Brain Death Flashcards
What is Consciousness?
Awareness (of self and the environment)
Alertness (or can be woken up!)
Make appropriate (and differential) responses
But is it also:
Thinking, feeling, emotions, functioning, planning, self-monitoring
Wakefulness: activity of reticular activating substance from the brainstem
Integrated with:
The connections between cells and areas of the cerebral cortex – essentially the information being relayed through the connectome!
What is Locked in Syndrome?
Aware and awake, able to breathe Cannot move or speak Damage to ventral pons Can communicate by blink or eye movement Can feel pain, touch and position of limbs No cure Usually a result of brainstem (basilar territory) stroke Recovery rare
What is a Vegetative State?
No evidence of:
Awareness of self or environment or ability to interact with others
Sustained purposeful or voluntary behaviours either spontaneously or in response to stimuli in any sensory modality
Language, comprehension or meaningful expression
What is a Persistent Vegetative State?
Diagnosed if no change at 30 days
50% chance of improvement within 6 months, though the vast majority remain severely disabled
Very difficult to be certain of diagnosis
How can you rule out awareness?
Published instances of improved abilities with zolpidem/neurostimulants
Not recognised as death legally
What are Persistent Disorders of Consciousness (PDOCs)?
Coma
PVS – reflexive, automatic and spontaneous behaviours may be observed but there is complete absence of evidence for awareness of self or the environment
MCS (Minimally Conscious State) – severely altered consciousness. Reproducible but inconsistent intentional/purposeful behavioural responses
Destruction of cortex and hemispheres
What is the assessment of PDOC?
Gold standard assessment is the Sensory Modality Assessment and Rehabilitation Techniques (SMART)
Others are used (Wessex Head Injury Matrix, Ranchos Los-Amigos, JFK coma recovery scale)
All rely on serial, standardised assessments of spontaneous behaviours and responses to a range of stimuli (SMART also uses family)
SMART has different levels:
1: No response to any stimulus
2: reflex response to stimuli and generalised responses e.g: startle/flexor/extensor
3: Withdrawal response: turn head/eyes/limbs away from stimulus
4: localising response: Turn head /limbs towards stimulus
5: Differentiating response: Patients may follow visual/auditory commands or use objects appropriately
.Some patients have ‘woken up’ from PDOC after long intervals. (though with severe disability)
Case reports of bilateral thalamic deep brain stimulation and neurostimulants improving MCS
Case reports of fMRI/EEG evidence of movement initiation when asked to imagine activities such as playing tennis
What is brain stem death?
Unable to breathe and unconscious
Destroyed reticular formation (brain stem)
No electrical activity
No clinical evidence of brain function
Preconditions: diagnosis compatible with brain stem death; presence of irreversiblestructural brain damage, apnoeic
Exclusions: Drug effects, hypothermia, metabolic abnormalities, endocrine abnormalities, intoxication
Clinical Tests:
Absent brain stem reflexes (pupils, corneal, no motor response in cranial nerves, gag, cough, vestibulo-ocular)
Persistent apnoea
2 practitioners (one consultant) on 2 occasions
What is a coma?
The patients eyes don’t open wither spontaneously or to external stimulation and the patient doesn’t follow any commands or demonstrate intentional movement (may have reflex) or speak, or cant see in a 45 angle arc when eyes are held open
What is the Glasgow coma scale?
eyes open 4 spontaneously 3: to command 2: to pain 1: none Best motor response out of 6 best verbal response out of 5
