Andres M Lozano

Andres M Lozano
University of Toronto | U of T · Division of Neurosurgery

MD PhD

About

1,048
Publications
139,913
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66,545
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Additional affiliations
January 1991 - present
University of Toronto
Position
  • Professor (Full)

Publications

Publications (1,048)
Article
Background MR-guided focused ultrasound (MRgFUS) thalamotomy has been shown to be a safe and effective treatment for essential tremor (ET). Objective To investigate the effects of MRgFUS in patients with ET with an emphasis on ipsilateral-hand and axial tremor subscores. Methods Tremor scores and adverse effects of 100 patients treated between 2012...
Article
Background: Deep brain stimulation (DBS) provides symptomatic relief in a growing number of neurological indications, but local synaptic dynamics in response to electrical stimulation that may relate to its mechanism of action have not been fully characterized. Objective: The objectives of this study were to (1) study local synaptic dynamics during...
Article
Objective: To describe a case of functional tremor occurring after a successful MR-guided focused ultrasound thalamotomy (MRgFUS) for essential tremor. Methods: A 71-year-old right-handed man with essential tremor was referred to us for consideration of deep brain stimulation surgery for worsening bilateral upper limb tremor after a successful l...
Preprint
Deep brain stimulation procedures offer an invaluable opportunity to study disease through intracranial recordings from awake patients. Herein, we address the relationship between single-neuron and aggregate-level (local field potential; LFP) activities in the subthalamic nucleus (STN) and thalamic ventral intermediate nucleus (Vim) of patients wit...
Article
Full-text available
Deep brain stimulation is a treatment option for patients with drug-resistant epilepsy. The precise mechanism of neuromodulation in epilepsy is unknown and biomarkers are needed for optimizing treatment. The aim of this study was to describe the neural network associated with deep brain stimulation targets for epilepsy and to explore its potential...
Article
Full-text available
Background: Obsessive-compulsive disorder (OCD) is a debilitating disease with a lifetime prevalence of 2-3%. Neuromodulatory treatments have been successfully used in severe cases. Deep brain stimulation (DBS) targeting the inferior thalamic peduncle (ITP) has been shown to successfully alleviate symptoms in OCD patients; however, the brain circu...
Article
Full-text available
Background Deep brain stimulation (DBS) is an established treatment for certain movement disorders and has additionally shown promise for various psychiatric, cognitive, and seizure disorders. However, the mechanisms through which stimulation exerts therapeutic effects are incompletely understood. A technique that may help to address this knowledge...
Chapter
Chapter on the history, present and future developments of neurosurgical treatments of Alzheimer Disease with a focus on Deep Brain Stimulation.
Preprint
Background Cognitive flexibility encompasses the ability to efficiently shift focus and forms a critical component of goal-directed attention. The neural substrates of this process are incompletely understood in part due to difficulties in sampling the involved circuitry. Methods Stereotactic intracranial recordings that permit direct resolution o...
Article
Full-text available
The neurophysiological footprint of brain activity after cardiac arrest and during near-death experience (NDE) is not well understood. Although a hypoactive state of brain activity has been assumed, experimental animal studies have shown increased activity after cardiac arrest, particularly in the gamma-band, resulting from hypercapnia prior to and...
Article
Objective: Peripheral nerve field stimulation (PNFS) is a tool in the armamentarium of treatment options for trigeminal pain. The efficacy of this modality in mitigating trigeminal pain remains unclear. The aim of this study was to examine the existing literature on PNFS and elucidate pain score outcomes associated with its use in patients with tr...
Article
Full-text available
The habenula (Hb) is a small, evolutionarily conserved epithalamic structure implicated in functions such as reward and mood regulation. Prior imaging work suggests that Hb's structural and functional properties may relate to treatment response in depression and other mood disorders. We used multimodal MRI techniques to investigate the potential in...
Article
Full-text available
Background: Deep brain stimulation (DBS) is a neuromodulatory technique that delivers adjustable electrical stimuli to brain targets to relieve symptoms associated with dysregulated neural circuitry. Over the last several decades, DBS has been applied to a number of conditions, including motor, pain, mood, and cognitive disorders. An assessment of...
