Coma and PVS

Question 1

Define what a coma is

Answer 1

A state of unrousable unresponsiveness in which subjects lie with eyes closed

and show no psychologically understandable response to external stimulus or internal need

Question 2

In relation to the Glasgow coma score (GCS), what are the features of a coma?

Answer 2

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

Question 3

What needs to work for you to be conscious?

Answer 3

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)

Question 4

This is gonna be a bitch to learn but gaan

Answer 4

Question 5

Generally, what causes decreased GCS?

Answer 5

Toxic/metabolic states - (all the biochemey sort of stuff)

Seizures

Damage to reticular activating system (loss of arousal)

Raised intracranial pressure

Question 6

What toxic/metabolic pathologies can cause severe decreases to GCS?

Answer 6

Hypoxia, hypercapnia, sepsis, hypotension

Drug intoxication, renal & liver failure

Diabetes stuff - Hypoglycaemia, ketosis (ketogenic acidosis etc)

Question 7

What are the causes of raised intracranial pressure?

Answer 7

Tumours

Stroke

Extradural haemorrhage

Subdural haemorrhage

Subarachnoid haemorrhage

Hydrocephalus

Question 8

Describe the immediate-short term assessment and management of a patient who presents in a coma-like state (unconscious)

Answer 8

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

Question 9

Different breathing patterns may indicate different causes of unconsciousness/coma

describe these

Answer 9

Depressed respiration:

• Drug overdose, metabolic disturbance

Elevated respiration:

• hypoxia, hypercapnia, acidosis

Fluctuating respiration:

• Brainstem lesion

Question 10

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

Answer 10

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

Question 11

Give an overview of the neurological examination protocol for Coma?

Answer 11

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

Question 12

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

Answer 12

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

Question 13

What features of eye movement may be found in the neurological examination of a patient in a coma?

Answer 13

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

Question 14

Coma without meningism and without focal/lateralising signs.

What are the likely causes of this?

What signs on examination would back this?

Answer 14

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)