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As operative capabilities have improved in conjunction with perioperative medical management, increasingly older patients with more comorbidities have become viable candidates for spine surgery. Unfortunately, the risk of wound complications inherent in modern procedures is amplified in these patients. This fact is particularly salient in the cervical spine, where infection or hematoma can involve the trachea and proximal spinal cord. Thus, it is imperative that risk factors are identified, modified when possible, and thoroughly explained to patients. Appropriate technique should be exercised, and a high index of suspicion must be maintained postoperatively. Timely diagnosis is the only way to treat complications optimally and to avoid medicolegal repercussions reliably. With a decided focus on surgical site infections (SSIs), this chapter reviews strategies for the avoidance and management of cervical spine wound complications.
Preoperative Complications
Prevalence
Contemporary antisepsis and antibiotics have dramatically reduced the prevalence and morbidity of SSIs across all disciplines. Spine surgery is no exception, with wound infection rates as low as 0.2% and 1.6% reported in the anterior cervical setting. In a reported series, 132 of 3174 (4.2%) patients undergoing any spinal procedure developed infection. At the authors’ center, acute SSIs complicated only 1.0% of 1001 consecutive posterior cervical cases. Despite these low figures, SSI is one of the most common adverse events in spine surgery. Furthermore, the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) is rising, thus making risk factor modification invaluable.
Demographic and Medical Risk Factors
Alcohol consumption, cigarette smoking, and intravenous drug abuse represent behavioral risk factors for SSI. Smoking intervention even a month before the surgical procedure may prove beneficial. Indwelling venous catheters serve as reservoirs for nosocomial organisms. To diminish such colonization, patients hospitalized for extended periods may be allowed to return home before elective procedures. Trauma victims and those admitted to an intensive care unit are at high risk, but their medical status often obviates interim discharge. Fortunately, the comorbidities associated with trauma can be addressed. Most importantly, active infection should be treated as long as the spinal disorder permits.
Ironically, both malnutrition and obesity predispose patients to SSI. Because malnutrition hampers antibody production, hyperalimentation is an attractive preventive measure. A lymphocyte count lower than 1500 mm −3 , albumin lower than 3.5 g/dL, or transferrin lower than 226 mg/dL should raise concern. The role of obesity is less clear. Whereas the dissection required for a corpulent neck entails a wide field for inoculation, adipose tissue is relatively immunoprivileged. Despite these mechanisms, the correlation of body mass to infection is perhaps more aptly described by comorbidity. The glucose level of uncontrolled diabetes (>200 mg/dL) retards leukocyte function and has been linked to a variety of complications including SSI. Optimizing glucose concentrations preoperatively is ideal.
Intuitively, immunosuppression augments the likelihood of infection. Causes include certain malignant diseases, cancer chemotherapeutics, drugs to combat graft-versus-host disease, and acquired immunodeficiency syndrome with a CD4 count lower than 200 mm −3 or a viral load greater than 10,000 mL −1 . Rheumatoid arthritis is an especially relevant medical risk factor. The disease itself promotes cervical instability, and antirheumatic agents hinder wound healing. Tapering of iatrogenic causes of immunosuppression and dehiscence demands careful risk-to-benefit discussions, often with an internal medicine specialist. For instance, an approximately 2-month window (6 weeks before and 2 weeks after surgical procedures) exists around which radiation therapy may be scheduled to maximize healing.
Radiation therapy and prior spine operations also increase scar tissue and intraoperative hemorrhage, which predisposes to hematoma. This can cause airway compression and serve as a nidus for infection. Evidence for the use of antifibrinolytic agents in major spine surgery has accumulated, although these agents are seldom indicated in the cervical surgical setting. Moreover, hypervascular tumor embolization may be appraised before resection.
Antibiotic Prophylaxis
Antibiotic prophylaxis is widely supported in spine surgery. Depending on body habitus, a dose of 1 to 2 gs of first-generation cephalosporins is favored, given that these drugs cover S. aureus and Staphylococcus epidermidis , which are constituents of normal skin flora and are common causes of SSI. Intravenous administration of cefazolin between 30 and 60 minutes before incision is generally regarded as optimal timing. Patients who have sustained traumatic soft tissue injury should be evaluated for gram-negative and polymicrobial infection before the drug is chosen. In patients with a cephalosporin allergy, clindamycin and vancomycin are considered. Vancomycin may also be a prudent choice for patients at risk of MRSA colonization, but it is rarely contraindicated because of potential toxicity in renal failure. Gram-negative coverage is recommended during transoral exposure. With the exception of immunodeficiency, broad-spectrum cocktails should be avoided to reduce the selection of bacterial resistance.
