Neurological complications in spinal angiography may include the same risk of cerebral ischaemic events that may occur during cerebral angiography when the cervical region is being studied (see Chap. 2). In addition, there is the risk of vessel dissection, embolic occlusion with thrombus, atherosclerotic plaque, or air emboli occluding the spinal cord vessels and producing myelopathy. Forbes et al. reported that a series of 134 spinal angiograms had three (2.2%) neurological complications, all transient.1 Two more recent series, with over 300 cases, have zero neurological complications from diagnostic spinal angiography.2,3 High-volume contrast injection in vessels feeding the spinal cord (although not necessarily performed as part of spinal angiography) has also been shown to produce temporary or permanent injury to the spinal cord.4–6

Non-neurological complications of spinal angiography via the femoral artery include the same local and systemic complications seen in cerebral angiography (as seen in Chap. 2). Forbes reported 8.2% puncture-site complications and 3.7% systemic complications from spinal angiography.1 More recently, 1% puncture site complications and 0.7% systemic complications were reported.3

The choice between general anesthesia and conscious sedation for spinal angiography depends upon the circumstances. General anesthesia allows for patient immobility including prolonged interruption of respiration while imaging tiny spinal vessels that are present in the thoracic and lumbar region. General anesthesia also spares the patient the potential discomfort of a long, involved angiographic procedure. Using non-ionic, iso-osmolar contrast, procedures can be done under local anesthesia with minimal sedation, and adequate image quality is possible in cooperative patients. The advantage of local anesthesia is the avoidance of any of the potential complications of general anesthesia and the ability to monitor the neurological status of the patient during the procedure. The limited ability to monitor the neurological status of the patient during general anesthesia may be partially mitigated by the use of neurophysiological monitoring, such as somatosensory and/or motor evoked potentials.2 However, neurophysiological monitoring adds to the cost and complexity of the procedure, and may not be readily available or reliable, depending on the institution.

Non-ionic contrast agents are almost always used due to their lower osmolality and better tolerance when injected into the small vessels feeding the spine. Iodixanol (Visipaque^TM, GE Healthcare, Princeton, NJ), an iso-osmolar and a nonionic contrast agent, is more expensive and more viscous than other contrast agents commonly used but is the best tolerated agent for spinal angiography.

Patients with normal renal function can tolerate up to 400–800 mL of Omnipaque^®, and 300 mg I/mL without adverse effects.7 Contrast volumes in spinal angiography can routinely approach these limits, given the large number of injections required.

Trans-femoral spinal angiography is almost always done with a sheath.

Sheath:

No Sheath:

Selective spinal angiography may be either complete spinal angiography, or a partial, focused study for a specific lesion. Complete spinal angiography is a major undertaking, in which all vessels that may relate to the spinal canal are selectively catheterized and studied. This is most often used in the evaluation of a patient with a suspected dural arteriovenous fistula causing myelopathy. The vascular lesion can be anywhere from the head to the sacrum, and evaluation of all vessels supplying these structures may be required (Table 3.2). When the lesion is obviously confined to a specific region of the spine, a more focused study may be more appropriate. This should include all the vessels that supply the area of interest, and the levels above and below the lesion, given the possibility of collateral flow from adjacent spinal vessels. Another useful rule of thumb is to visualize normal spinal cord vessels above and below any lesion affecting the cord. Assessing spinal cord blood supply may require selective angiography of the vertebral arteries (Fig. 3.2), thyrocervical and costocervical trunks, subclavian arteries, intercostal arteries (Fig. 3.3), lumbar arteries (Fig. 3.4), and lateral and medial sacral arteries.

Roadmapping can be used to aid catheterization of the supra-aortic vessels, such as vertebral arteries, and the thyrocervical and costocervical trunks. Roadmapping is less helpful in catheterizing the intercostal and lumbar arteries, since respiratory motion degrades the image.

Catheter flushing technique is discussed in Chap. 2. Although some practitioners advocate double flushing of catheters only in the supra-aortic vessels, it makes more sense to use a meticulous flushing technique anywhere in the vascular system. This ensures that one will not forget to use good technique when it is most needed. Moreover, thrombus or air emboli in spinal cord vessels can be just as disabling as cerebral ischemia.

Three-way stopcock or manifolds can be used to provide a heparinized saline drip through the catheter. This is particularly useful for long spinal angiographic ­procedures. In-line air filters (B. Braun, Bethlehem, PA) on the saline drip tubing provide added protection from bubbles (as discussed in Chap. 4). A rotating adapter on the stopcock is needed to prevent the stopcock from being a drag on free manipulation of the catheter. Using both a rotating three-way stopcock and a rotating hemostatic valve on the catheter allows for two pivot points to allow free rotation of the catheter. This is important, as the catheter may not be in a stable position in the small lumbar and intercostal arteries.

Frequent small injections (“puffing”) of contrast can be used to help manipulate the catheter into the desired lumbar and intercostal arteries. A 20 mL syringe containing contrast can be left attached to the catheter for these injections, and then used immediately for hand injections of contrast for angiographic runs. As is done in the cerebral vasculature, the syringe is held vertically and care is taken not to allow bubbles to enter the catheter. Most spinal vessels are best imaged with hand injections of contrast, to allow for modulation of the injection rate and volume, depending on the size of the vessel and stability of the catheter. An adequate angiographic run can be usually done with a single 2–3 s injection of 4–6 mL (100% contrast) of contrast. The goal is to adequately opacify the vessel of interest without displacing the catheter or refluxing too much into the aorta or into the ever-present collaterals to other spinal vessels. Patients should be warned that they will experience warmth and/or cramping in the territory of the injected vessel, and breathing should be suspended during the angiographic run, but the phase of respiration at which the breath-holding should occur depends on the spinal level being imaged (see below).

A power contrast injector is necessary for thoracic or lumbar aortic angiograms, and for large vessels such as subclavian or iliac arteries. As stated in Chap. 2, the pressure and flow rate settings should not exceed the ratings of the stopcock or catheter. Common power injector settings for vessels studied in spinal angiograms using a 5F catheter are listed in Table 3.3. Note that one may need to increase or decrease these rates and volumes, depending on the size of the vessels, the stability of the catheter, and the quickness of the runoff of the contrast on a test injection. Use extreme caution if the catheter is wedged in the vessel and be especially careful if there is a possibility that a spinal cord vessel is arising from the branch one is injecting, since high-pressure power injections can damage the cord. When in doubt, use careful hand-injections of contrast.

If the exact level of the lesion is known from non-invasive imaging, the spinal angiogram should begin with those vessels supplying that area. Following catheterization of the vessel of interest, it is then customary to work systematically above and below the lesion to include normal territory adjacent to the lesion. Lesions of the cord itself usually require mapping of the spinal cord supply above and below the lesion. For complete spinal angiography, it is particularly important to image the intercostal and lumbar arteries in a systematic fashion so that one does not inadvertently miss or repeat a level. It is helpful to maintain a worksheet during the procedure, and list the sides and vessels injected during each angiographic run. Radio-opaque marker rulers can be placed under the patient on the table or marker tapes can be affixed to the patient’s back, slightly off midline to have a reference available on each film to help confirm the levels studied. Additionally, bony landmarks, such as the 12th rib, can also help with keeping track of the vessels being studied.