Scandinavian journal of pain
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Bleeding into the vertebral canal causing a spinal haematoma (SH) is a rare but serious complication to central neuraxial blocks (CNB). Of all serious complications to CNBs such as meningitis, abscess, cardiovascular collapse, and nerve injury, neurological injury associated with SH has the worst prognosis for permanent harm. Around the turn of the millennium, the first guidelines were published that aimed to reduce the risk of this complication. These guidelines are based on known risk factors for SH, rather than evidence from randomised, controlled trials (RCTs). RCTs, and therefore meta-analysis of RCTs, are not appropriate for identifying rare events. Analysing published case reports of rare complications may at least reveal risk factors and can thereby improve management of CNBs. The aims of the present review were to analyse case reports of SH after CNBs published between 1994 and 2015, and compare these with previous reviews of case reports. ⋯ The annual number of published cases of spinal haematoma after central neuraxial blocks increased during the last two decades (1994-2015) compared to previous decades. Case reports on elderly women account for this increase. Antihaemostatic drugs, heparins in particular, are still major risk factors for developing post-CNB spinal bleedings. Other risk factors are haemostatic and spinal disorders and complicated blocks, especially "bloody taps", whereas multiple attempts do not seem to increase the risk of bleeding. In a large number of cases, no risk factor was reported. Guidelines issued around the turn of the century do not seem to have affected the number of published reports. In most cases, guidelines were followed, especially during the second half of the study period. Thus, although guidelines reduce the risk of a post-CNB spinal haematoma, and should be strictly adhered to in every single case, they are no guarantee against such bleedings to occur.
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Pain after surgery is not uncommon with 30% of patients reporting moderate to severe postoperative pain. Early identification of patients prone to postoperative pain may be a step forward towards individualized pain medicine providing a basis for improved clinical management through treatment strategies targeting relevant pain mechanisms in each patient. Assessment of pain processing by quantitative sensory testing (QST) prior to surgery has been proposed as a method to identify patients at risk for postoperative pain, although results have been conflicting. Since the last systematic review, several studies investigating the association between postoperative pain and more dynamic measures of pain processing like temporal summation of pain and conditioned pain modulation have been conducted. ⋯ Although preoperative QST does not show consistent results, future studies in this area should include assessment of central pain mechanisms like temporal summation of pressure pain, conditioned pain modulation, and responses to pain above the pain threshold since these variables show promising associations to pain after surgery.