Tandem lesion (cerebrovascular)

Tandem lesion (or tandem occlusion) is a term used in cerebrovascular imaging and intervention to refer to the simultaneous presence of high-grade stenosis or occlusion of the cervical internal carotid artery and thromboembolic occlusion of the intracranial terminal internal carotid artery or its branches, usually the middle cerebral artery¹. 

This has implications for endovascular clot retrieval as the proximal lesion needs to be traversed and/or treated before the intracranial thromboembolism retrieved. 

Epidemiology

Tandem lesions are encountered in approximately 15% of cases undergoing endovascular clot retrieval ¹. As the proximal occlusion is usually due to complication preexisting atherosclerotic carotid artery stenosis which is more common in men, the same predilection is seen in tandem lesions ¹. 

Treatment and prognosis

The presence of a tandem lesion is generally associated with a poorer prognosis ¹. 

Thrombolysis is less effective than in individuals with isolated intracerebral thromboembolic occlusion ¹. 

Similarly, the added time and complexity of endovascular therapy poses challenges. 

At the time of writing (2020) it appears that treating the carotid stenosis with carotid stent placement at the time of endovascular clot retrieval is preferable although this will depend on local preference, equipment and individual patient factors ¹. 

Differential diagnosis

• cervical carotid pseudo-occlusion due to terminal internal carotid occlusion ²
• cervical carotid dissection