Coma, Persistent Vegetative State and Brain Death Flashcards
How is a coma neurologically assessed?
Glasgow coma scale
Brainstem function
Motor function and reflexes
What does GCS stand for?
Glasgow coma scale
What does the GCS look at?
Eye opening
Verbal response
Motor response
Eye opening scores of the GCS
Spontaneous - 4
To speech - 3
To pain - 2
None - 1
Verbal response score of the GCS
Orientated - 5 Confused - 4 Inappropriate words - 3 Incomprehensible sounds - 2 None - 1
Motor response scores of the GCS
Obeying commands - 6 Localizing to pain - 5 Withdrawing from pain - 4 Flexing to pain - 3 Extending to pain - 2 None - 1
Scores if a GCS score = 8 or under
Eye - 2 or less
Verbal - 2 or less
Motor - 4 or less
What is a full score of the GCS?
15
How do you test the brainstem function?
Pupillary reactions Corneal responses Spontaneous eye movements Oculocephalic responses (dolls eye) Oculovestibular responses Resp pattern
What CNs control pupillary reactions?
II and III
What CNs control corneal responses?
V and VII
What CNs control spontaneous eye movements?
III, IV and VI
What CNs control oculocephalic responses?
III, IV, VI, VIII
What CNs control oculovestibular responses?
III, IV, VI and VIII
What controls the respiratory pattern?
Medullary centre
How to test the motor function?
Motor response
Muscle tone
Tendon reflexes
Seizures
What GCS score is needed to indicate a coma?
< 8
Causes of a coma with no meningism and no focal brainstem or lateralising cerebral signs
Intoxications Anoxic/ischaemic conditions Metabolic disturbances Systemic infections Hyperthermia/hypothermia Epilepsy
Causes of a coma with meningism and no focal brainstem or lateralising cerebral signs
SAH
Meningitis
Encephalitis
Causes of a coma with possible meningism with focal brainstem and lateralising cerebral signs
Focal cerebral e.g. tumour infarct
Causes of coma with focal brainstem or lateralising cerebral signs
Cerebral tumour
Cerebral haemorrhage
Cerebral infarction
Cerebral abscess
Medical causes of coma lasting more than 5 hours
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. DM, Hepatic failure, renal failure, sepsis, hypercapnia/hypoxia
Investigations of coma without focalising or lateralising signs and without meningism
Toxicology screen including alcohol level Blood sugar Electrolytes Hepatic and renal function Acid-base measurement and blood gases Measure BP Consider CO poisoning
Investigations of a coma without focal or lateralising signs but with meningism
CT head scan
LP
Investigations of coma with focal brainstem or lateralising cerebral signs
CT or MRI obligatory If CT/MRI not diagnostic, then investigate as far as can for other causes of coma e.g. - metabolic screens - LP - EEG
Causes of a patient in a coma with decreased respiration
Drug overdose
Metabolic disturbance
Causes of a patient in a coma with increased respiration
Hypoxia
Hypercapnia
Acidosis
Causes of a patient in a coma with fluctuating respiration
Brainstem lesion
Factors affecting the outcome of a coma
Age Cause of coma Depth of coma Duration of coma Certain clinical signs, most important of which are brainstem reflexes
What % of patients in a non traumatic coma for more than 6 hours will make a good or moderate recovery?
15%
Continuing care of patients in a coma
Maintenance of vital functions Care of skin, avoidance of pressure sores Attention to bladder and bowel function Control of seizures Prophylaxis of CVT, peptic ulceration Prevention of contractures Consider the "locked in" syndrome
Definition of coma
A state of unarousable psychological unresponsiveness in which the subjects lie with their eyes closed and show no psychologically understandable response to external stimulus or inner need
What does consciousness depend on?
AROUSAL - An intact ascending reticular activating system to act as the alerting or awakening element of consciousness
AWARENESS OF THE ENVIRONMENT - A functioning cerebral cortex or both hemispheres which determines the content of that consciousness
Definition of persistent vegetative state
A state in which the brainstem recovers to a considerable extent but there is no evidence of recovery of cortical function
Causes of decreased GCS
Toxic/metabolic states - hypoxia - hypercapnia - sepsis - hypotension - drug intoxication - renal or liver failure - hypoglycaemia - ketoacidosis Seizures Damage to the reticular activating system Causes of raised ICP - Tumour - Stroke - EDH - SDH - SAH - hydrocephalus
Why do elderly patients have loads of space around their brain?
Their brain shrinks
Does focal damage to part of the cortex affect the conscious level?
No
Causes of diffuse hemisphere damage
Trauma
Ischaemia
Hypoglycaemia
Hepatic or renal failure
Give an example of a condition that can cause bilateral thalamic involvement
Astrocytoma
Causes of brain stem involvement
Ischaemia
Haemorrhage
Tumour
Drugs (sedatives, hypnotics)
What is the “locked in” syndrome?
The patient has total paralysis below the level of the third nerve nuclei, and although able to open, elevate and depress the eyes, has no horizontal eye movements and no other voluntary eye movement. They can still breath. Usually fully aware
What types of head injury can lead to focal neurological signs/epilepsy?
Diffuse axonal injury Contusion (bruise) Intracerebral haematoma Extracerebral haematoma - extra dural haematoma - sub dural haematoma
What does a subdural haematoma look like on CT?
Convex/convex
What does a extradural haematoma look like on CT?
Concave/convex (lens)
Treatment of head injury
Stabilize cervical spine ABC If GCS < 8 = intubation and ventilation Treat raised ICP Cranial imaging - may need decompressive surgery or removal of haematoma Neuro-observation
Treatment of raised ICP
Surgery to relieve pressure - haematoma, ventricular shunt Osmotic agents e.g. mannitol Head at 30-45% venous return Reduce pain Maintain good PO2, reduce PCO2 Reduce metabolism (reduce temp, barbituates)
