impaired consciousness and coma

Question 1

what are the 2 components of conciousness

Answer 1

1. arousal;
2. awareness

Question 2

what brain structures is arousal dependent on

Answer 2

1. the ascending reticular activating system (RAS - part of the midbrain and pons)
2. diencephalon (thalamus, hypothalamus, subthalamus, and the epithalamus)

Question 3

what can cause diminished arousal (3)

Answer 3

damage to RAS/thalamus by:
1. brain shift;
2. brainstem displacement;
3. direct destruction

Question 4

what brain area maintains awareness

Answer 4

cerebral cortex

Question 5

what is a coma

Answer 5

a state of being where one is unaware and un-awake

Question 6

initial management of unconciouss/coma pt (7)

Answer 6

1. ABCDE
2. Improve oxygenation (face mask 40% oxygen aiming at a pulse oximeter saturation of >95%);
3. Intubate if patient cannot protect the airway (ie, increased work of breathing, pooling secretions, gurgling sounds, GCS<8);
4. Intubate any comatose patient with irregular ineffective respiratory drive and poor oxygenation;
5. Correct hypotension or extreme hypertension;
6. early recognition and treatment of the cause (e.g. hypoglycemia, increased ICP, untreated seizure, infection etc.)
7. neurological examination

Question 7

when should glucose be administered in a coma pt

Answer 7

if <2.5mM

Question 8

what should be done if raised ICP/herniation suspected as cause for coma (2)

Answer 8

1. ventilation
2. mannitol (0.5-1.0g/kg)

Question 9

what should be given if come + BM <2.2mM (2)

Answer 9

1. thiamine (100g)
2. glucose

Question 10

what should be given for opioid overdose

Answer 10

naloxone (0.4-2mg IV)

Question 11

what should be given for benzodiazepine overdose

Answer 11

flumazenil

Question 12

what should be done if coma due to drug intoxication suspected (3)

Answer 12

1. intubate
2. gastric leverage
3. activated charcoal

Question 13

5 important questions when taking hx of a coma pt (from fam/witnesses)

Answer 13

1. onset (gradual/abrupt);
2. recent complains (headache, focal weakness, vertigo, depression etc.);
3. medical comorbidities (diabetes, heart disease);
4. recent injury;
5. access to drugs;

Question 14

3 categories of coma

Answer 14

1. coma without focal signs or meningism;
2. coma with meningism but no focal signs;
3. coma with focal/ raised pressure signs;

Question 15

breathing patterns in unconscious pts + describe them (5)

Answer 15

1. cheyne-stokes (a period of fast, shallow breathing followed by slow, heavier breathing and moments without any breath at all);
2. neurogenic (deep and rapid breaths at a rate of at least 25 breaths per minute);
3. apneustic (regular deep inspirations with an inspiratory pause followed by inadequate expiration);
4. cluster (clusters of breaths followed by apneic episodes of variable duration);
5. ataxic (complete irregularity of breathing, with irregular pauses and increasing periods of apnea)

Question 16

damage to what area can cause cluster breathing

Answer 16

low pontine or high medullary lesions

Question 17

damage to what area can cause apneustic breathing

Answer 17

upper pons (usually due to stroke/trauma)

Question 18

what can cause neurogenic respiration

Answer 18

metabolic acidosis - renal failure, CKA, aspirin etc.

Question 19

asymmetrical pupils vs symmetrical pupils indication for coma cause

Answer 19

asymmetrical - structural cause (i.e. brain lesion);
symmetrical - metabolic cause more likely

Question 20

3 eye movements to note when examining coma pt

Answer 20

1. primary eye position (corneal light reflex test - light should appear as a pin point in the center of both eyes if they are aligned);
2. roving eye movements (slow random predominantly horizontal conjugate eye movements -> indicates brainstem preservation);
3. Dolls eyes (occulo-cephalic refelx -> head is moved side to side and the eyes should move in the opposite direction to the head i.e. the eyes always look at the same point despite which way the head is turned)

Question 21

3 stimuli for eliciting a motor response

Answer 21

1. supraorbital nerve;
2. nailbed;
3. sternum

Question 22

decortate (cortical lesion) vs decerebrate (brainstem lesion) posturing

Answer 22

decortate - curled wrists and balled hands against chest, pointed + turned in toes;

decerebrate - straight tense arms parallel to the body, curled fingers, flexed wrists, pointed + turned in toes

Question 23

what does myoclonus indicate

Answer 23

hypoxic cortical injury

Question 24

how to differentiate “locked in” vs comatose

Answer 24

ask pt to blink, look up/down

Question 25

7 signs of psychiatric unresponsiveness (rather than coma)

Answer 25

1. lids close actively;
2. pupils reactive;
3. physiologic oculovestibular responses (nystagmus);
4. motor tone is inconsistent/normal;
5. normal breathing/hyperventilation;
6. no pathological reflexes;
7. normal EEG;

Question 26

what does coma without focal signs/meningism usually arise from (5)

Answer 26

neuronal depression due to:
1. hypoxia;
2. metabolic derangement;
3. toxic + drug induced;
4. infection;
5. post seizure states

Question 27

8 features for metabolic derangement

Answer 27

C - CO2
O - O2
A - ammonia
T- temp
P - pH
E - electrolytes
G - glucose
S - serum osmolality

Question 28

causes for coma with meningism but no focal signs (2)

Answer 28

1. meningitis
2. SAH

Question 29

coma with focal signs causes

Answer 29

structural brain injury to RAS/thalami (bilaterally)/ cortex (bilaterally) due to:
1. ICH
2. infarction
3. tumour
4. abscess

Question 30

symptoms/sign of raised ICP (4)

Answer 30

1. headache
2. vomiting
3. progressive drowsiness
4. swollen optic nerve (papilloedema)

Question 31

what might post-traumatic amnesia be a marker for

Answer 31

diffuse axonal injury

Question 32

3 areas of herniation (brain)

Answer 32

1. sub falcine
2. trans-tentorial
3. tonsillar

see ppt

Question 33

Management of acute supratentorial mass with brain shift – raised ICP (6)

Answer 33

Stabilising measures:
1. Intubation and mechanical ventilation
2. Correct hypoxaemia/hypercarbia
3. Elevate head to 30o
4. Treat extreme agitation with lorazepam 2mg IV or propofol
5. Mannitol 20%, 1g/kg
6. Dexamethasone, 100mg IV (in tumours only)

Question 34

Specific surgical measures for acute supratentorial mass with brain shift (3)

Answer 34

1. Evacuation of haematoma
2. Drain abscess
3. Decompressive craniectomy for mono-hemispheric swelling

Question 35

when should a CT head be performed within 1 hr (7)

Answer 35

Within 1 hour if any of:
1. GCS <13/15 on A&E assessment
2. GCS <15/15, 2 hours after injury
3. Suspected skull #
4. Focal neurological deficit
5. Any sign of basal skull fractrure
(Haemotypanum, panda eyes, CSF from nose or ears, Battle’s signs)
6. Post-traumatic seizure
7. > 1 vomiting episode

Question 36

when should a CT head be performed within 8 hrs (3)

Answer 36

1. On anticoagulants with evidence of head injury
2. Any loss of consciousness or amnesia since injury and one of:
   - Retrograde amnesia > 30 mins
   -Clotting or bleeding disorder
   -Age > 65
3. Dangerous mechanism of injury e.g. Fall from a height of > 1m or 5 stairs, Pedestrian/ cyclist hit by motor vehicle, Ejection from motor vehicle