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  1. Article ; Online: Clinical Image: Contrast-Induced Encephalopathy Mimicking Subarachnoid Hemorrhage.

    Muhammad, Najib / Ramayya, Ashwin G / Srinivasan, Visish M

    World neurosurgery

    2023  Volume 176, Page(s) 227–228

    Abstract: A 72-year-old female with a history of hypertension and hyperlipidemia presented to the emergency department from an outside hospital with acute confusion and global amnesia immediately following cervical epidural steroid injection with fluoroscopic ... ...

    Abstract A 72-year-old female with a history of hypertension and hyperlipidemia presented to the emergency department from an outside hospital with acute confusion and global amnesia immediately following cervical epidural steroid injection with fluoroscopic guidance for radiculopathy relief. On exam, she was oriented to self, but disoriented to place and situation. Otherwise, she was neurologically intact with no deficits. Head computed tomography (CT) revealed diffuse subarachnoid hyperdensities most prominent in the parafalcine region concerning for diffuse subarachnoid hemorrhage and tonsillar herniation concerning for intracranial hypertension. CT angiograms of head and neck were negative for vascular abnormalities. Dual-energy head CT was subsequently performed 4 hours later without IV contrast. The 80 kV sequence revealed prominent diffuse hyperdensity throughout the cerebrospinal fluid spaces in bilateral cerebral hemispheres, basal cisterns, and posterior fossa consistent with the initial CT, but these corresponding regions were relatively less dense on the 150 kV sequence. These findings were consistent with contrast material in the cerebrospinal fluid spaces without evidence of intracranial hemorrhage or transcortical infarct. Three hours later, the patient's transient confusion resolved, and she was discharged home the next morning without any neurological deficit.
    MeSH term(s) Female ; Humans ; Aged ; Subarachnoid Hemorrhage/diagnostic imaging ; Subarachnoid Hemorrhage/cerebrospinal fluid ; Head ; Confusion ; Intracranial Hemorrhages
    Language English
    Publishing date 2023-05-18
    Publishing country United States
    Document type Case Reports ; Journal Article
    ZDB-ID 2534351-8
    ISSN 1878-8769 ; 1878-8750
    ISSN (online) 1878-8769
    ISSN 1878-8750
    DOI 10.1016/j.wneu.2023.05.043
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: MTL neurons phase-lock to human hippocampal theta.

    Schonhaut, Daniel R / Rao, Aditya M / Ramayya, Ashwin G / Solomon, Ethan A / Herweg, Nora A / Fried, Itzhak / Kahana, Michael J

    eLife

    2024  Volume 13

    Abstract: Memory formation depends on neural activity across a network of regions, including the hippocampus and broader medial temporal lobe (MTL). Interactions between these regions have been studied indirectly using functional MRI, but the bases for ... ...

    Abstract Memory formation depends on neural activity across a network of regions, including the hippocampus and broader medial temporal lobe (MTL). Interactions between these regions have been studied indirectly using functional MRI, but the bases for interregional communication at a cellular level remain poorly understood. Here, we evaluate the hypothesis that oscillatory currents in the hippocampus synchronize the firing of neurons both within and outside the hippocampus. We recorded extracellular spikes from 1854 single- and multi-units simultaneously with hippocampal local field potentials (LFPs) in 28 neurosurgical patients who completed virtual navigation experiments. A majority of hippocampal neurons phase-locked to oscillations in the slow (2-4 Hz) or fast (6-10 Hz) theta bands, with a significant subset exhibiting nested slow theta × beta frequency (13-20 Hz) phase-locking. Outside of the hippocampus, phase-locking to hippocampal oscillations occurred only at theta frequencies and primarily among neurons in the entorhinal cortex and amygdala. Moreover, extrahippocampal neurons phase-locked to hippocampal theta even when theta did not appear locally. These results indicate that spike-time synchronization with hippocampal theta is a defining feature of neuronal activity in the hippocampus and structurally connected MTL regions. Theta phase-locking could mediate flexible communication with the hippocampus to influence the content and quality of memories.
    MeSH term(s) Humans ; Theta Rhythm/physiology ; Hippocampus/physiology ; Neurons/physiology ; Temporal Lobe ; Entorhinal Cortex
    Language English
    Publishing date 2024-01-09
    Publishing country England
    Document type Journal Article
    ZDB-ID 2687154-3
    ISSN 2050-084X ; 2050-084X
    ISSN (online) 2050-084X
    ISSN 2050-084X
    DOI 10.7554/eLife.85753
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Surgical Management of Idiopathic Thoracic Spinal Cord Herniation.

