Publications by authors named "Peter Konrad"

Background And Objectives: Deep brain stimulation (DBS) is an effective treatment for Parkinson's disease (PD) motor symptoms. DBS is also associated with postoperative cognitive change in some patients. Previous studies found associations between medial active electrode contacts and overall cognitive decline.

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Magnetic resonance-guided, focused ultrasound thalamotomy is a neurosurgical treatment for refractory essential tremor. This study examined cognitive outcomes following unilateral magnetic resonance-guided, focused ultrasound thalamotomy, targeting the ventral intermediate nucleus of the thalamus for essential tremor. The research was conducted at two sites: Sunnybrook Research Institute in Toronto, Canada, and West Virginia University School of Medicine Rockefeller Neuroscience Institute in West Virginia, USA.

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Transcranial-focused ultrasound (tFUS) procedures such as neuromodulation and blood-brain barrier (BBB) opening require precise focus placement within the brain. MRI is currently the most reliable tool for focus localization but can be prohibitive for procedures requiring recurrent therapies. We designed, fabricated, and characterized a patient-specific, 3-D-printed, stereotactic frame for repeated tFUS therapy.

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Objective: The goal of this study was to assess the safety of mapping spinal cord locomotor networks using penetrating stimulation microelectrodes in Yucatan minipigs (YMPs) as a clinically translational animal model.

Methods: Eleven YMPs were trained to walk up and down a straight line. Motion capture was performed, and electromyographic (EMG) activity of hindlimb muscles was recorded during overground walking.

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Background: Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that causes persistent synovitis, bone damage, and progressive joint destruction. Neuroimmune modulation through electrical stimulation of the vagus nerve activates the inflammatory reflex and has been shown to inhibit the production and release of inflammatory cytokines and decrease clinical signs and symptoms in RA. The RESET-RA study was designed to determine the safety and efficacy of an active implantable device for treating RA.

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Drug-induced tremor is a common side effect of lithium with an occurrence of approximately 25% of patients. Cessation of the offending drug can be difficult, and many medical treatments for drug-induced tremor are ineffective. Deep brain stimulation (DBS) has been shown in a limited number of case reports to effectively reduce drug-induced tremor, however, which remains an invasive therapeutic option.

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Objective: Subthalamic nucleus (STN) and globus pallidus internus (GPI) deep brain stimulation (DBS) effectively treat motor symptoms in Parkinson's disease (PD) but may be associated with cognitive and psychiatric changes in some patients. Evaluation of changes in cognitive and psychiatric symptoms following DBS is complicated by changes in these symptoms that occur as part of the natural disease course. The aim of this study was to evaluate whether electrode position was associated with changes in neurocognitive symptoms in patients who underwent STN and GPI DBS.

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Night shift work has been associated with breast, prostate, and colorectal cancer, but evidence on other types of cancer is limited. We prospectively evaluated the association of rotating night shift work, sleep duration, and sleep difficulty with thyroid cancer risk in the Nurses' Health Study 2 (NHS2). We assessed rotating night shift work duration (years) at baseline and throughout follow-up (1989-2015) and sleep characteristics in 2001.

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Background: Deep brain stimulation (DBS) is commonly performed with patients awake to perform intraoperative microelectrode recordings and/or macrostimulation testing to guide final electrode placement. Supplemental information from atlas-based databases derived from prior patient data and visualised as efficacy heat maps transformed and overlaid onto preoperative MRIs can be used to guide preoperative target planning and intraoperative final positioning. Our quantitative analysis of intraoperative testing and corresponding changes made to final electrode positioning aims to highlight the value of intraoperative neurophysiological testing paired with image-based data to optimise final electrode positioning in a large patient cohort.

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Background: Essential tremor (ET) and Parkinson's disease (PD) are the most common tremor disorders and are common indications for deep brain stimulation (DBS). In some patients, PD and ET symptoms overlap and diagnosis can be challenging based on clinical criteria alone. The objective of this study was to identify structural brain differences between PD and ET DBS patients to help differentiate these disorders and improve our understanding of the different brain regions involved in these pathologic processes.

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Introduction: The pilot trial of deep brain stimulation (DBS) in early-stage Parkinson's disease (PD) randomized 30 patients (medication duration 0.5-4 years; without dyskinesia or motor fluctuations) to receive optimal drug therapy alone (early ODT) or subthalamic nucleus (STN) DBS plus ODT (early DBS + ODT). This study reports long-term neuropsychological outcomes from the early DBS pilot trial.

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Background: Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive alternative to surgical resection for drug-resistant mesial temporal lobe epilepsy (mTLE). Reported rates of seizure freedom are variable and long-term durability is largely unproven. Anterior temporal lobectomy (ATL) remains an option for patients with MRgLITT treatment failure.

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Objective: This study was undertaken to describe relationships between electrode localization and motor outcomes from the subthalamic nucleus (STN) deep brain stimulation (DBS) in early stage Parkinson disease (PD) pilot clinical trial.

