Consciousness and Syncope

Consciousness and Syncope

• Consciousness requires both awareness and wakefulness, involving the interaction between the ascending reticular activating system (ARAS) and the hemisphere
• The ARAS is responsible for arousal, while the hemisphere provides content with different locations having different contents

Syncope

• Transient loss of consciousness due to hypoperfusion, which can last up to 20 seconds
• A part of a larger group of transient loss of consciousness, including status epilepticus
• Causes of syncope:
  • Cardiac: arrhythmia, obstructions, and structural defects, with no damage to the nerves
  • Neurological: involves neurological deficit
  • Vasovagal reflex: psychogenic, triggered by pain or emotions, affecting the medullary vasomotor centre
  • Situational syncope: coughing, defecating, urinating, and post-exercise
  • Carotid sinus syndrome: triggered by pressure on the carotid sinus
  • Psychogenic: hypotension, orthostatic, and drug-induced
  • Volume depletion: dehydration and anaemia
  • Autonomic failure: postural tachycardia

Symptoms and Risk Stratification

• Prodrome: dizziness, lightheadedness, visual and auditory disturbances, neurological deficit, and diaphoresis
• Risk stratification:
  • High-risk: arrhythmia, electrolyte imbalance, anaemia, hypotension, and cardiac structural defects
  • Low-risk: normal cardiac conditions, neurogenic or orthostatic hypotension

Management

• Leg-raise to reduce pressure on the body
• Treatment based on cause:
  • Non-cardiac: vasovagal, conservative, and medication (β-blocker, SSRI, proamatine)
  • Orthostatic hypotension: gradual change in position, compression stockings, rehydration, and avoiding diuretics and vasodilation
  • Cardiac: pacemaker, implanted defibrillator, and supportive treatment (ECG, echocardiography, EEG, and 6-minute walk test)

Psychogenic Syncope

• Transient loss of consciousness and postural tone, followed by spontaneous recovery
• Causes:
  • Vasovagal: sudden drop in heart rate and blood pressure
  • Volume depletion
  • Medication
  • Cardiovascular: dysrhythmia and other cardiac issues
  • Psychogenic panic attacks

Psychogenic Pseudosyncope

• Apparent loss of consciousness in the absence of impaired cerebral perfusion
• No changes to physiology, but manifestation of CNS pathology without lesions
• Intense neuronal firing due to cognitive function affecting organ function, triggered by psychic conflicts

Learn about the components of consciousness, including awareness and wakefulness, and understand syncope, a transient loss of consciousness due to hypoperfusion.