The sleep patterns of brain injury patients could hold the key to identifying the likelihood of long-term recovery, researchers say.
Columbia University and NewYork-Presbyterian Hospital researchers monitored the overnight brain activity in 226 comatose patients’ electroencephalograms, or EEGs, a test that measures electrical activity in the brain.
They were looking for sleep spindles — bursts of brain activity during sleep that are linked to memory and other cognitive functions.
“Spindles happen normally during sleep and they’re showing some level of organisation in the brain, suggesting circuits between the thalamus and cortex needed for consciousness are intact,” said Jan Claassen, associate professor of neurology at Columbia University Vagelos College of Physicians and Surgeons.
The patients also underwent more complex testing for cognitive motor dissociation, which is when a patient appears unconscious but shows brain activity indicating they can think and remember.
About a third of patients had well-defined sleep spindles, including about half of patients with cognitive motor dissociation.
Among patients with sleep spindles and cognitive motor dissociation, more than three quarters of patients (76 per cent) showed evidence of consciousness by hospital discharge.
One year later, 41 per cent of these patients had recovered neurological function and could care for themselves during the day, with either minor deficits or moderate disability.
Published in Nature Medicine, the early stage research shows sleep spindle detection could be a promising early predictor of whether acute brain injury patients could recover consciousness.
“We’re at an exciting crossroad in neurocritical care where we know that many patients appear to be unconscious, but some are recovering without our knowledge,” Dr Claassen said.
“We’re starting to lift the lid a little bit and find some signs of recovery as it’s happening.”