    Neale, Natalie / Ramayya, Ashwin / Welch, William

    World neurosurgery

    2019  Volume 129, Page(s) 81–84

    Abstract: Background: Idiopathic spinal cord herniation is a rare condition that involves spinal cord herniation through a defect in the ventral dura.: Case description: We present a case of a 61-year-old woman who initially presented in 2016 with an ... ...

    Abstract Background: Idiopathic spinal cord herniation is a rare condition that involves spinal cord herniation through a defect in the ventral dura.
    Case description: We present a case of a 61-year-old woman who initially presented in 2016 with an approximately 1-year history of burning right lower extremity pain and gait instability. Her neurologic examination was consistent with thoracic Brown-Sequard syndrome, and spinal magnetic resonance imaging showed a focal defect in the ventral dura at the superior aspect of T4 with the left aspect of the cord herniating into the defect. In 2018, she underwent a T3-T4 laminectomy with T3 pedicle take down and medial facetectomy, with reduction of the herniated cord.
    Conclusions: Idiopathic spinal cord herniation is an uncommon spinal cord disorder with a paucity of data reported. Our case report of a classic case of idiopathic spinal cord herniation presenting as Brown-Sequard syndrome and managed surgically will contribute to the data in this field.
    MeSH term(s) Brown-Sequard Syndrome/etiology ; Brown-Sequard Syndrome/surgery ; Female ; Hernia/complications ; Hernia/diagnosis ; Hernia/pathology ; Herniorrhaphy/methods ; Humans ; Middle Aged ; Spinal Cord Diseases/etiology ; Spinal Cord Diseases/surgery
    Language English
    Publishing date 2019-05-31
    Publishing country United States
    Document type Case Reports ; Journal Article
    ZDB-ID 2534351-8
    ISSN 1878-8769 ; 1878-8750
    ISSN (online) 1878-8769
    ISSN 1878-8750
    DOI 10.1016/j.wneu.2019.05.219
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Conference proceedings: Red Pill or Blue Pill: Assessing Health Utilities Using the Standard Gamble among Patients with Trigeminal Neuralgia

    Ajmera, Sonia / Miranda, Stephen P. / Blue, Rachel / Romeo, Dominic / Ramayya, Ashwin / Lee, John

    Journal of Neurological Surgery Part B: Skull Base

    2023  Volume 84, Issue S 01

    Event/congress 32nd Annual Meeting North American Skull Base Society, JW Marriott Tampa Water Street, Tampa, Florida, United States, 2023-02-17
    Language English
    Publishing date 2023-02-01
    Publisher Georg Thieme Verlag KG
    Publishing place Stuttgart ; New York
    Document type Article ; Conference proceedings
    ZDB-ID 2654269-9
    ISSN 2193-634X ; 2193-6331
    ISSN (online) 2193-634X
    ISSN 2193-6331
    DOI 10.1055/s-0043-1762190
    Database Thieme publisher's database

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  5. Article ; Online: Social Determinants of Health and Neurosurgical Outcomes: Current State and Future Directions.

    Glauser, Gregory / Detchou, Donald K / Dimentberg, Ryan / Ramayya, Ashwin G / Malhotra, Neil R

    Neurosurgery

    2021  Volume 88, Issue 5, Page(s) E383–E390

    Abstract: The relationship between social determinants of health (SDOH) and neurosurgical outcomes has become increasingly relevant. To date, results of prior work evaluating the impact of social determinants in neurosurgery have been mixed, and the need for ... ...

