What should a non‑contrast head CT scan show in a patient with suspected acute intracranial injury?

What a Non-Contrast CT Scan Should Show in Acute Head Trauma

A non-contrast head CT in suspected acute intracranial injury should demonstrate the presence or absence of intracranial hemorrhage (subdural, epidural, subarachnoid, intraparenchymal), skull fractures, midline shift, cisternal compression, cerebral edema, and mass effect 1, 2.

Key Findings to Identify

Primary Traumatic Lesions

• Intracranial hemorrhage (any type: epidural, subdural, subarachnoid, intraparenchymal, or intraventricular)

  • Non-contrast CT has pooled sensitivity of 92% and specificity of 87% for detecting intracranial hemorrhage 3
  • Hemorrhage volume should be assessed, as lesions <10 mL in neurologically normal patients may not require routine repeat imaging 1

• Skull fractures (including skull base fractures)

  • CT bone algorithm reconstructions provide superior sensitivity compared to plain radiographs 2
  • Depressed skull fractures or open fractures require specific attention

Secondary Injury Markers (Critical Prognostic Indicators)

• Midline shift

  • Shift >5 mm is significantly associated with in-hospital mortality (OR: 3.6) 3
  • Automated measurements show high correlation (0.93) with expert assessments 4

• Cisternal compression or obliteration

  • Compressed basal cisterns indicate elevated intracranial pressure and poor prognosis 3
  • Cistern volume quantification can be performed with high accuracy 4

• Cerebral edema and mass effect

  • Indicates evolving secondary brain injury
  • May necessitate urgent neurosurgical intervention

Additional Structural Findings

• Cerebral contusions (may be subtle on initial CT)
• Pneumocephalus (air within the cranial vault)
• Ventricular size and configuration (for hydrocephalus assessment)

Clinical Context Matters

The ACR Appropriateness Criteria 1 establish that non-contrast head CT is usually appropriate for:

• Mild head trauma (GCS 13-15) when imaging is indicated by clinical decision rule (e.g., 2008 ACEP Clinical Policy)
• Moderate (GCS 9-12) or severe (GCS 3-8) head trauma
• Penetrating head trauma
• Any patient with new or progressive neurologic deficits

Common Pitfalls to Avoid

Do not use IV contrast for initial acute head trauma evaluation 1, 2. There is no relevant literature supporting routine contrast use, and it may obscure acute hemorrhage.

Do not rely on skull radiographs 1. CT provides superior sensitivity for both intracranial injury and skull fractures.

Do not dismiss small hemorrhages in anticoagulated patients or those with abnormal coagulation, as these have higher risk of expansion.

When Non-Contrast CT May Be Insufficient

Consider additional imaging when:

• Suspected vascular injury: Obtain CTA of head and neck for arterial injury or CTV for venous injury based on mechanism (e.g., cervical spine fracture, skull base fracture) 1
• Subacute/chronic symptoms: MRI becomes more sensitive than CT for detecting diffuse axonal injury, contusions, and chronic sequelae 1
• CSF leak suspected: High-resolution temporal bone CT is the appropriate initial study 1

The scan interpretation should be rapid and systematic, as time-sensitive decisions regarding neurosurgical intervention depend on these findings 3.