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Clinical Assessment of Patients to Decrease Risk

Vittorio Schweiger MD, Massimo Parolini MD, Alvise Martini MD, and Enrico Polati MD

Pain Therapy Centre, University of Verona, Verona, Italy

Introduction

The incidence of complications in interventional pain management remains difficult to estimate. A high number of procedures are performed each year worldwide, but a low incidence of complications is generally reported with some of these being catastrophic, as inferred from the ASA Closed Claims Project Database 1970–2000 [1]. In a recent study on 26 061 consecutive interventional pain procedures, an overall complication rate of 1.9% was reported and no major complications such as permanent neurologic deficit, clinically significant bleeding or epidural hematoma [2] were observed. This improvement is likely due to the implementation of standardized patients’ clinical assessment before interventional procedures in order to minimize the risk of complications and to improve patient outcomes. Therefore, collecting physical, medical, and pharmacologic information and drawing conclusions through clinical observation, instrumental tests, and psychologic evaluation is essential before scheduling any interventional pain procedure.

Medical and Pharmacologic Assessment

A thorough medical and pharmacologic assessment is mandatory in all patients undergoing interventional pain treatments, regardless of type of procedure. In addition to the identification of drug and material allergies (NSAIDs, steroids, local anesthetics, antibiotics, iodine or gadolinium contrast-medium, latex, and others), evaluation of patients’ co-morbidities is pivotal. For instance, in diabetic patients, corticosteroid injections have proven to worsen control of glucose levels and post-procedural hyperglycemia [3]. In this set of patients, a thorough evaluation of disease severity and viable treatments is necessary, aiming toward a reduction in corticosteroid dosage, as advocated by some authors for epidural steroid injections [4].

Bleeding diathesis due to both platelet aggregation and coagulation disturbances requires specific and accurate preoperative evaluation, even with specialist consultation [5]. Regarding platelet count, the most recent evidence recommends a platelet count of > 80 000 μL for low- to medium-risk invasive procedures and a platelet count of >100 000 μL for high-risk procedures [6].

The same caution is required in patients’ post-operative infective risk stratification. Surveillance data on Spinal Cord Stimulation (SCS) and Intrathecal Drug Delivery System (IDDS) revealed that 38% and 70% of patients respectively suffering from post-procedural infections showed pre-existing medical co-morbidities that would increase their infective risk. Among these co-morbidities were older age, poor nutritional status, diabetes, smoke addiction, obesity, remote-site moderate to severe infections, Staphylococcus aureus colonization, and immune status dysregulations [7]. Both patient-related infective risk screening and correction of modifiable factors (blood glucose optimization, tobacco cessation for at least four weeks, optimization of viral load in HIV patients, minimizing/avoiding perioperative oral steroids, and treatment of remote infections) are the gold standard in the preoperative period. In the case of non-modifiable factors, increased infective risk should be discussed and accepted by the patient prior to intervention. Nonetheless, neuroinvasive procedures in patients with an active infection requiring antibiotics should be postponed because of the potential risk of bacteremia or bacterial spread into the epidural or subarachnoid space. Regarding patients with cardiovascular disease, preoperative evaluation and risk stratification must thoroughly comply with the most recent guidelines on the topic [8].

Moreover, both structural and functional abnormalities possibly impacting on either the anesthesiologic interventional procedure itself or the response to anesthetics (through conscious sedation or general anesthesia) must be highlighted. The health professional might want to inquire specifically about spinal deformities, severe obesity, osteoporosis, dyskinesia, and other neurologic diseases, local malignancies, cognitive dysfunction, pregnancy, and cardiopulmonary diseases.

