The data selected for this review consisted of 230 angiographies performed in 164 pediatric patients (under 18 years). The studies can be divided into two groups, diagnostic arteriography (n173) and angiograms performed as part of an endovascular treatment (n147). The study population included 92 boys and 72 girls, aged between 1 week and 18 years (mean of 9. 3 years). The angiographic diagnosis for the study population are listed in table 1. No vascular anomalies were found in 35 patients, confirmed in subsequent follow-ups with new angiography, MRI or CT.
1. INDICATIONS FOR DIAGNOSTIC CEREBRAL ANGIOGRAPHY
Cerebral angiography can be performed as a diagnostic or therapeutic procedure. Nowadays, advances in non-invasive vascular imaging have replaced many of the classic angiography indications, preserving its usefulness for inconclusive cases. Nevertheless, Society of Neurointerventional Surgery (SNIS) Pediatric committee recommends the use of diagnostic arteriography in few pathologies, such as the detection of intracranial aneurysms in non-traumatic subarachnoid hemorrhage or Moyamoya's disease, and considers it the primary treatment modality for Galen venous malformation and arteriovenous fistulas (AVFs).
Indications for pediatric angiography, considering both intracranial and extracranial conditions, are described in table 2.
2. ANGIOGRAPHIC PROTOCOL
Arteriography is a minimally invasive test that represents a challenge in regard to safety aspects in pediatric patients. Children differ from adults in neurologic development, cerebrovascular anatomy and natural history of disease. Moreover, their long-life expectancy demands long-lived treatment options and closer monitoring comparing to adults with less radiation exposure.
- Technical considerations
- One of the most important aspects of pediatric ASD is to limit the radiation dose according to ALARA principles, since the risk of developing cancer (usually leukaemias) is higher in this age group. For this, and other key points such as the risk of contrast-induced nephropathy, as well as the risk of bleeding at the puncture site.
- SNIS makes some recommendations for these endovascular procedures (Table 3 and 4).
- Image Acquisition
- Arteriography of 4 vessels
- General anesthesia
- The use of general anesthesia (GA) is recommended for all pediatric DCAs, with few exceptions, such as a balloon test occlusion (if performed with awake neurological testing).
- Few older children (16 years of age or above), who were considered candidates for conscious sedation and local anesthesia, if they are cooperative.
3. COMPLICATIONS
Complications were categorized as neurologic or non-neurologic, and severity was graded using a standard diagram.
Despite not finding intra or post-procedure complications in our institution, there have been reported iatrogenic complications with rates of nearly 0,4% and groin haematoma with rates of 5%. The most common in children are: arterial vasospasm and hematoma at the vascular access.
4. TYPES OF ENDOVASCULAR PROCEDURE
- Diagnostic arteriography and specific test
- DSA it allows execution of functional tests, in example, petrosal sinus sampling (in Cushing syndrome) or balloon test occlusion internal carotid artery (for preoperative evaluation, to evaluate tolerance to occlusion of a vessel).
- Embolization
- Procedure that uses materials to close the blood supply of vascular malformations, cerebral aneurysms or tumors under fluoroscopic guidance. It can be made intraarterial, intravenous or percutaneously.
- Cerebral and carotid angioplasty with stenting
- Procedure used in the treatment of vascular dissections, aneurysms and thrombosis associated with significant venous sinus stenosis.
- Sclerotherapy
- Procedure that is performed by direct percutaneous puncture of the lesion and produces an immediate thrombosis. (It is reviewed in Venous and lymphatic malformation).
- Mechanical thrombectomy
- It is a procedure performed in ischemic stroke to remove a thrombus that causes occlusion of a large vessel.
- Intra-arterial chemotherapy in retinoblastoma
- Local administration in the retina of chemotherapy drugs.
5. PAEDIATRIC VASCULAR PATHOLOGY
For a more practical view of pediatric vascular pathology, we will divide them into two large groups: intracranial pathology proper and extracranial pathology, understanding as such the pathology that develops in the cervicofacial space.
5.1 INTRACRANIAL PATHOLOGY
Cerebrovascular Malformations (CVM)
These lesions are secondary to a defect in the embryonic capillary maturation process, which causes the abnormal formation of arteries, veins and/or capillaries.
Cerebral vascular malformations have been classified in various ways by many authors. We will use the classification CVMs according to their main distinguishing feature, the presence or absence of arteriovenous shunts within the lesion (Table 7).
- Arteriovenous malformations
- Consist of arteriovenous shunting with a vascular intermediate net, called nidus. They are high flow and low resistance systems likely to bleed.
- Pediatric arteriovenous malformations represent about 5-20% out of the total of cerebrovascular malformations. Its most common clinical manifestation is cerebral hemorrhage (63-75%), followed by seizures (13%).
- On the contrary to adults, incidental detection of AMV in the pediatric population is uncommon.
- Arteriovenous fistulas
- Arteriovenous fistulas (AVF), are divided into pial and dural fistulas, depending on their location.
- Consist of a direct connection between cerebral arteries and venous sinus without an anomalous intermediate net.
- Vein of Galen malformation
- They are rare congenital malformations (1:25.000 newborns), representing 1-2% out of the total of intracranial vascular malformations.
- It occurs between 6th and 11 weeks of intrauterine life as a result of the persistence of the median prosencephalic vein (Markowski vein), located in the choroid fissure.
- Carotid Cavernous Fistulas
- It consists of a direct communication between the intracavernous internal carotid artery and the cavernous sinus, usually secondary to trauma, rupture of an aneurysm in the cavernous sinus or iatrogenic arterial dissection after surgical procedures.
- Venous developmental anomaly
- It is the most common cerebrovascular malformation.
Arterial ischemic stroke cerebral
Lower incidence in children, especially after one month of age, where incidence is estimated to be between 2,5 and 13/100,000/ year.
It causes great morbidity and mortality, as at least 50% of patients suffer severe neurological sequelae and 7–28% die.
Mechanical thrombectomy is standard treatment for large vessel occlusion (LVO) in adults. Nevertheless, the prevalence of LVO in children is unknown, being estimated to be around 7% of all ischemic strokes.
Moyamoya disease/syndrome
The term moyamoya disease should be reserved for an idiopathic condition, which leads to characteristic intracranial vascular changes.
Numerous entities have been described which mimic the appearance, in which case the term moyamoya syndrome (or phenomenon or pattern) is used, being vasculitic/inflammatory causes the most important in children.
The staging system for this entity is known as Suzuki staging, which evaluates the severity of the disease taking into account 3 aspects:
- Stenosis grade
- Moyamoya vessels
- Collateralization grade
Arteriography is needed for preoperative study, as it determines which arteries are susceptible to be used for bypass and helps to detect microaneurysms. Moreover, it allows to determine surgery efficacy in the postoperative stage.
Takayasu arteritis
Central Nervous System Vasculitis
Venous Thrombosis
5.2 INTRACRANIAL AND EXTRACRANIAL PATHOLOGY
Aneurysm, post-traumatic pseudoaneurysm and dissection
Highly vascularized neoplasms
Preoperative diagnostic angiography allows a detailed description of arterial feeders as well as a functional study using the balloon test occlusion of internal carotid artery (when evaluation of ischemic tolerance after permanent occlusion of this artery if required).
5.3 EXTRACRANIAL PATHOLOGY
Venous and lymphatic malformation.
Venous malformations are the result of a restricted development of the venous system during the embryogenesis.
Epistaxis
Endovascular embolization is indicated in cases of refractory epistaxis.