Controlling a Robotic Arm with a Patient’s Intentions

28 05 2015

Neural prosthetic devices implanted in the brain’s movement center, the motor cortex, can allow patients with amputations or paralysis to control the movement of a robotic limb—one that can be either connected to or separate from the patient’s own limb. However, current neuroprosthetics produce motion that is delayed and jerky—not the smooth and seemingly automatic gestures associated with natural movement. Now, by implanting neuroprosthetics in a part of the brain that controls not the movement directly but rather our intent to move, Caltech researchers have developed a way to produce more natural and fluid motions.

Example of an fMRI scan used for targeting the device implantation location.

In a clinical trial, the Caltech team and colleagues from Keck Medicine of USC have successfully implanted just such a device in a patient with quadriplegia, giving him the ability to perform a fluid hand-shaking gesture and even play “rock, paper, scissors” using a separate robotic arm.

The results of the trial, led by principal investigator Richard Andersen, the James G. Boswell Professor of Neuroscience, and including Caltech lab members Tyson Aflalo, Spencer Kellis, Christian Klaes, Brian Lee, Ying Shi and Kelsie Pejsa, are published in the May 22 edition of the journal Science.

“When you move your arm, you really don’t think about which muscles to activate and the details of the movement—such as lift the arm, extend the arm, grasp the cup, close the hand around the cup, and so on. Instead, you think about the goal of the movement. For example, ‘I want to pick up that cup of water,’” Andersen says. “So in this trial, we were successfully able to decode these actual intents, by asking the subject to simply imagine the movement as a whole, rather than breaking it down into myriad components.”

For example, the process of seeing a person and then shaking his hand begins with a visual signal (for example, recognizing someone you know) that is first processed in the lower visual areas of the cerebral cortex. The signal then moves up to a high-level cognitive area known as the posterior parietal cortex (PPC). Here, the initial intent to make a movement is formed. These intentions are then transmitted to the motor cortex, through the spinal cord, and on to the arms and legs where the movement is executed.

High spinal cord injuries can cause quadriplegia in some patients because movement signals cannot get from the brain to the arms and legs. As a solution, earlier neuroprosthetic implants used tiny electrodes to detect and record movement signals at their last stop before reaching the spinal cord: the motor cortex.

The recorded signal is then carried via wire bundles from the patient’s brain to a computer, where it is translated into an instruction for a robotic limb. However, because the motor cortex normally controls many muscles, the signals tend to be detailed and specific. The Caltech group wanted to see if the simpler intent to shake the hand could be used to control the prosthetic limb, instead of asking the subject to concentrate on each component of the handshake—a more painstaking and less natural approach.

Andersen and his colleagues wanted to improve the versatility of movement that a neuroprosthetic can offer by recording signals from a different brain region—the PPC. “The PPC is earlier in the pathway, so signals there are more related to movement planning—what you actually intend to do—rather than the details of the movement execution,” he says. “We hoped that the signals from the PPC would be easier for the patients to use, ultimately making the movement process more intuitive. Our future studies will investigate ways to combine the detailed motor cortex signals with more cognitive PPC signals to take advantage of each area’s specializations.”

In the clinical trial, designed to test the safety and effectiveness of this new approach, the Caltech team collaborated with surgeons at Keck Medicine of USC and the rehabilitation team at Rancho Los Amigos National Rehabilitation Center. The surgeons implanted a pair of small electrode arrays in two parts of the PPC of a quadriplegic patient. Each array contains 96 active electrodes that, in turn, each record the activity of a single neuron in the PPC. The arrays were connected by a cable to a system of computers that processed the signals, decoded the intent of the subject, and controlled output devices that included a computer cursor and a robotic arm developed by collaborators at Johns Hopkins University.

Imagen de previsualización de YouTube

After recovering from the surgery, the patient was trained to control the computer cursor and the robotic arm with his mind. Once training was complete, the researchers saw just what they were hoping for: intuitive movement of the robotic arm.

“For me, the most exciting moment of the trial was when the participant first moved the robotic limb with his thoughts. He had been paralyzed for over 10 years, and this was the first time since his injury that he could move a limb and reach out to someone. It was a thrilling moment for all of us,” Andersen says.

