In cases of inadequate collateral vascular compensation, acute carotid occlusion is very dangerous and can lead to massive cerebral infarction, where the patient becomes comatose and even life-threatening.
In the case of only partial compensation, reversible symptoms such as transient hemiparesis, hemianesthesia, and speech inability may occur and require aggressive treatment. If the collateral vessels are adequately compensated, the patient is asymptomatic but requires medical management of risk factors.