    Abstract The relationship between social determinants of health (SDOH) and neurosurgical outcomes has become increasingly relevant. To date, results of prior work evaluating the impact of social determinants in neurosurgery have been mixed, and the need for robust data on this subject remains. The present review evaluates how gender, race, and socioeconomic status (SES) influence outcomes following various brain tumor resection procedures. Results from a number of prior studies from the senior author's lab are summarized, with all data acquired using the EpiLog tool (Epilog Laser). Separate analyses were performed for each procedure, evaluating the unique, isolated impact of gender, race, and SES on outcomes. A comprehensive literature review identified any prior studies evaluating the influence of these SDOH on neurosurgical outcomes. The review presented herein suggests that the effect of gender and race on outcomes is largely mitigated when equal access to care is attained, and socioeconomic factors and comorbidities are controlled for. Furthermore, when patients are matched upon for a number of clinically relevant covariates, SES impacts postoperative mortality. Elucidation of this disparity empowers surgeons to initiate actionable change to equilibrate future outcomes.
    MeSH term(s) Brain Neoplasms/epidemiology ; Brain Neoplasms/mortality ; Brain Neoplasms/surgery ; Humans ; Neurosurgical Procedures/adverse effects ; Neurosurgical Procedures/mortality ; Neurosurgical Procedures/statistics & numerical data ; Social Determinants of Health/statistics & numerical data ; Treatment Outcome
    Language English
    Publishing date 2021-03-05
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 135446-2
    ISSN 1524-4040 ; 0148-396X
    ISSN (online) 1524-4040
    ISSN 0148-396X
    DOI 10.1093/neuros/nyab030
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article: Preoperative Predictors of Survival in Patients With Spinal Metastatic Disease.

    Miranda, Stephen P / Sullivan, Patricia Zadnik / Albayar, Ahmed / Ramayya, Ashwin G / Blue, Rachel / Ali, Zarina S / Malhotra, Neil / Marcotte, Paul / Yoon, Jang / Saifi, Comron / Welch, William C / Schuster, James / Ozturk, Ali K

    International journal of spine surgery

    2023  Volume 17, Issue 4, Page(s) 557–563

    Language English
    Publishing date 2023-03-08
    Publishing country Netherlands
    Document type Journal Article
    ISSN 2211-4599
    ISSN 2211-4599
    DOI 10.14444/8444
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: Postoperative Sagittal Spinal Alignment Changes Following Corrective Surgery in Adult Spinal Deformity.

    Albayar, Ahmed / Ramayya, Ashwin / Sullivan, Patricia Zadnik / Yoon, Jang / Saifi, Comron / Roche, Abigail / Ali, Zarina S / Welch, William C / Arlet, Vincent / Ozturk, Ali K

    International journal of spine surgery

    2022  Volume 15, Issue 6, Page(s) 1082–1089

    Abstract: Background: There is a paucity of literature covering the spinal alignment changes following adult spinal deformities (ASD) corrective surgeries. In theory, patients' posture and overall alignment may vary with postoperative pain, bracing, and other ... ...

    Abstract Background: There is a paucity of literature covering the spinal alignment changes following adult spinal deformities (ASD) corrective surgeries. In theory, patients' posture and overall alignment may vary with postoperative pain, bracing, and other external variables requiring further radiographic follow-up. The purpose of the study is to investigate changes in sagittal alignment in the first 3 months postoperatively.
    Methods: This is a retrospective case series of ASD patients who underwent deformity surgeries from October 2015 to June 2018. Patients < 40 years old, had < 6 levels fused, had acute proximal junctional kyphosis (PJK) or failure, or lacked imaging were excluded. Physiologic measures, spine alignment changes measured in whole-spine radiographs. Lumbar lordosis (LL), thoracic kyphosis (TK), and sagittal vertical axis (SVA) at immediate and 3-month postoperative time points were measured, then compared via 2-sample Student
    Results: Thirty-six patients (24 females, 67%) with a mean age of 61.5 years (range, 40-75 years) were included. Spinal alignment comparisons showed a significant increase in TK at the 3-month time point (
    Conclusions: Our results suggest that as postoperative pain subsides and the body settles into its new alignment, significant changes occur in spine sagittal parameters in the subacute period following surgery.
    Level of evidence: 4.
    Language English
    Publishing date 2022-01-25
    Publishing country Netherlands
    Document type Journal Article
    ISSN 2211-4599
    ISSN 2211-4599
    DOI 10.14444/8194
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Tractography-Based Surgical Targeting for Thalamic Deep Brain Stimulation: A Comparison of Probabilistic vs Deterministic Fiber Tracking of the Dentato-Rubro-Thalamic Tract.

