Coma, Persistent Vegatative State and Brain Death Flashcards
Coma
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
What does consciousness depend on?
- An intact ascending reticular activating system to act as the alerting or awakening element of consciousness
- A functioning cerebral cortex of both hemispheres which determines the content of that consciousness
What are the 2 components of consciousness?
-Arousal (Reticular activating system)
-Awareness of environment (Cerebral hemispheres)
Lethargy/Stupurous/Obtunded/Coma
What can cause a decrease in GCS?
- Toxic/metabolic states
- Seizures
- Damage to reticular activating system
- Causes of raised ICP
What toxic/metabolic states can decrease GCS?
- Hypoxia /hypercapnia /sepsis /hypotension
- Drug intoxication /renal or liver failure
- Hypoglycaemia, ketoacidosis
What can cause raised ICP?
- Tumour
- Stroke
- EDH
- SDH
- SAH
- Hydrocephalus
Persistent vegetative state
- 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 purposeful behaviour of any kind
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
What does diagnosis of locked in syndrome depend on?
The diagnosis depends on recognising that the patient can open their eyes voluntarily and signal numerically by eye closure
What algorithm should be used fro resuscitation?
ABC
- Airway
- Breathing
- Circulation
What may depressed respiration suggest?
- Drug overdose
- Metabolic disturbance
What may increased respiration suggest?
- Hypoxia
- Hypercapnia
- Acidosis
What may fluctuating respiration suggest?
Brainstem lesion
After assessing ABC, what resuscitation should be carried out?
- Bloods (glucose, biochemistry, haematology, blood gas, toxicology)
- Establish baseline blood pressure, pulse, temperature, I.V. access and stabilise the neck
- Examine for evidence of meningitis - treat on suspicion
What types of history may someone present with?
- ? Predictable progression of underlying illness
- ? Unpredictable event in patient with previously known disease
- ? Totally unexpected event
What examination and monitoring should be carried out?
- Temperature
- Heart rate, Blood -Pressure, CVS
- Respiration
- Skin, breath
- Abdomen
- Meningism
- Fundal examination
What neurological assessment of coma can be carried out?
- GCS
- Brainstem function
- Motor function and reflexes
What are the 3 components of the CGS?
- Eye opening
- Best verbal response
- Best motor response
How is eye opening scored in the GCS?
4 Spontaneous
3 To speech
2 To pain
1 None
How is best verbal response scored in GCS?
5 Orientated 4 Confused 3 Inappropriate 2 Incomprehensible sounds 1 None
How is best motor response scored in GCS?
6 Obeying commands 5 Localising to pain 4 Withdrawing from pain 3 Flexing to pain 2 Extending to pain 1 None
Who is regarded as being in a coma?
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
What is the criteria for coma?
GCS 8 or less
- Eye opening 2 or less
- Verbal response 2 or less
- Motor response 4 or less
What are the functions of the brainstem?
- Pupillary reactions
- Corneal responses
- Spontaneous eye movements
- Oculocephalic responses (Doll’s eyes)
- Oculovestibular responses
- -Respiratory pattern
What cranial nerves are responsible for pupillary reactions?
II
III
What cranial nerves are responsible for corneal responses?
V
VII
What cranial nerves are responsible for spontaneous eye movements?
III
IV
VI
What cranial nerves are responsible for oculocephalic responses (Doll’s eye)?
III
IV
VI
VIII
What cranial nerves are responsible for oculovestibular responses?
III
IV
VI
VIII
What is responsible for respiratory pattern?
Medullary centre
What can give an indication of levels of motor function?
- Motor response
- Muscle tone
- Tendon reflexes
- Seizures
Give examples of causes of coma without focal or lateralising signs and without meningism.
- Anoxic/ ischaemic conditions
- Metabolic disturbances
- Intoxications
- Systemic infections
- Hyperthermia/ Hypothermia
- Epilepsy
How should coma without focal or lateralising signs and without meningism be investigated?
- 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
What can cause coma without focal or lateralising signs but with meningism?
- Subarachnoid Haemorrhage
- Meningitis
- Encephalitis
How should coma without focal or lateralising signs but with meningism be investigated?
- CT head
- LP
What is looked at on LP?
- Appearance
- Cell count
- Glucose level
- Capsular antigen tests
What can cause coma with focal brainstem or lateralising cerebral signs?
- Cerebral tumour
- Cerebral haemorrhage
- Cerebral infarction
- Cerebral abscess
How should coma with focal brainstem or lateralising cerebral signs be investigated?
- 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
What are the 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. diabetes, hepatic failure, renal failure, sepsis, hypercapnia/hypoxia
What factors affect the outcome of coma?
- Age
- Cause of coma
- Depth of coma
- Duration of coma
- Certain clinical signs, the most important of which are the brain stem reflexes
What is usually the outcome of coma?
Overall, only 15% of patients in non-traumatic coma for more than 6 hours will make a good or moderate recovery, the other 85% will die, remain vegetative or reach a state of severe disability in which they remain dependent
In non-traumatic coma >6 hours, good recovery is seen in…
- 35% of those with underlying metabolic cause
- 11% of those with hypoxic ischaemic insult
- 7% of those with cerebrovascular disease
What continue care is important in coma patients?
- Maintenance of 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 contractures
- Consider the “Locked - in” Syndrome
Head injury can lead to focal neurological signs/Epilepsy due to…
- Diffuse axonal injury
- Contusion
- Intracerebral haematoma
- Extra-cerebral haematoma (extra-dural haematoma, sub-dural haematoma)
How does a subdural haematoma appear on CT?
- Elllipse
- Brain is convex/convex
How does an extradural haematoma appear on CT?
- Lens shaped bleed
- Brain is concave, convex
How should head injury be managed?
-Stabilise cervical spine
-Airway/Breathing/Circulation
If GCS≤8 - intubation+ventilation
-Treat raised ICP
-Cranial imaging - may need decompressive surgery or removal of haematoma
-Neuro observation
How should raised ICP be treated?
- Surgery to relieve 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)
