Peripheral Venous Disease in the Neurosurgery Patient

Introduction

Venous thromboembolism (VTE) is a major source of perioperative complications in cranial and spinal neurosurgery. Patients with lower or upper extremity deep venous thrombosis (DVT) can experience clot progression or dislodgement that evolves into symptomatic pulmonary embolism (PE). Mortality rates for PE of between 9% and 50% have been reported. Many risk factors have been characterized, with neurosurgical patients exhibiting a strong overlap with the Virchow triad of thrombosis: immobility, hypercoagulability, and endothelial damage. The advent of anticoagulants in the 1960s enabled reduction of DVT and subsequent PE incidences; however, their potential to contribute to compartmental bleeding within the CNS imposes unique limitations for neurosurgical patients. ^, The rise of direct oral anticoagulants (DOACs) over the last several years has presented the same challenges, but these agents are of increasing interest after the recent availability of reversal agents.

Epidemiology

The occurrence rates of VTEs are higher for spinal and cranial neurosurgical patients relative to the overall population, with one recent database study citing 0.6% and 1.1%, respectively. The precise incidence is challenging to determine because of varying diagnostic criteria and technology used across series. Incidence also varies by individual risk factors, including history of prior VTE, malignancy, sepsis, ventilator dependence, immobilization, elderly age, obesity, smoking, chronic steroid use, pregnancy, postpartum considerations, estrogen therapy, and inherited thrombophilia. ^, Predisposing factors particular to the neurosurgical population include history of cranial procedures, operative time longer than 4 hours, transient ischemic attack, stroke, seizures, and residual tumor tissue.

Within the neurosurgical population, brain tumor patients exhibit one of the highest VTE rates as a result of intrinsic thrombogenic upregulation of tissue factor and other coagulation cascade proteins. Certain tumors do seem more predisposed to thrombosis, namely high-grade glioma, with one National Surgical Quality Improvement Program (NSQIP) study reporting a VTE rate of 3.1%. A different single-institution series showed that metastatic lesions, low-grade glioma, meningioma, and lymphoma were also at elevated risk relative to other tumors, such as pituitary lesions and medulloblastoma ( Table 20.1 ). Based on the NSQIP report of craniotomy for primary malignant brain tumors, nearly two-thirds of postoperative VTEs occurred after discharge. Median time to in-hospital VTE was on postoperative day 6; postdischarge VTE occurred 13 days after discharge.

There is also a predisposition for VTEs among patients with intracranial hemorrhage secondary to the hypercoagulability induced by the primary brain injury, independent of any functional deficit. ^, In some series, the rate of DVT formation in subarachnoid hemorrhage patients can reach 18%. Patients with traumatic brain injury (TBI) without chemoprophylaxis have demonstrated VTE rates of up to 25%. Even with mechanical prophylaxis and chemoprophylaxis, the risk of DVT in TBI patients is increased threefold to fourfold compared with patients with non-TBI trauma, and this risk further increases with TBI severity. ^,

In general, spine patients are at low to moderate risk, with incidence varying based on the ability to mobilize postoperatively, given the presenting pathology or required procedure. DVT rates after surgery for spinal trauma, deformity, and degenerative spine have been cited to reach 19%, 14%, and 9%, respectively. ^, In a systematic review, cervical spine procedures had a decreased likelihood of VTE relative to lumbar procedures (odds ratio [OR], 0.23; 0.03%–0.06% versus 0.1%–0.2%). In one NSQIP study on lumbar interbody fusions, anterior/direct lateral approaches were associated with higher DVT rates relative to posterior and transforaminal approaches (1% versus 0.6%, P = .017). In another NSQIP study, VTE rates were considerably lower for elective procedures, with the overall rate cited as 0.61%. The same study also did not identify increased risk with either anterior or posterior procedures ( Table 20.2 ).

Meanwhile, patients with spinal cord injury (SCI) are in a higher risk category, secondary to prolonged, decreased immobility. The cited incidence of DVT varies widely, with one study even reporting 100% incidence based on radiofibrinogen evaluation among patients with SCI who were paralyzed after trauma. On the other hand, a low-dose heparin protocol has been described, resulting in a DVT incidence of 7%. Comparisons between studies is difficult, given variations in disease severity as well as timing and involvement of prophylactic regimens, but there is consistent evidence that the majority of thromboembolic events occur within the first 3 months and that residual risks last through 1 year. ^,

The pediatric population should be managed differently from adults. Although there are limited available studies, retrospective data consistently show lower DVT rates in children than in adults. Even among patients with brain tumors, DVTs have been found to occur in <1% of pediatric patients. Based on trauma data, the relative risk of DVT in children is still 7.2 times lower than in adults, or 24 per 10,000 pediatric traumas.