2. William James (1890) defined consciousness
as awareness of oneself (or one's own
cognitive experience) and environment.
Consciousness encompasses two main
components: wakefulness and awareness.
Wakefulness-state in which eyes are open
and have degree of motor arousal.
Awareness-ability to have and having of
experience of any kind
3. Bedside, wakefullness observed by looking at
presence of eye opening.
Bedside, awareness mostly inferred by
command following.
4. Dependent on ascending reticular activating
system in upper brainstem tegmentum and
midline and intralaminar nuclei of thalamus.
Extends through to cerebral cortex
Thalamic reticular nucleus-responsible for
"gating" specific reticular information that is
transmitted to cerebral cortex
Also provides feedback to brainstem centers
that play a role in arousal and alertness.
5. Neurotransmitter systems relevant to arousal
are cholinergic, monoaminergic, and γ-
aminoburtyric acid–ergic.
Neuropeptides (thyrotropin-releasing
hormone, vasopressin corticotropin-releasing
hormone, somatostatin, substance P, and
neuropeptide Y)-modulating cortical activity
and influencing cognitive processes.
6. Requires cerebral cortical activity that is
intimately connected to subcortical structures
On EEG gamma or 40-Hz rhythm-produced
by thalamocortical circuits during attention
and sensory processing tasks.
Require binding of processed sensory
information with memory, attention, and
motor responses.
Synchronous across various regions, linking
thalamocortical networks as well as the
hippocampus and neocortex.
7. Necessary for conscious appreciation.
Involves awareness, on part of individual, of
something happening as a result of stimulus
acting on sensory receptor.
Have discrete (modular) primary cerebral cortical–
receiving regions and association areas for
processing.
Primary sensory modalities include visual,
auditory, somatosensory, olfactory, gustatory,
vestibular, and visceral sensations.
Have temporal and spatial characteristics and are
modality specific.
Are linked with memory and affect.
8. Involves processing of sensory information,
allowing a symbolic concept of what is happening
in the external world.
Perception overrides sensation when both are
present.
Conscious vision involves object recognition,
process involving primary visual cortex, visual
association areas and reciprocal connections with
memory stores.
Prefrontal regions-plays role in choosing
information to be consciously perceived with
processing and linkage to other modalities
including memory, motivational and motor areas.
9. Control process that enables individual to
select, from a number of alternatives, task he
will perform or stimulus he will process, and
cognitive strategy he will adopt to carry out
these operations.
Prerequisite, he must be awake and alert.
Main features include directivity and
selectivity of mental processes.
10. Anterior cingulate gyrus, dorsolateral
prefrontal cortex, inferior parietal lobule,
centromedian and parafasicular thalamic
nuclei, thalamic reticular nucleus, reticular
formation of midbrain tegmentum and
superior colliculus.
Dopaminergic and noradrenergic systems are
important in attentional responses.
11. When axon of cell A is near enough to
excite cell B and repeatedly and persistently
takes part in firing it, some growth process
or metabolic change takes place in one or
both cells such that A's efficiency, as one of
cells firing B, is increased.
Anterograde memory: hippocampus,
parahippocampal gyrus, subiculum,
entorhinal and perirhinal cortex,
mammillary bodies, dorsomedial thalamic
nucleus, cingulate cortex, fornix and tracts
connecting these structures.
12. Amnestic individual, without ability to store
conscious, explicit memories, cannot be
considered unconscious as alertness is
preserved and can interacts with
environment.
Explicit, but not implicit, memories are
accompanied by consciousness.
Explicit-hippocampus and related structures.
Short-term retention of limited number of
items held in consciousness for immediate
use.
13. Motivational drives help to determine behavior
after person has attended to stimulus and
assessed its significance relevant to competing
internal or external factors.
Closely allied to crude consciousness, perception,
goal-directed activity, and emotions.
Emotional cognition, including motivation-limbic
and nonlimbic system.
Motivation-amygdala, hypothalamus, and
associated limbic structures.
14. Hippocampus and amygdala on each side
receive parallel-convergent projections from
various sensory systems.
Hippocampus consolidates information into
memory and accesses stores of recent
memory in neocortex.
Amygdala-gives sensory information
affective, experiential tone and expression of
emotion.
15. Hypothalamus-role in outward expressions of
emotion—autonomic phenomena and
behaviors.
