Penetrating cerebrovascular injuries (PCVIs) are often life-threatening, with trauma to the carotid or vertebral arteries potentially causing severe neurological deficits. This study aimed to retrospectively examine two cases of severe penetrating cerebrovascular injury with unstable hemodynamics that resulted in markedly different neurological outcomes. The first patient was struck by a high-speed metal rod, sustained injuries to the right common carotid and right vertebral arteries and was admitted to our hospital 10 h after the trauma. The second patient, who was stabbed, sustained an injury to the right vertebral artery and was admitted to our hospital 1 h after the trauma. Both patients had injuries in zone II of the right lateral neck. The first patient underwent ligation of the right vertebral artery and anastomosis of the right common carotid artery using an interposition graft from the autologous great saphenous vein, resulting in an asymptomatic infarction of the ipsilateral frontal lobe. The second patient only underwent ligation of the right vertebral artery, which ultimately led to an occipital lobe infarction and subsequent visual field deficits. These contrasting outcomes underscore the critical influence of cerebrovascular anatomical variations. Penetrating cerebrovascular injuries may pose significant risks of neurological impairment, particularly in the presence of important vascular anatomical variants. Revascularization should be considered as a primary treatment option for patients with cerebral vessel malformations.