A 35-year-old woman is admitted with a moderate head injury (GCS 12) following a fall. Initial non-contrast CT head shows a small acute subdural hematoma (< 10 mm) with no midline shift or herniation signs. She is neurologically stable. After 48 hours, she develops progressive headache, drowsiness, and a new focal motor deficit. Which investigation is most appropriate to assess for deterioration?

## Repeat Imaging in Head Injury with Clinical Deterioration **Key Point:** Any patient with known intracranial hemorrhage who develops new or worsening neurological signs requires immediate repeat CT head to assess for expansion of hematoma, new hemorrhage, or herniation. **High-Yield:** Progressive drowsiness and new focal deficit in a patient with known subdural hematoma is a red flag for hematoma expansion or secondary injury. Repeat CT is mandatory and urgent. ### Clinical Context: Why Repeat CT? **Clinical Pearl:** This patient had a small, stable subdural hematoma on initial CT. The development of: - Progressive headache - Drowsiness (altered consciousness) - New focal motor deficit ...suggests **hematoma expansion** or **secondary brain injury** (cerebral edema, increased ICP). Repeat CT will: 1. Measure hematoma thickness and assess for expansion 2. Detect new hemorrhage or contusion 3. Identify midline shift or herniation signs 4. Guide urgent neurosurgical intervention (evacuation if indicated) ### Timing and Indications for Repeat CT | Scenario | Indication for Repeat CT | | --- | --- | | **Deteriorating GCS or new focal deficit** | **Urgent** — within 30 min | | **Stable patient with small SDH, no signs** | Routine follow-up at 24–48 h | | **Persistent headache, mild drowsiness** | Consider repeat if no improvement in 6–12 h | | **Seizure after head injury** | Yes, to exclude new hemorrhage | **Tip:** "Deterioration = Repeat CT" is the cardinal rule in head injury management. Do not wait for further clinical decline. ### Why Other Investigations Are Inappropriate **Warning:** Transcranial Doppler, EEG, and angiography do NOT assess for hematoma expansion or acute hemorrhage. - **Transcranial Doppler:** Measures cerebral blood flow velocity; useful for vasospasm detection in subarachnoid hemorrhage, not for acute SDH expansion. - **EEG:** Detects seizure activity or diffuse brain dysfunction; does not visualize structural lesions or hemorrhage. - **Cerebral angiography:** Invasive; reserved for vascular injury (arterial dissection, pseudoaneurysm) or vasospasm — not indicated for acute SDH management.