But I would need to know where they are reading the brain signals
from. From the forearm it seems, so not applicable to most stroke survivors unless they get the signals directly from the brain. Motor cortex? Pre-motor cortex? Executive control? Both my motor
cortex and premotor cortex are heavily dead or damaged. Of course my
doctor didn't tell me that, I got that from a research MRI scan. But I
bet with enough training I could use my good motor cortex to send those
signals.
Clinically Significant Gains in Skillful Grasp Coordination by an Individual With Tetraplegia Using an Implanted Brain-Computer Interface With Forearm Transcutaneous Muscle Stimulation
Graphical Abstract
Keywords
List of abbreviations
Individuals with tetraplegia prioritize recovery of upper limb strength and dexterity to facilitate their independence.1, 2, 3, 4, 5 Voluntary control of hand grasp has been restored to paralyzed limbs using noninvasive6, 7, 8, 9, 10, 11 and cortical microelectrode array (MEA)-based12, 13, 14, 15, 16 brain-computer interfaces (BCIs) that translate brain activity to hand movements evoked through implanted10, 11, 12 or transcutaneous6, 7, 8, 9, 13, 14, 15, 16 functional electrical stimulation (FES).6, 7, 8, 9, 12, 13 However, clinically significant gains on tests of upper limb function have not been demonstrated using BCI-FES. The critical translational path for BCI neuroprosthetics requires demonstration of clinically meaningful gains in speed, dexterity, and smooth integration of grip with other arm movements to perform complex tasks.
Our goal was to evaluate whether an individual with tetraplegia could make clinically significant gains in skillful grasp coordination17, 18 using an investigational MEA-BCI-FES. We formulated a framework19 called Generalizability, Ability, Independence, Neurologic Level (GAIN) that reflects design goals for BCI neuroprosthetics to assist in this assessment. GAIN was inspired by end-user perspectives,4, 20, 21 challenges to translation,22, 23 and clinical evaluations developed for surgical interventions for tetraplegia.24 We anticipate it being useful for comparing performance across neuroprosthetic technologies and justifying (eg, to regulatory or payer sources) that a device measurably improves function on the International Classification of Functioning, Disability, and Health domains recognized by the World Health Organization.25
Devices meeting the GAIN standard include the following: (1) demonstrate generalizability, defined as performing well without retraining for objects with similar grip features (e.g., lateral, tip-to-tip, palmar, pincer grasps); (2) confer clinically significant gains in motor ability on standardized, psychometrically validated, and expert-endorsed24, 26, 27, 28, 29, 30, 31, 32, 33 tests of upper limb function; (3) affect daily life by facilitating functional independence for activities of daily living (ADLs) on psychometrically validated assessments24, 26, 27, 28, 29, 30, 31, 32, 33; and (4) improve the user’s neurologic level of function on validated measures normed to the International Standards for the Neurological Classification of Spinal Cord Injury standards.34
Methods
This was a Phase I trial of a MEA-BCI interfaced with the Neurolifea transcutaneous, forearm FES. Like similar intracortical BCI studies,12, 13, 14, 15, 16, 17, 18, 35, 36 this report was limited to 1 participant, the first to use the system, due to the invasive nature of the investigational brain implant and time required for training and assessment. Technical BCI-FES features13, 37 (fig 1), the Utah Arrayb MEA implantation procedures, and machine learning algorithms used to generate decoders were described previously. The participant provided written informed consent as approved by our local institutional review board.
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