Reclaiming autonomy: the repaired human

Around twenty indi­vidu­als are train­ing today in a rather unusu­al gym, on bicycles and sta­tion­ary row­ing machines. These people are spe­cial in that they are all liv­ing with a dis­ab­il­ity. Their legs and arms shouldn’t be able to move, but thanks to elec­trostim­u­la­tion, their muscles can now respond again.

Vance Ber­ger­on, dir­ect­or of research at the Phys­ics Labor­at­ory of the ENS in Lyon, him­self tet­ra­ple­gic fol­low­ing a cyc­ling acci­dent, is at the ori­gin of the S.P.O.R.T (Stim­u­lat­ing People and Organ­iz­ing Recre­ation­al Ther­apies) room, cre­ated in 2018 by the asso­ci­ation ANTS (Advanced Neuro-rehab­il­it­a­tion Ther­apies & Sports).

“The idea of elec­tric­ally stim­u­lat­ing muscles is not new,” explains Vance Ber­ger­on. “In fact, it was a French­man, Dr Duch­enne de Boulogne, who stud­ied the physiology of move­ment using elec­tric­al exper­i­ments in a book pub­lished in 1867 that has remained a ref­er­ence ever since! The devel­op­ment of exo­skel­et­ons came later, start­ing in the 1950s, but research in the field stag­nated until the semi­con­duct­or and elec­tron­ics boom of the 1990s.”

Japan is lead­ing the way in this area, with exo­skel­et­ons seen as a good way to sup­port an age­ing pop­u­la­tion. The United States, on the oth­er hand, is focus­ing on mil­it­ary applic­a­tions. What remains is to com­bine the two tech­no­lo­gies; exo­skel­et­on and elec­tric­al stim­u­la­tion. This is what the com­pany Clin­atec, foun­ded in 2006 by Pro­fess­or Alim-Louis Ben­a­bid, a neurosur­geon in Gren­oble, is doing. By design­ing an implant­able device that col­lects the brain sig­nals emit­ted when a per­son intends to make a move­ment, the Clin­atec research­ers hope to give tet­ra­ple­gics the pos­sib­il­ity of men­tally con­trolling an exo­skel­et­on robot to walk and manip­u­late objects.

Grégoire Courtine, a neur­os­cient­ist at the Ecole Poly­tech­nique Fédérale de Lausanne (EPFL), is also work­ing towards this goal and has just tested the pos­sib­il­ity of allow­ing tet­ra­ple­gics to walk again using an abdo­men-implanted car­di­ac neur­ostim­u­lat­or and spin­al-cord-implanted elec­trodes (see box). These devices are very invas­ive, how­ever, and res­ults still uncer­tain. Main­tain­ing phys­ic­al activ­ity in the dis­abled brings imme­di­ate bene­fits though and is safe. “Stim­u­lat­ing injured limbs effect­ively com­bats the risk of sec­ond­ary com­plic­a­tions that can arise fol­low­ing an injury to the spin­al cord,” explains Vance Ber­ger­on, “wheth­er it is caused by an acci­dent or a stroke.”

Fol­low­ing his acci­dent, Vance Ber­ger­on reori­ented his laboratory’s activ­ity to devel­op an elec­trostim­u­la­tion bicycle. It works as fol­lows: the ped­alling move­ment is recre­ated via non-invas­ive sur­face elec­trodes, simply placed on the legs of the para­lysed per­son. An elec­tric cur­rent stim­u­lates the motor nerves to trig­ger muscle con­trac­tions in a sequence that allows them to ped­al again. “We thus pre­vent vari­ous phys­ic­al risks, such as bed­sores, bone demin­er­al­isa­tion and blood cir­cu­la­tion dis­orders,” con­tin­ues Vance Ber­ger­on. “Elec­trostim­u­la­tion also has a psy­cho­lo­gic­al impact: main­tain­ing muscle volume gives the per­son a bet­ter body image and makes daily move­ments easi­er, espe­cially trans­fers from the wheel­chair, which require con­sid­er­able phys­ic­al effort.”

Finally, being in a place such as a gym makes social rein­teg­ra­tion easi­er, reduces isol­a­tion and there­fore the risk of depres­sion. Two bicycles and a row­ing machine are now avail­able in the S.P.O.R.T room, which is still the only one of its kind in France. There is prob­lem with these elec­trostim­u­la­tion devices, how­ever, in that they cause sig­ni­fic­ant muscle fatigue. “When a mara­thon run­ner trains, he uses dif­fer­ent muscles from those used by a sprint­er,” explains Vance Ber­ger­on. “In the labor­at­ory we are try­ing to see how we can tar­get cer­tain muscles, and not stim­u­late them all at the same time.”

The labor­at­ory is also work­ing on improv­ing the equip­ment, with a Bluetooth sys­tem that would make it pos­sible to get rid of the wires by integ­rat­ing the elec­trodes into cloth­ing. Finally, the aim is to offer fin­an­cially com­pet­it­ive equip­ment. “The first bike designed for elec­trostim­u­la­tion that I impor­ted from the US and adap­ted it so that it could be used in France cost €30,000! Now I’m work­ing with a Ger­man com­pany¹ on a mod­el that is access­ible to the pub­lic, at around €2,000.”

What equip­ment will be used by dis­abled people in the future? Exo­skel­et­ons cer­tainly allow people to stand up, but even in their non-invas­ive ver­sion, they are very heavy, and their oper­at­ing-time is lim­ited by bat­tery life. In com­par­is­on, elec­trostim­u­la­tion is very simple: a few watts are enough to make the device work…