Receives afferents from various parts of brain
including amygdala-diencephalon and
hippocampal-forniceal-mammillary
subdivision, cerebral cortex and reticular
formation.
Hypothalamus- responsible for maintaining
homeostasis through endocrine, autonomical,
and behavioral inputs and outputs.
16. Involves network of numerous interconnected
modular processors across vast regions of
cerebral cortex (with reciprocal connections with
subcortical structures) that provide parallel
processing of information.
Executive function of frontal lobes-impact on
conscious experience.
Frontal lobes-organize input, devise retrieval
strategies, verify output, and place it in proper
historic context.
Prefrontal-use this information to direct and plan
further action.
18. Alertness-ascending reticular formation's activating role
Awareness depends on an infrastructure of attention.
Awareness of outside world (for all but olfaction) requires
parietal cortex for sensory processing and interpretation,
after initial reception in primary sensory areas.
Sensory information channeled into limbic system through
temporal lobes, especially amygdala.
Memory stores allow for appreciation of relevance or
importance of contemporary experiences.
Motivation, self-awareness, and communications with the
motor system relate to widespread integration of various
cortical and subcortical regions.
Frontal lobes-executive role in directing and maintaining
attention and in planning behavior.
19.
20.
21.
22. State of non-responsiveness to external as
well as internal need
No awareness of self or of environment
Patients lie with eyes closed and cannot be
awakened even when intensively stimulated.
Lack of sleep–wake cycles
No verbal production nor response to
command
Can present reflexive responses to painful
stimulation.
23. Autonomous functions and thermoregulation
reduced.
May require respiratory assistance
Global brain metabolism diminished by 50–70%
of normal
Caused by diffuse cortical or white matter
damage or brainstem lesion
Coma must last at least 1 h to be distinguished
from states of transient unconsciousness.
Prognosis made within 3 days.
Can last 2–5 weeks.
24. Unresponsive wakefulness syndrome
Defined by eyes opening, either spontaneously or
after stimulation.
Sleep–wake cycles characterized by alternating
phases of eye opening.
Autonomous functions are preserved
Breathing occurs usually without assistance.
No intelligible verbalization
No voluntary response
No signs of awareness of self or environment
Awake but not aware.
25. Brainstem functions are preserved
Cortical and thalamic injuries are present.
Brain metabolism diminished by 40–50% of
normal values.
Able to perform a variety of movements such as
grinding teeth, blinking and moving eyes,
swallowing, chewing, yawning, crying, smiling,
grunting or groaning.
Motor behavior is reduced to a few stereotyped
or reflexive movements
Do not track a moving object or their image in
mirror.
26. Persistent vegetative state >1month.
Permanent vegetative state >3month non
traumatic etiology and >1 year traumatic
etiology.
27.
28. Characterized by primary and inconsistent
signs of consciousness of self and
environment.
Pts. are unable to communicate functionally
Can sometimes respond adequately to verbal
commands and make understandable
verbalizations.
Emotional behaviors, such as smiles, laughter
or tears may be observed.
May track a moving object, mirror or person.
29. Responses must be reproducible in order to
conclude that action is intentional.
Cerebral metabolic activity is reduced by 20–
40%
Autonomous functions are preserved
Thalamocortical and corticocortical
connections are partly restored.
State may be transitory, chronic or
permanent.
30. MCS-plus patients-show more complex
behaviours such as command following.
MCS-minus patients-show only non-reflexive
movements such as orientation to noxious
stimuli, pursuit eye movements, etc
Continuing MCS >4 weeks.
Permanent MCS >5 years.
31. Functional interactive communication
(verbalization, writing, signaling or
augmentative communication devices)-
answer 6 out of 6 basic yes/no questions on
2 separate occasions regarding personal or
environmental orientation
Functional use of objects-demonstrating the
ability to appropriately use 2 different objects
on 2 consecutive evaluations.
32. Atleast one consistent response
1. Functional use of objects-at least 2
different objects on 2 consecutive
evaluations(with or without instruction)
2. Consistent discriminatory choice-making-
correct choice from 2 pictures or matches
paired objects on 6/6 trials on 2
consecutive evaluations.
