After an initial training period, the patient was able to control up to three different types of grips with the robotic hand, with a success percentage of more than 85% in terms of the neural interface being able to recognize the commands sent by the brain.

The possibility to execute three different types of grips, interfacing through the tf-LIFE electrodes with a five-fingered robotic hand, can enable a person to carry out almost all activities required in daily life and working life situations. These performances were also made possible thanks to a complex acquisition and processing system of neural signals, developed by the Bioengineers of the Scuola Superiore Sant’Anna of Pisa and of the University “Campus Bio-Medico” of Rome.

After approximately a month of training side by side with the patient, the system proved to be capable of extracting, among all the nervous signals sent by the brain through the tf-LIFE interfaces, only those signals actually useful to codify the intention to execute a specific grip. As expected, the tf-LIFE electrodes were also used during the first weeks of the experiment to deliver stimuli to the nerves of the stump, and the patient perceived and translated these stimuli into natural tactile sensations coming from the area of the limb lost years before.  

The perceptive channels, however, stopped working unexpectedly after two weeks, probably due to local reaction phenomena inside the nerve in the region where the electrodes were inserted. These phenomena are currently the topic of further studies aimed at understanding how they can be mitigated and controlled so that they have no impact on the operation of the interface for long-term implants.

Furthermore, Italian researches evaluated for the first time the changes that occurred at the cerebral cortex level – known as neuroplasticity phenomena – as a result of the implant and the use of tf-LIFE neural interfaces by the patient.

Specifically, Transcranial Magnetic Stimulation (TMS) showed a significant reorganization of the motor areas pertaining to the muscles of the stump, which became clinically associated with a significant reduction of phantom limb pain – a pathology that afflicts more than 65% of amputees who continue to feel pain from the missing limb. The experiments carried out thus provided crucial objective data that confirms the hypothesis advanced so far that phantom limb pain is directly caused by an “aberrant cortical reorganization”.

In other words the invasion of motor areas of the brain originally associated with the amputated limb by adjacent areas occurs for the need of central neurons to exchange bidirectional information to/from the periphery. Although the time is not ripe for a wide clinical diffusion of this method for the control of hand prostheses, the evidence provided by the applicative phase of the experimentation on a human subject represents an important step towards the achievement of the final goal: putting the brain and its nervous ramifications in direct communication with artificial machines.

In the specific case, the results obtained with the LifeHand project lead to interesting perspectives with regards to the use of peripheral neural interfaces as an alternative to other solutions. One of these is the hand transplant from a cadaver donor, which so far has provided rather controversial results in terms of functional recovery and has forced the patient to undergo very strong anti-rejection therapies. Another solution consists of interfaces implanted directly in the cerebral cortex, already being experimented on humans.

The Italian study seems to make the use of peripheral interfaces decisively more appropriate, at least for the control of limb prostheses, since at present these devices can guarantee the best performance with a smaller degree of invasiveness and less complexity of the physiological signals requiring interpretation.

However, there are still quite a few technological and medical problems that need to be resolved. For example, an integrated and miniaturized version that can be implanted is being developed of all electronic devices needed to both acquire neural signals sent by the brain (efferent) and translate them into commands for the prosthesis and to generate signals flowing into the brain (afferent) obtained starting from the artificial sensors in contact with the environment.

The LifeHand researchers are already working feverishly on various new projects, both national and European, that focus on this and on many other fronts of medical and bioengineering research, aimed at satisfying the expectations of Pierpaolo Petruzziello and many other patients who, like him, have yet to find an adequate solution for regaining full autonomy after losing a limb.

Because of his willingness to undergo this first session of experiments, Pierpaolo Petruzziello will be the first candidate patient to receive the permanent implantation of the entire prosthesis system, which is expected to be commercially available a few years from now.