Improving prognostication after severe brain injury

The road to improving diagnosis and prognostication in patients who are not responsive after brain injury has been a long and winding one. In 2006, functional MRI was used—for the first time—to show that a clinically non-responsive patient with a severe brain injury, who fulfilled all standard clinical criteria for the vegetative state, was in fact consciously aware and could reliably modulate their brain activity to specific commands. 1 Owen AM Coleman MR Boly M Davis MH Laureys S Pickard JD Detecting awareness in the vegetative state. Science. 2006; 3131402 Crossref Scopus (1174) Google Scholar The vegetative state (now often referred to as unresponsive wakefulness syndrome) is a chronic condition in which patients have periods of wakefulness but appear to be entirely unaware of themselves or their environment. In 2011, in a study of 16 patients with unresponsive wakefulness syndrome, EEG was used at the bedside, and three (19%) patients showed non-behavioural signs of preserved awareness. 2 Cruse D Chennu S Chatelle C et al. Bedside detection of awareness in the vegetative state: a cohort study. Lancet. 2011; 378: 2088-2094 Summary Full Text Full Text PDF PubMed Scopus (470) Google Scholar Many similar studies followed and, by 2016, a comprehensive meta-analysis 3 Kondziella D Friberg CK Frokjaer VG Fabricius M Møller K Preserved consciousness in vegetative and minimal conscious states: systematic review and meta-analysis. J Neurol Neurosurg Psychiatry. 2016; 87: 485-492 Crossref PubMed Scopus (123) Google Scholar of more than 1000 cases showed that this form of covert consciousness, which has been termed cognitive-motor dissociation, 4 Schiff ND Cognitive motor dissociation following severe brain injuries. JAMA Neurol. 2015; 72: 1413-1415 Crossref PubMed Scopus (168) Google Scholar could be detected in approximately 15% of patients with unresponsive wakefulness syndrome using either functional MRI or EEG. Moreover, several cohort studies have shown that such signs of preserved cortical function, whether detected with functional MRI or EEG, have prognostic utility, in that such patients are more likely to show subsequent signs of improvement than are patients who do not show non-behavioural signs of consciousness, despite their indistinguishable behavioural signs and similar clinical profiles. 5 Coleman MR Davis MH Rodd JM et al. Towards the routine use of brain imaging to aid the clinical diagnosis of disorders of consciousness. Brain. 2009; 132: 2541-2552 Crossref PubMed Scopus (220) Google Scholar , 6 Pan J Xie Q Qin P et al. Prognosis for patients with cognitive motor dissociation identified by brain-computer interface. Brain. 2020; 143: 1177-1189 Crossref PubMed Google Scholar Nevertheless, most of these studies have focused on patients with chronic brain injury—ie, those who have survived for months or years with diminishing prospects for any meaningful improvement in their condition. Cognitive-motor dissociation and time to functional recovery in patients with acute brain injury in the USA: a prospective observational cohort studyRecovery trajectories of clinically unresponsive patients diagnosed with cognitive-motor dissociation early after brain injury are distinctly different from those without cognitive-motor dissociation. A diagnosis of cognitive-motor dissociation could inform the counselling of families of clinically unresponsive patients, and it could help clinicians to identify patients who will benefit from rehabilitation. Full-Text PDF