypoperfusion Razavi, B., Meador, K. LIPPINCOTT WILLIAMS & WILKINS. 2016

  View details for Web of Science ID 000411279000024