脳特定領域への電気刺激、脊髄損傷患者の歩行改善 スイス研究

【パリＡＦＰ＝時事】脳の特定の領域に電気刺激を与えることで、脊髄を損傷した患者の歩行が改善する可能性があるとする研究論文が２日、学術誌ネイチャー・メディシンに発表された。（写真はインプラントを用いた治療で歩く脊髄損傷患者。スイス・ローザンヌで）
　研究を行ったスイスのチームはこれまでにも、脊髄への電気刺激を用いて、複数のまひ患者の歩行を回復するなどの研究を先導してきた。新技術は、脳と脊髄の神経経路が完全に遮断されておらず、足をいくらか動かせる脊髄損傷患者を対象としている。
　研究チームは今回、脊髄損傷からの回復に最も関与している脳の領域を特定するために、３Ｄイメージング技術を用いて脊髄を損傷したマウスの脳活動をマッピングし、「全脳アトラス（全脳地図）」と呼ばれるものを作製。探していた領域が、覚醒や摂食、動機付けの調整を担う視床下部外側野にあることを新たに発見した。
　スイス連邦工科大学ローザンヌ校の神経科学者グレゴワール・クルティーヌ氏は、この領域の特定のニューロン群が「脊髄損傷後の歩行回復に関与していると思われる」とＡＦＰに語った。
　次にチームは、パーキンソン病患者の運動障害の治療法として一般的な脳深部刺激療法（ＤＢＳ）を用い、これらのニューロンからの信号を増幅しようと試みた。これは脳の該当する領域に電極を埋め込み、それを患者の胸に埋め込まれた装置に接続する手術を伴う。装置を起動すると、電気パルスが脳に送られる。
　ラットとマウスを用いた検証では「即座に」歩行能力が改善されたという。
　神経外科医のジョセリン・ブロッホ氏によると、２０２２年に最初に被験者となった女性患者は、装置のスイッチが入った途端に「足を感じる」と語った。
　初期試験に参加したもう１人の患者、ウォルフガング・イェーガーさん（５４）もすぐに「大きな違い」があったと述べた。
　イェーガーさんは論文と同時に公開された動画で「今では数段の階段を見ても、自分で対処できるとわかる」と語った。装置がオンになると「階段の上り下りが問題なくできた」と言う。
　さらに使用を重ねるにつれ、歩行が「速くなり」、装置がオフのときでも「長く歩けるようになった」と話した。
　しかし、神経科学者のクルティーヌ氏は、今後さらなる研究が必要だとし、この技術がすべての患者に有効とは限らないと強調した。
　研究チームは、将来的に脊髄損傷からの回復には、脊髄と視床下部外側野の両方を刺激することが最良の選択肢となる可能性があるとしている。【翻訳編集ＡＦＰＢＢＮｅｗｓ】
〔ＡＦＰ＝時事〕（2024/12/03-19:42）

Scientists said Monday that electrically stimulating a particular region in the brain could help people with injured spinal cords walk more easily, with one patient describing how the technique allowed him to conquer his fear of stairs.
The new technique is intended for people with spinal cord injuries where the connection between their brain and spinal cord has not been totally severed, and who still have some movement in their legs.
Wolfgang Jaeger, one of two patients who took part in an early trial, said that it immediately made a big difference to his mobility.
Now when I see a staircase with just a few steps, I know I can handle it on my own, the 54-year-old said in a video released alongside a new study in the journal Nature Medicine.
The research was conducted by a Swiss team that has pioneered several recent advances, including using electrical stimulation of the spinal cord to let several paralysed patients walk again.
This time around, the researchers wanted to figure out which region of the brain was most responsible for people recovering from spinal cord injuries.
- 'I feel the urge to walk' -
Using 3D imaging techniques to map out the brain activity of mice with these injuries, the team created what they called a brain-wide atlas.
They were surprised to find that the brain region they were looking for was in the lateral hypothalamus, which is otherwise known as a regulator for arousal, feeding and motivation.
A particular group of neurons in this region appears to be involved in the recovery of walking after spinal cord injury, neuroscientist Gregoire Courtine at Switzerland's Ecole Polytechnique Federale de Lausanne told AFP.
Next, the team sought to amplify the signal from these neurons using a procedure called deep brain stimulation, which is commonly used to treat movement problems in people with Parkinson's disease.
It involves a surgeon implanting electrodes in the brain region, which are connected to a device implanted in the patient's chest. When switched on, the device sends electrical pulses up to the brain.
First, the team tested their theory on rats and mice, finding that it immediately improved walking, the study said.
The first human participant of the 2022 Swiss trial was a woman who, like Jaeger, has an incomplete spinal cord injury.
Neurosurgeon Jocelyne Bloch told AFP that when the women's device was turned on for the first time, she said: I feel my legs.
When they turned up the electrical current, the women said, I feel the urge to walk, according to Bloch.
The patients could turn on their device whenever they needed, and also went through months of rehab and strength training.
The woman's goal was to walk independently without a walker, while Jaeger's was to climb stairs by himself.
Both of them reached their goal, Bloch said.
- 'No problem' -
Jaeger, who is from the Swiss municipality of Kappel, spoke about facing eight steps down to the sea during a holiday last year.
With the device turned on, walking up and down the stairs was no problem, he said.
It's a great feeling when you don't have to rely on others all the time.
Over time, he became faster and could walk longer even when the device was switched off, he added.
More research is still needed -- and this technique will not be effective for all patients, Courtine emphasised.
Because it depends on boosting the brain's signal to the spinal cord, it depends how much signal was getting through in the first place.
And while deep brain stimulation is now fairly common, some people are not so comfortable with someone operating on their brain, Courtine added.
The researchers believe that in the future, the best option for recovering from these kinds of injuries could be stimulating both their spinal cord and lateral hypothalamus.