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Prolonged Disorders of
Consciousness
A Wake Up Call
Consciousness
• No clear agreed definition by neuroscientists
• Generally accepted 2 components
– Wakefulness
– Awareness
Neural Basis of Consciousness
Reticular activating
system in brain stem
Cerebral cortex
Thalamus
AWAKE
AWARE
Cerebral cortex
Thalamus
Cerebellum
Brain stem
Spinal cord
Normal
Cortex: working
AWARE
Reticular activating
system : working
AWAKE
Neural Basis of Consciousness
Reticular activating
system
STATE
AWAKE
Cerebral cortex
Thalamus
CONTENT
• sensations
• emotions
• images
• memories
• Ideas etc.
AWARE
Disturbance of consciousness
Common terms
• Sleep: a state of reduced responsiveness to, and interaction
with, the environment which is readily reversible
• Confusional state: minor disorientation, faulty memory, short
attention span, some difficulty following commands
• Delirium: disorientation, irritability, restlessness,
hallucinations
• Stupor: unresponsive & only aroused by vigorous stimulation
• Coma: unresponsive & unrousable
Glasgow Coma Scale
•
•
Eye Opening
4 = spontaneous
3= to verbal command
2= to pain
1= none to pain
Verbal Response
5 = orientated to time & place
4 = confused: talking in sentences
but disorientated
3 = words: utters occasional words
rather than sentences
2 = sounds: grunts & groans
1 = none
•
Motor Response
6 = Obeys commands
5 = Localises to pain
4 = Flexion withdrawal
3= Abnormal flexion
2 = Extends to pain
1 = none
Definition of Coma
• A state of unrousable psychological
unresponsiveness in which subject lies with
eyes closed & shows no response to external
stimulus or inner need
• GCS: at best E 2; M 4; V 2 (no eye opening to
voice; weak flexion to pain; grunt to pain)
Prolonged disorders of consciousness
after severe brain damage
• Vegetative state
• Minimally conscious state
• Locked in syndrome
• Brain stem death
Consciousness
Being consciousness requires a person to be
awake and aware.
To be both, the reticular activating system
and the cerebral cortex ( & thalamus) need
to be intact.
Normal
Cortex: working
AWARE
Reticular activating
system : working
AWAKE
Vegetative State
• A clinical condition of unawareness of self &
environment
• Usually the patient
– breathes spontaneously
– has a stable circulation
– shows cycles of eye closure & opening (simulating
sleep & waking.)
Vegetative state
Cortex: NOT working
UNAWARE
Reticular activating
system : working
AWAKE
Vegetative State
[European : Unresponsive Wakefulness
Syndrome(UWS) ; apallic syndrome]
Usually:
• Breathe spontaneously
• Stable circulation
• Cycles of eye closure/opening (like
sleep/wake)
Observed Behaviours during
VEGETATIVE STATE
•
•
•
•
•
•
Chewing; teeth grinding; tongue pumping
Roving eye movements
Non-purposeful limb movements
Facial movements (e.g. smiles or grimaces)
Shedding tears
Grunts or groans
Prevalence of VS
• Estimate: 0.5-2/100,000
• Thus:
– ~26-106 cases in Scotland
– ~6-24 cases in Greater Glasgow & Clyde NHS
– ~4-16 cases in Lothian NHS
Minimally Conscious State
One or more of following
– follows simple commands
– gestural or verbal yes/no responses
– intelligible verbalization
– stereotypical movements (e.g. blink, smile) in
meaningful relationship to the eliciting stimulus &
not reflexive
– manipulation of objects
Minimally Conscious State(MCS)
•
•
•
•
Crying, smiling, laughing in response to emotional stimuli
Vocalisation or gestures to comments/questions
Reaching for objects
Touching/holding objects in a manner that accommodates the
size & shape of object
• Sustained fixation or pursuit eye movements in direct
response to stimuli
• Other localising or discriminating behaviours that constitute:
– Movement towards a perceived object
– Differential responses to different objects or people
Emergence from MCS
Responses become RELIABLE & CONSISTENT
• Functional Communication: verbal, written ,
using augmentative communication device ;
or yes/no signals.
