Issue 33.1 read , but after the implant I bought a book , Where the Crawdads Sing , and loved it and remembered it . And I don ’ t have that quick temper .”
For Arata and four others , the experimental deep-brain-stimulation device restored , to different degrees , the cognitive abilities they had lost to brain injuries years before . The new technique , developed by Stanford Medicine researchers and collaborators from other institutions , is the first to show promise against the long-lasting impairments from moderate to severe traumatic brain injuries .
The results of the clinical trial were published in Nature Medicine .
Dimmed lights More than 5 million Americans live with the lasting effects of moderate to severe traumatic brain injury — difficulty focusing , remembering and making decisions . Though many recover enough to live independently , their impairments prevent them from returning to school or work and from resuming their social lives .
“ In general , there ’ s very little in the way of treatment for these patients ,” said Jaimie Henderson , MD , professor of neurosurgery and co-senior author of the study .
But the fact that these patients had emerged from comas and recovered a fair amount of cognitive function suggested that the brain systems that support attention and arousal — the ability to stay awake , pay attention to a conversation , focus on a task — were relatively preserved .
These systems connect the thalamus , a relay station deep inside the brain , to points throughout the cortex , the brain ’ s outer layer , which control higher cognitive functions .
“ In these patients , those pathways are largely intact , but everything has been down-regulated ,” said Henderson , the John and Jene Blume-Robert and Ruth Halperin Professor . “ It ’ s as if the lights had been dimmed and there just wasn ’ t enough electricity to turn them back up .”
In particular , an area of the thalamus called the central lateral nucleus acts as a hub that regulates many aspects of consciousness .
“ The central lateral nucleus is optimized to drive things broadly , but its vulnerability is that if you have a multifocal injury , it tends to take a greater hit because a hit can come from almost anywhere in the brain ,” said Nicholas Schiff , MD , a professor at Weill Cornell Medicine and co-senior author of the study .
The researchers hoped that precise electrical stimulation of the central lateral nucleus and its connections could reactivate these pathways , turning the lights back up .
Precise placement In the trial , the researchers recruited five participants who had lasting cognitive impairments more than two years after moderate to severe traumatic brain injury . They were aged 22 to 60 , with injuries sustained three to 18 years earlier .
The challenge was placing the stimulation device in exactly the right area , which varied from person to person . Each brain is shaped differently to begin with , and the injuries had led to further modifications .
“ That ’ s why we developed a number of tools to better define what that area was ,” Henderson said . The researchers created a virtual model of each brain that allowed them to pinpoint the location and level of stimulation that would activate the central lateral nucleus .
Guided by these models , Henderson surgically implanted the devices in the five participants .
“ It ’ s important to target the area precisely ,” he said . “ If you ’ re even a few millimeters off target , you ’ re outside the effective zone .”
A pioneering moment After a two-week titration phase to optimize the stimulation , the participants spent 90 days with the device turned on for 12 hours a day .
Their progress was measured by a standard test of mental processing speed , called the trail-making test , which involves drawing lines connecting a jumble of letters and numbers .
“ It ’ s a very sensitive test of exactly the things that we ’ re looking at : the ability to focus , concentrate and plan , and to do this in a way that is sensitive to time ,” Henderson said .
At the end of the 90-day treatment period , the participants had improved their speeds on the test , on average , by 32 %, far exceeding the 10 % the researchers had aimed for .
“ The only surprising thing is it worked the way we predicted it would , which is not always a given ,” Henderson said .
For the participants and their families , the improvements were apparent in their daily lives . They resumed activities that had seemed impossible — reading books , watching TV shows , playing video games or finishing a homework assignment . They felt less fatigued and could get through the day without napping .
The therapy was so effective the researchers had trouble completing the last part of their study . They had planned a blinded withdrawal phase , in which half the participants would be randomly selected to have their devices turned off . Two of the patients declined , unwilling to take that chance . Of the three who participated in the withdrawal phase , one was randomized to have their device turned off . After three weeks without stimulation , that participant performed 34 % slower on the trail-making test .
The clinical trial is the first to target this region of the brain in patients with moderate to severe traumatic brain injury , and it offers hope for many who have plateaued in their recovery .
“ This is a pioneering moment ,” Schiff said . “ Our goal now is to try to take the systematic steps to make this a therapy . This is enough of a signal for us to make every effort .” g
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