Stimulation without trepanation
One of the approaches to the treatment of Parkinson's disease is to use deep electrical stimulation of the brain, which alleviates the symptoms that greatly worsen the quality of life, such as rigidity (stiffness) of muscles and tremor (uncontrollable trembling) of different parts of the body. However, this procedure is very complicated and not harmless – it involves opening the skull and direct electrical stimulation of brain tissue. Obviously, such operations are associated with a long list of risks, including the likelihood of brain injury.
Australian researchers led by Dr. Nick Opie from the University of Melbourne have been working on an alternative method since 2012. They are developing a stimulating device that can be implanted into blood vessels in the immediate vicinity of the motor cortex using a minimally invasive procedure that requires only a small incision in the neck.
The wireless device they created, called Stentrode, is only 4 mm in diameter and is made of a durable but very flexible alloy known as nitinol. In 2016, the authors demonstrated the ability of Stentrode to register nerve signals generated by the brain.
To date, the device allows not only to "listen" to brain signals, but also to "respond" to them by emitting electrical impulses directly into the target zones, providing focal or focal stimulation, manifested by the contraction of certain muscles.
Stentrode is injected into a small blood vessel passing under the skull. It is placed in a precisely specified place using a microwire and a microcatheter under the control of contrast angiography – a special radiographic method that allows doctors to observe what is happening inside the vessels. Several electrodes, adjacent to different regions of the brain, depart from the device. With the help of an electric current passing through these electrodes, the authors were able to stimulate various regions of the brain and observe the corresponding reactions, such as contractions of the muscles of the neck, lips and eyelids.
The developers believe that the potential range of application of Stentrode is very wide. Its most obvious areas include its use as an alternative to deep brain stimulation, currently used to treat symptoms of Parkinson's disease, as well as instead of a number of drugs prescribed for certain types of epilepsy.
Deep brain stimulation is in some cases used to treat severe mental disorders, such as deep depression. The authors hope that Stentrode may become a less invasive alternative for such patients as well.
The latest modification of the device allows you to use it to work simultaneously with the motor cortex (responsible for planning, regulating and performing movements) and the sensitive area of the cerebral cortex (receiving feedback about body movements). This, as well as the possibility of providing two-way communication (signal recording and stimulation), makes it possible to predict the possibility of its use by patients with spinal cord injuries to control prosthetic limbs. For example, with the help of Stentrode, such patients will be able to use a prosthetic arm, sending him a signal to compress something and receive feedback from this action, which will allow adjusting the compression force.
Currently, the authors are studying the parameters of stimulation, namely, determining the minimum effective power of an electric discharge. Their primary task today is to ensure maximum safety of the device, after which it will be possible to proceed to conducting clinical trials. A study is already planned for the beginning of next year, in which Stentrode will be used to help paralyzed patients gain the ability to move with the help of a wheelchair or even an exoskeleton.
Article by Nicholas L. Opie et al. Focal stimulation of the sheep motor cortex with a chronically implanted minimally invasive electrode array mounted on an endovascular stent is published in the journal Nature Biomedical Engineering.
Evgenia Ryabtseva, portal "Eternal Youth" http://vechnayamolodost.ru based on the materials of the University of Melbourne: Stimulating the brain – without major surgery.