Rationale: Congenital internal carotid artery hypoplasia (CICAH) is rarely reported. This study aimed to discuss the epidemiological characteristics, clinical manifestation, imaging and treatment of CICAH.
Patient concerns: The case was male who showed barylalia and limited abilities of the left limbs as their main clinical manifestation. This patient was diagnosed CICAH by digital subtraction angiography (DSA) and computed tomography (CT).
Diagnosis: CICAH.
Interventions: The patient underwent anti platelet aggregation, lipid-lowering, improving cerebral circulation.
Outcomes: The patient was in a stable condition after management of cerebrovascular risk.
Lessons: Given the asymptomatic and congenital nature of carotid agenesis, no treatment is necessary or possible to re-establish the internal carotid artery (ICA). However, with the high risk of aneurysm and cerebrovascular insufficiency, management of cerebrovascular risk is important. Urgent radiological assessment is necessary for patients with suspicious neurological symptoms.