Introduction
Complications and adverse events in the management of spinal trauma can occur in any organ system. Avoidance and prevention of these complications requires multidisciplinary knowledge in spinal cord medicine. Unfortunately, there is no consensus in the literature regarding the true incidence of complications, which have been reported between 10% and 20%. Nasser and colleagues reported the incidence of complications in a systematic review. They reviewed 105 articles including 79,471 patients, of whom 13,067 had a complication for an overall incidence of 16.4% per patient. Interestingly, in a similar comparison in the thoracolumbar literature, complications were more than double when compared to cervical (17.8% vs. 8.9%, respectively). This topic is important because of the increased growth of case volume, use of new technology in the field of spine surgery, and severity of complications.
Complications are categorized into three general divisions for simplicity: the preoperative, intraoperative, and postoperative. This provides a simple and logical method to analyze prevention and management paradigms. Preoperative complications refer to early patient evaluation, assessments, decision making, and timing of treatment. Intraoperative decision making refers to complications related to surgical technique, approach, and risk. Postoperative decision making refers to both perioperative management and outpatient management. These arbitrary delineations in complication management are often ambiguous in outcome reports. For example, the definition of the postoperative time period that constitutes or determines when a postoperative event is attributed to the surgical procedure varies ( Table 38-1 ). This lack of standardization can result in misleading data that prevents the direct comparison among studies.
| Preoperative | Intraoperative | Postoperative |
|---|---|---|
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|
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Another important attribute of complications is their severity. Lebude and coworkers graded severity complications into major or minor categories. The definition of a major complication is that which produces a permanent detriment or that which requires reoperation. This definition intends to include all adverse events in a perioperative period of 30 days. Minor complications were defined as causing transient detrimental effects including medical adverse events. Other systems for spine surgery grade severity using four to six categories. Rampersaud and colleagues developed the Spine Adverse Events Severity System (SAVES); validation studies on the use of this tool supports author claims of its simplicity in capturing spine-specific events commonly missed by hospital metrics.
The most common area of study regarding adverse events in spinal surgery is understanding the true incidence and prevalence. However, the scope of this chapter will be primarily focused on the identification and prevention of complications at the various stages of care as related to the spine trauma patient.
Preoperative
Preoperative Evaluation and Decision Making
Patients who are injured and in severe pain or who have a spinal cord injury (SCI) are willing to undergo a procedure with a higher complication rate. It is, therefore, important that the spine surgeon provide the best estimation of the complication rate, numerical risk of most commonly encountered complications for a procedure, as well as a “likelihood of success.” Specific goals of surgery must be addressed and the patient’s objectives must match that of the surgeon to ensure the greatest patient satisfaction. Bono and colleagues in a preoperative questionnaire asked patients to score leg and back pain on a scale of 0 to 10. These same patients were then asked to list acceptable scenarios of complications that were presented. A multivariate analysis showed that patients with high-intensity low back pain (LBP), history of prior spinal injections, high educational status, white race, occupation, and a history of nonspinal surgery were indicators of patients with the greatest acceptance of a complication.
Complications with Preoperative Cervical Collar Management
The use of cervical collars is common in suspected spinal trauma patients, as it is suspected that up to 25% of SCIs are caused by pathologic motion of injured cervical vertebrae segments after the initial time of injury. The American Association of Neurological Surgeons (AANS)/Congress of Neurological Surgeons (CNS) cervical spine guidelines state that there is insufficient evidence for the use of cervical collars for the prevention of additional injury. However, when any spine trauma is suspected and there is a mechanism that could potentially have caused a cervical injury, then cervical immobilization is reasonable. Prolonged use of a hard cervical collar, however, can cause skin breakdown and ulceration. This is especially true in patients who are cognitively impaired or are in intensive care units (ICUs). An effort to clear the spine as outlined in Chapter 10 with a goal to remove the collar as early as possible should be performed. Geriatric patients with type II odontoid fractures are common where prolonged treatment with a hard cervical collar has inconsistent results. Skin problems are frequent and efficacy is questionable. Prolonged collar use is needed and subsequent skin breakdown becomes a common finding because of pressure ulcers from long-term collar use. Many surgeons argue for early operative intervention in this population to encourage early mobilization and not require prolonged immobilization in a collar. The Arbeitsgemeinschaft für Osteosynthesefragen (AO) Spine Odontoid Fracture Study, a retrospective review of operative versus nonoperative treatment for type II odontoid fractures, reported that treatment with rigid cervical collars resulted in a higher mortality rate than operative treatment.
Preoperative Timing
The timing of surgical intervention after a traumatic spinal cord injury has been controversial. Research into the timing of surgery has been slowed because of the lack of standardized definition. Widely quoted studies defined “early” as surgery performed within 72 hours or after 5 days illustrating the variability in the term “acute.” In these studies, no statistical difference was found with regard to hospital length of stay or neurologic improvement by American Spinal Injury Association (ASIA) grade between groups. Recent literature prospectively compared neurologic outcomes by the ASIA Impairment Scale (AIS) between patients with SCI treated earlier or later than 24 hours. This multicenter, international study group reported that early surgical stabilization for acute traumatic SCI resulted in a greater chance of improvement of AIS by 2 points at 6 months with an odds ratio of 2.8.
