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Neural engineering
Published in Alex Mihailidis, Roger Smith, Rehabilitation Engineering, 2023
Over the past several decades, the field of neural engineering has evolved to include the “indirect” use of electrical nerve stimulation to treat chronic neurological disorders, such as urinary dysfunction, movement disorders, epilepsy, and depression. This clinical tool is called electrical neuromodulation and is defined as the process by which altered neural activity caused by electrical stimulation in one part of the nervous system modulates the ongoing activity of a targeted neural circuit. For example, electrical stimulation of peripheral nerves in the lower leg can inhibit bladder contractility via neural pathways that connect through the brainstem and also the lumbosacral spinal cord. There are numerous clinically effective therapies based on electrical neuromodulation that can suppress disease symptoms and significantly improve quality of life.
Synapses
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
Neuromodulation is broadly defined as the alteration of neuronal activity through application of a stimulating agent, which could be electrical or chemical. In the present context, the term neuromodulator refers to a chemical agent that affects neurons over a relatively large area of the brain or the spinal cord, mostly through G protein-coupled receptors. Neuromodulators could be neurotransmitters, such as norepinephrine, acetylcholine, dopamine, serotonin, and histamine released by certain groups of neurons but not reabsorbed by the presynaptic neuron – nor broken down. They may be released at nerve endings, as in slow chemical synapses, or they may be carried by the cerebrospinal fluid. Neuromodulators could also be hormones circulating through the blood, such as thyroid hormones, steroid hormones (such as androgen and estrogen), metabolic hormones (such as insulin), stress hormones (such as cortisol), sex hormones (such as testosterone), or neuropeptides such as adenosine or oxytocin.
Medical device implants for neuromodulation
Published in Ze Zhang, Mahmoud Rouabhia, Simon E. Moulton, Conductive Polymers, 2018
According to the North American Neuromodulation Society, neuromodulation is the “therapeutic alteration of (neural) activity either through stimulation or medication” delivered through implanted devices, such as an IPG for DBS or drug pumps. Neuromodulation may target the central or peripheral nervous systems, including the spinal cord, brain, or spinal nerves. Traditionally, therapeutic neuromodulation has treated chronic pain, movement disorders, epilepsy, gastrological disorders, and urological disorders (Lewis et al. 2016). Recently, neuromodulation has been studied for the treatment of traumatic spinal cord and brain injuries (Shin et al. 2014) and psychiatric disorders (Wichmann and Delong 2006). Neuromodulation may be applied or investigated by clinicians and researchers from a range of disciplines, including neurosurgery, neurology, neuroscience, psychiatry, physical therapy, and rehabilitation.
The future potential of the Stentrode
Published in Expert Review of Medical Devices, 2019
Sam E. John, David B. Grayden, Takufumi Yanagisawa
The StentrodeTM was also used to stimulate the motor cortex to generate gross movements [2]. Neuromodulation or stimulation of the brain has offered life-changing treatments for people with neurological conditions such as Parkinson’s disease and epilepsy, usually by deep-brain stimulation. Using the venous approach, the StentrodeTM can reach prefrontal brain regions, motor and somatosensory regions, and parietal regions adjacent to the interhemispheric fissure [1,10]. Although more challenging, an intravascular device like the StentrodeTM may potentially reach the thalamus, fornix, nucleus accumbens, subgenual cingulate white matter, and ventral capsule [11]. However, the device will need to be made substantially smaller to access these regions with smaller blood vessels. At present, the StentrodeTM has not been able to show reliable stimulation since approximately 60% of experiments were successful in generating a motor response when stimulating in the region of the motor cortex of sheep [2]. An important first step to showing neuromodulation of the brain would be to generate consistent cortical responses. Initial evidence is positive and future work should be able to ascertain the limits of endovascular stimulation and its effect on the vasculature.
Neuromodulatory effect of repetitive transcranial magnetic stimulation pulses on functional motor performances of spastic cerebral palsy children
Published in Journal of Medical Engineering & Technology, 2018
Meena Gupta, Bablu Lal Rajak, Dinesh Bhatia, Arun Mukherjee
The emergence of neuromodulation as a new therapeutic tool towards treatment of neurological disorders is due to the paradigm change of the clinicians that is shifting from the drug-related medication to modulating the neural circuitry of the brain using new medical devices such as vagus nerve stimulation (VNS), repetitive Transcranial magnetic stimulation (rTMS) and deep brain stimulation (DBS) [1]. The era of neuromodulation began in the early 1960s with the use of DBS to resolve chronic and intractable pain and henceforth, further applications of new simulation devices for the same purpose are governed by the International Neuromodulation Society (INS). INS defines the therapeutic neuromodulation as “the alteration of nerve activity through targeted delivery of a stimulus, such as electrical stimulation or chemical agents, to specific neurological sites in the body”. Neuromodulation approaches range from non-invasive techniques such as rTMS to implanted devices, such as a spinal cord stimulation or a deep brain stimulation system. The most common neuromodulation treatment device is the spinal cord stimulation system for chronic neuropathic pain [2] and in addition to this, other neuromodulation treatments employed for different disorders include epilepsy, Parkinson’s disease, essential tremors, dystonia, etc. [3–5]. Since neuromodulation is used to treat and enhance the quality of life in individuals who suffer from severe chronic illness due to persistent pain, spasticity and movement disorders, thus, we applied rTMS for the treatment of cerebral palsy patients.
The future of neuromodulation: smart neuromodulation
Published in Expert Review of Medical Devices, 2021
Dirk De Ridder, Jarek Maciaczyk, Sven Vanneste
Therefore, a new non-medicated way to treat brain disorders is crucial. Interestingly, the methodology for this is already available, albeit in a rudimentary form. Indeed, more than 60 years ago, in 1952, Delgado described the implantation of electrodes into the brain to measure electrical brain activity as a diagnostic tool, and deep brain stimulation through the same electrodes as a possible treatment for mental disorders [15]. This was based on the clinically beneficial effects of psychosurgery, by making lesions in the brain, and the development of stereotaxy [16], through which very targeted small lesions could be made [17]. The described technique was adapted for movement disorders in 1963 by Bechtereva in Russia [18] and later, in 1987, by Benabid in the western world [19]. However, the last 50 years have been characterized by a relative stagnation, in the development of new technology for brain stimulation, in stark contrast to the exponential technological progress in consumer devices such as smartphones, personal computers, etc. The discrepancy between the highly advanced consumer devices and brain implantation devices demonstrates there is a very large margin for improvement. In summary, neuromodulation consists of an electrode that is placed in the brain, on the spinal cord or near a nerve and affects the offended nerves and support cells. The International Neuromodulation Society defines neuromodulation as the alteration of nerve activity through targeted delivery of a stimulus, such as electrical stimulation or chemical agents, to specific neurological sites in the body [20]. The battery and the software that controls the stimuli are contained in an internal pulse generator (IPG), an adapted and derivative of the classic cardiac pacemaker.