    Yang, Andrew I / Parker, Drew / Vijayakumari, Anupa A / Ramayya, Ashwin G / Donley-Fletcher, Melanie P / Aunapu, Darien / Wolf, Ronald L / Baltuch, Gordon H / Verma, Ragini

    Neurosurgery

    2022  Volume 90, Issue 4, Page(s) 419–425

    Abstract: Background: The ventral intermediate (VIM) thalamic nucleus is the main target for the surgical treatment of refractory tremor. Initial targeting traditionally relies on atlas-based stereotactic targeting formulas, which only minimally account for ... ...

    Abstract Background: The ventral intermediate (VIM) thalamic nucleus is the main target for the surgical treatment of refractory tremor. Initial targeting traditionally relies on atlas-based stereotactic targeting formulas, which only minimally account for individual anatomy. Alternative approaches have been proposed, including direct targeting of the dentato-rubro-thalamic tract (DRTT), which, in clinical settings, is generally reconstructed with deterministic tracking. Whether more advanced probabilistic techniques are feasible on clinical-grade magnetic resonance acquisitions and lead to enhanced reconstructions is poorly understood.
    Objective: To compare DRTT reconstructed with deterministic vs probabilistic tracking.
    Methods: This is a retrospective study of 19 patients with essential tremor who underwent deep brain stimulation (DBS) with intraoperative neurophysiology and stimulation testing. We assessed the proximity of the DRTT to the DBS lead and to the active contact chosen based on clinical response.
    Results: In the commissural plane, the deterministic DRTT was anterior (P < 10-4) and lateral (P < 10-4) to the DBS lead. By contrast, although the probabilistic DRTT was also anterior to the lead (P < 10-4), there was no difference in the mediolateral dimension (P = .5). Moreover, the 3-dimensional Euclidean distance from the active contact to the probabilistic DRTT was smaller vs the distance to the deterministic DRTT (3.32 ± 1.70 mm vs 5.01 ± 2.12 mm; P < 10-4).
    Conclusion: DRTT reconstructed with probabilistic fiber tracking was superior in spatial proximity to the physiology-guided DBS lead and to the empirically chosen active contact. These data inform strategies for surgical targeting of the VIM.
    MeSH term(s) Deep Brain Stimulation/methods ; Essential Tremor/diagnostic imaging ; Essential Tremor/surgery ; Humans ; Retrospective Studies ; Thalamus/diagnostic imaging ; Thalamus/physiology ; Thalamus/surgery ; Tremor
    Language English
    Publishing date 2022-01-17
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 135446-2
    ISSN 1524-4040 ; 0148-396X
    ISSN (online) 1524-4040
    ISSN 0148-396X
    DOI 10.1227/NEU.0000000000001840
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Expectation modulates neural representations of valence throughout the human brain.

    Ramayya, Ashwin G / Pedisich, Isaac / Kahana, Michael J

    NeuroImage

    2015  Volume 115, Page(s) 214–223

    Abstract: The brain's sensitivity to unexpected gains or losses plays an important role in our ability to learn new behaviors (Rescorla and Wagner, 1972; Sutton and Barto, 1990). Recent work suggests that gains and losses are ubiquitously encoded throughout the ... ...

