Subacute Infarct on CT Head: Diagnosis and Management
Temporal Definition and Pathophysiology
- The subacute phase of cerebral infarction is typically defined as occurring between 8 days and 1 month after the initial ischemic event, during which secondary injury processes develop including worsening parenchymal edema, ischemia, hydrocephalus, and progressive or delayed hemorrhage 1
- Up to 30% of contusions may cause worsening mass effect during the subacute phase due to toxic metabolites released into surrounding tissue and cerebral autoregulation dysfunction 1
CT Imaging Characteristics
- Noncontrast CT is more sensitive for evaluating the extent of ischemic changes on follow-up imaging than in the hyperacute setting, according to the American College of Radiology 2, 3
- Mass effect, characterized by swelling and edema, may be prominent, potentially causing midline shift or herniation 1
Critical Imaging Considerations
- The American College of Radiology recommends avoiding IV contrast in the CT evaluation of evolving or subacute infarct, as it can cause confusion with other brain lesions or hemorrhagic conversion of prior infarcts 2, 3
- Noncontrast CT is useful for early surveillance of ischemic strokes to evaluate for complications such as hemorrhagic conversion, mass effect, and herniation when clinically indicated 2, 3
Clinical Implications
- Patients with significant changes in neurologic status during the subacute phase are at high risk for progressive intracranial injury and may require neurosurgical intervention, as stated by the American College of Radiology 1
- CT can provide rapid, accurate assessment for progressive hemorrhage, herniation, and hydrocephalus 1