Coma

What is Coma? 

A persistent pathological state of unconsciousness. 

What do I do about it? In the comatose patient immediately ensure a clear airway, check that they are breathing, establish haemodynamic stability, and check for life-threatening injuries.

Take a history from relatives or bystanders and ask if anyone saw how the patient became unconscious? Is there any past medical history such as diabetes, alcohol abuse, or drug overdose that might explain the coma?

Examine the patient in an attempt to distinguish metabolic causes of coma from brainstem causes. It is particularly important to identify coma due to brainstem compression since surgical relief of the enlarging mass may be urgently required. Use the Glasgow coma score (GCS).

Look for the following signs when reviewing the patient:

Fever Meningitis or encephalitis Cerebral malaria Metabolic coma of infection Hypothermia Hypothyroidism; hypothermic coma Hypertension Coma may be due to stroke Hypotension Shock Pallor, cyanosis Metabolic disease Bleeding, bruising    Head trauma

Progressive deterioration suggests brainstem compression. Look for focal CNS signs. Search for asymmetry (e.g. in response to pain or in the face during expiration). If the response to pain is different, the side with lower response in the GCS is the side with hemiparesis.

Diagnosis

There are three broad categories.

• Metabolic
  • Normal pupil responses
  • Normal or absent eye movements depending on the depth of coma
  • Suppressed, Cheyne–Stokes, or ketotic respiration
  • Symmetrical limb signs, usually hypotonic
• Intrinsic brainstem disease
  From the outset there may be:
  • Abnormal pupil responses and eye movements
  • Abnormal respiratory pattern
  • Bilateral long tract signs
  • Cranial nerve signs
• Extrinsic brainstem disease due to compression
  Papilloedema and hemiparesis with progressive
  • Loss of pupillary responses
  • Loss of eye movements
  • Abnormal respiratory pattern
  • Long tract signs