Article
Background: Patients with Parkinson's disease might develop treatment-resistant axial dysfunction after bilateral subthalamic stimulation. Objectives: To study whether lateralized stimulation (unilateral 50% amplitude reduction) for ≥21 days results in ≥0.13 m/s faster gait velocity in the dopaminergic ON state in these patients, and its effects...
Article
OBJECTIVE Individuals with autism spectrum disorder (ASD) may display extreme behaviors such as self-injury or aggression that often become refractory to psychopharmacology or behavioral intervention. Deep brain stimulation (DBS) is a surgical alternative that modulates brain circuits that have yet to be clearly elucidated. In the current study the...
Article
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Neuro-oncology research is broad and includes several branches, one of which is neuroimaging. Magnetic resonance imaging (MRI) is instrumental for the diagnosis and treatment monitoring of patients with brain tumors. Most commonly, structural and perfusion MRI sequences are acquired to characterize tumors and understand their behaviors. Thanks to t...
Article
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Background Leukoencephalopathy with brain calcifications and cysts (LCC; also known as Labrune syndrome) is a rare genetic microangiopathy caused by biallelic mutations in SNORD118. The mechanisms by which loss-of-function mutations in SNORD118 lead to the phenotype of leukoencephalopathy, calcifications and intracranial cysts is unknown. Case pre...
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Introduction After several years of brain-sensing technology development and proof-of-concept studies, adaptive deep brain stimulation (aDBS) is ready to better treat Parkinson’s disease (PD) using aDBS-capable implantable pulse generators (IPGs). New aDBS devices are capable of continuous sensing of neuronal activity from the subthalamic nucleus (...
Article
Deep brain stimulation (DBS) is a neuromodulatory treatment used in patients with drug-resistant epilepsy (DRE). The primary goal of this systematic review and meta-analysis is to describe recent advancements in the field of DBS for epilepsy, to compare the results of published trials, and to clarify the clinical utility of DBS in DRE. A systematic...
Article
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Objective Transcranial ultrasound stimulation (TUS) is a promising non-invasive brain stimulation technique with advantages of high spatial precision and ability to target deep brain regions. This study aimed to develop a TUS protocol to effectively induce brain plasticity in human subjects. Methods An 80 s train of theta burst patterned TUS (tbTU...
Article
Deep brain stimulation targeting the subcallosal cingulate area, a hub with multiple axonal projections, has shown therapeutic potential for treatment-resistant mood disorders. While subcallosal cingulate deep brain stimulation drives long-term metabolic changes in corticolimbic circuits, the brain areas that are directly modulated by electrical st...
Article
Full-text available
The evaluation and manipulation of structural and functional networks, which has been integral to advancing functional neurosurgery, is beginning to transcend classical subspecialty bound- aries. Notably, its application in neuro-oncologic surgery has stimulated an exciting paradigm shift from the traditional localizationist approach, which is lack...
Article
Full-text available
Background Parkinson’s disease is a disabling neurodegenerative movement disorder characterized by dopaminergic neuron loss induced by α-synuclein oligomers. There is an urgent need for disease-modifying therapies for Parkinson’s disease, but drug discovery is challenged by lack of in vivo models that recapitulate early stages of neurodegeneration....
Article
Objective. Adaptive deep brain stimulation (aDBS) is a form of invasive stimulation that was conceived to overcome the technical limitations of traditional DBS, which delivers continuous stimulation of the target structure without considering patients’ symptoms or status in real-time. Instead, aDBS delivers on-demand, contingency-based stimulation....
Article
Background: Alterations of synaptic excitability and reduced brain metabolism are some of the earliest changes associated Alzheimer's disease (AD) pathogenesis (Reiman et al., 2004; Sperling et al., 2009). Among different approaches for therapeutics, the stimulation of synaptic activity exerts protective effects in models of AD, and deep brain sti...
Article
Full-text available
Background: Subthalamic nucleus deep brain stimulation (STN DBS) is an established therapy for Parkinson's disease (PD) patients suffering from motor response fluctuations despite optimal medical treatment, or severe dopaminergic side effects. Despite careful clinical selection and surgical procedures, some patients do not benefit from STN DBS. Pr...
