A fully implanted brain-computer interface has allowed a "locked-in" patient with late-stage amyotrophic lateral sclerosis (ALS) to accurately and independently communicate with her caregiver at home using a computer typing program.
With training, practice, and fine-tuning of the system, the 59-year-old woman was able to wirelessly transmit her thoughts to the computer to spell out messages on a tablet.
"By attempting to move her hand and by using software that automatically extracted electrocortical signal features, the patient was able to control commercial communication software that could type, albeit at a slow rate," report Nick Ramsey, PhD, from the Brain Center Rudolf Magnus, University Medical Center Utrecht, the Netherlands, and colleagues.
The brain-computer interface provided autonomous communication that supplemented and at times took the place of the patient's only means of communication, which was through eye movements and "yes or no" blinks, they note.
The research was reported online November 12 in The New England Journal of Medicine to coincide with presentation at the Society for Neuroscience 2016 Annual Meeting in San Diego, California.
Options for patients with severe paralysis who have lost the ability to communicate by speech are limited. Current strategies for communication depend largely on eye movements that are followed by a camera, which allows the patient to select items on a computer screen ("eye tracker"). When that fails, communication may rest on eye movements or blinks in response to closed-ended questions, which limits the options for independent and private communication.
The brain-computer interface used by Dr Ramsey's group consists of four subdural electrode strips (Resume II, Medtronic) implanted over the sensorimotor and dorsolateral prefrontal cortex, a transmitter (Activa PC+S, Medtronic) placed subcutaneously beneath the left clavicle, a receiving antenna placed on the chest over the device, a receiver, and a tablet computer.
"By attempting to move the hand on the side opposite the implanted electrodes, the patient accurately and independently controlled a computer typing program 28 weeks after electrode placement, at the equivalent of two letters per minute," the researchers say.
The patient has successfully used the system at home with minimal assistance, aside from having someone place the antenna on her chest. The patient reports "high levels" of satisfaction with the device and uses it several times per week, Dr Ramsey and colleagues report in their paper.
"These results," they add, "show that the system is capable of meeting the requirements for independent communication and could be a method of communication for patients who are unable to use conventional communication tools such as eye trackers. Factors that may limit the use of the system by future patients include cortical damage, cognitive impairment, and unsupportive caregiving."
Real Clinical Benefit
Reached for comment, Grégoire Courtine, PhD, who was not involved in the research, told Medscape Medical News, "What is remarkable in this study is the use of technology that is ready for clinical deployment, minimally invasive, and stable for extensive duration."
"Although the speed of prosthetic operations is relatively slow, this study opens an avenue for the development of real clinical treatments that can restore communication for locked-in people," said Dr Courtine, International Paraplegic Foundation Chair in Spinal Cord Repair, Center for Neuroprosthetics and Brain Mind Institute, Swiss Federal Institute of Technology, Lausanne, Switzerland.
But in an interview with Medscape Medical News, Timothy Denison, PhD, from the Neuromodulation Core Technology Group at Medtronic and an author on the paper, cautioned that the system is investigational in the United States.
The device was designed for deep-brain stimulation and biopotential recording, which allows for long-term electrocorticography with two strips. It is currently certified according to Conformité Européene for use in patients with Parkinson's disease, essential tremor, and epilepsy.
"The system was designed to allow us to measure brain rhythms off of the electrodes that are placed. Primarily we are interested in Parkinson's disease, essential tremor and dystonia," Dr Denison explained.
As for what Dr Ramsey's group is exploring with ALS, Dr Denison said, "we were interested in seeing how might those similar brain rhythms be applied in that specific case. But from our point of view, we see this as an entire ecosystem of movement disorders. We are looking at the similarities and differences between these different states from Parkinson's to tremor to ALS and the like, and how those signals might be measured and how they might be applied in order to improve the outcomes of patients suffering from these diseases."
The research was funded by the government of the Netherlands and the European Union. Medtronic provided all components of the implant, plus the antenna and receiver, free of charge to the University Medical Center Utrecht. Medtronic contributed funds to the Dutch government agency but did not provide funds directly to the institution, the researchers, or the patient. Dr Denison holds shares in the company, directed the team that was responsible for developing the implanted parts and the receiver, wrote portions of the "Implant Components" subsection of the Supplementary Appendix, but was not involved in the interpretation of the results.
N Engl J Med. Published online November 14, 2016. Full text
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Cite this: Locked-in ALS Patient 'Speaks' With Brain-Computer Interface - Medscape - Nov 17, 2016.