Does a malacic focus on a cranial CT (Computed Tomography) scan suggest an acute or chronic Cerebrovascular Disease (CVD) infarct?

Malacic Focus on CT Suggests Chronic Infarct

A malacic focus (encephalomalacia) on cranial CT scan indicates a chronic, not acute, cerebrovascular infarct. Encephalomalacia represents the end-stage of brain tissue necrosis with cystic degeneration and gliosis that develops weeks to months after the initial ischemic event 1.

Key Imaging Distinctions

Chronic Infarct Features (Malacia)

• Encephalomalacia appears as well-defined hypodense areas with tissue loss and ex-vacuo dilatation of adjacent ventricles on CT 1
• CT can demonstrate parenchymal brain calcifications within old ischemic lesions, which are characteristic of chronic rather than acute infarcts 1
• The presence of encephalomalacia indicates completed infarction with tissue resorption that has occurred over an extended timeframe 1

Acute Infarct Features

• CT is relatively insensitive for acute infarcts, particularly in the first 6-24 hours after symptom onset 1, 2
• When visible acutely, findings include hyperdense vessel sign, loss of gray-white differentiation, insular ribbon loss, and sulcal effacement—not malacia 2, 3
• Early parenchymal changes show reduced attenuation rather than the frank tissue loss seen with encephalomalacia 2, 3

Clinical Implications

Timing Considerations

• MRI is far more sensitive than CT for detecting acute infarcts (77% vs 16% sensitivity in the hyperacute period), making CT an unreliable tool for acute stroke diagnosis 1
• CT abnormalities in acute stroke typically show only 30% sensitivity in the first hours, whereas malacic changes represent the chronic sequelae visible weeks to months later 1

Diagnostic Approach

• When evaluating suspected acute stroke, normal or malacic findings on CT do not exclude acute ischemia and should prompt MRI with diffusion-weighted imaging if acute stroke is suspected 1
• The presence of encephalomalacia on CT indicates prior completed infarction and should trigger investigation for vascular risk factors and secondary stroke prevention 1

Common Pitfalls

• Do not confuse chronic encephalomalacia with acute ischemic changes—malacia represents tissue loss from old infarcts, not ongoing acute ischemia 1
• In patients with vascular dementia workup, encephalomalacia from multiple cortical and subcortical infarcts is a classic chronic finding, not an acute process requiring emergent intervention 1
• CT's limited sensitivity means that absence of malacia does not exclude prior small infarcts, particularly lacunar infarcts which may not be visible on CT 1