Mar Cortes | Weill Cornell Medicine (original) (raw)

Papers by Mar Cortes

Journal of neurotrauma, Jan 28, 2015

While various approaches have been proposed in clinical trials aimed at improving motor function ... more While various approaches have been proposed in clinical trials aimed at improving motor function after spinal cord injury in humans, there is still limited information regarding the scope, methodological quality and evidence associated with single-intervention and multi-intervention approaches. A systematic review carried out using the PubMed search engine and the keywords "spinal cord injury motor recovery" identified 1,973 records, of which 39 were selected (18 from the search records and 21 from reference list inspection). Study phase (clinicaltrials.org criteria) and methodological quality (Cochrane criteria) were assessed. Studies included proposed a broad range of single-intervention (encompassing cell therapies, pharmacology, electrical stimulation, rehabilitation) (encompassing cell therapies, pharmacology, electrical stimulation, rehabilitation), and multi-intervention approaches (that combined more than one strategy). The highest evidence level was for phase III ...

Neurology, Jan 17, 2015

The nonlesioned motor cortex (M1NL) is thought to be hyperexcitable in patients with subacute or ... more The nonlesioned motor cortex (M1NL) is thought to be hyperexcitable in patients with subacute or chronic stroke and offers a promising therapeutic target. However, whether M1NL excitability behaves the same for subcortical and cortical strokes is unknown. The aim of the present study was to determine whether cortical, or purely subcortical, strokes have a different effect on M1NL excitability. We looked for correlations between the Fugl-Meyer (FM) score and M1NL resting motor threshold (RMTNL) in 34 stroke survivors classified according to lesion location (cortico-subcortical or purely subcortical). In addition to the FM, the Wolf Motor Score and motor power were measured. FM correlated with RMTNL for subcortical (r = 0.82; p = 0.001) but not for cortical strokes (r = 0.11; p = 0.62). Likewise, Wolf Motor Score (r = -0.62; p = 0.03) and motor power (r = 0.64; p = 0.023) were correlated with RMTNL for the subcortical group, but not for the cortical group. We show that the impact on M...

PURPOSE: The RBPE was designed to discover, via novel technologies & integrative science, the com... more PURPOSE: The RBPE was designed to discover, via novel technologies & integrative science, the complexity of human performance, with the explicit goal of developing strategies that advance human athletic potential. This year’s project investigated the neurophysiological correlates (corticomotor excitability) of fatiguing exercise in world-class athletes, with contemporary methods of examining work and physiologic response. We aimed to identify if transcranial magnetic stimulation could identify a central reserve, how this changed with fatigue, and whether preceding interventional brain stimulation (tDCS) would alter this response. This paper focuses on cardio-respiratory responses and cycling performance during a 4k time-trial (4kTT) following repeated bouts of high-intensity exercise over a five day period. METHODS: Four world-class athletes exhibiting four cycling phenotypes participated (BMX sprint cyclist, cyclo-cross bike racer, half-Ironman triathlete, and an extreme ultra-endu...

Archives of Physical Medicine and Rehabilitation, 2014

5 6 7 Objective: To investigate the effects of anodal transcranial direct current stimulation (a-... more 5 6 7 Objective: To investigate the effects of anodal transcranial direct current stimulation (a-8 tDCS) intensity on corticospinal excitability and affected muscle activation in individuals 9 with chronic spinal cord injury (SCI). 10 11 Design: Single blind, randomized, sham-controlled, crossover study. 12 13 Setting: Medical Research Institute and Rehabilitation Hospital. 14 15 Participants: Nine volunteers with chronic SCI and motor dysfunction in wrist extensor 16 muscles. 17 18 Intervention: Three single session exposures to 20 minutes of a-tDCS (anode over the 19 extensor carpi radialis (ECR) muscle representation on the left primary motor cortex, 20 cathode over the right supraorbital area), using 1 mA, 2 mA or sham stimulation, delivered 21 at rest, with at least one week between sessions. 22 23 Outcome Measures: Corticospinal excitability was assessed with motor evoked potentials 24

Cognitive Plasticity in Neurologic Disorders, 2014

ABSTRACT In a historical context, the concept of brain plasticity is new. The extent to which bra... more ABSTRACT In a historical context, the concept of brain plasticity is new. The extent to which brain plasticity underlies human adaptive behavior and cognition, in both health and disease, has emerged as a field at the forefront of scientific discovery. At least 50 years of exploration in this area, together with progressively advancing technology, have enabled the rapid advancement of, and innovative approaches to, the examination and treatment of human neurological disorders.