“It was a big surprise that the patient was able to control the limb on day one—the very first day he tried,” he adds. “This attests to how intuitive the control is when using PPC activity.”

The patient, Erik G. Sorto, was also thrilled with the quick results: “I was surprised at how easy it was,” he says. “I remember just having this out-of-body experience, and I wanted to just run around and high-five everybody.”

Over time, Sorto continued to refine his control of his robotic arm, thus providing the researchers with more information about how the PPC works. For example, “we learned that if he thought, ‘I should move my hand over toward to the object in a certain way’—trying to control the limb—that didn’t work,” Andersen says. “The thought actually needed to be more cognitive. But if he just thought, ‘I want to grasp the object,’ it was much easier. And that is exactly what we would expect from this area of the brain.”

This better understanding of the PPC will help the researchers improve neuroprosthetic devices of the future, Andersen says. “What we have here is a unique window into the workings of a complex high-level brain area as we work collaboratively with our subject to perfect his skill in controlling external devices.”

“The primary mission of the USC Neurorestoration Center is to take advantage of resources from our clinical programs to create unique opportunities to translate scientific discoveries, such as those of the Andersen Lab at Caltech, to human patients, ultimately turning transformative discoveries into effective therapies,” says center director Charles Y. Liu, professor of neurological surgery, neurology, and biomedical engineering at USC, who led the surgical implant procedure and the USC/Rancho Los Amigos team in the collaboration.

“In taking care of patients with neurological injuries and diseases—and knowing the significant limitations of current treatment strategies—it is clear that completely new approaches are necessary to restore function to paralyzed patients. Direct brain control of robots and computers has the potential to dramatically change the lives of many people,” Liu adds.

Dr. Mindy Aisen, the chief medical officer at Rancho Los Amigos who led the study’s rehabilitation team, says that advancements in prosthetics like these hold promise for the future of patient rehabilitation. “We at Rancho are dedicated to advancing rehabilitation through new assistive technologies, such as robotics and brain-machine interfaces. We have created a unique environment that can seamlessly bring together rehabilitation, medicine, and science as exemplified in this study,” she says.

Although tasks like shaking hands and playing “rock, paper, scissors” are important to demonstrate the capability of these devices, the hope is that neuroprosthetics will eventually enable patients to perform more practical tasks that will allow them to regain some of their independence.

“This study has been very meaningful to me. As much as the project needed me, I needed the project. The project has made a huge difference in my life. It gives me great pleasure to be part of the solution for improving paralyzed patients’ lives,” Sorto says. ”I joke around with the guys that I want to be able to drink my own beer—to be able to take a drink at my own pace, when I want to take a sip out of my beer and to not have to ask somebody to give it to me. I really miss that independence. I think that if it was safe enough, I would really enjoy grooming myself—shaving, brushing my own teeth. That would be fantastic.”

To that end, Andersen and his colleagues are already working on a strategy that could enable patients to perform these finer motor skills. The key is to be able to provide particular types of sensory feedback from the robotic arm to the brain.

Although Sorto’s implant allowed him to control larger movements with visual feedback, “to really do fine dexterous control, you also need feedback from touch,” Andersen says. “Without it, it’s like going to the dentist and having your mouth numbed. It’s very hard to speak without somatosensory feedback.” The newest devices under development by Andersen and his colleagues feature a mechanism to relay signals from the robotic arm back into the part of the brain that gives the perception of touch.

“The reason we are developing these devices is that normally a quadriplegic patient couldn’t, say, pick up a glass of water to sip it, or feed themselves. They can’t even do anything if their nose itches. Seemingly trivial things like this are very frustrating for the patients,” Andersen says. “This trial is an important step toward improving their quality of life.”

The results of the trial were published in a paper titled, “Decoding Motor Imagery from the Posterior Parietal Cortex of a Tetraplegic Human.” The implanted device and signal processors used in the Caltech-led clinical trial were the NeuroPort Array and NeuroPort Bio-potential Signal Processors developed by Blackrock Microsystems in Salt Lake City, Utah. The robotic arm used in the trial was the Modular Prosthetic Limb, developed at the Applied Physics Laboratory at Johns Hopkins. Sorto was recruited to the trial by collaborators at Rancho Los Amigos National Rehabilitation Center and at Keck Medicine of USC. This trial was funded by National Institutes of Health, the Boswell Foundation, the Department of Defense, and the USC Neurorestoration Center.

