Coma

Question 1

What is coma?

Answer 1

A state of unrousable psychological unresponsiveness in which the subjects lie with eyes closed and show no psychologically understandable response to external stimulus or inner need

Question 2

What does consciousness depends on?

Answer 2

1. An intact ascending RETICULAR ACTIVATING SYSTEM to act as the alerting or awakening element of consciousness
2. A functioning CEREBRAL CORTEX OF BOTH HEMISPHERES which determines the content of that consciousness

Question 3

What can be the causes of decreased GCS?

Answer 3

Toxic/ metabolic states

• Hypoxia/ hypercapnia/ sepsis/ hypotension
• Drug intoxication/ renal or liver failure
• Hypoglycaemia, ketoacidosis

Seizures

Damage to reticular activating system

Causes of rased intracranial pressure:
-Tumour, stroke, EDH, SDH, SAH, hydrocephalus

Question 4

What is a persistent vegetative state?

Answer 4

A state in which the brain stem recovers to a considerable extent but there is no evidence of recovery of cortical function

There is arousal and wakefulness but the patient does not regain awareness or purposedul behaviour of any kind

Question 5

What is “locked in” syndrome?

Answer 5

The patient has total paralysis below the level of the third nerve nuclei and, although able to pen, elevate and depress the eyes, has no horizontal eye movements and no other voluntary eye movement

The diagnosis depends on recognising that the patient can open their eyes voluntarily and signal numerically by eye closure

Question 6

What is involved in resusitation of unconscious patients?

Answer 6

Airway

Breathing

• Depressed respiration (drug overdose, metabolic disturbances)
• Increased respiration (hypoxia, hypercapnia, acidosis)
• Fluctuating respiration (brainstem lesion)

Circulation

Blood samples

• glucose, biochemistry, haematology, blood gas
• Toxicology

Establish baseline blood pressure, pulse, temperature, IV access and stabilise the neck

Examine for evidence of meningitis- treat on suspicion

Question 7

What is usually present in the history of patients presenting with decreased conscious state?

Answer 7

?Predictable progression of underlying illness (liver failure, renal failure, epilepsy, diabetes)

?Unpredictable event in patient with previously known disease

?Totally unexpected event
-Head injury, sudden collapse, limb twitching, prev history of drug or alcohol abuse

Question 8

What shouls you keep an eye out for on examination and monitoring?

Answer 8

Temperature
Heart rate, BP, CVS
Respiration
Skin, breath (ketones)
Abdomen
Meningism
Fundal examination

Question 9

How is a Neurological assessment of a coma carried out?

Answer 9

Glasgow coma scale
Brainstem function
Motor function + reflexes

Question 10

How is someone classed as being in a coma using GCS?

Answer 10

Patients who fail to show eye opening in response to voice, perform no better than weak flexion in response to pain and make at best only unrecognisable grunting noises in response to pain are regarded as being in coma

Eye opening (2 or less)
Verbal resonse (2 or less)
Motor response (4 or less)

GCS = 8

Question 11

How do you test brainstem function?

Answer 11

Pupillary reactions (II + III)

Corneal reactions (V + VII)

Spontaneous eye movements (III, IV + VI)

Oculocephalic responses (doll’s eye) (III, IV, VI, VIII)

Oculovestibular responses (III, IV, VI, VIII)

Respiratory pattern (Medullary centre)

Question 12

What may cause a coma wihout focal or lateralising signs and without meningism?

Answer 12

• Anoxic/ ischaemic conditions
• Metabolic disturbances
• Intoxications
• Systemic infections
• Hyperthermia/ Hypothermia
• Epilepsy

Question 13

What investigations can you carry out in coma without focal or lateralising signs and without meningism?

Answer 13

Toxicology screen including alcohol level

Measure blood sugar and electrolytes

Assess hepatic and renal function

Acid-base assessment and blood gases

Measure blood pressure

Consider carbon monoxide poisoning

Question 14

What may cause coma without focal or lateralising signs but with meningism?

Answer 14

Subarachnoid haemorrhage
Meningitis
Encephalitis

Question 15

What investigations would you carry out in coma without focal or lateralising signs but with meningism?

Answer 15

CT head scan

Lumbar puncture

• Appearance
• Cell count
• Glucose level
• Capsular antigen tests

Question 16

What may cause coma with focal brainstem or lateralising cerebral signs?

Answer 16

Cerebral tumour
Cerebral haemorrhage
Cerebral infarction
Cerebral abcess

Question 17

What investigations should you carry out in a coma with focal brainstem or lateralising cerebral signs?

Answer 17

CT or MRI obligatory

If CT/MRI not diagnostic, then investigate as for other causes of coma e.g. including:

• Metabolic screens
• Lumbar puncture
• EEG

Question 18

What are the “medical” causes of coma lasting more than 5 hours?

Answer 18

40% due to drug ingestion +/- alcohol

25% due to hypoxia (e.g. secondary to MI

20% due to cerebrovascular event, either haemorrhage or infarction

15% metabolic e.g. diabetes, hepatic failure, renal failure, sepsis, hypercapnia/ hypoxia

Question 19

What are the factor affecting outcome in coma?

Answer 19

Age
Cause of coma
Depth of coma
Duration of coma
Certain clinical signs, the most important of which are the Brain stem reflexes

Question 20

How many patients in a non-traumatic coma for more than 6 hours will make a good or moderate recovery?

Answer 20

Overall, only 15% of patients

The other 85% will die, remain vegetative or reach a state of severe disability in which they remain dependent

Question 21

In non traumatic coma over 6 hours, good recovery is seen in….

Answer 21

35% of those with underlying metabolic cause

11% of those with hypoxic ischaemic insult

7% of those with cerebrovascular disease

Question 22

How do you continue the care of patients in a coma?

Answer 22

• Maintain vital functions
• Care of skin, avoidance of pressure sores
• Attention to bladder and bowel function
• Control of seizures
• Prophylaxis of DVT, peptic ulceration
• Prevention of contractors
• Consider “locked in” syndrome

Question 23

Head injury can lead to focal neurological signs/ Epilepsy due to what?

Answer 23

Diffuse axonal injury

Contusion

Intracerebral haematoma

Extra-cerebral haematoma

• Extra-dural haematoma
• Sub-dural haematoma

Question 24

How do you manage head injury?

Answer 24

• Stabilise cervicle spine
• Airway/ Breathing/ Circulation
• If GCS 8 or less intubation + ventilation
• Treat raised ICP
• Cranial imaging - may need decompressive surgery or removal of haematoma
• Neuro-observation

Question 25

how do you treat raised ICP?

Answer 25

Surgery to releave pressure -Haematoma, ventricular shunt Osmotic agents e.g. mannitol Nurse with head at 30-45% (venous return) Reduce pain Maintain good PO2, reduce PCO2 Reduce metabolism (reduce temperature, barbiturates)