Intraoperative Complications
Surgical Risk Factors
Because preoperatively administered antibiotics are inevitably cleared from the body, repeat doses are warranted at the 3- to 4-hour threshold. Blood loss greater than 1 L correspondingly depletes the serum of antibiotics. Conceivably a proxy for anemia, allogeneic transfusion is a risk factor for SSI. The risk of allogeneic bone graft, alternatively, may result from inflammatory changes incited by the foreign tissue. Microscopes and undue nonessential personnel may also increase contamination.
A greater incidence of spinal wound infection has been found with posterior approaches and more than three surgical levels. Because cervical disease is frequently addressed with less invasive anterior cervical diskectomy and fusion, cervical operations have a lower rate of SSI. Furthermore, anterior dissection is carried out through avascular planes, whereas posterior exposure entails muscle stripping, and necrotic tissue is often spared from débridement for the sake of wound coverage. Instrumentation provides a substrate for biofilms, and persistent micromotion may cause inflammation and edema. Recombinant human bone morphogenetic protein-2 has been implicated in the development of seroma as well and should not be used in the anterior cervical spine unless it is overwhelmingly necessary. Dehiscence resulting from instrumentation prominence can provide an entry route for pathogens. Implants and graft may be padded with muscle or fat. Similarly, esophageal perforations and transoral exposures communicate with the gastrointestinal tract. In these cases, antibiotics should be modified.
Antisepsis and Technique
Thorough hand and forearm scrubbing and double gloving are mandatory. Nearby hair should be shaved with an electric trimmer. At the authors’ center, the skin and surrounding drapes are pre-prepared with alcohol foam. The surgical site is then cleansed with either povidone-iodine or chlorhexidine-alcohol solution. Occlusive membranes may complete the preparation. Intraoperatively, meticulous hemostasis is crucial. To this end, bipolar electrocautery, Gelfoam, and Surgicel are all valuable. Self-retaining retractors are periodically loosened to maintain perfusion, and the wound is generously irrigated.
During closure, necrotic tissue should be débrided, but large defects may preclude coverage. Integument compromised by corticosteroids or radiation therapy is predisposed to dehiscence even in the absence of infection. The authors advise soliciting the assistance of a plastic surgeon for soft tissue flap transfer. In any case, elimination of dead space and watertight closure are essential. Before posterior closure, 500 mg of topical, intrawound vancomycin powder is applied, and a subfascial drain is placed. Superficial drains are added in patients with more than 2 cm of subcutaneous adipose tissue.
Postoperative Complications
General Care
Postoperatively, the same risk factors identified and addressed before the surgical procedure continue to play a role. Previously bedridden patients with spinal cord injury should be monitored for decubitus ulcers and incontinence. All patients should be mobilized and encouraged to walk as soon as possible. Prophylactic antibiotics are customarily readministered every 6 hours and are terminated within 24 hours. Drains, barring evidence of infection, are removed within 48 hours. Dressing changes are dictated by the condition of the wound, as noted on daily inspection. Therefore, the signs and symptoms of wound complications must be explained to the patient and relatives, who should be instructed to contact the hospital or present to an emergency department immediately if such problems are heralded.
Clinical Presentation
Because SSIs can manifest with a broad continuum of signs and symptoms, some far more overt than others, a high index of suspicion is essential. Acute superficial SSI occurs in the epidermis and dermis within 3 to 4 weeks, usually before full healing. As such, characteristic swelling, warmth, erythema, and drainage often become quite apparent. Pain is a ubiquitous symptom. It may arise after initial relief and seem incongruent with other signs. These features can be difficult to discern from the normal recuperative response to surgery. When the signs and symptoms persist after day 3, suspicion is raised. Other red flags include prolonged or putrid drainage, purulence, expanding erythema, and constitutional signs and symptoms such as fever, chills, malaise, and lethargy.
Differentiating deep from superficial infections is also challenging in the acute stage. Conversely, the evident nature of superficial SSI may mask an occult deep infection below the fascia overlying the platysma and paraspinal muscles. The signs mimic those of a superficial infection but may not manifest as early ; multilayer closure contributes to an initially benign appearance. Patients commonly present with increasing pain and drainage, which proves recalcitrant to routine care. Left untreated, myonecrosis and cellulitis may develop. Local problems eventually give way to systemic sequelae, possibly culminating in septic shock. The diagnosis of deep SSI is further complicated when it occurs months or years after successful healing ( Fig. 54-1 ). Pain and tenderness may be the only ostensible findings.