+/or
• Functional use of objects: discrimination
between at least 2 different objects
Assessment tools
• JFK Coma Recovery Scale-Revised (CRS-R)
• Wessex Head Injury Matrix (WHIM)
• Sensory Modality Assessment and Rehabilitation
Technique (SMART)
• Western Neuro Sensory Stimulation Profile (WNSSP)
• Sensory Stimulation Assessment Measure (SSAM)
• Disorders of Consciousness Scale (DOCS)
Investigative techniques
• Functional MRI (fMRI) scans
• Electrophysiology
– Sleep EEG
– Evoked potentials
Treatment approaches
• Medications:
– Amantadine
– Zolpidem
– Methylphenidate
• Neurostimulation:
– Deep brain stimulation
– Transcranial magnetic stimulation
– Transcranial direct current stimulation
• Sensory stimulation (Coma arousal programmes)
Deep brain stimulation (DBS)
Transcranial magnetic stimulation(TMS)
Transcranial direct current stimulation(tDCS)
Prognosis in VS & MCS
• Likelihood of functional improvement
diminishes over time
• Shorter window for recovery in non-TBI cf. TBI
(e.g. VS : 3mths non-TBI; 12mths TBI)
• MCS ~70% emerge by 2yrs. ; ~30% by 4 yrs
post-injury
Permanent Vegetative State
• > 6 months after non-traumatic brain injury
• > 1 year after traumatic brain injury
Care Pathway (RCP)
ITU/ Neurosurgery
Assessment by N-rehab team at 4 days
Hospital ward
Neurorehabilitation
Specialist Nursing Home
24 hour care programme
Medical management of complications
Assessment of responses
Best interests meeting
3-4 months
Formal review : Non-TBI 6mths.
TBI 1 year
MCS annually for 5 years
Neurorehabilitation
24 hour programme
• Airway
• Nutrition & hydration
• Oral care
• Bowel & bladder
• Pressure care
• Positioning/stretching
• Supportive seating
Medical management
• Hydrocephalus
• Diabetes insipidus
• Epilepsy
• Spasticity
• Pain
• Intercurrent infection
• Deep vein thrombosis
prevention
Neurorehabilitation (Cont.)
• Assessment of responses
• Family communication re: diagnosis &
prognosis
• Best interest meeting
– Resuscitation
– Use of antibiotics etc.
• Discharge planning
Care Pathway (RCP)
ITU/ Neurosurgery
Assessment by N-rehab team at 4 days
Hospital ward
Neurorehabilitation
24 hour care programme
Medical management of complications
Assessment of responses
Best interests meeting
3-4 months
Specialist Nursing Home
Long term care
Formal review : Non-TBI 6mths.
TBI 1 year
MCS annually for 5 years
Locked-in Syndrome
•
•
•
•
•
Consciousness intact
Can open eyes & move up & down
Total limb paralysis
No speech (anarthria)
Difficulty swallowing (dysphagia)
• GCS: E 4,M 1, V 1
Locked in syndrome
Cortex: working
AWARE
Reticular activating
system: working
BUT!!
AWAKE
Ventral pons damaged: quadriplegia
Brainstem
Cerebellum
MIDBRAIN
PONS
IVth ventricle
MEDULLA
Locked in Syndrome
Vertical eye movements
Cardiovascular &
Respiratory Centres
VENTRAL PONS
Motor pathways
to limbs & trunk
Reticular Activating
System
Cause & Mechanism
Cause
Mechanism
Ischaemic
Basilar artery occlusion; hypotension/hypoxia
Haemorrhage
Haemorrhage in pons
Trauma
Contusion; vertebrobasilar dissection
Tumour
Infiltration of ventral pons
Metabolic
Central pontine myelinolysis
Demyelination
Multiple sclerosis
Infection
Brain stem encephalitis; abscess
Brain stem death
1. Irremediable brain damage of known cause
2. Deep coma: effects of drugs & potentially
reversible metabolic/endocrine disturbances
excluded
3. Ventilator dependent
Brain stem death
Nothing working including
respiratory, vasomotor
centre etc
Brain stem death
Brainstem reflexes
• No pupil response to light
• No corneal reflex
• No vestibulo-ocular reflex
• No cranial motor response
to pain
• No gag reflex or response to
suction
• Loss of doll’s head eye
movements
Brainstem death
• Unconscious
• No cyclical eye opening
• No motor function other
than reflex spinal
• GCS: E 1, M 1-2, V 1
• Switch off ventilator for 3-5
minutes: no respiration
NORMAL
LOCKED IN SYNDROME
VEGETATIVE STATE
BRAIN STEM DEATH