Persistent intracranial murmur, a persistent murmur like the roar of a machine, aggravated by heart contraction, often interfering with sleep, can be heard in the frontal area with a stethoscope and diminished or disappeared by compression of the affected common carotid artery with a finger. So, what are the causes of persistent intracranial murmur in patients? The following is a brief introduction: 1, skull base fracture can cause injury to the cavernous sinus segment of the internal carotid artery or its branches, skull base fracture is mostly a continuation of the fracture line of the skull cap fracture to the skull base, with linear fracture; when the fracture line passes through the paranasal sinus or rocky mastoid airspace and communicates with the nasal cavity or external auditory canal, accompanied by dural rupture to form an occult open fracture. 2. The wall of the internal carotid artery in the sinus segment is ruptured by the violent turbulence of blood flow during trauma, and the above-mentioned factors can also cause punctate bleeding or limited injury of the arterial wall, and later the cavernous sinus segment is ruptured due to the violent fluctuation of blood pressure. Because the cavernous sinus segment of the internal carotid artery is firmly fixed by the dura at its entrance and exit, the fracture line can tear the artery or its branches when it crosses the middle cranial fossa or penetrates to the saddle side. This can sometimes be caused by direct injury from fracture fragments, penetrating injuries, or flying projectiles. The damaged artery may rupture immediately or with delay, so the time between the injury and the onset of symptoms of arteriovenous fistula varies, from immediate in acute cases to days or weeks in delayed cases, often with an asymptomatic interval followed by onset.