Research Reports - Early detection of consciousness in patients with acute severe traumatic brain injury

Brain. 2017 Sep 1;140(9):2399-2414. doi: 10.1093/brain/awx176.

Edlow BL(1)(2)(3), Chatelle C(1)(2)(4), Spencer CA(2), Chu CJ(2), Bodien
YG(1)(2)(5), O'Connor KL(2), Hirschberg RE(5)(6), Hochberg LR(1)(2)(7), Giacino
JT(5)(6), Rosenthal ES(2), Wu O(3).

See Schiff (doi:10.1093/awx209) for a scientific commentary on this
article. Patients with acute severe traumatic brain injury may recover
consciousness before self-expression. Without behavioural evidence of
consciousness at the bedside, clinicians may render an inaccurate prognosis,
increasing the likelihood of withholding life-sustaining therapies or denying
rehabilitative services. Task-based functional magnetic resonance imaging and
electroencephalography techniques have revealed covert consciousness in the
chronic setting, but these techniques have not been tested in the intensive care
unit. We prospectively enrolled 16 patients admitted to the intensive care unit
for acute severe traumatic brain injury to test two hypotheses: (i) in patients
who lack behavioural evidence of language expression and comprehension,
functional magnetic resonance imaging and electroencephalography detect
command-following during a motor imagery task (i.e. cognitive motor dissociation)
and association cortex responses during language and music stimuli (i.e.
higher-order cortex motor dissociation); and (ii) early responses to these
paradigms are associated with better 6-month outcomes on the Glasgow Outcome
Scale-Extended. Patients underwent functional magnetic resonance imaging on
post-injury Day 9.2 ± 5.0 and electroencephalography on Day 9.8 ± 4.6. At the
time of imaging, behavioural evaluation with the Coma Recovery Scale-Revised
indicated coma (n = 2), vegetative state (n = 3), minimally conscious state
without language (n = 3), minimally conscious state with language (n = 4) or
post-traumatic confusional state (n = 4). Cognitive motor dissociation was
identified in four patients, including three whose behavioural diagnosis
suggested a vegetative state. Higher-order cortex motor dissociation was
identified in two additional patients. Complete absence of responses to language,
music and motor imagery was only observed in coma patients. In patients with
behavioural evidence of language function, responses to language and music were
more frequently observed than responses to motor imagery (62.5-80% versus
33.3-42.9%). Similarly, in 16 matched healthy subjects, responses to language and
music were more frequently observed than responses to motor imagery (87.5-100%
versus 68.8-75.0%). Except for one patient who died in the intensive care unit,
all patients with cognitive motor dissociation and higher-order cortex motor
dissociation recovered beyond a confusional state by 6 months. However, 6-month
outcomes were not associated with early functional magnetic resonance imaging and
electroencephalography responses for the entire cohort. These observations
suggest that functional magnetic resonance imaging and electroencephalography can
detect command-following and higher-order cortical function in patients with
acute severe traumatic brain injury. Early detection of covert consciousness and
cortical responses in the intensive care unit could alter time-sensitive
decisions about withholding life-sustaining therapies. 

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