An important trial in Lausanne on two patients with leg paralysis. The patients’ urge to walk has come back and they’re able to walk short distances thanks to DBS of the lateral hypothalamus (an area of the brain previously never associated with movement).
Until now, deep brain stimulation (DBS) – done by implanting thin electrodes into the brain – has mainly been used to lessen tremors in Parkinson's disease. But it could also open up new horizons for treating spinal cord injuries that cause leg paralysis.
The role of the lateral hypothalamus in starting to walk again
The first two patients treated with DBS at Lausanne University Hospital by doctors from the NeuroRestore centre, in partnership with researchers from the Swiss Federal Institute of Technology (EPFL) in Lausanne, have shown promising results, bringing fresh hope.
In this trial, to the surprise of the scientific community, the Swiss neurosurgeons chose to arrange the electrodes near a region of the brain that had previously never been considered significant for movement: the lateral hypothalamus. And yet the stimulation with mild electrical currents “immediately improved walking” in both patients, as soon as it began, write the researchers in the journal Nature Medicine. What’s more, functional recovery persisted even after DBS was turned off, partly down to a special rehabilitation programme.
A super-detailed atlas
How did they achieve this? The two coordinators, Grégoire Courtine and Jocelyne Bloch, carefully examined the wealth of information (especially images from functional magnetic resonance scans of the brain) that had been collected over the years in laboratory animals (mice and rats) with various forms of paralysis. The researchers thus created a map – which they called a “space-time atlas” – of the neurons that sent impulses in the best cases, in other words in situations where the animals had at least partly recovered walking after an incomplete spinal cord injury (an injury that causes paralysis but still leaves some nerve fibres intact).
“Unexpectedly,” write the Swiss researchers, “interrogation of this atlas [to identify brain regions that contributed to the functional recovery of previously paralysed limbs] nominated the lateral hypothalamus.” So the neurosurgeons then decided to try performing deep brain stimulation in that area of the brain, even on the two patients.
The first patient to have the operation was a woman. Once the electrodes were correctly in place, she immediately said, "I feel my legs.” And when the stimulation with mild electrical currents was increased, she exclaimed, “I feel the urge to walk!”
Something similar also happened to the second patient, a 54-year-old man who had been in a wheelchair since a skiing accident in 2006. He recovered a small amount of independent movement after the operation. “Last year on vacation,” he said, “it was no problem to walk a couple of steps down and back to the sea using the stimulation.” In addition to walking, the therapy has also improved his day-to-day activities. “I can finally reach things in the cupboards in my kitchen,” he added.
Towards a comprehensive recovery strategy
“This research,” explained Professor Courtine, co-director of the NeuroRestore centre, “demonstrates that the brain is needed to recover from paralysis [editor’s note: and therefore that medical treatments mustn’t be focused solely on the injured area of the spinal cord]. Surprisingly, the brain is not able to take full advantage of the neuronal projections that survive after a spinal cord injury. Here, we found how to tap into a small region of the brain that was not known to be involved in the production of walking in order to engage these residual connections and augment neurological recovery in people with spinal cord injury.”
New “combinations” also with other technologies
The identification of the lateral hypothalamus as a key area for motor recovery after paralysis is an important scientific discovery in itself, given that this region had traditionally only been associated with controlling food intake and regulating the body’s energy balance.
The Lausanne-based researchers will continue their research into this over the coming months, while also seeking to integrate DBS with other technologies, such as spinal implants, which have already shown their potential to restore movement after paralysis. “Integrating our two approaches –brain and spinal stimulation – will offer a more comprehensive recovery strategy,” concluded Prof. Courtine. But it’ll be a while before these procedures can be applied on a large scale.
