Par­a­lyzed men take steps again with spinal im­plant

The Sun News (Sunday) - - News - BY BENE­DICT CAREY

David Mzee broke his neck in 2010. He was a col­lege stu­dent in Zurich at the time, an ath­lete who en­joyed risk and con­tact, and he flipped off a tram­po­line and onto a foam pad.

“The foam pad, it didn’t do its job,” he said.

Mzee, now 33, is one of three men who lost the use of their legs years ago af­ter se­vere spinal in­juries but who now are able to walk with­out any sup­ports, if briefly and awk­wardly, with the help of a pace­maker-like im­plant, sci­en­tists re­ported on Wednes­day.

The break­through is the lat­est achieve­ment in the sci­en­tific ef­fort to un­der­stand and treat such lifechang­ing in­juries. Sev­eral re­cent stud­ies have re­stored mo­tion to par­a­lyzed or par­tially par­a­lyzed pa­tients by ap­ply­ing con­tin­u­ous elec­tri­cal stim­u­la­tion to the spinal cord.

The new re­port, de­scribed in the jour­nal Na­ture, is the first demon­stra­tion of so-called pat­terned stim­u­la­tion: An im­plant sends bursts of tar­geted stim­u­la­tion to the mus­cles that in­tend to move. In ef­fect, the stim­u­la­tion oc­curs on an as­needed ba­sis, roughly mim­ick­ing the body’s own sig­nal­ing mech­a­nism.

The treat­ment is still ex­per­i­men­tal, and its ef­fec­tive­ness for oth­ers with com­plete or par­tial paral­y­sis is yet to be worked out. The three men had some sen­sa­tion in their legs be­fore the trial be­gan, and they needed months of in­ten­sive train­ing to achieve their first awk­ward steps. They still rely on wheel­chairs; two can walk out in the com­mu­nity, us­ing walk­ers.

Each of them has learned to move pre­vi­ously limp mus­cles with­out help from the im­plant – an in­di­ca­tion that the elec­tri­cal stim­u­la­tion prompted nerves to re­grow.

“At first ev­ery­thing was new and, of course, ex­cit­ing, but it took so much work to see any dif­fer­ence,” said Mzee. “I would go home af­ter re­hab, eat, then go straight to bed. Then it got eas­ier to get the move­ment I wanted, and the big­gest step for me was when I could move hands free, for the first time, on the tread­mill. I wasn’t able to do that for so many years; it was a re­ally cool feel­ing.”

Chet Moritz, a brain sci­en­tist at the Uni­ver­sity of Wash­ing­ton, who was not in­volved in the study, was im­pressed by the re­sults.

“The ex­cit­ing thing about these find­ings is that they hold out the prom­ise that spinal cord in­juries can be cured, to an ex­tent that re­stores walk­ing, and that many move­ments per­sist even when stim­u­la­tion is turned off,” he said.

Other re­searchers cau­tioned that the study was small and that the pa­tients were only par­tially par­a­lyzed.

“We’re still a long way from peo­ple be­ing able to ac­cess this as stan­dard med­i­cal care,” said Dr. Kim­berly An­der­son, pro­fes­sor of phys­i­cal medicine and re­ha­bil­i­ta­tion at Case Western Re­serve Uni­ver­sity School of Medicine, although she added that the ap­proach has great po­ten­tial.

In re­cent years, re­searchers have used brain im­plants – elec­trode chips, placed below the skull on the mo­tor area of the cor­tex – to de­code neu­ral sig­nals and re­store move­ment in peo­ple and non­hu­man pri­mates who have lost the use of limbs. Still other sci­en­tists are in­ves­ti­gat­ing nerve growth fac­tors, chem­i­cal com­pounds that are in­jected at the site of an in­jury to pro­mote re­pair.

The au­thors of the new re­port, who are based at the Swiss Fed­eral In­sti­tute of Tech­nol­ogy, in Lau­sanne, pre­vi­ously had demon­strated that rats that had lost the use of their hind legs could be trained to run again when con­tin­u­ous cur­rent was ap­plied through the spinal cord to the mus­cles. Other re­search teams re­cently have re­ported that con­tin­u­ous stim­u­la­tion could also re­store some move­ment in hu­man pa­tients.

But in peo­ple, con­tin­u­ous stim­u­la­tion seems to send mixed sig­nals to the mus­cles, ac­ti­vat­ing some and con­fus­ing oth­ers, the au­thors of the new study ar­gue in a com­pan­ion pa­per in the cur­rent is­sue of Na­ture Neu­ro­science.

JEAN-BAP­TIST MIGNARDOT Ecole Polytech­nique Fed­erale de Lau­sanne

David Mzee, who was par­a­lyzed in 2010, is able to walk with­out any sup­ports with the help of a pace­maker-like im­plant that sends tar­geted stim­u­la­tion to his mus­cles.

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