A new technique for measuring consciousness offers a reliable way to guide treatment of patients with brain injuries who can’t respond to commands, according to a study.
By using a device that shakes the entire brain with strong magnetic stimulation, researchers led by a team at University of Milan in Italy measured the amount of information flow occurring in the brain. They were able to discriminate between various levels of consciousness with a numerical index they developed. The study was published today in Science Translational Medicine.
The technique may be particularly useful in assessing improvements in patients in intensive-care units who have low levels of consciousness, for which no objective measure exists, resulting in high rates of incorrect diagnoses, said Marcello Massimini, one of the study authors. With the brain stimulation technique, they found that such patients actually had much higher levels of consciousness than subjects who were sleeping or were anesthetized, he said.
“It will be very important to perform measurements right in the ICU in the acute phase to have an objective marker of what’s happening and to track improvements occurring spontaneously or brought about by treatment,” Massimini said in a phone interview. “If you have a number, you can start working towards an evidence-based treatment.”
The method was tested on 52 subjects including healthy ones while they were awake, sleeping, and under anesthesia, and also on brain-injured patients who had emerged from a coma.
“Measures that can reliably distinguish vegetative states from minimally conscious states are crucial and will have an impact on clinical practice,” said Nicholas Schiff, a professor of neurology and neuroscience at Weill Cornell Medical College in New York, in a comment accompanying the paper. “Misdiagnosis rates are high when behavioral evidence of consciousness is limited.”
The researchers used a trans-cranial magnetic stimulation device made by Nexstim, based in Helsinki, Massimini said. The device also records electrical responses of the brain induced by the stimulation pulses. Brainsway Ltd. of Jerusalem also produces a TMS device for treating neurological conditions such as depression.