Malignant Infarction
The term for worsening mass effect in stroke is "malignant infarction" or "malignant middle cerebral artery (MCA) infarction," which describes a large territorial infarct that develops life-threatening brain swelling within 24-48 hours, causing brain herniation. 1
Definition and Clinical Characteristics
"Malignant" has been affixed to brain swelling to delineate a group of patients with a large territorial infarct that swells within 24 hours, causing brain herniation signs. 1 This terminology was introduced in 1996 and originally defined as infarction of the entire MCA territory appearing on CT within 48 hours, with or without infarction in other vascular territories. 1
The condition is characterized by:
- Rapid and fulminant course within 24-36 hours 1
- Development of space-occupying cerebral edema between day 1 and day 3 after symptom onset 2
- Progressive clinical deterioration with brain herniation signs 1
- Mortality rates exceeding 80% with conventional medical treatment alone 3, 2
Pathophysiology and Mass Effect Indicators
The mass effect manifests through specific radiographic findings:
- Compression of the frontal horn 1
- Shift of the septum pellucidum 1
- Shift of the pineal gland 1
- Pineal gland shift >4mm identifies patients at high risk for early death (specificity 89%, sensitivity 46%) 4
Clinical Context and Terminology Usage
While "malignant MCA infarction" is the most commonly used term in the literature 1, closely related terms include:
The term specifically applies to anterior circulation strokes, particularly MCA territory infarctions, though rapid deterioration from cerebellar infarcts with swelling also occurs and may be associated with sudden apnea from brain stem compression. 1
Important Clinical Pitfall
The proportion of patients with this malignant form is unknown, and its clinical profile is not well defined, leading to frequent missed diagnoses by neurologists despite well-defined clinical and neuroimaging criteria. 3 Early recognition is critical as the overall risk of brain swelling in anterior circulation ischemic stroke is only 10-20%, but when it occurs in this malignant pattern, outcomes are catastrophic without surgical intervention. 1