12. Brain death

loss of all brainstem reflexes and the demonstration of continuing apnoea in a persistently comatose patient

• absence of arousal and thus also of consciousness

• at least 1 hour

• traumatic brain injuries

• stroke

• tumors

• infections

• awake but are unaware of self or of the environment

• persistent: 1 month after traumatic or non traumatic brain damage but does not imply ireversibility

• permanent: denotes ireversibility ( 3 m after non tra, 12 month after tra)

• arrousal but no awarness

  
  

• limited but clearly discernible evidence of consciousness of self or environment on a reproducible or substained basis

• following simple commands

• gestural or verbal yes/no response

• intelligible verbalization

• arrousal but a bit awareness

• presence of sustained eye opening

• preserved awareness

• aphonia and hypophonia

• quadirplegia or quadriparesis

• primary mode of communication that uses vertical or lateral eye movement or blinking of the upper eyelid to signal yes or no

• arrousal and awarness

The hollow skull phenomenon refers to a radiological image (CT or MRI) showing a skull that appears empty, with almost no visible brain tissue, replaced by fluid (CSF). It indicates severe, irreversible brain damage — often after prolonged coma, hypoxia, or brain death. Though not a formal diagnosis, it reflects a near-total loss of brain structure and function.

-> Often associated with long-term vegetative state or clinical brain death.

• motor repsonse

• brainstem reflexes (corneal reflex, gag refelx, pupillary light reflex)

• apnea test

Coma can result from:

• Diffuse cortical or white matter injury (bihemispheric

• Brainstem lesions, especially in the pontomesencephalic tegmentum

• Bilateral paramedian thalamic damage

Comatose patients show lower brain metabolism, especially in the:

• Thalamus

• Brainstem

• Cerebellar cortex

• This reflects a global depression of cerebral activity.

When anesthesia is adjusted to cause unresponsiveness, the brain's metabolic activity drops to a level similar to that in coma, showing that both states involve global cerebral depression.

• eye opening

• verbal response

• motor response

• assess the level of consciousness in a person with a suspected brain injury or coma.

• helps guide clinical decisions

EEG in coma usually shows slowed and reduced brain activity, including:

• Dominance of delta (0.5–4 Hz) and theta (4–8 Hz) waves

• Sometimes burst-suppression patterns (brief bursts interrupted by silence)

• In very deep coma: isoelectric EEG (flat line) → poor prognosis

• The brainstem is relatively spared, allowing basic functions like breathing and sleep-wake cycles

• There is severe damage to grey and/or white matter in both cerebral hemispheres

• Cerebral metabolism is widely reduced, especially in associative cortices involved in: – Attention – Memory – Language

• These changes explain the absence of awareness despite wakefulness

medial posterior cortex

• normally for visual-spatial perception and sttention

• evidence that involved in much more