Isolated carotid occlusion – to treat or not to treat?
Isolated carotid artery occlusion (ICAO) is defined as carotid artery occlusion without associated occlusion of the circle of Willis. Its clinical presentation may be highly variable – from asymptomatic, by transient ischemic attack (TIA), minor stroke to severe stroke manifestation and chronic ocular ischemia. The prognosis and the optimal treatment of acute ICAO are poorly established.
When carotid artery occlusion presents acutely with disabling symptoms, concomitant intracranial occlusion, and favorable brain imaging, current standard treatment is endovascular thrombectomy (EVT). However, the role of EVT is less clear for those with isolated ICAO without tandem intracranial artery occlusion, particularly if the initial symptoms are relatively mild. In these cases, collateral supply may be sufficient to avoid major ischemia, and there is considerable uncertainty as to whether the potential advantages of intervention, such as avoidance of recurrent or progressive ischemia, outweigh the procedural risks of distal embolization, and/or vessel injury[1,2].
Carotid occlusions. This figure shows the different types of carotid occlusions, with thrombus being represented in red. Isolated carotid occlusions = without associated occlusion of circle of Willis correspond to: A (short occlusive lesion), B (I occlusion) and C (long occlusive lesion, i.e. cervical–intracranial occlusion).
From Ter Schiphorst, Adrien, et al. "Symptomatic isolated internal carotid artery occlusion with initial medical management: a monocentric cohort." Journal of Neurology 268.1 (2021): 346-355.
Medical therapy alone
Conservative treatment for ICAO includes antiplatelet drugs, anticoagulants, intravenous thrombolysis, and elevation of blood pressure.
There is strong evidence for a benefit of dual antiplatelet therapy in patients with minor stroke or TIA due to large artery atherosclerosis with a significant reduction in early stroke recurrence. Intravenous thrombolysis remains the mainstay of acute therapy; however, a minority of patients present within the eligible time frame. Moreover, thrombolysis has demonstrated poor recanalization for LVOs and has been associated with an increased risk of symptomatic intracranial hemorrhage (sICH) and death. Additional medical strategies have targeted augmenting collateral blood flow and/or inhibiting clot propagation through induced hypertension and anticoagulation, respectively[2,4].
The main risk of ICAO remains ischemic recurrence that may lead to early neurologic deterioration (END). Ischemic recurrence may occur due to new emboli related to spontaneous ICAO recanalization or continuous embolization from the ICAO stump and/or may be caused by hemodynamic compromise. This will lead in some patients to worse functional outcomes at 3 months.
In terms of functional outcome, observational studies of symptomatic ICAO have reported that only 33% achieve an mRS of 0–2. Similarly, Mokin et al found that approximately 27% of patients with ICAO treated with only intravenous thrombolysis achieved a good functional outcome compared with approximately 44% of those treated with endovascular therapy.
Below you fill find some publication data on medical management:
Endovascular treatment (EVT)
Currently, prospective studies in this area are lacking (awaiting results from ETICA). Retrospective studies suggest that EVT in selected patients with isolated ICAO may be safe and associated with low risk of recurrent ischemia. In the largest series of patients treated for symptomatic ICAO in the absence of LVO, recanalization was successfully achieved in 92% of patients, 83% of patients had stable or improved post-procedure neurological status, with 57% demonstrating improvement by ≥8NIHSS points or post-procedure NIHSS ≤2, 65% of patients were functionally independent at 3-month follow-up.
Main risks of EVT include symptomatic intracranial hemorrhage (sICH) and thrombus migration during the procedure. SICH prevalence is estimated for 0-8% and might be explained by cerebral hyperperfusion and/or hemorrhagic conversion of ischemic stroke worsened by dual antiplatelet treatment. A limitation of carotid stenting is the need for short-term dual antiplatelet therapy, especially in patients at risk for hyperperfusion with sizeable acute infarcts (known risk factors for hemorrhagic transformation). In patients undergoing carotid stenting, cerebral hyperperfusion syndrome has been noted to peak within 12 hours of the procedure and is usually associated with insufficient post-procedural blood pressure control.
Below you fill find some publication data on EVT and its complication rate:
From Jadhav, Ashutosh, et al. "Angioplasty and stenting for symptomatic extracranial non-tandem internal carotid artery occlusion." Journal of NeuroInterventional Surgery 10.12 (2018): 1155-1160
Key message to conclude:
Neurological presentation in patients with ICAO may be related to new emboli and/or hemodynamic impairment.
It is crucial to evaluate clinical/imaging mismatch for the patients with ICAO
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