17A. Types and etiology of unconsciousness. Coma

From greek.doctor

Loss of consciousness can only occur if there is injury to the brainstem, injury to both hemispheres, or a metabolic disorder which affects the entire brain. Hungarian literature classifies unconsciousness as either hypnoid or non-hypnoid.

Hypnoid types of decreased consciousness

  • Somnolence – patient responds to voice
  • Sopor – patient responds to pain
  • Coma – patient is completely unresponsive

These can be caused by:

  • High intracranial pressure -> Brain herniation
  • Intoxication
  • Brainstem lesion
  • Metabolic cause

Non-hypnoid types of decreased consciousness

  • Tenebrosity – decreased awareness after seizure
  • Delirium – acute disorientation with agitation, restlessness, etc.
    • Due to alcohol, drugs, meningitis, dehydration, infection, etc.
  • Decortication – flexion of upper extremities + extension of lower extremities
    • Due to diffuse brain hypoxia, like cardiac arrest, with subcortical areas intact
  • Akinetic mutism – patient is awake but completely unresponsive, no voluntary activity, no communication, no speech
    • Due to frontal lobe lesion
  • Locked-in syndrome – patient is awake and aware, but the entire body except the eyelids are paralysed
    • Due to brainstem lesion