Written by Jessica Stoller-Conrad

Contact: 

Deborah Williams-Hedges

(626) 395-3227

debwms@caltech.edu

 

 

Caltech.edu [en línea] Pasadena, CA (USA): caltech.edu 28 de mayo de 2015 [ref. 21 de mayo de 2015] Disponible en Internet: http://www.caltech.edu/news/controlling-robotic-arm-patients-intentions-46786



Neuroprosthetics for paralysis: an new implant on the spinal cord

12 01 2015

New therapies are on the horizon for individuals paralyzed following spinal cord injury. The e-Dura implant developed by EPFL scientists can be applied directly to the spinal cord without causing damage and inflammation. The device is described in an article appearing online January 8, 2015, in Science.

 Imagen de previsualización de YouTube

EPFL scientists have managed to get rats walking on their own again using a combination of electrical and chemical stimulation. But applying this method to humans would require multifunctional implants that could be installed for long periods of time on the spinal cord without causing any tissue damage. This is precisely what the teams of professors Stéphanie Lacour and Grégoire Courtine have developed. Their e-Dura implant is designed specifically for implantation on the surface of the brain or spinal cord. The small device closely imitates the mechanical properties of living tissue, and can simultaneously deliver electric impulses and pharmacological substances. The risks of rejection and/or damage to the spinal cord have been drastically reduced. An article about the implant will appear in early January in Science Magazine.

So-called “surface implants” have reached a roadblock; they cannot be applied long term to the spinal cord or brain, beneath the nervous system’s protective envelope, otherwise known as the “dura mater,” because when nerve tissues move or stretch, they rub against these rigid devices. After a while, this repeated friction causes inflammation, scar tissue buildup, and rejection.

 

An easy-does-it implant


Flexible and stretchy, the implant developed at EPFL is placed beneath the dura mater, directly onto the spinal cord. Its elasticity and its potential for deformation are almost identical to the living tissue surrounding it. This reduces friction and inflammation to a minimum. When implanted into rats, the e-Dura prototype caused neither damage nor rejection, even after two months. More rigid traditional implants would have caused significant nerve tissue damage during this period of time.

The researchers tested the device prototype by applying their rehabilitation protocol — which combines electrical and chemical stimulation – to paralyzed rats. Not only did the implant prove its biocompatibility, but it also did its job perfectly, allowing the rats to regain the ability to walk on their own again after a few weeks of training.

“Our e-Dura implant can remain for a long period of time on the spinal cord or the cortex, precisely because it has the same mechanical properties as the dura mater itself. This opens up new therapeutic possibilities for patients suffering from neurological trauma or disorders, particularly individuals who have become paralyzed following spinal cord injury,” explains Lacour, co-author of the paper, and holder of EPFL’s Bertarelli Chair in Neuroprosthetic Technology.

 

Flexibility of tissue, efficiency of electronics


Developing the e-Dura implant was quite a feat of engineering. As flexible and stretchable as living tissue, it nonetheless includes electronic elements that stimulate the spinal cord at the point of injury. The silicon substrate is covered with cracked gold electric conducting tracks that can be pulled and stretched. The electrodes are made of an innovative composite of silicon and platinum microbeads. They can be deformed in any direction, while still ensuring optimal electrical conductivity. Finally, a fluidic microchannel enables the delivery of pharmacological substances – neurotransmitters in this case – that will reanimate the nerve cells beneath the injured tissue.

The implant can also be used to monitor electrical impulses from the brain in real time. When they did this, the scientists were able to extract with precision the animal’s motor intention before it was translated into movement.

“It’s the first neuronal surface implant designed from the start for long-term application. In order to build it, we had to combine expertise from a considerable number of areas,” explains Courtine, co-author and holder of EPFL’s IRP Chair in Spinal Cord Repair. “These include materials science, electronics, neuroscience, medicine, and algorithm programming. I don’t think there are many places in the world where one finds the level of interdisciplinary cooperation that exists in our Center for Neuroprosthetics.”

