[Multiple pulmonary embolisms caused by acrylic cement after vertebroplasty].

The number of vertebral fractures related with osteoporosis has become more frequent in developed countries given the increase in population age. Percutaneous vertebroplasty with acrylic cement is one of the palliative therapies available. A rare complication provoked from this technique is cement embolism. We present the case of a multiple pulmonary embolism caused by acrylic cement observed in our radiodiagnostic department. The patient is an 85-year-old woman with history of osteoporosis and fracture of the dorsal vertebra treated with vertebroplasty. Multiple hyperdense, branching linear opacities were identified in a chest x-ray, necessary according to pre-anaesthetic protocol to perform a new vertebroplasty procedure. The opacities were discovered in both pulmonary fields and were in line with vascular structures (fig. 1). The findings described above were not found in previous radiological tests, considering the diagnosis to be a pulmonary embolism caused by cement leaking into the circulation system. Multiple linear hyperdense structures (cement) were found inside the segmental pulmonary arteries of several lobes during the high resolution CT (HRCT). Vertebroplasty with acrylic cement is an alternative to conventional vertebral fracture treatments. Its main function is to alleviate the pain associated with the fracture, given that the cement used in the solidification process is extremely hot, damaging the nerve endings of the fracture’s focal point. Secondly, it achieves functional stabilisation by increasing the vertebra’s resistance to compression, ensuring that the fracture does not evolve into vertebral collapse.1 The acrylic cement is mixed with a radioopaque substance so that it is visible during the procedure2 and injected into the vertebral body through the skin. It is usually controlled by CT or biplane fluoroscopy. Pulmonary embolism is considered as one of the rarest possible complications associated with vertebroplasty (0-4.8%).3 It is caused by accidental leakage of acrylic cement emboli into the circulatory system through perivertebral venous plexus and through the inferior vena cava to the pulmonary vascular network.2 This complication is more frequent if the cement has not solidified enough when it is injected into the vertebral body.2 Furthermore, the exothermic reaction, which is associated with the cement hardening, increases the intramedullary pressure.4 Both of these factors make it more likely for material to come away and for emboli to migrate. This complication is also more frequent when the treated vertebra has hypervascularised injuries.2 Our case is similar to others published as the patient showed no usual symptoms of pulmonary embolism during or after the procedure.3-5 Krueger et al conducted a literature review which included 76 asymptomatic cases and 43 with pulmonary embolism symptoms (the most common being dypsnoea). Of the 43 patients with pulmonary embolism symptoms 5 died.5 Given that most cases are asymptomatic, some authors recommend a chest x-ray to be performed 24 hours after the intervention to ensure that emboli are not present.3,5 No agreement has been reached regarding the therapeutic strategy to be used for pulmonary embolism caused by cement. Krueger et al recommend that asymptomatic peripheral embolisms are not treated and that only a clinical follow-up is necessary.5 Recommendations for symptomatic embolisms indicate that pulmonary thromboembolism therapy protocols are to be followed, although other authors suggest for centrally located embolisms to be surgically removed.6 Anticoagulant treatment for longer than 6 months has not been indicated.5 Although authors have described that emboli caused by cement could gradually cause the pulmonary arteries to become occluded, and that anticoagulant therapy leads to embolisms being endothelised, minimising this risk.5 Patients that have undergone 12-month followup with CT have not shown significant after effects or delayed reactions to cement in the arteries.3