Imaging characteristics and treatment strategies for carotid artery occlusion caused by skull base fracture

Abstract

The internal carotid artery occlusion caused by head and neck trauma, also known as traumatic intracranial artery occlusion, is relatively rare clinically. Traumatic skull base fracture is a common complication of traumatic brain injury. Traumatic skull base fracture is one of the causes of traumatic internal carotid artery occlusion. If not detected early and treated in time, the prognosis of patients is poor. This editorial makes a relevant analysis of this disease.

Key Words: Skull base fracture; Traumatic internal carotid artery occlusion; Blunt cerebrovascular injury; Imaging; Imaging characteristics; Treatment strategies

Core Tip: The internal carotid artery occlusion caused by head and neck trauma, also known as traumatic intracranial artery occlusion, is relatively rare clinically. Traumatic skull base fracture is a common complication of traumatic brain injury. Traumatic skull base fracture is one of the causes of traumatic internal carotid artery occlusion. If not detected early and treated in time, the prognosis of patients is poor.

TO THE EDITOR

The internal carotid artery (ICA) occlusion caused by head and neck trauma, also known as traumatic intracranial artery occlusion, is relatively rare clinically. Traumatic skull base fracture is a common concomitant of traumatic brain injury. Traumatic skull base fracture can cause cranial nerve and cerebrovascular injury[1,2]. Skull base fracture can be complicated by internal carotid artery intima and elastic fiber rupture, internal wall bleeding or atherosclerotic plaque injury and loss, thrombosis and internal carotid artery occlusion. Although traumatic internal carotid artery occlusion is very rare in clinic, it can lead to acute cerebral ischemia, which makes its clinical incidence dangerous, high mortality and disability rate, and poor prognosis. In addition, computerized tomography (CT) scans of such patients in the early stage of the disease show no abnormal manifestations, and neurological symptoms may gradually appear after injury, with a certain delay (generally 8 to 10 hours), which often causes difficulties in early diagnosis. Once cerebral infarction symptoms occur, the consequences are difficult to recover. Therefore, timely detection and correct treatment are very important for saving the lives of such patients[3,4].

ANATOMICAL STRUCTURE ANALYSIS

Traumatic ICA occlusion caused by head trauma can be caused by a variety of reasons, even minor neck injury can occur, and can occur in various parts of the ICA neck and skull base travel[5]. However, skull base fracture is considered to be the main cause. The anatomical structure of the skull base is complex, and endoscopic transnasal skull base surgery can expose these structures more extensively than before[6,7]. Anatomically, ICA is not only relatively free in the neck segment, but also wrapped and fixed by the carotid sheath. In the skull base segment, ICA is bent through the bone duct of the skull base and is fixed in the bone duct. This is also one of the reasons why trauma leads to skull base fracture and carotid artery occlusion after bone injury. In addition, trauma can also cause pathological changes in the vascular wall of ICA[8]. For example, if the carotid artery injury involves the intima and media, thrombosis or dissecting aneurysm of the artery wall may result in stenosis or occlusion of the vascular cavity[9,10].

IMAGING FEATURES

The auxiliary examination methods of neck blood vessels are: CT, CT angiography (CTA), magnetic resonance imaging (MRI), magnetic resornance angiography (MRA), cervical vascular two-dimensional ultrasound (duplex ultrasound), transeranial doppler (TCD) and digital subtraction angiography (DSA).

CT examination of cerebral infarction patients has the characteristics of fast speed, popular equipment, high spatial resolution and good contrast. At present, it is the primary means of exclusion for clinical emergency treatment. However, within 6h of the onset of cerebral infarction, there was no obvious abnormality in brain morphology on CT, and the lesions could not be shown. However, if there is an obvious low-density infarction, the occurrence of ischemia has been more than 12 hours. There is a delay.

Compared with CT plain scan, head magnetic resonance examination can detect ischemic infarction earlier, but its examination time is long and the emergency examination is inconvenient.

CTA imaging can obtain the developed image of the blood vessel, and the shape, size and surface of the vascular plaque can be correctly observed through the original image in time, which can well display the patency of the cerebral artery and effectively diagnose the stenosis and occlusion of the cerebral artery.

DSA can display the overall picture of the examined cerebral artery, especially the collateral circulation vascular network and cerebral artery stenosis after occlusion. Its disadvantage is that it cannot evaluate the thickness of intravascular plaque, surrounding soft tissue and calcification plaques.

The examination of the neck with 2D ultrasound and transcranial Doppler is non-invasive, economical, simple, easy to perform and can be repeated. Cervical ultrasound can detect the thinning of the internal carotid artery and the hematomas between the artery walls, and can even detect the endovascular flap floating in response to the impact of blood flow. Transcranial Doppler ultrasound can indirectly reflect the patency of the internal carotid artery through the flow velocity and direction of the middle cerebral artery and the anterior communicating artery[11].

DIAGNOSTIC CHARACTERISTICS

Traumatic ICA occlusion has the following characteristics: (1) It is often associated with skull base fracture. Most of these patients have skull base fracture, fracture displacement and compression of the internal carotid artery or fracture end injury of the internal carotid artery. It is difficult for such patients to be diagnosed by CT at the early stage of the disease[12], so it is necessary to be vigilant about whether vascular examination should be further improved to rule out the possibility of internal carotid artery injury as soon as possible; and (2) Patients with typical traumatic ICA occlusion symptoms are not difficult, and it is difficult to make a definitive diagnosis before cerebral ischemia reaches irreversible damage, so the time factor is very important. However, most of the patients with traumatic internal carotid artery occlusion have a certain course of disease and progressive deterioration. Symptoms such as focal neuropathy in awake patients unexplained by CT scanning, focal neuropathy with skull base fracture, and Horner sign after head injury are included in this list[9,13]. For such patients, skull base fracture and aggravation of the disease exist, and corresponding vascular examination should be arranged in time to eliminate the possibility of internal carotid artery injury, stenosis and occlusion. Acute occlusion of ICA results in insufficient collateral circulation of the brain, resulting in severe ipilateral cerebral ischemia, acute cerebral infarction, diffuse cerebral edema, progressive exacerbation of post-injury disturbance of consciousness, and even cerebral hernia crisis within a few hours[5,14]. It seriously endangers the prognosis of patients.

Fabian et al[15] proposed that further examination should be performed in the following four cases to rule out internal carotid artery injury: (1) Neck soft tissue injury; (2) Physical examination of nervous system was inconsistent with CT results; (3) New neurological signs appeared after admission; and (4) Horner syndrome.

TREATMENT

For patients with neck injury, especially skull base fracture, it is recommended to improve the vascular examination of the neck as far as possible to avoid missed diagnosis. If no abnormality is found, the patient and guardian should be fully informed. Once hemiplegic signs or Horner sign appear[9,13], and intracranial hematoma and contusion are excluded, TCD, MRA and other internal carotid artery examination should be performed. Although angiography is a reliable method to diagnose the disease, it is often not the first choice in the early stage because of the damage. For patients found to have internal carotid artery injury, drugs (anticoagulation and thrombolysis) or interventional stent treatment can be performed, such as large-scale cerebral infarction and other conditions, depending on the condition of craniotomy decompressive treatment.