For the time being, the e-Dura implant has been primarily tested in cases of spinal cord injury in paralyzed rats. But the potential for applying these surface implants is huge – for example in epilepsy, Parkinson’s disease and pain management. The scientists are planning to move towards clinical trials in humans, and to develop their prototype in preparation for commercialization.

 

Actu.epfl.ch [en línea] Lausanne (CH): actu.epfl.ch, 12 de enero de 2015 [ref. 08 de enero de 2015] Disponible en Internet: http://actu.epfl.ch/news/neuroprosthetics-for-paralysis-an-new-implant-on-t/



Gene inhibitor, salmon fibrin restore function lost in spinal cord injury

13 11 2014

UCI Reeve-Irvine researchers identify novel combination treatment

A therapy combining salmon fibrin injections into the spinal cord and injections of a gene inhibitor into the brain restored voluntary motor function impaired by spinal cord injury, scientists at UC Irvine’s Reeve-Irvine Research Center have found.

In a study on rodents, Gail Lewandowski and Oswald Steward achieved this breakthrough by turning back the developmental clock in a molecular pathway critical to the formation of corticospinal tract nerve connections and providing a scaffold so that neuronal axons at the injury site could grow and link up again.

Oswald Steward is director of the Reeve-Irvine Research Center at UCI

Results appear in the July 23 issue of The Journal of Neuroscience.

The work expands on previous research at UCI. In 2010, Steward helped discover that axons flourish after the deletion of an enzyme called PTEN, which controls a molecular pathway regulating cell growth. PTEN activity is low during early development, allowing cell proliferation. PTEN subsequently turns on, inhibiting this pathway and precluding any ability to regenerate.

Two years later, a UCI team found that salmon fibrin injected into rats with spinal cord injury filled cavities at the injury site, giving axons a framework in which to reconnect and facilitate recovery. Fibrin is a stringy, insoluble protein produced by the blood clotting process and is used as a surgical glue.

“This is a major next step in our effort to identify treatments that restore functional losses suffered by those with spinal cord injury,” said Steward, professor of anatomy & neurobiology and director of the Reeve-Irvine Research Center, of the current findings. “Paralysis and loss of function from spinal cord injury has been considered irreversible, but our discovery points the way toward a potential therapy to induce regeneration of nerve connections.”

In their study, he and Lewandowski treated rodents with impaired hand movement due to spinal cord injury with a combination of salmon fibrin and a PTEN inhibitor called AAVshPTEN. A separate group of rodents got only AAVshPTEN.

The researchers saw that rats receiving the inhibitor alone did not exhibit improved motor function, whereas those given AAVshPTEN and salmon fibrin recovered forelimb use involving reaching and grasping.

“The data suggest that the combination of PTEN deletion and salmon fibrin injection into the lesion can significantly enhance motor skills by enabling regenerative growth of corticospinal tract axons,” Steward said.

According to the Christopher & Dana Reeve Foundation, about 2 percent of Americans have some form of paralysis resulting from spinal cord injury, due primarily to the interruption of connections between the brain and spinal cord.

An injury the size of a grape can lead to complete loss of function below the site of occurrence. For example, an injury to the neck can cause paralysis of the arms and legs, an absence of sensation below the shoulders, bladder and bowel incontinence, sexual dysfunction, and secondary health risks such as susceptibility to urinary tract infections, pressure sores and blood clots due to an inability to move the legs.

Steward said the next objective is to learn how long after injury the combination treatment can be effectively administered. “It would be a huge step if it could be delivered in the chronic period weeks and months after an injury, but we need to determine this before we can engage in clinical trials,” he said.

Lewandowski is a project scientist in the Reeve-Irvine Research Center. The study received support from the National Institutes of Health (grant R01 NS047718) and donations from Cure Medical and Unite 2 Fight Paralysis.

About the Reeve-Irvine Research Center: The mission of the Reeve-Irvine Research Center is to find new treatments for spinal cord injury through the collaborative research and educational efforts of prominent scientists and clinicians both at UCI and around the world. For more information, visit www.reeve.uci.edu.