PURPOSE: During fatiguing exercise in healthy humans, the central governor theory posits that the... more PURPOSE: During fatiguing exercise in healthy humans, the central governor theory posits that the brain output slows before peripheral fatigue, leaving a central reserve. We proposed that highly trained athletes might have access to the central reserve. The primary test to examine this was transcranial magnetic stimulation (TMS) with single pulse stimulation over the primary leg motor cortex during maximal quadriceps muscle activation in a fresh condition, and then immediately following exhaustive cycling exercise. METHODS: In four professional cyclists, we tested the EMG silent period duration following the motor evoked potential (stimulus intensity adjusted for ~1mV, or max tolerated intensity) during five maximal voluntary isometric contractions (MVIC), in the fresh state and then repeated post exercise (~6min; 4000m time trial). Tests were conducted at the velodrome over two consecutive days, as part of a broader 5-day testing schedule involving both laboratory and velodrome tes...

BMJ case reports, 2014

Tinnitus may become refractory to treatment and disabling. Brain transcranial magnetic stimulatio... more Tinnitus may become refractory to treatment and disabling. Brain transcranial magnetic stimulation (TMS) has shown promise as a therapy, but has been employed primarily short-term. We treated a patient with 5 weeks of weekly repetitive TMS (rTMS), followed by 6 months of monthly rTMS. He was a 75-year-old dentist with chronic tinnitus from occupational noise exposure. Physical examination and MRIs of the auditory canals and brain had revealed no lesions. The patient showed a general gradual, progressive improvement on per cent of severe tinnitus diary days (from baseline 100% to 33%), tinnitus handicap inventory (from baseline score 70 to 18), and mini-tinnitus questionnaire (from baseline score 17 to 6). No changes occurred in serial audiograms. Transient adverse events were a headache during stimulation, and dizziness 30 min after treatment. Implications and questions for future non-invasive neuromodulation clinical research raised by our case are discussed.

Recovering upper-limb motor function has important implications for improving independence of pat... more Recovering upper-limb motor function has important implications for improving independence of patients with tetraplegia after traumatic spinal cord injury (SCI). To evaluate the feasibility, safety and effectiveness of robotic-assisted training of upper limb in a chronic SCI population. A total of 10 chronic tetraplegic SCI patients (C4 to C6 level of injury, American Spinal Injury Association Impairment Scale, A to D) participated in a 6-week wrist-robot training protocol (1 hour/day 3 times/week). The following outcome measures were recorded at baseline and after the robotic training: a) motor performance, assessed by robot-measured kinematics, b) corticospinal excitability measured by transcranial magnetic stimulation (TMS), and c) changes in clinical scales: motor strength (Upper extremity motor score), pain level (Visual Analog Scale) and spasticity (Modified Ashworth scale). No adverse effects were observed during or after the robotic training. Statistically significant improvements were found in motor performance kinematics: aim (pre 1.17 ± 0.11 raduans, post 1.03 ± 0.08 raduans, p = 0.03) and smoothness of movement (pre 0.26 ± 0.03, post 0.31 ± 0.02, p = 0.03). These changes were not accompanied by changes in upper-extremity muscle strength or corticospinal excitability. No changes in pain or spasticity were found. Robotic-assisted training of the upper limb over six weeks is a feasible and safe intervention that can enhance movement kinematics without negatively affecting pain or spasticity in chronic SCI. In addition, robot-assisted devices are an excellent tool to quantify motor performance (kinematics) and can be used to sensitively measure changes after a given rehabilitative intervention.

Classical de-afferentation studies, as well as experience-dependent visual plasticity paradigms, ... more Classical de-afferentation studies, as well as experience-dependent visual plasticity paradigms, have confirmed that both the developing and adult nervous system are capable of unexpected levels of plasticity. This capacity is underscored by the significant spontaneous recovery that can occur in patients with mild-to-moderate impairment following stroke. An evolving model is that an interaction of biological and environmental factors during all epochs post-stroke influences the extent and quality of this plasticity. Here, we discuss data that have implicated specific epigenetic proteins as integrators of environmental influences in 3 aspects of stroke recovery: spontaneous impairment reduction in humans; peri-infarct rewiring in animals as a paradigm for developing therapeutically-driven impairment reduction beyond natural spontaneous recovery; and, finally, classical hippocampal learning and memory paradigms that are theoretically important in skill acquisition for both impairment reduction and compensatory strategies in the rehabilitation setting. Our discussion focuses primarily on B lymphoma Mo-MLV1 insertion region proteins of the polycomb repressive complex, alpha thalassemia/mental retardation syndrome X-linked chromatin remodeling factors, and the best known and most dynamic gene repressors, histone deacetylases. We will highlight exciting current data associated with these proteins and provide promising speculation about how they can be manipulated by drugs, biologics, or noninvasive stimulation for stroke recovery.

