Symptomatic Non-stenosed Carotid Artery causing progressive White Matter Disease Receiving Delayed Intervention

We report a case of an 84-year-old male who presented with acute on chronic neurological deterioration in the setting of a symptomatic atherosclerotic carotid artery. The patient was first admitted under the stroke unit in 2021, when he presented with acute onset right upper limb weakness on a background of hypertension, type 2 insulin-dependent diabetes, hypercholesterolaemia and migraines. MRI of the brain revealed multi-focal acute on chronic left middle cerebral artery (MCA) strokes (Figure 1, LEFT). Non-invasive imaging identified a left internal carotid artery (ICA) stenosis of less than 50% and therefore no surgical intervention was pursued, despite the stroke having been accredited to this left ICA atherosclerosis. Management therefore entailed antiplatelet therapy and optimisation of vascular risk factors. During clinic follow up in the subsequent three years, the patient presented with mild but progressive cognitive impairment which corresponded to progressive left hemispheric subcortical white matter pathology on serial CT brain imaging. These changes, were restricted to the left hemisphere, within the internal and external watershed zones.

In 2024, the patient was readmitted with a two-week history of fluctuating expressive dysphasia. Episodes were observed by family to last for 10 - 15 minutes with spontaneous resolution. Examination revealed that he was hemodynamically stable with a systolic blood pressure of 140mmHg, and in sinus rhythm on 12 lead electrocardiograms. He demonstrated subtle conductive and expressive speech deficits, but no nominal deficits. There were no motor, or sensory deficits and visual fields were normal on bedside testing. The patient was oriented however cognitive testing revealed deficits with recall, loss of short-term memory and tangential speech.

Repeat neuroimaging with MRI brain demonstrated an acute infarct at the left pre-central gyrus on a background of multiple left hemispheric infarcts involving the internal and external watershed zones (Figure 2). The white matter changes had significantly progressed compared to those from the index stroke admission in 2021. Repeat CT angiogram demonstrated mild stenosis of the intracranial left MCA and increased stenosis of the left ICA, now reported at 50-69%, and confirmed on carotid ultrasound.

Following multi-disciplinary discussions, and given the evidence of increased left ICA stenosis, the consensus was for intervention. Given the patient’s age and comorbidities, ICA stenting was chosen over endarterectomy. During the intra-operative angiogram, a high-grade left ICA stenosis was identified (Figure 2), higher grade than previously suggested by ultrasound or CT angiogram. It is hoped that improved flow through the patient’s left ICA post-stenting will prevent further cerebral insults and white matter changes.