Red Book - Disorders Of Conciousness

Question 1

What are the main types of Disorders of Conciousness

Answer 1

Concious comprises both AROUSAL and AWARENESS

DOC happen when there is a disrupted relationship betwee these two

Types - COMA - abesent arousal/wakefulness, absent awareness)
VEGETATIVE - wakefut but no arousal
MINIMALLY CONCIOUS - wakeful and only minimally aware

Patients can progress through these stages and get to full awareness. Some remain at any stage.

Question 2

Describe Coma

Answer 2

Not wakeful, not aware

Unrousable unresponsiveness for more than 6 hours

1) cannot be wakened
2) no response to painful stimula/sound
3) lacks a normal sleep wake cycle
4) No voluntary actions

Question 3

Describe Vegetative state

Answer 3

Wakeful but now aware

Severe cortical damage but brain stem intact

Capacity to spontaneous or stimuli induced arousal:
Sleep wake cycles
Range of reflexes

No environmental awareness or aware of self

Question 4

Describe minimally concious state

Answer 4

Wakeful with minimal awareness

Severely altered conciousness with minimal but discernable behaviours and evidence of environmental awareness

Inconsistent but reproducible responses , some interaction with environment

Question 5

Causes

Answer 5

Any brain injury giving rise to disordered conciousness

TBI - Direct or diffuse axonal

Vascaular - ICH, SAH, Stroke

Toxic - alcohol, drug OD, hypoglycaemia, hyper/hypo-osmolar

Infection/inflammation - enceph, abscess, sepsis, vasculitis

Hypoxia/perfusion - cardiac arrest, hypovolaemia, drowning

Systemic - liver and renal failure, myxoedema

Question 6

Principles of management

Answer 6

ABCDE

Goals - maintain the airway, protect a secondary injury, facilitate imaging

History, exam and investigate

Maintain physiology

Review medications

Neuro investigations —> EEG and manage ICP

Further specialist tests —> SSEPs

Question 7

Describe the history/exam/investigations

Answer 7

Identify the cause of the injury
Exclude other conditions —> metabolic, infections, hydroceph etc

Bloods - usual, TFT, ammonia, ABC
Micro specimiens
Toxicology and alcohol
LP
Imaging - CT/MRI

Question 8

How to prognosticate

Answer 8

1) allow 72 hours for sedative drugs and NMBA to wear off for 72 hours
2) allow for normothermia

Testing

1) unconcious patient for 72hr after ROSC
2) Motor score 1-2
3) absent SSEP N20 wave
4) no pupilary, corneal reflexes

After this:

5) consider biomarkers
EEG
Imaging

Question 9

Prognostic tests after cardiac arrest

Answer 9

SSEP -  Bilateral absence of N20 wave at 72 hours
			Reliable to predict poor outcome
			No influence from sedation, NMBA etc
					Needs expertise
					Affected by hypothermia

EEG - 	absence of EEG reactivity
		Presence of burst supression
		Status
			non invasive
			Detects non convulsive status
					Operatory dependent
					Non-qualitative
					Not standardised

Biomarkers NSE S100B
Released following neuronal injury, correlates with level of injury
Quantitative
Independent of sedatives
What is the threshold??
False positives in haemolysis
Measugin techniques need standardising

Imaging - MRI/CT
Exclude causes
MRI detects isschamia, better definition
MRI in unstable pts —> difficult
Limited role for prognostication e.g. grey white matter

Question 10

What is locked in syndrome

Answer 10

Brainstem pathology —> disruptes voluntary movement
Wafefulness and awareness maintained

Paralysed and concious. Communicate by blinking