Presentation
Memory loss
Patient Data
- Severe diminution of flow-related enhancement in the right internal carotid artery and middle cerebral artery, suggestive of upstream stenosis.
- No acute or subacute infarct. Old infarcts in the left frontal corona radiata and left cerebellar hemisphere. Encephalomalacia in the left superior frontal gyrus.
- Right cerebral convexity enhancing subdural effusion without significant mass effect. Right parietal burr holes consistent with prior subdural hematoma evacuation.
- Scattered parenchymal microhemorrhages at lobar grey-white junctions. Superficial siderosis at the bilateral superior frontal sulci. These may be related to prior trauma or cerebral amyloid angiopathy.
- Generalized parenchymal volume loss without a regional predominance. No signs of disproportionately enlarged subarachnoid space hydrocephalus aside from ventriculomegaly.
There is a critical stenosis of the proximal cervical right internal carotid artery and small caliber of the distal vessel compared to the contralateral side and to the external carotid artery. The intracranial right internal carotid artery attenuation is less than that of the left, suggesting differential peak contrast bolus arrival. Together, the findings are consistent with right carotid near-occlusion with partial collapse.
Thin slice (0.625 mm) axial images through the carotid bifurcations and curved planar reformations (CPR) of the right internal carotid artery (RICA) best demonstrate the finding.
The left internal carotid artery origin shows only mild (<50%) stenosis, taking the normal distal vessel diameter as the denominator.
Catheter digital subtraction angiography was performed (not shown). Right common carotid artery angiogram showed significant stenosis at the proximal internal carotid artery with anterograde flow distally. Left common carotid artery angiogram showed significant cross fill of the right middle cerebral artery via the anterior communicating artery, confirming the hemodynamic significance of the right sided atherosclerotic disease.
Case Discussion
Carotid near-occlusion, with partial or complete collapse distally, is a special subgroup of carotid artery stenosis that may carry a lower risk of stroke than other degrees of severe stenosis. This case illustrates some of the intracranial vascular findings that can be a clue to significant upstream arterial disease (diminished flow-related enhancement on time-of-flight MRA, decreased enhancement and caliber of the internal carotid artery at the skull base), prompting dedicated imaging of the neck vessels. Notably, the patient did not have evidence of right anterior circulation cerebral infarcts.