Introduction

Medical complications after neurosurgical procedures are common and contribute substantially to morbidity and mortality. They can adversely impact the surgical outcome and are also implicated in increasing resource utilization by prolonging the hospital stay. Whereas most neurosurgical literature on outcome-based prediction has laid emphasis on surgery-related complications, the literature on medical complications based on current evidence is scarce. Considering the deleterious impact of medical complications on overall surgical outcome, it is pertinent to reiterate commonly occurring medical complications associated with neurosurgical care to optimize patient-oriented outcome and minimize resource utilization as well as cost of care. In this chapter, we provide a comprehensive overview of common medical complications that are likely to occur after a cranial or spinal procedure, their catastrophic impact on patient management, and the prophylactic/preventive strategies to reduce their incidence.

Definition and Classification Scheme

Medical complication after a neurosurgical procedure is defined as an unanticipated adverse event that is not directly related to the neurosurgical technique or procedure. The timing of its occurrence can range from any time during initial hospitalization to later on as a part of routine care. These complications comprise a myriad of conditions such as venous thromboembolism, cardiorespiratory complications, acute renal failure (ARF), and infectious gastrointestinal (GI) and metabolic complications. A recent proposition by Landriel Ibañez et al. aggregated 167 potential complications into a four-point scale grading system, of which 38 complications were classified as medical (grade IV) events not directly related to surgery or surgical technique; however, little information was provided on the specifics of the complications. In the context of pediatric patients with spinal deformity, Smith et al. proposed a complication grading system that incorporated disease-related inpatient medical complications as a subset, emphasizing the impact of medical complications on outcomes. Although disease- or procedure-specific grading systems are useful, most complications overlap several procedures. In the current chapter, we focus on medical complications that are limited to those occurring post–cranial or spinal interventions, rather than preoperatively occurring comorbidities or events. Based upon current literature, medical complications are broadly categorized based on the organ system involved; they are summarized in Table 4.1 .

Thromboembolic Complications: Deep Venous Thrombosis and Pulmonary Embolism

Thromboembolic events are life threatening and can often lead to rapid clinical deterioration including mortality. Deep venous thrombosis (DVT) and pulmonary embolism are major contributors to this morbidity and mortality in postoperative neurosurgical patients. The incidence of thromboembolic events is estimated to be 0% to 50%, of which DVT, as measured by the labeled fibrinogen technique, accounts for around 29% to 43%. Major events usually occur within the first week after a neurosurgical procedure. Most DVT patients are asymptomatic, and 15% of silent DVTs can lead to pulmonary embolism. Significant thrombi are thought to arise from the popliteal and iliofemoral veins. Risk factors include prolonged surgery and immobilization, previous DVT, malignancy, ischemic stroke, direct lower-extremity trauma, limb weakness, seizure disorder, chronic smoking, use of oral contraceptives, pregnancy and the puerperium, obesity, gram-negative sepsis, advanced age, pregnancy, and congestive heart failure. Patients with deficiencies in antithrombin III, protein C, or protein S and with various genetic clotting factor abnormalities, such as factor V Leiden, are also at risk for venous thromboembolism. Specific to neurosurgical procedure, patients undergoing brain surgery for intracranial tumors—especially meningioma, traumatic brain injury, and spinal cord injury—are the high-risk groups for developing a thromboembolic event.

Even though the clinical signs can give a clue regarding DVT, Doppler ultrasonography and impedance plethysmography are the preferred investigation modalities. When Doppler results are equivocal, extremity venography can be used to diagnose distal and proximal DVTs. Similarly, a postoperative patient developing acute-onset chest pain, hemoptysis, and breathlessness should be evaluated for pulmonary embolism, and computed tomography (CT) angiogram or pulmonary angiogram are considered the investigation methods of choice.

Because DVT can very often lead to pulmonary embolism, the prophylactic measures to prevent these complications are very important. Many studies have confirmed the utility of sequential pneumatic leg compression devices in preventing DVT. These devices are placed on the patient preoperatively and should be continued until the patient is ambulatory. The prophylactic use of low-dose (minidose) subcutaneous heparin (e.g., 5000 IU twice daily) has been well studied over the past several years and has been demonstrated to be efficacious in preventing DVT. Several meta-analyses have been conducted, but it remains unclear whether unfractionated heparin or low-molecular-weight heparin is superior for DVT prophylaxis in neurosurgical patients, or whether increased efficacy correlates with increased hemorrhagic complications. Many neurosurgeons believe that in the immediate and early postoperative period, neurosurgical patients with documented DVT should undergo transvenous Greenfield filter placement. Anticoagulation using heparin followed by warfarin may be continued for 6 weeks to 3 months in uncomplicated cases. The treatment guidelines followed for DVT are applicable for pulmonary embolism also. Pulmonary embolectomy may be performed as the last lifesaving measure when all other treatment options fail.