33. 3. Evidence of awareness of self-Gives correct
yes/no responses to 6/6 autobiographical
questions on 2 occasion
4. Evidence of awareness of their
environment-Correct yes/no responses to
6/6 basic situational questions on 2
evaluations
34. Irreversible loss of all reflexes of brainstem
Demonstration of continuing cessation of
brain function and respiration in persistently
comatose patient.
Absence of electrical brain activity EEG
Absence of cerebral blood flow
35. Pseudocoma
Complete paralysis of body from lesion in
brainstem
Oral and gestural communications are impossible
Able to blink and move the eyes.
Fully aware of their environment and themselves
Communication skill (E-T-A-O-I-N-S-R-H-L-D-
C-U-M-F-P-G-W-Y-B-V-K-X-J-Q-Z) where
patient blinks when pronounces desired letter.
Brain computer interface developed.
90% vascular etiology
Cognitive functions are fully preserved.
36. 1 Detailed clinical history, examination and general investigation
• To identify cause of brain injury and any complications arising
from it.
• To exclude other conditions (eg metabolic/infective disorders,
hydrocephalus)
2 Review of medication
• To identify and, if possible, withdraw or reduce any drugs which
could affect arousal.
3 Standard imaging (computed tomography or magnetic resonance
imaging scan of the brain)
• To exclude specific structural, operable causes (such as
hydrocephalus) and localise areas of injury
within the brain.
4 Standard EEGs or trial of anticonvulsant, if subclinical seizure
activity is suspected.
37. 5 Detailed neurological evaluation to include
assessment of:
• primary visual pathways:
– pupillary light reflex, response to visual threat, or
evidence of visual tracking.
• primary auditory pathways:
– startle or blink reflexes in response to sudden loud
noises, or any evidence of localisation towards sound.
• primary somatosensory pathways:
– stretch reflexes, response to touch or pain.
• primary motor output pathways:
– any spontaneous or reflexive movements
• spinal pathways
38.
39. A screening tool to identify patients with
PDOC
Not a valid diagnostic tool for VS and MCS.
Patients with locked-in syndrome may score
lower than PDOC
40. Behaviour assessment scale
62-item hierarchical scale
Developed to monitor changes from coma
through to emergence from post-traumatic
amnesia.
Paid manual.
41. Developed to detect awareness, functional
and communicative capacity in VS and MCS
Used where there no consistent or reliable
responses elicited and where the pts.
potential function has not yet been fully
explored
Family perspectives recorded
Takes significantly longer(10-12hrs) than
other tools(3hrs).
Training mandatory.
42. Informal component (Smart-informs)-
information from family and carers-observed
behaviours and pre-morbid interests, likes and
dislikes.
Formal component-10 sessions within a 3-week
period:
◦ SMART Behavioural Observation Assessment – a 10-
minute quiet period observes any reflexive, spontaneous
and purposeful behaviours
◦ SMART Sensory Assessment
◦ sensory modalities (visual, auditory, tactile, olfactory,
gustatory)
◦ motor function, functional communication, wakefulness.
43. Assessed on 5-point hierarchical scale:
1. No response – to any stimulus
2. Reflexive and generalised responses-startle,
flexor or extensor patterns
3. Withdrawal-turning head or eyes away or
withdrawing limbs from a stimulus
4. Localising – turning head or moving upper
limbs towards a stimulus
5. Discriminating responses-following visual or
auditory commands or using object
appropriately.
44. 25 hierarchically arranged items with 6
subscales (auditory, visual, motor, oromotor,
communication and arousal)
45. Conventional imaging(CT,MRI)
Functional MRI-indirectly measures regional
increases in blood flow by analyzing magnetic
resonance properties of hemoglobin
PET scan-measure changes in brain’s
metabolism using radioactive tracer labeled
glucose
EEG
Sensory evoked potentials
Cognitive evoked potentials
53. The neurology of consciousness:cognitive
neuroscience and neuropathology; steven
Laureys and Giulio Tononi; Elsevier Ltd. 2009
Disorders of Consciousness: Coma, Vegetative
and Minimally Conscious States. States of
Consciousness; Olivia Gosseries et al;Springer-
Verlag Berlin Heidelberg 2011
Neurobiological Basis of Consciousness;G. Bryan
Young, MD; Susan E. Pigott; Arch
Neurol. 1999;56(2):153-157.
Prolonged disorders of consciousness: National
clinical guidelines 2013; Royal college of
physicians
