Altered Level of Consciousness

 

• Background

  Pathophysiology

  Usually reflects a problem with the cortex – affecting thought content or awareness – or the reticular activating system – affecting arousal/alertness.

  Definitions

  From high to low level of consciousness:

  • Confusion: disorientation, clouding of thoughts, impaired perception, impaired memory.
  • Delirium: disorientation, may be hypoactive or hyperactive. Restless motor symptoms, transient hallucinations, delusions.
  • Obtundation: reduced alertness, psychomotor slowing.
  • Stupor: appear asleep, but respond with some basic movements (e.g. withdrawal form pain).
  • Coma: profoundly unconscious with no response to external stimuli or inner need.

• Coma

  Definition

  • Unconscious and with no response to external stimuli or inner need.
  • Some define it as a GCS ≤8.
  • Occasional groans, eye, or limb movements are possible, but these are essentially random and not in response to stimuli.

  Causes

  • Vascular or traumatic: infarct, haemorrhage.
  • Inflammatory: encephalitis, meningitis.
  • Metabolic: ↓↑glucose, ↓↑electrolytes.
  • Toxic: overdose, especially opioids or benzodiazepines.
  • Hypoxia or hypercapnia.
  • Epilepsy

  Associated signs

  • Meningism suggests meningitis, encephalitis, or sub-arachnoid haemorrhage.
  • Focal neurology suggests stroke or tumour.
  • Pinpoint pupils suggest opioid OD or pontine lesions.

  Coma-like syndromes

  • Persistent vegetative state: coma patient progresses to partial arousal but no awareness, with spontaneous respiration and stable circulation.
  • Locked-in syndrome: conscious but with complete muscle paralysis (de-efferented), with the exception of the eye muscles (though these may also be absent in total locked in syndrome). Caused by bilateral ventral pontine lesions, due to posterior circulation stroke, MND, or central pontine myelinolysis.
  • Psychogenic unresponsiveness.

• Glasgow coma scale (GCS)

  Overview

  • Rating of consciousness level from 3 to 15.
  • Severe ≤8, moderate 9-12, minor ≥13.
  • Painful stimuli used in testing: trapezius pinch, nailbed rub with pen, sternal rub, supraorbital.

  Eye opening

  Speccy 4 eyes:

  1. Nil
  2. To pain.
  3. To voice.
  4. Spontaneous

  Verbal response

  V, the Roman 5:

  1. Nil
  2. Incomprehensible sounds.
  3. Inappropriate words.
  4. Confused conversation.
  5. Orientated

  Motor response

  M6 motorway:

  1. Nil
  2. Abnormal (arm) extension to pain (cerebral).
  3. Abnormal (arm) flexion to pain (cortical).
  4. Flexion to pain/withdrawing.
  5. Localising to pain.
  6. Obeying commands.