    Abstract The brain's sensitivity to unexpected gains or losses plays an important role in our ability to learn new behaviors (Rescorla and Wagner, 1972; Sutton and Barto, 1990). Recent work suggests that gains and losses are ubiquitously encoded throughout the human brain (Vickery et al., 2011), however, the extent to which reward expectation modulates these valence representations is not known. To address this question, we analyzed recordings from 4306 intracranially implanted electrodes in 39 neurosurgical patients as they performed a two-alternative probability learning task. Using high-frequency activity (HFA, 70-200 Hz) as an indicator of local firing rates, we found that expectation modulated reward-related neural activity in widespread brain regions, including regions that receive sparse inputs from midbrain dopaminergic neurons. The strength of unexpected gain signals predicted subjects' abilities to encode stimulus-reward associations. Thus, neural signals that are functionally related to learning are widely distributed throughout the human brain.
    MeSH term(s) Adult ; Algorithms ; Anticipation, Psychological/physiology ; Brain/anatomy & histology ; Brain/physiology ; Brain Mapping ; Dopaminergic Neurons/physiology ; Drug Resistant Epilepsy/surgery ; Electrodes, Implanted ; Electroencephalography ; Emotions/physiology ; Female ; Humans ; Learning/physiology ; Male ; Mesencephalon/physiology ; Reinforcement (Psychology) ; Reward
    Language English
    Publishing date 2015-07-15
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 1147767-2
    ISSN 1095-9572 ; 1053-8119
    ISSN (online) 1095-9572
    ISSN 1053-8119
    DOI 10.1016/j.neuroimage.2015.04.037
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Surface-Registration Frameless Stereotactic Navigation Is Less Accurate During Prone Surgeries: Intraoperative Near-Infrared Visualization Using Second Window Indocyanine Green Offers an Adjunct.

    Cho, Steve S / Teng, Clare W / Ramayya, Ashwin / Buch, Love / Hussain, Jasmin / Harsch, Jessica / Brem, Steven / Lee, John Y K

    Molecular imaging and biology

    2020  Volume 22, Issue 6, Page(s) 1572–1580

    Abstract: Background: Frameless neuronavigation allows neurosurgeons to visualize and relate the position of surgical instruments to intracranial pathologies based on preoperative tomographic imaging. However, neuronavigation can often be inaccurate. Multiple ... ...

    Abstract Background: Frameless neuronavigation allows neurosurgeons to visualize and relate the position of surgical instruments to intracranial pathologies based on preoperative tomographic imaging. However, neuronavigation can often be inaccurate. Multiple factors have been proposed as potential causes, and new technologies are needed to overcome these challenges.
    Objective: To evaluate the accuracy of neuronavigation systems compared to near-infrared (NIR) fluorescence imaging using Second Window Indocyanine Green, a novel technique, and to determine factors that lead to neuronavigation errors.
    Methods: A retrospective analysis was conducted on 56 patients who underwent primary resections of intracranial tumors. Patients received 5 mg/kg ICG approximately 24 h preoperatively. Intraoperatively, neuronavigation was used to plan craniotomies to place the tumors in the center. After craniotomy, NIR imaging visualized tumor-specific NIR signals. The accuracy of neuronavigation and NIR fluorescence imaging for delineating the tumor boundary prior to durotomy was compared.
    Results: The neuronavigation centers and NIR centers were 23.0 ± 7.7 % and 2.6 ± 1.1 % deviated from the tumor centers, respectively, relative to the craniotomy sizes. In 12 cases, significant changes were made to the planned durotomy based on NIR imaging. Patient position was a significant predictor of neuronavigation inaccuracy on both univariate and multivariate analysis, with the prone position having significantly higher inaccuracy (29.2 ± 8.1 %) compared to the supine (16.2 ± 8.1 %, p value < 0.001) or the lateral (17.9 ± 5.1 %, p value = 0.003) positions.
    Conclusion: Patient position significantly affects neuronavigation accuracy. Intraoperative NIR fluorescence imaging before durotomy offers an opportunity to readjust the neuronavigation image space to better align with the patient space.
    MeSH term(s) Craniotomy ; Female ; Humans ; Indocyanine Green/chemistry ; Male ; Middle Aged ; Monitoring, Intraoperative ; Multivariate Analysis ; Neuronavigation ; Prone Position ; Spectroscopy, Near-Infrared ; Stereotaxic Techniques
    Chemical Substances Indocyanine Green (IX6J1063HV)
    Language English
    Publishing date 2020-03-30
    Publishing country United States
    Document type Clinical Trial ; Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 2079160-4
    ISSN 1860-2002 ; 1536-1632
    ISSN (online) 1860-2002
    ISSN 1536-1632
    DOI 10.1007/s11307-020-01495-8
    Database MEDical Literature Analysis and Retrieval System OnLINE

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