Mehak Vohra
Disorders of consciousness (DoC) are medical conditions with inhibited consciousness such as minimally conscious states, a persistent vegetative state, and even chronic coma. DoC presents unique problems during diagnosis, prognosis and treatment, since it is extremely difficult to assess an individual’s consciousness and is caused by traumatic head injuries. Due to the difficulties in forming an accurate diagnosis, and inadequate knowledge about the residual symptoms experienced, there is difficulty in forming rehabilitation techniques for DoC. This paper will look at how rehabilitation techniques for disorders of consciousness could be improved by eliminating the possibilities of misdiagnosis through better aids.
In a research study conducted by Macdonald et al on patients thought to be in the vegetative state (VS) of a comma under DoC, it was found that they were often misdiagnosed as covert signs of conscious awareness went unnoticed. The cost of a misdiagnosis was such that it resulted in inaccurate prognosis and incorrect pain management, affected the life-or-death consequences the patient faces. This warrants further attempts to detect covert signs of preserved conscious awareness in patients of DoC. (Macdonald et al)
A multiple case study by Aubinet et al studied different patients recovering from DoC using Coma Recovery Scale- Revised (CRS-R) which is used to diagnose DoC and Cognitive Assessment by Visual Election (CAVE) scale which is a neuropsychological measurement to assess the residual cognitive symptoms they face. The study measured a patient’s cognitive abilities to assess how a greater traumatic injury may have impacted someone in a greater way. It was seen that individuals with a higher CRS-R score also had a higher CAVE score. The case study has a very small sample size of six patients and could not represent the heterogeneity of DoC but the implications of the study are useful in the preparation of improved rehabilitation programs for patients of DoC to help their daily routines through better characterization of a patient’s cognitive profile.
The development of rehabilitation programs to treat the residual symptoms and cognitive effects of DoC is hence, very crucial. There is a need for better diagnostic tools, as well as new behaviour assessment and neuropsychological techniques for DoC, to avoid misdiagnosis and further problems in treatment. The amount of heterogeneity seen in DoC makes it difficult to design structured treatments or anticipate what a patient may experience, which is why the research in this area of study becomes integral. It is important to consider the structural, functional and cognitive changes brought about in a person’s brain once they have experienced forced unconsciousness or a coma after a traumatic brain injury, leading to them developing a Disorder of Consciousness (DoC).
While considering the impairments one may face during or after a DoC, the functioning of a normal brain in different levels of conscious awareness have to be studied. This is done through an induced loss of consciousness through the use of anesthetics. Anesthetics are used to induce different states of conscious awareness and then ask the person to perform tasks which may measure any hampered functioning of the brain. (MacDonald et al) Neuroimaging such as functional and structural magnetic resonance imaging (MRI) and fluorodeoxyglucose positron emission tomography (FDG-PET) used by Aubinet et al, have proven to be useful aids in this research. Hence, anesthetics and neuroimaging can be used to form better diagnostic tools.
The study and understanding of DoC and its residual effects and implications is useful in exploring different rehabilitation techniques, paving the way for further research and improved understanding of DOC for improved diagnostic and prognostic tools. Research in this area gives a clearer aftermath of traumatic brain injury, ie, DoC in the form of residual cognitive impairments which are unique to every case. A new finding of Active paradigms, techniques developed to reveal conscious awareness in patients who were previously assumed to be entirely vegetative, helps avoid misdiagnosis in DoC. (Naci et al 2013) However, there is scope for further research in investigating the neural correlates of behaviour and cognition in patients with severe brain injury and how it could improve rehabilitation techniques for DoC.
References:
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Schrouff, J. et al. (2011) Brain functional integration decreases during propofol-induced loss of consciousness. Neuroimage 57, 198-205
Naci, L.et al. (2013) The brain’s silent messenger: using selective attention to decode human thought for brain-based communication. J. Neurosci. 33, 9385-9393
Tononi, G. and Koch, C. (2008) The neural correlates of consciousness: an update. Ann.N.Y. Acad. Sci. 1124, 239-261.
Monti, M.M. et al. (2010). The vegetative state. BMJ 341, c3765 Boly.
M. et al. (2013) Consciousness in humans and non-human animals: recent advances and future directions. Front. Psychol. 4, 625
MacDonald, Alex A.et al . (2015) "Anesthesia And Neuroimaging : Investigating The Neural Correlates Of Unconsciousness." Trends in Cognitive Sciences 19.2 : 100-107. Web.
Aubinet, C. et al. (2018). Brain, Behavior, and Cognitive Interplay in Disorders of Consciousness: A Multiple Case Study. Frontiers in Neurology, 9. doi: 10.3389/fneur.2018.00665
Vohra (2019) The use of Anesthesia and Neuroimaging to detect the effect on cognition during different levels of consciousness.
Vohra (2019) The use of Anesthesia and Neuroimaging to detect the effect on cognition during different levels of consciousness.
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