TMS-EEG Investigation of Cortical Activity Induced by Individualized rTMS in Patients with Prolonged Disorders of Consciousness

When a severe brain injury leaves a person awake but unresponsive, or aware but unable to move or speak, the medical world calls this a prolonged disorder of consciousness. For decades, doctors have struggled to find reliable ways to help these patients regain awareness. While some treatments exist, they often rely on a "one-size-fits-all" approach, stimulating the same part of the brain for every patient regardless of their unique injury. This method frequently falls short because every brain injury is different, leaving many patients without a clear path to recovery. Scientists have long suspected that the key to unlocking consciousness lies not just in stimulating a specific spot, but in understanding how the remaining healthy parts of the brain are still talking to one another. If a doctor could identify which specific neural pathways are still strong enough to carry a signal, they might be able to use that information to wake up the rest of the network.

A team of researchers at Xuanwu Hospital in Beijing set out to test this idea using a technique called repetitive transcranial magnetic stimulation, or rTMS. This non-invasive treatment uses a magnetic coil held against the scalp to gently stimulate brain cells. In this study, the researchers wanted to see if they could improve the treatment by first mapping each patient's brain to find the single best spot to stimulate. They enrolled 42 patients who had been in a state of prolonged unconsciousness for at least 28 days. Before any treatment began, the team used a sensitive brain activity monitor called an electroencephalogram, or EEG, to listen to the electrical signals of the patients' brains while they rested. By analyzing these signals, they calculated which areas of the brain were acting as the strongest leaders, sending the most information to other parts of the network. For some patients, this "leader" was in the front part of the brain; for others, it was in the back.

The patients were then divided into three groups to compare different approaches. One group received the new, personalized treatment where the magnetic coil was placed exactly on the brain area that the EEG had identified as the strongest leader. A second group received the standard treatment, where the coil was placed on a common target area chosen at random, without looking at the individual's brain map. The third group received a fake treatment, where the coil was held in a way that made a noise but delivered no magnetic pulse to the brain. All active treatments lasted for ten days, with one session each day. To measure success, the researchers used a detailed scale called the Coma Recovery Scale-Revised to check for any improvements in the patients' ability to hear, see, move, or communicate. They also used a special combination of the magnetic stimulation and the brain monitor to see how the brain reacted in real-time, measuring the strength and spread of electrical waves immediately after the stimulation.

The results showed a clear difference between the groups. Both the personalized group and the standard group saw significant improvements in their behavioral scores, meaning they showed more signs of awareness and interaction than before. The group that received the fake treatment showed no such improvement. However, when the researchers looked deeper into how the brains were working, the personalized approach stood out. Using the brain monitor, they found that the personalized group showed a much stronger and longer-lasting electrical response in the brain after stimulation. While the standard group saw a quick burst of activity that faded, the personalized group's brain activity continued to ripple through the network for a longer period, reaching further into the brain's deeper regions. This suggests that by hitting the right "leader" node, the treatment was able to keep the signal alive and let it travel through the remaining healthy connections, effectively waking up more of the brain.

The study also found a direct link between these brain changes and the patients' recovery. The more the electrical signals in the brain grew stronger and lasted longer, the more the patients' behavioral scores improved. This connection was strongest in the group that received the personalized treatment. The findings suggest that the old method of picking a standard spot for everyone is less effective than tailoring the treatment to the individual's specific brain wiring. By using the brain's own electrical map to guide the stimulation, doctors may be able to help the brain's remaining networks work together more efficiently. This work does not claim to have solved the problem of consciousness, but it provides strong evidence that moving away from fixed targets toward personalized, precision-based care could be the next major step in helping patients recover from severe brain injuries.