Treatment of Calcified Thrombus in the Middle Cerebral Artery
Mechanical thrombectomy is the primary treatment for calcified cerebral emboli causing large vessel occlusion in the middle cerebral artery, though recanalization rates are significantly lower than with standard thrombi and outcomes remain poor despite intervention. 1, 2
Definition and Clinical Significance
A calcified thrombus in the middle cerebral artery represents a rare but devastating cause of acute ischemic stroke, accounting for approximately 1.3-2.7% of large vessel occlusions requiring thrombectomy 2, 3. These emboli appear as hyperdense material on non-contrast CT, with mean maximal density of 327 HU (range 150-1200 HU) 2. The M1 segment is affected in 83% of cases 3.
The most common sources are calcific aortic stenosis (36%), carotid atherosclerotic plaque (30%), and mitral annular calcification (11%). 3
Acute Treatment Approach
Mechanical Thrombectomy as First-Line Treatment
Endovascular thrombectomy should be prioritized over intravenous thrombolysis for calcified cerebral emboli, as thrombolysis is likely insufficient given the calcified composition of these emboli. 1 A small case series demonstrated EVT was significantly superior to intravenous rtPA (p = 0.048) 1.
The most successful retrieval technique combines:
- Stent retriever with local aspiration through a distal access catheter
- Flow arrest and dual aspiration using a balloon guide catheter 4
Expected Recanalization Rates
Recanalization outcomes are considerably worse than standard thrombi 2:
- Modified TICI ≥2b achieved in only 57.5% of patients
- Minimal-to-no reperfusion (TICI 0-1) in 32.5%
- Incomplete reperfusion (TICI 2a) in 10% 2
This contrasts sharply with standard thrombectomy where TICI 2b/3 is achieved in the majority of cases 5.
Clinical Outcomes and Prognosis
Functional outcomes remain poor despite intervention, with 90-day mortality of 55.9% and functional independence (mRS 0-2) achieved in only 26.5% of patients. 2 This represents substantially worse outcomes compared to non-calcified thrombi.
The risk of recurrent stroke is substantial, with 41% of patients experiencing at least one recurrent embolic event 3.
Post-Thrombectomy Management
Blood Pressure Control
Maintain systolic blood pressure 130-150 mmHg to prevent hemorrhagic complications 5. Monitor blood pressure every 15 minutes for 2 hours, then every 30 minutes for 6 hours, then hourly for 16 hours 6.
Antithrombotic Therapy
Anticoagulation therapy should be initiated after ruling out hemorrhagic transformation for cardioembolic sources (calcific aortic stenosis, mitral annular calcification). 5 However, because calcific emboli may not respond to anticoagulation as effectively as thrombotic emboli, the benefit is uncertain 6.
For atherosclerotic sources (carotid plaque), consider antiplatelet therapy rather than anticoagulation 5.
Addressing the Embolic Source
Surgical intervention to address the underlying source is critical, as 64% of patients with calcific aortic stenosis underwent aortic valve replacement and 53% with carotid disease underwent endarterectomy. 3 This is essential given the high recurrence rate.
Common Pitfalls
Misdiagnosis on imaging: 27% of calcified emboli are misdiagnosed on initial CT interpretation, with 9% completely overlooked 3. The hyperdense middle cerebral artery sign should prompt consideration of calcified embolus 6.
Attempting thrombolysis alone: Given the calcified composition, intravenous rtPA is likely insufficient and delays definitive mechanical treatment 1.
Failing to identify the embolic source: Without addressing the underlying cardiac or vascular pathology, recurrent stroke risk remains unacceptably high at 41% 3.
Premature anticoagulation in large infarcts: This increases hemorrhagic transformation risk, particularly given the already poor recanalization rates with calcified emboli 5.
Surgical Considerations for Complex Cases
For giant MCA aneurysms with calcified thrombus, emergent surgical procedures including microsurgical embolectomy may be considered in select cases, though experience is extremely limited and outcomes are uncertain 6. The morbidity of operation appears high among patients with intraluminal thrombus demonstrated by angiography 6.
Emergency surgical procedures for acute ischemic stroke are not recommended outside of research settings due to lack of evidence for safety and efficacy. 6