Carotid artery dissection is one of the most important causes of cerebral stroke in young age. Although most cases of carotid artery dissection appear spontaneously, sometimes it may result from a microtrauma which the patient does not take seriously. This article reports a case of extracranial internal carotid artery dissection starting from intense swimming and manifesting itself only as neck swelling and neck pain. Other analyses showed that the patient also suffered from a cronic venous sinus thrombosis and stroke. Moreover, genetic testing revealed a MTHFR gene mutation. This case is presented because of the multiple vascular events are seen in the same patient.