Prolonged disorder of consciousness, brainstem death, and coma Flashcards
What is a prolonged disorder of consciousness?
Any disorder of consciousness that has continued for at least 4 weeks following sudden onset brain injury
What is wakefulness?
State in which eyes are open and degree of motor arousal
What is sleep?
State of eye closure and motor quiescence
What is awareness?
Ability to have, and having of, experience of any kind
What is a coma?
State of unrousable unresponsiveness lasting more than 6 hours in which a person is
- Unconscious and cannot be awakened
- Fails to respond normally to painful stimuli, light or sound
- Lacks a normal sleep-wake cycle
- Doesn’t initiate voluntary actions
What is a vegetative state?
A state of wakefulness without awareness in which there is preserved capacity for spontaneous or stimulis-induced arousal - evidenced by sleep-wake cycles and a range of reflexive and spontaneous behaviours
Absence of behavioural evidence for self or environmental awareness
What is a minimally conscious state?
State of severely altered consciousness in which minimal but clearly discernible behavioural evidence of self or environmental awareness is demonstrated
Inconsistent, but reproducible responses above level of spontaneous or reflexive behaviour indicating some degree of interaction with their surrounds
What is damaged in a persistent vegetative state?
Damage to cortex and hemispheres
What is damaged in locked-in syndrome?
Damage to ventral pons
What is locked-in syndrome?
Disruption of voluntary control of movement without abolishing either wakefulness or awareness
What should you do to assess an unconscious patient?
Causation
- Nature of injury - location, extent, reversibility
- Additional causes - medications, complications, another disorder
Aetiology
- Trauma, vascular event, hypoxic/hypoperfusion, infection/inflammation, toxic/metabolic
Imaging
- Brain imaging - nature, extent, location
- Assess fluctuating for deteriorating patient
- Determine extent and location of brain damage for clinical decision-making or to aid in prognosis
Check primary neurological pathways are intact - hear, see, feel
What are the 3 types of behavioural responses?
Spontaneous - no external stimuli - try not to mistake behaviour in response to stimuli
To normal incidental stimuli
To structured planned stimuli
What should you do to assess behavioural responses?
Auditory function Visual function Motor function Oromotor/verbal function Communication Arousal
What should you do to optimise response to treatment?
Excellent physical care Appropriate seating Sleep and rest - prevent altering circadian rhythm eg not feeding at night Quiet room Arousal
How is brainstem death diagnosed?
Made by at least 2 medical practitioners who have been registered for > 5 years and competent in conduct and interpretation of brainstem testing - at least one must be consultant
Testing performed completely and successfully on 2 occasions with both present
What needs to be present to diagnose brainstem death?
Pupils fixed and dilated and don’t respond to sharp changes in light intensity
No corneal reflex
Oculo-vestibular reflexes absent, no eye movements seen on slow injection of at least 50ml ice cold water
No motor responses within cranial nerve distribution
No cough reflex response to bronchial stimulation
No evidence of spontaneous respiration or respiratory effort during apnoea test
What is stupor?
State of near-unconsciousness or insensibility
What is obtundation?
State similar to lethargy in which the patient has lessened interest in the environment, slowed responses to stimulation, and tends to sleep more than normal with drowsiness in between sleep states
What are the structural causes of coma?
Extra-dural haemorrhage Sub-dural haemorrhage SAH Intracranial bleeds Malignant MCA syndrome Tumour Hydrocephalus (Encephalitis)
What are the non-structural causes of coma?
Diabetic - hypo, DKA, hyperosmolar Hypoxia Drugs - opiates, benzodiazepines, others Hypercapnia Meningitis Sepsis (Encephalitis) Wernicke's Other metabolic - like hepatic failure
