Anatomic and Metabolic Causes of Coma: Structured Differential

Coma etiology is categorized by anatomic level and pathophysiology.

Structural (Anatomic) Lesions

Supratentorial (above tentorium)

• Intracerebral hemorrhage, ischemic stroke, tumor, subdural/epidural hematoma, abscess, encephalitis, meningitis.

Infratentorial (posterior fossa)

• Cerebellar/brainstem hemorrhage, infarction, tumor, abscess, encephalitis, meningitis.

Metabolic/Toxic/Encephalopathic

• Glucose: hypoglycemia, hyperglycemia (DKA, HHS).
• Electrolytes: Na⁺, K⁺, Ca²⁺, Mg²⁺ disorders.
• Acid-base: respiratory/metabolic acidosis/alkalosis.
• Organ failure: hepatic (encephalopathy), renal (uremia), cardiac, respiratory.
• Sepsis/SIRS/MODS.
• Endocrine: myxedema, adrenal crisis.

Toxicologic

• Drug overdose (opioids, sedatives, TCA, etc.).
• Alcohol, CO, cyanide, heavy metals, pesticides, envenomations.

Anoxic/Hypoxic

• Cardiac arrest, respiratory failure, severe anemia, CO/cyanide, vascular (stroke, vasospasm).

Psychiatric (Psychogenic Unresponsiveness)

• Catatonia, conversion, malingering, factitious – diagnosis of exclusion.

Localization guides imaging (CT head ± CTA, MRI) and urgent interventions.