Article
OBJECTIVE Pain is the most common nonmotor symptom of Parkinson’s disease (PD) and is often undertreated. Deep brain stimulation (DBS) effectively mitigates the motor symptoms of this multisystem neurodegenerative disease; however, its therapeutic effect on nonmotor symptoms, especially pain, remains inconclusive. While there is a critical need to...
Article
Background: Deep brain stimulation (DBS) of the nucleus basalis of Meynert (NBM) is an emerging target to potentially treat cognitive dysfunction. Objectives: The aim of this study is to achieve feasibility and safety of globus pallidus pars interna (GPi) and NBM DBS in advanced PD with cognitive impairment. Methods: We performed a phase-II do...
Preprint
Full-text available
Background Deep brain stimulation (DBS) provides symptomatic relief in a growing number of neurological indications, but local synaptic dynamics in response to electrical stimulation that may relate to its mechanism of action have not been fully characterized. Objective The objectives of this study were to (1) study local synaptic dynamics during...
Article
Full-text available
Spinal cord stimulation (SCS) is an established treatment for refractory pain syndromes and has recently been applied to improve locomotion. Several technical challenges are faced by surgeons during SCS lead implantation, particularly in the confined dorsal epidural spaces in patients with spinal degenerative disease, scarring and while targeting c...
Article
Full-text available
Background: Postoperative outcome following deep brain stimulation (DBS) of the subthalamic nucleus is variable, particularly with respect to axial motor improvement. We hypothesized a genetic underpinning to the response to surgical intervention, termed "surgicogenomics". Objective: We aimed to identify genetic variants associated with clinical...
Chapter
Deep brain stimulation (DBS) is known to both modulate local circuits and impact distributed brain networks. These networks can be studied in vivo using functional MRI (fMRI) and diffusion-weighted MRI (dMRI), although these sequences are not routinely acquired in DBS patients. Normative connectomes – aggregate connectivity datasets assembled from...
Book
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The book is available here: https://www.elsevier.com/books/connectomic-deep-brain-stimulation/horn/978-0-12-821861-7
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Background Numerous neuromodulatory therapies are currently under investigation or in clinical use for the treatment of psychiatric conditions. Objective/hypothesis We sought to catalogue past and present human research studies on psychiatric neuromodulation and identify relevant trends in this field. Methods ClinicalTrials.gov (https://www.clini...
Article
Low-intensity transcranial ultrasound stimulation (TUS) is a promising non-invasive brain stimulation technique that can modulate the excitability of cortical and deep brain structures with a high degree of focality. Previous human studies showed that TUS decreases motor cortex (M1) excitability measured by transcranial magnetic stimulation (TMS),...
Article
Full-text available
This study compares the effects on motor symptoms between conventional deep brain stimulation (cDBS) and closed-loop adaptive deep brain stimulation (aDBS) in patients with Parkinson’s Disease. The aDBS stimulation is controlled by the power in the beta band (12–35 Hz) of local field potentials recorded directly by subthalamic nucleus electrodes. E...
Article
Full-text available
Deep brain stimulation (DBS) represents an important treatment modality for movement disorders and other circuitopathies. Despite their miniaturization and increasing sophistication, DBS systems share a common set of components of which the implantable pulse generator (IPG) is the core power supply and programmable element. Here we provide an overv...
Article
Objectives Programming deep brain stimulation (DBS) is still based on a trial-and-error approach, often becoming a time-consuming process for both treating physicians and patients. Several strategies have been proposed to streamline DBS programming, most of which are preliminary and mainly address Parkinson's disease, a condition readily responsive...
Article
Full-text available
Background: Chronic pain is a debilitating condition that imposes a tremendous burden on health-care systems around the world. While frontline treatments for chronic pain involve pharmacological and psychological approaches, neuromodulation can be considered for treatment-resistant cases. Neuromodulatory approaches for pain are diverse in both mod...
