Coma and PVS Flashcards
Define what a coma is
A state of unrousable unresponsiveness in which subjects lie with eyes closed
and show no psychologically understandable response to external stimulus or internal need
In relation to the Glasgow coma score (GCS), what are the features of a coma?
Patients who:
- Fail to open eyes in response to voice
- Perform no more than weak flexion in response to pain
- Unrecognisable grunting in response to pain
- GCS 8 or less
What needs to work for you to be conscious?
Consciousness depends on:
Arousal:
- must have an Intact ascending reticular activating system - to act as the alerting/awakening element of consciousness
Awareness:
- must have a Functioning cerebral cortex of both hemispheres - to determine the content of our consciousness (to think)
This is gonna be a bitch to learn but gaan
Generally, what causes decreased GCS?
Toxic/metabolic states - (all the biochemey sort of stuff)
Seizures
Damage to reticular activating system (loss of arousal)
Raised intracranial pressure
What toxic/metabolic pathologies can cause severe decreases to GCS?
Hypoxia, hypercapnia, sepsis, hypotension
Drug intoxication, renal & liver failure
Diabetes stuff - Hypoglycaemia, ketosis (ketogenic acidosis etc)
What are the causes of raised intracranial pressure?
Tumours
Stroke
Extradural haemorrhage
Subdural haemorrhage
Subarachnoid haemorrhage
Hydrocephalus
Describe the immediate-short term assessment and management of a patient who presents in a coma-like state (unconscious)
ABCDE assessment (always)
Measure blood glucose ± give glucose if hypo
Treat any seizures
Assess for fever & meningism ± give IV abx
Try to obtain as full a history as possible from family members or paramedics etc
Different breathing patterns may indicate different causes of unconsciousness/coma
describe these
Depressed respiration:
- Drug overdose, metabolic disturbance
Elevated respiration:
- hypoxia, hypercapnia, acidosis
Fluctuating respiration:
- Brainstem lesion
What investigations and management follow the care of an unconscious/coma patient?
ie once they’ve been admitted and the immediate stuff is all done
Blood samples:
- Glucose, biochem, blood gasses, haematology
- Toxicology
Establish baseline stuff:
- temperature
- pulse & BP
- IV access (put in an IV line)
- stabilise neck
Examine for meningitis:
- treat with IV abx on suspicion
Give an overview of the neurological examination protocol for Coma?
Repeated GCS assessment:
- 8 or less
Brainstem function:
- pupils!
- eye movement!
- corneal reflex, gag reflex
- respiratory drive
Motor function & reflexes:
- lateralisation!
- muscle response & tone
- tendon reflexes
- seizures
The examination of pupils for patients in comas revolves around their size and response to light
Describe the possible findings, and what they may indicate
Bilateral mid-point reactive pupils - normal:
- Metabolic coma
- Coma following sedative drugs (excluding opiates)
Asymmetric - dilation of contralateral eye:
- Compression of CN III - requires immediate surgery
Bilateral, light-fixed, dilated pupils:
- Deep coma of any cause
- Barbiturate intoxication & hypothermia
Bilateral, pin-point, light-fixed pupils:
- Pontine lesions (haemorrhage)
- Opiates
What features of eye movement may be found in the neurological examination of a patient in a coma?
Skew deviation (disconjugate):
- brainstem lesion
Conjugate gaze deviation:
- frontal lobe lesion - eyes deviate towards the site of lesion
- brainstem lesion - eyes deviate away from lesion
Vestibulo-ocular reflex (negative finding):
- reflex is maintaining gaze in spite of rotation
- if absent - deep coma, brainstem lesion, brain death
Windscreen wiper eyes:
- Light coma or deep coma w/ extensive cortical damage
Coma without meningism and without focal/lateralising signs.
What are the likely causes of this?
What signs on examination would back this?
Negative meningism & Negative focal/lateralising signs
Cause is likely - toxic, metabolic or systemic
Examination of the pupils would likely show no signs (ie normal pupils)