One subset of patients for which it has been even more difficult to determine a benefit is those with central cord syndrome. Timing for surgery of central cord syndrome is more controversial. Because of the relatively older age group, higher frequency of spontaneous improvement, and its lack of homogeneous pathologies of SCI, many studies have excluded central cord syndrome from timing studies.
Steroids in Spinal Cord Injury: Indications and Potential Complications
The use of methylprednisolone was recommended for acute traumatic SCI within 8 hours of onset by the second National Acute Spinal Cord Injury Study (NASCIS-2). In the NASCIS-2 study, Bracken and coworkers reported that there was a neurologic benefit at 6 and 12 months in the methylprednisolone groups who were at the risk for pneumonia and sepsis. There is still much debate on this topic, but given the minimal benefit reported in this study and potential complications, numerous surgeons have stopped using these medications. The most recent 2013 guidelines by the AANS/CNS Joint Section have for the first time discouraged the use of methylprednisolone in SCI. Regardless, the perceivable benefit is outweighed by the added morbidity of its use.
Preoperative Nutritional Status
Nutrition and metabolic requirements during acute traumatic injuries and wound healing are much greater than baseline. Klein and colleagues retrospectively reviewed 27 patients who underwent lumbar spinal surgery for vertebral osteomyelitis finding that a significant proportion (24/26) of the chronically malnourished had postoperative complications. Further, in the same study of 114 patients who underwent lumbar decompressive surgery, poor nutritional status was a factor in 11 of 13 (85%) postoperative infections encountered. It is, therefore, important to maximize nutrition and initiate enteral nutrition as soon as safely possible to enhance wound healing in spinal injured patients.
Obesity
Although malnourishment is an independent risk factor for infection, obesity is also a concern for increased morbidity. Weight loss has always been a recommendation for patients with symptomatic spinal disease but not relevant in spinal trauma. This is important as there is a significant contribution of obesity to morbidity. In a retrospective review, Patel and colleagues found that increasing body mass index (BMI) correlated with a risk for significant perioperative complications. However, these conclusions have been contradicted by a prospective study that found that BMI did not correlate with the incidence of minor or major perioperative complications.
Prognostic Implications of Diagnosis
Further preoperative considerations by the surgeon regarding risk of complications should be associated with the patient’s diagnosis and treatment. Yadla and coworkers found in a review of 248 consecutive spinal surgery patients that there was a higher likelihood of adverse events when the patient had a diagnosis of infection or neoplasm in the thoracolumbar spine, rather than degenerative disease or trauma alone. However, this difference was not statistically significant, most likely because there were too few participants. In the literature, patient populations who undergo operations for the treatment of infection and neoplasm have generally had an overall higher complication rate.
Intraoperative Management
Neurophysiologic Monitoring
The literature supports the use of electrophysiologic monitoring for spine deformity cases. However, these benefits are less precise in the treatment of degenerative cases or trauma cases. In a survey of spine surgeons, the majority reported they used somatosensory evoked potential (SSEP) monitoring for spinal surgery, in addition to other neurophysiologic modalities. In this study, the presence of fellowship training was highly correlative with the use of neurophysiologic modalities. In addition, the use of motor-evoked potentials were frequently used for the surgical decompression of myelopathic patients.
A position statement by the American Society of Neurophysiologic Monitoring said that multimodality neurophysiologic monitoring and the pedicle screw stimulation technique is not proven to reduce neurologic injury by prospective, randomized controlled trials (RCTs), but is an effective technique. Similarly, Resnick and colleagues in a statement for AANS/CNS Joint Section on Spine and Peripheral Nerve Disorders said that the pedicle screw stimulation technique is one diagnostic measure that can enhance the accuracy of pedicle screw placement. More than 1000 papers were reviewed spanning a decade of practice, concluding that due to the lack of prospective, randomized data there is no evidence to support the use of this procedure as a measure to significantly improve patient outcomes. The difficulty of determining if a technique and its improvements translate to improved outcomes is ongoing.
Preoperative and Intraoperative Imaging
Preoperative imaging is of great importance for adequate localization of the disease, characterization with a spinal pathology, and, particularly, for localization in the operative suite ( Fig. 38-1 ). Intraoperative localization is important to limit the possibility of wrong level surgery. This requires appropriate imaging review, knowledge of regional anatomy, and correlation with the patient’s clinical symptoms. This is particularly concerning for the physician given the medicolegal implications, in addition to the emotional and medical cost to the patient. In a AANS/CNS spine section survey, as many as 50% of respondents in an anonymous survey reported at least one wrong-level surgery during the course of their careers. From the data collected, the prevalence of wrong-site surgery was estimated at 1 in 3110 surgical cases, with approximately 70% occurring in the lumbar region and a 17% incidence of legal settlement.