Article
Full-text available
Background The application of stimulators implanted directly over deep brain structures (i.e., deep brain stimulation, DBS) was developed in the late 1980s and has since become a mainstream option to treat several neurological conditions. Conventional DBS involves the continuous stimulation of the target structure, which is an approach that cannot...
Article
Parkinson's disease can be associated with significant cognitive impairment that may lead to dementia. Deep brain stimulation (DBS) of the subthalamic nucleus is an effective therapy for motor symptoms but is associated with cognitive decline. DBS of globus pallidus internus (GPi) poses less risk of cognitive decline so may be the preferred target....
Article
Subcallosal cingulate deep brain stimulation produces long-term clinical improvement in approximately half of patients with severe treatment-resistant depression. We hypothesized that both structural and functional brain attributes may be important in determining responsiveness to this therapy. In a treatment-resistant depression subcallosal cingul...
Article
Background In patients with medically refractory essential tremor, unilateral magnetic resonance–guided focused ultrasound thalamotomy can improve contralateral tremor. However, this procedure does not address ipsilateral symptoms. Objective The objective of the current study was to determine whether bilateral thalamotomies can be performed with a...
Article
Full-text available
The habenula is a small bilateral epithalamic structure that plays a key role in the regulation of the main monoaminergic systems. It is implicated in many aspects of behaviour such as reward processing, motivational behavior, behavioral adaptation, and sensory integration. A role of the habenula has been indicated in the pathophysiology of a numbe...
Article
Background Deep brain stimulation (DBS) of the subthalamus (STN) is effective for the treatment of cardinal motor signs of Parkinson disease (PD). Structures around the STN can suppress dyskinesia and tremor (zona incerta) and improve gait and balance (substantia nigra pars reticulata). Objective Is the newer 8-contact linear lead connected to a ‘...
Article
Full-text available
Introduction: Programming directional leads poses new challenges as the optimal strategy is yet to be established. We designed a randomized control study to establish an evidence-based programming algorithm for patients with Parkinson's disease undergoing subthalamic nucleus deep brain stimulation with directional leads. Methods: Fourteen consec...
Article
Objective Anterior nucleus of thalamus (ANT) deep brain stimulation (DBS) has shown promise as a treatment for medically refractory epilepsy. To better understand the mechanism of this intervention, we used functional magnetic resonance imaging (fMRI) to map the acute blood oxygen level-dependent (BOLD) response pattern to thalamic DBS in fully imp...
Article
Obsessive-compulsive disorder is a debilitating and often refractory psychiatric disorder. Magnetic resonance-guided focused ultrasound is a novel, minimally invasive neuromodulatory technique that has shown promise in treating this condition. We investigated the relationship between lesion location and long-term outcome in patients with obsessive-...
Article
Full-text available
Background: Age may affect treatment outcome in trials of mild probable Alzheimer's disease (AD). Objective: We examined age as a moderator of outcome in an exploratory study of deep brain stimulation targeting the fornix (DBS-f) region in participants with AD. Methods: Forty-two participants were implanted with DBS electrodes and randomized t...
Article
Objective Surgical resection can decrease seizure frequency in medically intractable temporal lobe epilepsy. The functional and structural consequences of this intervention on brain circuitry are poorly understood, however. We investigated structural changes that occur in brain circuits following mesial temporal lobe resection for refractory epilep...
Article
Full-text available
Commonly used for Parkinson's disease (PD), deep brain stimulation (DBS) produces marked clinical benefits when optimized. However, assessing the large number of possible stimulation settings (i.e., programming) requires numerous clinic visits. Here, we examine whether functional magnetic resonance imaging (fMRI) can be used to predict optimal stim...
Article
BACKGROUND The therapeutic challenge of glioblastoma (GBM) has catalyzed the development of clinical trials to evaluate novel interventions. With increased understanding of GBM biology and technological advances, the neurosurgeon's role in neuro-oncology has evolved. OBJECTIVE To evaluate the current landscape of procedure-based clinical trials fo...
Article
Full-text available
Background Deep brain stimulation is an established therapy for several neurological disorders; however, its effects on neuronal activity vary across brain regions and depend on stimulation settings. Understanding these variable responses can aid in the development of physiologically-informed stimulation paradigms in existing or prospective indicat...