GS Brainstem Death

Question 1

The mid brain passes through the tentorlal notch and presents two ventral bulges known as the cerebral peducles. Within these structures run three groups of descending fibres:

Answer 1

Coriticospinal: Receives fibres from the pre-motor cortex, primary motor cortex and the supplementary motor area.

Rubrospinal: Originates in red nucleus, UL flexor muscle activation with contralateral extensor inactivation

Tectospinal: Co-ordinates head movements in relation ot vision stimuli

Question 2

Two superior colliculi concerned with —————————————-reflexes

Answer 2

Visual reflexes

Question 3

Two inf colliculi concerned with —————————————-reflexes

Answer 3

Auditory reflexes

Question 4

The reticular formation which plays a key role in ______ ___ ______________and the transmission of pain is located in the midbrain, pons and medulla.

Answer 4

The reticular formation which plays a key role in sleep and consciousness and the transmission of pain is located in the midbrain, pons and medulla.

Question 5

Which CNs run between the pons and medulla?

Answer 5

Abducens CN VI
Facial VII
Vestibulocochlear VIII

Question 6

Autonomic fibres are also located in the brainstem principally running with the following cranial nerves:

Answer 6

1. Oculomotor nerve which interacts with the ciliary ganglia
2. Facial nerve which interacts with the submandibular and pterygopalatine ganglia
3. Glossopharyngeal nerve which interacts with the otic ganglia
4. Vagus nerve

Question 7

BS functions…

Answer 7

1. Regulation of arousal and conscious awareness (reticular activating system)
2. Maintenance of spontaneous respiration and cardiovascular control
3. Transmission of motor and sensory impulses to and from central and peripheral nervous systems

Question 8

Why is the brain particularly susceptible to severe/permanent damage?

Answer 8

high metabolic oxygen demand
the effects of swelling with in a fixed rigid bony container (skull)
the inability of neuronal tissue to regenerate.

Question 9

One definition of death is the irreversible ……

Answer 9

One definition of death is the irreversible loss of the capacity for consciousness, combined with irreversible loss of the capacity to breathe.

Question 10

What are the benefits in diagnosing brainstem death?

Answer 10

Diagnosing brainstem death allows discontinuation of intensive care treatment in a patient with no chance of recovery and allows the family to understand that the patient has died. Diagnosis of brainstem death allows consideration of organ donation although the two processes must be kept very clearly separate from each other.

Question 11

3 essential components of brainstem death diagnosis?

Answer 11

1. Fulfilment of essential preconditions: The patient has suffered irreversible brain damage from a known cause and is deeply unconscious, apnoeic and mechanically ventilated. Common causes of brainstem death include hypoxic brain damage, intracranial haemorrhage, trauma and ischaemic stroke.
2. Reversible influences on conscious level must be excluded. These include sedative drugs, hypothermia (temp must be >340C at time of testing) and endocrine and metabolic disturbances
3. Formal testing for the absence of brain stem activity is carried out once the pre conditions are met and reversible influences have been excluded.

Question 12

What are the 6 tests to illicit absent of reflexes used in BS death diagnosis

Answer 12

1. The pupils are fixed and do not respond to sharp changes in the intensity of incident light. Cranial nerves: III
2. There is no corneal reflex – care should be taken to avoid damage to the cornea. Cranial nerves: V –> VII
3. The oculo-vestibular reflexes are absent.
   No eye movements are seen during or following the slow injection of at least 50mls of ice cold water over one minute into each external auditory meatus in turn. Clear access to the tympanic membrane must be established by direct inspection and the head should be at 300 to the horizontal plane, unless this positioning is contraindicated.
   Cranial nerves: III, IV, VI, VIII
4. No motor responses within the cranial nerve distribution can be elicited by adequate
   stimulation of any somatic area. No motor response can be elicited within the cranial nerve or somatic distribution in response to supraorbital pressure.
   Cranial nerves: V
5. There is no cough reflex response to bronchial stimulation by a suction catheter placed down the trachea to the carina, or gag response to stimulation of the posterior pharynx with a spatula.
   Cranial nerves: V2 –> IX, X
6. The process for testing the respiratory response to hypercarbia (apnoea test) should be the last brain-stem reflex to be tested and should not be performed if any of the preceding tests confirm the presence of brain-stem reflexes. The patient is disconnected from the ventilator allowing the pCO2 to rise above 6.5 kPa and the pH to fall below 7.4. Oxygenation is maintained by insufflating oxygen down the tracheal tube via a catheter. The patient is observed for respiratory effort for a period of five minutes.

Question 13

Although death is not confirmed until the second test has been completed the legal time of death is when the ____ test indicates death due to the absence of brain-stem reflexes.

Answer 13

Although death is not confirmed until the second test has been completed the legal time of death is when the first test indicates death due to the absence of brain-stem reflexes.