 

 

News.uci.edu [en línea] Irvine, CA (USA): news.uci.edu, 13 de noviembre de 2014 [ref. 23 de julio de 2014] Disponible en Internet: http://news.uci.edu/press-releases/gene-inhibitor-salmon-fibrin-restore-function-lost-in-spinal-cord-injury/



Un nuevo robot permite operar epilepsias que hasta ahora no tenían tratamiento

23 05 2013

Médicos del Hospital del Mar han operado con éxito las 5 primeras intervenciones realizadas en España

El robot ROSA permite delimitar con gran precisión el foco de la epilepsia en el cerebro

 

Barcelona, a 13 de mayo de 2013-. El Hospital del Mar ha llevado a cabo, por primera vez en España, cirugía de la epilepsia con un brazo robotizado. Esta nueva tecnología permite al cirujano operar pacientes que hasta ahora estaban condenados a padecer la enfermedad toda la vida y pone al Hospital de Mar y la sanidad pública catalana al frente del tratamiento de la epilepsia.

Gracias al nuevo robot ROSA, los médicos han logrado incrementar considerablemente la precisión y la eficacia de las intervenciones para extraer del cerebro el foco donde se originan las descargas eléctricas que provocan las crisis epilépticas.

El Dr. Rodrigo Rocamora, jefe de la Unidad de Epilepsia del Hospital del Mar, explica que “el robot permite operar epilepsias altamente complejas para las que antes no se contemplaba la cirugía”. De hecho, si bien es cierto que sólo se valora la posibilidad de practicar cirugía en pacientes que no responden al tratamiento farmacológico -alrededor de un 30% del total-, también lo es que en muchos de estos no se les podía practicar la cirugía porque no era posible localizar con precisión el foco origen que había que extraer. Con la adquisición de esta nueva tecnología, los médicos pueden superar este obstáculo y un número mucho más alto de pacientes encuentran un tratamiento a su enfermedad.

 

Trayectorias de los electrodos en el cerebro

Trayectorias de los electrodos en el cerebro

En las 5 intervenciones realizadas en el Hospital del Mar, el robot ROSA ha permitido colocar con gran precisión una media de 12 electrodos para intervención (puede llegar a colocar más de 20) sin haber registrado ninguna complicación. Esto ha permitido al equipo de tratamiento de la epilepsia estudiar con mucha precisión el foco origen de la enfermedad de cada paciente y definir las funciones cerebrales de las áreas del cerebro que se deberían extirpar para curarla.

 

De esta manera los médicos pueden delimitar de forma mucho más precisa la parte del cerebro que se debe extraer. “Esta tecnología nos permite procesar las imágenes del cerebro en un sistema informático y, gracias a la neuronavegación, ejecutar de forma precisa las trayectorias para colocar los electrodos en el interior del cerebro, evitando cualquier daño a venas, arterias u otras zonas sensibles del cerebro” explica el Dr. Gerard Conesa, cirujano responsable de las intervenciones.

Otra gran ventaja que presenta el robot es su rapidez. “La automatización del proceso que supone el robot permite reducir la duración de la intervención para colocar los electrodos de ocho horas a sólo dos, facilitando la labor de los cirujanos y reduciendo el riesgo de complicaciones”, añade el Dr. Conesa.

 

La epilepsia es una enfermedad que padece entre un 0,5 y un 1% de la población, unas 400.000 personas en España. Su origen son descargas eléctricas que se originan en el cerebro de los pacientes y activan neuronas de forma repentina y desorganizada. Las causas pueden ser muy diversas: alteraciones en el desarrollo de las neuronas, infecciones, tumores, alteraciones vasculares como los ictus cerebrales, trastornos degenerativos o golpes en el cerebro que dejan cicatrices muy pequeñas. Sus consecuencias pueden llegar a ser muy graves: la calidad de vida del enfermo se ve muy deteriorada por el peligro de pérdida del conocimiento durante las crisis, que puede dar lugar a situaciones peligrosas como caídas repentinas. Aunque no es lo habitual, las crisis epilépticas son, en sí mismas, un peligro real ya que pueden llegar a matar al paciente mientras ocurren o, si no se logran controlar, derivar en trastornos neuropsiquiátricos y en trastornos cognitivos crónicos.

