Neuro - 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 between 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 hours1) cannot be wakened2) no response to painful stimula/sound3) lacks a normal sleep wake cycle4) 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 awarenessSeverely altered conciousness with minimal but discernable behaviours and evidence of environmental awarenessInconsistent 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

The management of a patient with disordered consciousness should follow an
ABCDE approach, treating abnormalities as they are found. A GCS ≤8 necessitates intubation to protect the airway, prevent secondary brain injury and
facilitate imaging. Other specific management includes:
1 History, examination and investigation
– Identify the cause of brain injury and potential complications
– Exclude other conditions that may impair consciousness (metabolic/
infective disorders, hydrocephalus etc.)
– Blood tests including glucose, haematology, full biochemistry, TFTs, ammonia (if hepatic encephalopathy suspected), ABG
– Specimens for culture
– Blood alcohol values, toxicology screen
– Consider lumbar puncture (LP) if no signs of raised ICP
– Imaging (CT or MRI) – Exclude structural, operable reasons for DOC (e.g.
hydrocephalus, haemorrhage)
2 Maintain normal physiology
– Rapidly correct hypoxaemia and hypotension
– Correct hypoglycaemia with 50 ml 50% glucose
– Correct hypo- and hyperthermia
– Correct electrolyte abnormalities and ensure adequate hydration
3 Review medication
– Review and withdraw any medications that may affect arousal
– Consider specific antagonists
4 Electroengephalogram (EEG) or trial of an anticonvulsant (if subclinical seizure activity is suspected)
5 Detailed neurological assessment
– Confirm sensory, visual and auditory pathways are intact
6 ICP management
– If raised ICP is present, consider insertion of an ICP monitor and initiate
therapy to reduce raised ICP
7 Further investigations
– Electrophysiological

Question 7

Describe the history/exam/investigations

Answer 7

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

Bloods - usual, TFT, ammonia, ABCMicro specimiensToxicology and alcoholLPImaging - CT/MRI

Question 8

How to prognosticate

Answer 8

1) allow 72 hours for sedative drugs and NMBA to wear off for 72 hours2) allow for normothermiaTesting1) unconcious patient for 72hr after ROSC2) Motor score 1-23) absent SSEP N20 wave4) no pupilary, corneal reflexesAfter this:5) consider biomarkersEEGImaging

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 standardisingImaging - 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 maintainedParalysed and concious. Communicate by blinking