Diagnostics

• CBC: to evaluate for signs of infection, e.g., leukocytosis

• BMP: to evaluate for electrolyte imbalances, acidosis, and renal dysfunction

• Blood gases: to evaluate for hypercarbia, hypoxia, and acid-base imbalances

• Liver chemistries, albumin, INR: if hepatic encephalopathy is suspected

• Blood cultures: if infection is suspected

• Urine analysis: Consider including urine toxicology screen.

• Consider serum drug levels: e.g., acetaminophen, salicylates, ethanol.

• Indications

  • Focal neurological deficits

  • History of head injury

  • Unclear etiology of AMS or coma

  • Persistent AMS despite treatment or resolution of the suspected cause

• Initial modality: CT head without contrast

May be indicated based on the clinical presentation and the suspected underlying etiology. For further information, see:

• “Symptom-based diagnostic workup for delirium”

• ”Toxicological risk assessment”

• “Diagnostics in TBI”

• “Diagnostic studies for secondary psychosis”

• “Diagnostics in agitated or violent patients.”

The following conditions can mimic coma. See “Causes of AMS and coma” for underlying etiologies.

• Conditions in which consciousness is preserved but the patient cannot produce voluntary movements or motor responses

  • Locked-in syndrome

  • Neuromuscular paralysis: e.g., secondary to paralytic medications, botulism, or snake bites

  • Akinetic mutism

• Psychogenic unresponsiveness: an unresponsive state caused by an underlying psychiatric disorder [17]

  • Etiologies include mood disorders, psychotic disorders, factitious disorder, malingering

  • Clinical features include:

    • Stupor

    • Coma

    • Catatonia

    • Dissociation

    • Psychogenic nonepileptic seizures

  • Diagnosis based on typical examination findings, e.g.: [12]

    • Active resistance to eye opening

    • Purposeful diversion of the arm when held above the face and dropped