A parte de la adquisición del robot, el Dr. Rocamora destaca que la cirugía de la epilepsia sólo se puede practicar en determinados centros sanitarios, con la infraestructura y los recursos humanos necesarios. Es necesario un equipo de personas 24 horas al servicio del paciente, ya que, además de las pruebas rutinarias (imágenes especiales, resonancias magnéticas, estudios neuropsicológicos, etc.) lo más importante es la monitorización (registro de datos del paciente), que exige ingresar el enfermo durante una o dos semanas para reducir o retirar de forma controlada la medicación, con el objetivo de detectar las crisis y localizar los focos que, posteriormente, serán extraídos por el cirujano.

En España hay muy pocos centros con capacidad para practicar cirugía de la epilepsia. Uno de ellos es el Hospital del Mar, que el pasado mes de septiembre firmó el convenio para conformar la Unidad Funcional de Cirugía de la Epilepsia de Cataluña junto con el Hospital Clínico y el Hospital de San Juan de Dios. La primera intervención robotizada se realizó en enero de 2013 y hasta el momento ya se ha podido practicar a un total de 5 operaciones, utilizando esta tecnología sin haber registrado vez complicación quirúrgica.

 

Parcdesalutmar.cat [en línea] Barcelona (ESP): parcdesalutmar.cat, 23 de mayo de 2013 [ref. 13 de mayo de 2013] Disponible en Internet: http://www.parcdesalutmar.cat/es_noticies/view.php?ID=289

 



Un neuronavegador virtual para la investigación del cerebro

11 04 2013

Brain Dynamics, una spin-off de la Universidad de Málaga, ha desarrollado un sistema de neuronavegación que permite realizar una reconstrucción tridimensional del cerebro. La herramienta facilitará la investigación y docencia sobre el cerebro y ayudará a realizar operaciones cerebrales menos invasivas, más eficientes y seguras para el paciente, según los responsables del proyecto.

 

La empresa Brain Dynamics, una spin-off de la Universidad de Málaga especializada en neurociencia y TIC, ha desarrollado un sistema de neuronavegación que permite una  reconstrucción tridimensional del cerebro. El proyecto ha sido financiado por la Corporación Tecnológica de Andalucía (CTA).

Según Antonio García Linares, director de esta spin-off, la nueva herramienta facilitará la investigación y la docencia sobre el cerebro y también ayudará a que la cirugía cerebral sea menos invasiva y más segura, ya que permitirá a los cirujanos ‘entrar’ en el cerebro del paciente y visualizar cuáles son las rutas quirúrgicas más convenientes para causar el menor daño posible.

“El cirujano podrá planificar la intervención incluso dentro del mismo quirófano. Usando esta herramienta, podrá ver si va por el buen camino en cuanto al abordaje que ha planificado”, subraya.

Además, el nuevo sistema de neuronavegación tiene como valor añadido la integración con la base de datos de conocimiento, también desarrollada por la empresa, que aglutina e interrelaciona los datos más importantes sobre el cerebro a partir de fuentes bibliográficas, conexiones tractográficas (tractos neurales), estudios funcionales, patrones de coactivación, etc., y los interpreta según los criterios de la neurociencia basada en la evidencia, explica el directivo.

 

Caudal de datos

Este caudal de datos posibilitará consultas, comparación con casos anteriores, obtención de diagnósticos y análisis de la evolución de una enfermedad, entre otras opciones.

García indica que en las aplicaciones del sistema en el ámbito de la docencia, los alumnos podrán disponer de un cerebro con una capacidad de información y conocimiento adicional que antes no existía. En investigación, el neuronavegador se constituye como una herramienta fundamental que integra todos los artículos que hasta el momento han sido publicados en esta materia.

Este proyecto ha contado con la colaboración del grupo de Inteligencia Computacional de la Universidad de Málaga, así como del Hospital Regional Universitario Carlos Haya de Málaga, y el Hospital Universitario y Politécnico la Fe de Valencia.

El proyecto Brain Dynamics forma parte de las alrededor de 50 iniciativas en el área de la biotecnología financiados hasta la fecha por Corporación Tecnológica de Andalucía, que considera este sector como una de sus siete áreas estratégicas.

