7 Diagnostic Spinal Angiography
General Description
A diagnostic spinal angiogram and any spinal neuroendovascular intervention start with proper navigation of the paired intersegmental (or radicular) arteries. Recognition of the normal and variant anatomy is essential. Diagnostic spinal angiograms provide information on vessel abnormalities such as spinal fistulas and spinal primary or metastatic tumor vascularity. The spinal angiogram is the foundation for interventional spinal neuroendovascular techniques such as tumor embolization and arteriovenous malformation (AVM) and fistula (AVF) identification and management.
Indications
Diagnostic spinal angiography is indicated for patients with hypervascular spinal tumors. The tumors may be primary (e.g., hemangioblastoma) or metastatic (e.g., renal cell carcinoma). The angiogram may be used for evaluation in consideration of preoperative embolization before surgical removal of the tumor. It is also indicated for evaluation of patients in whom AVM or AVF is suspected.
Neuroendovascular Anatomy
The femoral artery is preferable for arterial access for spinal angiograms and spinal interventions. When searching for spinal arteriovenous fistulae (sAVF), the entire neuroaxis must be imaged. The neurointerventionist should be familiar with the complete vascular anatomy pertinent to the central nervous system from sacrum to cranium.
Arterial System
The lateral sacral vessels (extending from the internal iliac artery), median sacral artery, and paired intersegmental vessels from L5 to T2 must be identified. The ostia for the paired vessels emerge from the dorsal aorta only millimeters apart from one another, which is contrary to depictions in most schematic illustrations. The costocervical trunk, the supreme-most intercostal vessel, typically supplies the T1 vessels. Some variation near the aortic arch can be encountered with some ostia being absent and supplied by adjacent levels. The artery of Adamkiewicz (T10-L1; usually on the patient’s left side, also known as the greater anterior radiculomedullary artery) must be identified prior to embolization or surgical procedures because disruption of this vessel can result in spinal cord infarct because of its large supply of the thoracic cord via the anterior spinal artery. The cervical spine is supplied by paired vertebral vessels. The vessels ascend from the thyrocervical trunk (ascending cervical artery). The vertebral arteries produce radiculomedullary branches. The branches are usually found at C6 and C3 (cervical artery of enlargement) and feed the anterior spinal artery. Muscular branches can also supply the spinal arteries in diseased states. The anterior and paired posterior spinal arteries arise from the vertebral arteries (V4 segment) near the foramen magnum and anastomose at the lower end of spinal dura. The anterior spinal artery runs in the median fissure of the spinal cord and supplies most of the anterior spinal cord via perforators with the exception of the posterior columns that are supplied by the two posterior spinal arteries.
There are 62 segmental arteries (31 on the left, 31 on the right). Each segmental artery corresponds with one spinal nerve root. Each radicular artery travels along with the spinal nerve and enters the corresponding neural foramen under the pedicle. The radiculomedullary and radiculopial vessels stem from the paired segmental vessels near the neural foramen of each spine segment. The paired vessels continue as intercostal arteries and posterior musculocutaneous vessels. The radicular arteries are remnants of segmental vessels in embryology and contribute to the epidural arterial plexus. Identification of the radiculomedullary vessels is generally aided by the appearance of a midline spinal artery and an ascending shepherd’s crook-like orientation of the radicular vessel. The posterior radicular spinal arteries are typically somewhat tortuous and the posterior spinal arteries are off midline.
Venous System
Paired veins drain the spinal cord. There is one anterior spinal vein, one posterior spinal vein, and two longitudinal veins that are located posteriorly and laterally. In the lumbar region, radicular veins drain back into spinal veins and into lumbar veins. In the thoracic region, radicular veins drain into hemiazygos (left) and azygos veins (right) and back to the vena cava system. Venous engorgement (hypertension) is a hallmark of sAVF at areas where radicular arteries enter the nerve root sleeve near radicular veins.
Epidural venous drainage is responsible for draining the spinal cord and adjacent bony structures. The epidural veins are valveless and nondistensible. In the cervical region, the vertebral veins drain into the superior vena cava via the suboccipital venous system (Batson’s venous plexus). Batson’s plexus is the epidural venous plexus that has implications in the spread of metastatic disease or infections to the spine. Near the skull, the intracranial venous sinus may provide spinal drainage and, in states of venous hypertension, it can also appear enlarged. The spinal venous plexus connects with the clival plexus, marginal sinus, and the transverse and cavernous sinuses.
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
