Injuries to vascular and visceral structures during anterior surgery on the cervical spine can occur. Meticulous dissection and careful placement of deep retractors minimize the potential for such complications. The recurrent laryngeal nerve runs between the esophagus and the trachea. When deep retractors are placed, the recurrent laryngeal nerve can be pinched between the retractor and the endotracheal cuff (Fig. 36.1). Releasing the endotracheal cuff and reinflating the cuff at a lower tension decreases the pressure on the recurrent laryngeal
nerve, thus decreasing the incidence of postoperative vocal cord paralysis. In addition, periodic relaxation of the surgical retractors minimizes associated soft tissue trauma. Inadvertent dissection over the longus colli or malpositioned retractor blades may injure the sympathetic chain, which rests on the muscle body of the longus colli. Injury to this structure results in an ipsilateral Horner syndrome.

The vertebral artery is at risk during both anterior and posterior approaches. It is at particular risk during placement of C1–C2 transarticular screws. There is also the potential for injury in anterior surgery when surgical dissection strays too far from the midline leading to violation of the foramen transversarium. Surgeons should pay particular attention to preoperative computed tomography (CT) scans to make sure there are no anomalies of the vertebral artery from side to side and that there is no unilateral or dominant vertebral artery. Some small vertebral artery lacerations can be treated by packing with thrombin-soaked absorbable gelatin sponges. In rare cases, ligation may be required for hemostasis. Although most patients tolerate unilateral vertebral artery ablation, a small percentage have symptomatic vertebrobasilar symptoms, including syncope, nystagmus, dizziness, or Wallenberg syndrome (ipsilateral loss of temperature and pain sensation of the face and contralateral loss in the extremities and trunk, dysphagia, dysarthria, and nystagmus). If possible, repair of an injured vertebral artery is prudent.

Injury to the esophagus is associated with a high incidence of deep infection. Palpation of the nasogastric tube can help identify the location of the esophagus. Subperiosteal elevation of the longus colli muscles from the anterolateral vertebral bodies with placement of deep retractors under the elevated muscle edge can also help prevent injury. If intraoperative injury is suspected, insertion of methylene blue dye through the nasogastric tube may aid in the identification of an esophageal tear. If a tear is undetected, postoperatively the most frequently occurring symptoms are neck pain, odynophagia, dysphagia, and hoarseness. Cervical osteomyelitis or cervical abscess develops in about 0.5% of patients, but any anterior cervical wound infection should raise suspicion for occult esophageal injury. Clinical findings include fever, cervical tenderness and induration, weight loss, tachycardia, mediastinal crepitus from emphysema, and hematemesis. A combination of endoscopy and a swallow study is regarded by most authors to have the highest diagnostic yield. Management of esophageal perforation is surgical. Nonoperative management, including observation, intravenous nutrition, placement of feeding tube or gastrostomy, appropriate antibiotic coverage, and aspiration precautions, should be reserved for small perforations in patients otherwise too sick to undergo surgery. The literature has shown high morbidity and mortality with nonoperative management of all but the smallest of perforations, especially with tears of the lower esophagus. Consultation with a thoracic or esophageal surgical specialist is recommended in all cases. The esophagus should be examined carefully after any anterior cervical spinal operation before closure. Any esophageal injury noted in the operating room should be repaired by an experienced surgeon. The repair can be augmented, if necessary, with a muscle flap, such as a proximally based sternocleidomastoid rotational flap. This augmentation is of particular utility in cases of delayed diagnosis and of large defects that are not amenable to primary repair.

Anterior thoracic and lumbar surgery can be complicated by pneumothorax, hemothorax, and chylothorax. Massive hemothorax may occur from profuse vertebral body bleeding. This condition typically requires surgical tamponade of the venous sinuses in the vertebral body with bone wax or ligation of the respective segmental vessels.

Anterior thoracic spine surgery may also put the thoracic duct at risk of injury. The thoracic duct has a winding course along the spine. In the lower thoracic spine, it lies anterior and slightly to the right of the spine between the aorta and azygos vein and behind the esophagus. In the upper spine, it crosses over to the left side, behind the aortic arch. Iatrogenic chyle leaks have been reported after spinal surgery. Most leaks are clinically insignificant and heal spontaneously. If a chylothorax is suspected postoperatively, diagnostic thoracentesis and tube thoracostomy should be performed. Oral intake should be discontinued because even low-fat clear liquids markedly increase chyle flow. Traditionally, continued chylous chest drainage for more than 6 weeks is an indication for open surgical intervention. Some authors recommend surgical treatment within 2 weeks to prevent ongoing protein and lymphocyte losses and to minimize the risk of infection.

Trauma or severe stenosis may make the spinal cord more sensitive to the effects of mild ischemia. Anterior procedures of the spine often require mobilization or ligation of the segmental vessels over numerous levels. In most instances, ligation of multiple ipsilateral segmental arteries can be performed without neurologic compromise. In some cases, especially in the setting of congenital deformity correction, segmental artery disruption may lead to neurologic compromise.

The anterior lumbar spine can be approached via the retroperitoneal or, less commonly, the transperitoneal approach. A left-sided approach is generally preferred because the aorta is easier to mobilize than the thin-walled vena cava. The left common iliac vein is the vessel most at risk during left-sided exposures. Regardless of approach, if the spine is instrumented anteriorly,
screws should be placed on the lateral side of the vertebral body and should not contact the great vessels. The ureters and great vessels are also at risk in retroperitoneal dissections, especially in the revision setting. Consideration should be given to preoperative ureteral stenting before revision procedures. Injury to the sympathetic plexus overlying the anterior aspect of the lower lumbar and upper sacral vertebrae may lead to retrograde ejaculation and even impotence.

Vascular complications during posterior lumbar spinal surgery are uncommon. Vascular injury can occur during discectomy if the anterior longitudinal ligament is violated. The pituitary rongeur is the most frequent culprit (Fig. 36.2). Unless acute hypotension occurs intraoperatively, these injuries initially may go unnoticed. Less than 50% of cases are associated with massive bleeding from the disk space. Late abdominal rigidity, abdominal pain, tachycardia, and anemia should alert the physician to the possibility of this complication. In the event that injury is identified intraoperatively, vascular surgery consultation should be obtained and a repair performed. In most cases, this requires an anterior abdominal approach.