From the Guidelines
Patients under the age of 60 years with large ischemic strokes in the middle cerebral artery (MCA) territory are at the highest risk for Malignant MCA syndrome. This condition is characterized by severe cerebral edema, increased intracranial pressure, and subsequent cerebral herniation, which can be life-threatening if not managed promptly and aggressively 1. The risk factors for Malignant MCA syndrome include:
- Complete MCA infarctions, especially those with National Institutes of Health Stroke Scale (NIHSS) scores above 15-20
- Large infarct volumes exceeding 145 cubic centimeters on imaging
- Younger age (typically under 60 years), as younger patients have less brain atrophy and therefore less space to accommodate swelling
- Hypertension
- Hyperglycemia
- Delayed presentation to medical care after stroke onset
- Involvement of additional vascular territories beyond the MCA, such as the anterior cerebral artery or posterior cerebral artery
According to the Canadian Stroke Best Practice Recommendations, patients who meet certain criteria, including those with malignant MCA infarct with evidence of significant edema and mass effect, should be considered for hemicraniectomy 1. The benefits of decompressive hemicraniectomy in patients under 60 years old have been established in several randomized controlled trials, which have shown a significant reduction in mortality and improved outcomes 1. However, the benefit of surgery in older patients is less certain, and discussions with patients and their families should include information about likely outcomes and the potential for survival with significant disabilities 1.
The fundamental pathophysiology of Malignant MCA syndrome involves severe cerebral edema following the large infarction, leading to increased intracranial pressure, brain herniation, and potentially death if not managed aggressively 1. Early identification of high-risk patients is crucial, as Malignant MCA syndrome typically develops within 2-5 days after stroke onset and carries a mortality rate of approximately 80% without appropriate intervention. Hemicraniectomy should be considered in patients in the early stages of extensive (malignant) MCA territory ischemic stroke as a life-saving measure for patients willing to accept a significant risk of living with a degree of disability that may leave them dependent on others for their activities of daily living 1.
From the Research
Risk Factors for Malignant Middle Cerebral Artery (MCA) Syndrome
The following factors have been identified as increasing the risk of developing Malignant Middle Cerebral Artery (MCA) syndrome:
- Poor collateral circulation, as assessed by multiphase computed tomographic angiography 2
- Older age, with studies suggesting that patients over 60 years are at higher risk of mortality and poor outcomes 3, 4
- Involvement of more than one vascular territory 4
- Presence of signs indicating clinical herniation before surgery 4
- Delayed treatment, with studies suggesting that treatment more than 24 hours after ictus is associated with higher mortality and poor outcomes 4
- Lower ratio of intracranial cerebrospinal fluid volume to intracranial volume (CSF/ICV) 5
- Poor collateral score, as defined by the University of Calgary CC Scale 2, 5
Patient Characteristics
Patients who are at risk of developing Malignant Middle Cerebral Artery (MCA) syndrome often present with:
- High National Institutes of Health Stroke Scale scores, indicating severe stroke symptoms 2, 5
- Occlusion of the M1-MCA or terminal internal carotid artery 2
- Large infarct volume, as assessed by imaging studies 3, 6
Predictive Models
Several predictive models have been developed to identify patients at risk of developing Malignant Middle Cerebral Artery (MCA) syndrome, including: