Short-term recurrence of stroke following misdiagnosis of carotid web masked by thrombus.

Background: Carotid webs are a potential cause of occult cerebral infarction. Although they occur frequently, proper diagnosis and treatment are crucial; surgery has been shown to provide a good outcome. Although thrombus on the carotid web have been reported, digital subtraction angiography (DSA)-confirmed cases of pre-dispersed thrombus are rare. In this study, we report a case in which a thrombus on the carotid web concealed a shelf-like defect, complicating its diagnosis.

Case description: A 47-year-old woman without stroke risk factors presented to our hospital with aphasia and right hemiplegia. On arrival, the symptoms had improved. Magnetic resonance (MR) imaging showed left middle cerebral artery stenosis; however, there was no cerebral infarction. DSA was performed post-admission to examine middle cerebral artery stenosis, which showed no middle cerebral artery stenosis but left internal carotid artery (ICA) origin stenosis and contrast pooling. We diagnosed a transient ischemic attack due to artery-to-artery embolism caused by left ICA stenosis and accompanied by a contralateral carotid web. The same symptoms appeared 6 days later. MR imaging showed a new cerebral infarction and the left middle cerebral artery occlusion. A mechanical thrombectomy procedure revealed a change in ICA origin shape compared to the 1^st time, with a shelf-like defect within the carotid web. She subsequently underwent carotid artery stenting and was discharged with mild dysesthesia in her right fingers (modified Rankin Scale of 1).

Conclusion: Thrombus on the carotid web conceals characteristic shelf-like defects and may cause misdiagnosis. However, contrast pooling and contralateral carotid web are important findings for early treatment.