Archives of Physical Medicine and Rehabilitation, 2014

Spinal Cord, 2013

Study design: Case report. Objectives: To identify preserved corticomotor connection in chronic s... more Study design: Case report. Objectives: To identify preserved corticomotor connection in chronic spinal cord injury (SCI) in the absence of clinically observable movement. Setting: Rehabilitation Hospital and Medical Research Institute, NY, USA. Methods: The motor-evoked potential (MEP) response to transcranial magnetic stimulation (TMS) was recorded using surface electromyography from the right biceps brachii, extersor carpi radialis (ECR), flexor carpi radialis (FCR) and abductor pollicis brevis (APB) muscles in a 31-year-old male traumatic SCI chronic patient-ASIA B, injury level C5. Motor power scores were additionally obtained from a clinician blinded to the results of TMS. Results: TMS could consistently elicit MEPs of normal latency, phase and amplitude, in the severely affected ECR muscle but not the similarly affected FCR muscle. The response in proximal and unaffected biceps muscle was larger than the healthy subject, whereas no response was obtained in the distal APB muscle as expected. Conclusion: TMS can identify residual pathways not apparent from clinical assessment alone, which may have prescriptive value for rehabilitation.

Neuromodulation: Technology at the Neural Interface, 2012

Rationale: An improved understanding of motor dysfunction and recovery after stroke has important... more Rationale: An improved understanding of motor dysfunction and recovery after stroke has important clinical implications that may lead to the design of more effective rehabilitation strategies for patients with hemiparesis.

Journal of neuroengineering and rehabilitation, 2012

The use of automated electromechanical devices for gait training in neurological patients is incr... more The use of automated electromechanical devices for gait training in neurological patients is increasing, yet the functional outcomes of well-defined training programs using these devices and the characteristics of patients that would most benefit are seldom reported in the literature. In an observational study of functional outcomes, we aimed to provide a benchmark for expected change in gait function in early stroke patients, from an intensive inpatient rehabilitation program including both robotic and manual gait training.

Brain Stimulation, 2013

Motor surround inhibition (mSI) is one mechanism by which the central nervous system individuates... more Motor surround inhibition (mSI) is one mechanism by which the central nervous system individuates finger movements, and yet the neuroanatomical substrate of this phenomenon is currently unknown. In this study, we examined the role of the cerebellum in the generation of mSI, using transcranial direct current stimulation of the cerebellum (cDC). We also examined intrasubject and intersubject variability of mSI. Twelve subjects completed a three session cross over study in which mSI was measured before and after (0 and 20 minutes) sham, anodal and cathodal cDC. mSI of the surround muscle (adductor digiti minimi) at the onset of flexion of the index finger was consistently observed. Anodal and cathodal cDC did not modulate the magnitude of mSI. For individual subjects (across the three sessions), the intrasubject coefficient of variation was 27%. Between subjects, the intersubject coefficient of variation was 47%. mSI was a stable effect in individual subjects across multiple sessions. This is an important observation and contrasts with other neurophysiological paradigms such as paired associative stimulation response, which exhibit great variability. In addition, we have quantified intrasubject variability of mSI, which will allow future therapeutic studies that attempt to modulate mSI to be adequately powered. We have not found evidence that the cerebellum contributes to the neuroanatomical network needed for the generation of mSI. Understanding the mechanisms of mSI remains a challenge but is important for disorders in which it is deficient such as Parkinson's disease and focal hand dystonia.

Journal of neurotrauma, Jan 28, 2015

Neurology, Jan 17, 2015

Archives of Physical Medicine and Rehabilitation, 2014

Cognitive Plasticity in Neurologic Disorders, 2014

BMJ case reports, 2014

Archives of Physical Medicine and Rehabilitation, 2014

Spinal Cord, 2013

Neuromodulation: Technology at the Neural Interface, 2012

Journal of neuroengineering and rehabilitation, 2012

Brain Stimulation, 2013