Coma

Aka: Coma

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II. Definition

  1. Coma
    1. Spectrum of dysfunction of awareness and arousal

III. Pathophysiology

  1. Bilateral cortical disease
    1. Unilateral disease does not cause coma
    2. Metabolic and toxic derangements most common
    3. Focal Neurologic signs absent except in Hypoglycemia
  2. Suppression of Reticular Activating System (RAS)
    1. Supratentorial pressure
      1. Subdural Hematoma
      2. Epidural Hematoma
      3. Intracranial Abscess
      4. Subarachnoid Hemorrhage
      5. Brain Tumor
    2. Infratentorial pressure
      1. Cerebellar Hemorrhage
      2. Posterior fossa tumor
    3. Intrinsic Brainstem lesion
      1. Traumatic pontine Hemorrhage
      2. Hypertensive pontine Hemorrhage
      3. Neurologic degenerative diseases
      4. Brainstem tumor
    4. Torque on Brainstem from sudden head blow

IV. Exam

  1. See Coma Exam

V. Differential Diagnosis

  1. See ALOC Causes
  2. See Delirium
  3. Psychogenic Coma
    1. Electroencephalogram (EEG)
    2. Amytal interview

VI. Evaluation

  1. See Altered Level of Consciousness
  2. Step 0: Review History, Exam, Labs
    1. Physiologic Coma with Nonfocal exam may suggest metabolic cause
  3. Step 1: Obtain CT Head and If Abnormal:
    1. Ischemic CVA: Supportive care
    2. Hemorrhagic CVA, Tumor or Brain Abscess
      1. Herniation
        1. Neurosurgical Consultation stat
        2. Decadron
        3. Mannitol
        4. Hyperventilation
      2. No Herniation
        1. Supportive care
        2. Neurosurgical Consultation
  4. Step 2: Obtain Lumbar Puncture and If Abnormal
    1. Meningitis
      1. Antibiotics
    2. Subarachnoid Hemorrhage
      1. Neurosurgical Consultation
  5. Step 3: Unclear etiology (above testing normal)
    1. Etiologies
      1. Brain Stem infarct
      2. Drug Overdose
      3. Complex partial Status Epilepticus
    2. Evaluation
      1. Electroencephalogram (EEG)
      2. MRI Head
    3. Management
      1. Supportive Care

VII. Management

  1. See Altered Level of Consciousness
  2. ABC Management

VIII. Prognosis

  1. Nontraumatic coma
    1. Persistent coma for 2 months(n=596)
      1. Mortality: 69% mortality
      2. With severe Disability: 20%
      3. Without severe Disability: 8%
    2. Mortality correlated with:
      1. Abnormal Brain Stem response
      2. Absent verbal response
      3. Absent withdrawal response to pain
      4. Creatinine > 1.5 mg/dl
      5. Age > 70 years
    3. Interpretation
      1. Four or more of above criteria: 96% mortality
  2. References
    1. Hamel (1995) JAMA 273:1842-8 [PubMed]

IX. References

  1. Orman and Chang in Herbert (2017) EM:Rap 17(4): 8-9

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