 

 

Agenciasinc.es [en línea] Madrid (ESP): agenciasinc.es, 11 de abril de 2013 [ref. 05 de abril de 2013] Disponible en Internet: http://www.agenciasinc.es/Noticias/Un-neuronavegador-virtual-para-la-investigacion-del-cerebro



Cirugía pionera restaura movimiento a hombre paralizado

24 05 2012

Una innovadora cirugía de derivación llevada a cabo en Estados Unidos logró restaurar el daño en la médula espinal de un individuo con parálisis y les permitió recuperar el uso de una mano.

La lesión que el paciente había sufrido impedía que su cerebro enviara señales de movimiento a su mano.

La operación quirúrgica, cuyos detalles aparecen publicados en Journal of Neurosurgery, (Revista de Neurocirugía), involucró volver a conectar los nervios de la mano para que éstos pudieran volver a comunicarse con el cerebro.

Los cirujanos de la Escuela de Medicina de la Universidad de Washington, que llevaron a cabo el procedimiento, “construyeron” una nueva ruta de comunicación de impulsos nerviosos entre la mano y el cerebro.

El paciente puede ahora utilizar la mano para alimentarse solo y está intentando volver a escribir.

El individuo de 71 años sufrió un accidente automovilístico en junio de 2008 que provocó una lesión en la médula espinal con daños en la base del cuello.

El hombre no pudo volver a caminar y aunque quedó con cierto movimiento en sus brazos, había perdido en ambas manos la capacidad de pellizcar y de agarre.

Lesión específica

Tal como explican los científicos, los nervios de la mano no estaban dañados, sólo habían perdido la capacidad de comunicarse con el cerebro, el cual debe darles instrucciones de movimiento.

A pesar de que la mano no recibía señales, el cerebro seguía enviando instrucciones al brazo.

La operación, dice el estudio, reconectó los nervios del brazo para establecer una nueva vía de comunicación desde el cerebro a la mano.

Para ello, los cirujanos extrajeron uno de los nervios que lleva a un músculo y se injertó al nervio interóseo anterior, que va hacia la mano.

“El circuito (en la mano) estaba intacto pero ya no estaba conectado al cerebro”, explica a la BBC la profesora Ida Fox, especialista en cirugía plástica y reconstructiva de la Universidad de Washington.

“Lo que hicimos fue tomar ese circuito y restaurar la conexión al cerebro”.

Según la investigadora, la operación es “realmente innovadora” y una forma “ingeniosa y estimulante” de restaurar el movimiento.

Pero advierte que este procedimiento no podrá nunca ser utilizado para restaurar las funciones normales de movimiento.

“Eso nunca sucederá”, dice la profesora Fox.

El movimiento limitado que se logró no ocurrió “de la noche a la mañana”, dice la investigadora.

Se requirió un entrenamiento intensivo del paciente para volver a adquirir el control de la mano.

Y ahora, los nervios que se utilizan para doblar el codo pueden realizar movimientos de pellizco.

Después de ocho meses de la operación, el paciente pudo volver a mover los dedos pulgar, índice y medio.

Ahora ya puede alimentarse solo y hace uso de una escritura “rudimentaria”.

Los médicos esperan que con más fisioterapia sus movimientos continúen mejorando.

Pero subrayan que el procedimiento sólo funcionará con pacientes que tienen lesiones muy específicas de la médula espinal en la base del cuello.

Si la lesión se ubica en una parte más alta la persona no tendrá funciones nerviosas en los brazos y en una parte más baja todavía tendrá movimiento en las manos.

“Uno de los problemas con este tipo de técnicas es la permanencia de los resultados”, dice a la BBC el doctor Mark Bacon, director de investigación de la organización Spinal Research.

“Una vez que se realiza es muy difícil revertirla”.

“E inevitablemente se debe sacrificar algunas de las funciones sanas en la parte superior de la lesión para poder obtener movimientos más útiles en la parte inferior”.

“Esto puede ser totalmente aceptable cuando estamos hablando de restaurar funciones que conducen a una mejor calidad de vida”.

“Y para el número limitado de pacientes que podrían beneficiarse con esta técnica parece ser un pequeño precio que deberán de pagar” afirma el experto.

Bbc.co.uk/ [en línea] London (UK): bbc.co.uk/ 24 de mayo de 2012 [ref. 16 de mayo de 2012] Disponible en Internet: http://www.bbc.co.uk/mundo/noticias/2012/05/120516_cirugia_paralisis_mano_men.shtml