Despite the use of intraoperative radiographic localization to confirm the operative level, errors persist. Malpositioning of pedicle screws still occurs, despite the use of intraoperative imaging ( Fig. 38-2 ). Segmental anomalies must be identified preoperatively and a common scheme for identification of the relevant anatomy must be used by the surgeon, cosurgeon, and radiologist. Examples of segmental anomalies that are fairly common include a lumbarized sacrum, sacralized fifth lumbar vertebrae, and six lumbar vertebra. Even in the thoracic and cervical spine, presence of anomalies such as a cervical rib or the absence of a pair of thoracic ribs, although rare, have been reported. It is important to realize that the radiologist typically localizes thoracic pathology numbering from C2. This is not possible in the operating room (OR) because fluoroscopy techniques typically cannot visualize through the upper thoracic spine ( Fig. 38-3 ). Thus, levels should be labeled preoperatively from scout images obtained showing the entire neuraxis. The use of intraoperative computed tomography (CT) or image navigation may aid in correct identification of levels if in doubt and to assess hardware position.
Intraoperative Blood Loss
Intraoperative blood loss should be limited, along with the use of blood products, which should be available for spine procedures, without exceptions. Tse and coworkers recommend a variety of measures to limit blood loss and to limit intraoperative transfusions: discontinuation of antiplatelet agents more than 1 week prior to elective surgery, proper positioning to lower venous pressure, intraoperative red-blood-cell salvage, and even preoperative blood self-donation are some recommended techniques. Further communication with the OR personnel (anesthesia, nursing, etc.) about potential bleeding and preparation for these events can limit morbidity.
Aminocaproic acid, an antifibrinolytic agent, has seen increased off-label use for the reduction of blood loss for prolonged spinal surgeries, particularly for deformity correction. In their RCT, Berenholtz and colleagues saw a 30% decrease in postoperative blood transfusions and a 1-day ( P < 0.05) decrease in ICU length of stay in the group treated with aminocaproic acid. Although the majority of results are supportive, there is conflicting evidence in the literature in more “routine” spinal surgeries.
Incidental Durotomy
Incidental spinal durotomy is a leading cause of medical malpractice in spine surgery. Takahashi and coworkers in a review of 1014 consecutive cases found an incidence of 4% incidental durotomy in nonrevision spinal cases. That incidence ranged from 2% in single-level lumbar discectomy to an incidence as high as nearly 19% in the presence of juxtafacet cysts. Durotomy occurrence in revision surgery, because of the difficulty with variable anatomy, is even greater.
Incidental durotomy should be managed with a watertight primary dural closure when possible. Some surgeons advocate the use of fibrin glue as reinforcement, followed by 24 to 48 hours of flat bed rest, to limit cerebrospinal fluid (CSF) pressures while the dura heals. Another technique is the use of lumbar drains to divert spinal CSF and provide a decreased pressure gradient. In trauma with a high-velocity mechanism, major dural injuries can occur, for example, as with a lumbar burst fracture. Repair can be provided by duraplasty with synthetic dural grafts. More novel repairs have been reported, involving a posterior transthecal approach to first repair the ventral dural tear, provide cauda equina decompression, followed last by posterior duraplasty.
Recombinant Human Bone Morphogenetic Protein-2
Carragee and colleagues, in a review of industry-sponsored recombinant human bone morphogenetic protein-2 (rhBMP-2) publications, estimated a 10% to 50% incidence of adverse events, depending on approach and dosages used. In fact, use of rhBMP-2 in anterior cervical fusion cases have had over a 40% risk of adverse events, the most concerning of which includes severe soft tissue swelling and airway compromise. Additionally, ectopic bone formation, fever, inflammation, radiculitis, osteolysis, and prolonged pain have also been associated with its use. Carragee and colleagues also highlighted the higher rate of retrograde ejaculation in males who had rhBMP-2 during one- and two-level anterior lumbar interbody fusions from L4 to S1. However, some authors have publications that disagree with these findings. In addition, rhBMP-2 is a growth factor and its potential for inducing oncologic effects is not known. Caution should be used when it is utilized with patients having a history of cancer. It is rarely needed in spinal trauma patients as they likely have already induced a brisk inflammatory response and high levels of bone morphogenic protein (BMP) cytokines.
Pulmonary Complications
Pulmonary complications after SCI are common and can lead to mortality and morbidity as well as prolonged hospitalization. Aarabi and coinvestigators sought to define predictors of pulmonary complications in SCI and found that the severity of overall injury was the chief predictor of pulmonary complications. In 178 complete cervical spinal cord patients, Aarabi and coworkers found a statistically significant relationship between age, prior preexisting medical and pulmonary conditions, higher cervical level of injury and the need for a tracheostomy and risk of pulmonary complication. As expected, all of the 19 patients with C2 and C3 injuries required a tracheostomy. SCI results in significant impairment of ventilation. These patients will initially have stable pulmonary function but will weaken and tire over time requiring respiratory support. This is especially true in those with higher levels of SCI. Anticipation of this deterioration and early tracheostomy may reduce subsequent pulmonary complications. As previously mentioned, the use of methylprednisolone in acute traumatic SCI has an elevated risk of pneumonia versus the minimal potential benefit of improved neurologic outcome as presorted by the NASCIS-2 study. In summary, SCI patients with multiple systemic injuries and pulmonary complications can quickly become critical if not treated aggressively.
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