Methods: To determine anatomical and network correlates associated with motor outcomes for subjects randomized to early DBS (n = 14), voxelwise sweet spot mapping and structural connectivity analyses were carried out using outcomes of motor progression (Unified Parkinson Disease Rating Scale Part III [UPDRS-III] 7-day OFF scores [∆baseline➔24 months, MedOFF/StimOFF]) and symptomatic motor improvement (UPDRS-III ON scores [%∆baseline➔24 months, MedON/StimON]).

Results: Sweet spot mapping revealed a location associated with slower motor progression in the dorsolateral STN (anterior/posterior commissure coordinates: 11.

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Objective: The deep brain stimulation (DBS) in early-stage Parkinson's disease (PD) pilot clinical trial randomized 30 patients (Hoehn & Yahr II off; medication duration 0.5-4 years; without dyskinesia/motor fluctuations) to optimal drug therapy (ODT) (early ODT) or bilateral subthalamic nucleus (STN) DBS plus ODT (early DBS+ODT). This study aims to report the 11-year outcomes of patients who completed the DBS in early-stage PD pilot clinical trial.

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Objective: MRI-guided low-intensity focused ultrasound (FUS) has been shown to reversibly open the blood-brain barrier (BBB), with the potential to deliver therapeutic agents noninvasively to target brain regions in patients with Alzheimer's disease (AD) and other neurodegenerative conditions. Previously, the authors reported the short-term safety and feasibility of FUS BBB opening of the hippocampus and entorhinal cortex (EC) in patients with AD. Given the need to treat larger brain regions beyond the hippocampus and EC, brain volumes and locations treated with FUS have now expanded.

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Article Synopsis
  • Vagus Nerve Stimulation (VNS) with rehabilitation was FDA-approved in 2021 for improving motor function in chronic stroke survivors with severe arm and hand impairments.
  • The study involved 108 participants who underwent outpatient VNS implantation, with minimal complications noted, and most had recovery within 48 hours.
  • The findings indicate that the Vivistim System has a favorable safety profile comparable to previous VNS treatments for epilepsy and depression, supporting its use in stroke patients.
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The objectives of this study were to assess gait biomechanics and the effect of overground walking speed on gait parameters, kinematics, and electromyographic (EMG) activity in the hindlimb muscles of Yucatan minipigs (YMPs).Nine neurologically-intact, adult YMPs were trained to walk overground in a straight line. Whole-body kinematics and EMG activity of hindlimb muscles were recorded and analyzed at six different speed ranges (0.

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Introduction: Subthalamic nucleus (STN) deep brain stimulation (DBS) is recognized as a safe and effective treatment in mid- and advanced-staged Parkinson's disease (PD) that decreases the need for PD medications and their associated costs. This study reports medication costs from the only clinical trial to evaluate DBS in patients with early-stage PD and projects costs through advanced-stage disease.

Methods: The DBS in early-stage PD pilot was a prospective, single-blind clinical trial that randomized 30 patients with early-stage PD 1:1 to receive bilateral STN-DBS plus optimal drug therapy (ODT) or ODT alone.

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Conventional testing and diagnostic methods for infections like SARS-CoV-2 have limitations for population health management and public policy. We hypothesize that daily changes in autonomic activity, measured through off-the-shelf technologies together with app-based cognitive assessments, may be used to forecast the onset of symptoms consistent with a viral illness. We describe our strategy using an AI model that can predict, with 82% accuracy (negative predictive value 97%, specificity 83%, sensitivity 79%, precision 34%), the likelihood of developing symptoms consistent with a viral infection three days before symptom onset.

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 Microvascular decompression (MVD) is a common surgical treatment for cranial nerve compression, though cerebrospinal fluid (CSF) leak is a known complication of this procedure. Bone cement cranioplasty may reduce rates of CSF leak.  To compare rates of CSF leak before and after implementation of bone cement cranioplasty for the reconstruction of cranial defects after MVD.

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Background: The workup for idiopathic normal pressure hydrocephalus (INPH) can be difficult to coordinate, and determining appropriate patients for ventriculoperitoneal shunting can be challenging. Therefore, we hypothesized that implementing a formalized protocol can improve patient selection for a shunt. In conjunction with neurology and neurosurgery, we instituted a standardized means of assessing patients whose presentation is concerning for INPH and compared their workup with similar patients seen without the Protocol (i.

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We report a case of a 31-year-old immunocompetent male who presented with altered mental status and agitation requiring intubation. As sedation was weaned, he demonstrated choreiform movements with associated hemiballismus of the right upper and lower extremities, and he was ultimately diagnosed with cryptococcal meningitis. The patient's chorea did not terminate after the completion of induction antifungal therapy and all pharmacologic options for the management of chorea were ineffective.

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Introduction: The efficacy of pharmacotherapy and deep brain stimulation of the subthalamic nucleus in treating Parkinson's disease motor symptoms is highly variable and may be influenced by patient genotype. The relatively common (prevalence about one in three) and protein-altering rs6265 single nucleotide polymorphism (C > T) in the gene BDNF has been associated with different clinical outcomes with levodopa.

Objective: We sought to replicate this reported association in early-stage Parkinson's disease subjects and to examine whether a difference in clinical outcomes was present with subthalamic nucleus deep brain stimulation.

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