Vascular injuries during lumbar spine surgery are underestimated in the present literature. The reported incidence of vascular injury is less than 1%.
The sequelae may not be detected for years after the index surgery.
Endovascular interventions are preferred over open surgery to encounter the sequelae of injury.
Lumbar discectomy (with/without instrumentation) is one of the most common operations performed in spinal surgery practice. Vascular injury complications can be classified in two broad groups: (1) arterial bleeding from back muscles and epidural venous bleeding and (2) major vessel injury. Vascular injury to a major vessel is rare but is a life-threatening complication. The prevalence of vascular complications during lumbar disc surgery is reported to vary between 1 and 5 in every 10,000 disc operations. About 300 cases with similar complications have been reported in the last 75 years. The offending vessels were abdominal aorta, inferior vena cava (IVC), common iliac arteries (CIAs) and/or common iliac veins (CIVs), and internal or external iliac artery. However, it may be an underestimation because complications often go unreported. Also, the complications may present in a delayed fashion.
Anatomic Insights ( Fig. 52.1 )
The most common vascular injury is related to L4–L5 and L5–S1 disc surgery. The proximity of susceptible vessels varies according to the spinal level. Thus proximal (L2–L3 and L3–L4) level is associated with injuries predominantly to the aorta and the IVC, whereas iliac vessel injuries are seen mainly with L4–L5 and L5–S1 space surgery. The course of the CIA begins at the distal portion of the abdominal aorta and extends inferolaterally for approximately 4 cm from the L4 vertebra to alongside the medial aspect of the psoas muscle, where it typically bifurcates anterior to the sacroiliac joint of the pelvis ( Fig. 52.1 ). The left CIA is more susceptible to injury due to its medial course and close relation with the L4–L5 intervertebral disc. Knowledge of common anomalies is also important. An aberrant iliac artery may impinge on the lumbar plexus, and a foraminal herniation at L4–L5 may pose difficulties in the transpsoas approach to an anterior lumbar interbody fusion (ALIF). Although the occurrence is rare, there are examples of other vessels getting injured as well. Injury to L4 lumbar artery, median sacral, the inferior mesenteric, and the superior rectal artery have been described during the approach to the lumbar spine. Injuries to large veins have been documented in the literature. Injury to the left CIV is more common than to the right common iliac, right/left internal iliac, or IVC in one report. Another report suggested that the left CIV was the vessel most commonly injured during an anterior approach to the lumbar spine.
In nearly all cases, the injury was caused by the pituitary rongeur pushed so far ventrally that it perforated the anterior vessels.
As the intervertebral disc is avascular, any unexpected bleeding from inside the disc should be considered suspicious. However, in more than half of the reported cases, bleeding is absent or mild.
Keep anesthesia involved: In very few reported cases, increase in heart rate and/or marked decrease in blood pressure occurred intraoperatively so as to lead to a suspicion of an abdominal vessel injury. Reduction in end-tidal CO 2 concentration may also be a clue on a few occasions.
Surgeons may erroneously feel safe when an abnormal bleeding stops rapidly. The resulting annular flap might close the breach, acting like a valve, in a very short time interval. The elasticity of the annulus and ligament also plays a role.
The iliac vessels, located laterally in the pelvis, may get compressed by the pads of the frame on which the patient was lying. Vessels may get compressed against lower lumbar vertebrae as well. This can lead to temporary hemostasis, which gets unmasked once the patient is back in the supine position.
Any episode of intraoperative hypotension or bleeding should be carefully investigated. The abdomen should be auscultated before discharge. Emergency laparotomy should be considered in the unstable patient suspected of vascular injury. When patients with leg edema/signs of cardiac insufficiency are examined, a history of previous discectomy should be sought to exclude an arteriovenous fistula (AVF).
A number of factors may predispose to vascular injury during lumbar disc surgery. The common factors can be classified as congenital, acquired, and technical factors. These are summarized in Table 52.1 . Annulus fibrosis and degeneration of the anterior longitudinal ligament (ALL), advanced discopathy, vertebral anomalies (transitional lumbosacral vertebra), adhesion of intervertebral disc to the ALL, previous disc surgery, current or previous osteomyelitis or discogenic infection, aggressive exploration, and complex patient positioning are considered as important risk factors for vascular injury. Current or previous osteomyelitis or discogenic infection, spondylolisthesis, osteophyte formation, and anterior migration of interbody device point to an increased risk of vascular complication. Few studies have suggested that the exposure of L4−5 was associated with an increased chance of vascular injury during anterior approach. Sasso et al. suggested that the use of threaded cage such as InterFix was associated with more vascular injury. The incidence of vascular injury is more common with the anterior approach than the posterior approach. The chance of injury is higher in the transperitoneal than in the retroperitoneal approach when performed anteriorly. As expected, the incidence is higher in revision surgery than in primary surgery.
|Congenital and Habitual|