Evaluation of current drug therapy must include past and present analgesic drug consumption. Antithrombotic and anticoagulant treatments need to be reported due to the significant bleeding risk associated with several interventional procedures. Such treatments must be amended according to the most recent guidelines, thus taking into account drug type, bridging modalities, and procedure-related bleeding risk [9]. A complete pain medication history must be collected including dosages, associations, effectiveness, and any related adverse events with particular attention to drug abuse, diversion, and misuse. The shift to intrathecal opioid delivery is an option for those patients who seem to be unresponsive to systemic opioids. It is still controversial whether or not it provides proper analgesia to switch to opioids intrathecal administration when systemic high doses have failed. According to some authors, in these patients, IDDS should be performed with medications other than morphine, e.g., ziconotide [10]. Finally, evaluation of pain medication overuse is a mainstay in chronic headache treatment. In these patients, detoxification is mandatory but may induce withdrawal symptoms lasting 2–10 days, with no pharmacologic strategies proven to be effective in preventing rebound symptoms [11]. Therefore, invasive interventions such as greater occipital nerve (GON) blocks or onabotulinum toxin A infiltrations might be efficaciously performed prior to drug withdrawal [12].

Pain Assessment

Pain therapists are often the last specialists to evaluate a patient with chronic pain and although the first request is that of a prompt pain relief, their mission is far more challenging. In real-life settings, history of previous pain patient’s evaluations often shows a lack of crucial information including clinical objectivity, instrumental and laboratory examinations, quality of life (QoL), and diagnosis in terms of “pain generator” identification [13]. Therefore, the aim of careful evaluation in a specialized pain center must settle some crucial questions such as the accuracy of pain physiopathologic classification, the relationship between clinical evidence and patients’ symptoms, including their severity, and functional limitations and appropriateness of performed investigations.

Further, one must consider whether a correct pain diagnosis has been made or an alternative one needs to be taken into consideration. Health professionals should thereafter ensure that previous treatments were up-to-date, evidence-based and carried out according to the correct pain diagnosis. Physiopathologic classification remains a mainstay of pain assessment, particularly in patients eligible for invasive interventions. To date, the categorical way of classifying human pain as nociceptive or neuropathic according to whether there is or is not a detectable neural lesion is still considered appropriate. Nonetheless, nociceptive and neuropathic mechanisms may coexist in mixed pain syndromes, for which no consensus on specific diagnostic criteria has yet been reached [14].

In preparation for an invasive procedure, however, chronic pain disorders with a neuropathic component (e.g., low back pain [LBP]) should not be mistaken for chronic nociplastic pain, i.e., pain arising from altered nociception with no evidence of tissue or somatosensory system damage [15]. In such a clinical entity as Fibromyalgia Syndrome (FMS), invasive procedures are by large consensus not recommended by international treatment guidelines [16]. Similarly, invasive procedures must be avoided in patients with pain of unknown origin (PUO), psychogenic pain and somatization disorders [13].

Indication for Interventional Procedures

As regards interventional procedures for pain management, these are performed in cases of unresponsiveness to conservative treatments or severe to unbearable side effects of the latter. However, each clinical case needs to be handled individually, applying the aforementioned recommendations accordingly. While opioid treatment is a pivotal tool in oncologic pain treatment, neuropathic, bone, spontaneous and breakthrough pain may result almost completely in being unresponsive to opioids. In these settings, non-pharmacologic treatments play an important role, even in the early stages of the disease [17]. Moreover, some oncologic diseases demonstrate partial responsiveness to opioids. For instance, in pancreatic cancer-related pain, invasive procedures might be considered as an early-stage treatment option in order to increase analgesia and reduce painkiller consumption and related adverse events [18].

On the other hand, the more intense type of pain related to advanced or end-stage pancreatic cancer may induce pain therapists to avoid neuroablative procedures of which the analgesic effect has proven to be negligible [19]. In non-cancer pain treatment, the situation has changed dramatically over the last few years in relation to the opioid epidemic and its deleterious sanitary consequences in some countries [20]. Attention to these concerns was raised by Pain Practitioners Societies, suggesting to start treating non-cancer pain with lower opioid doses together with interventional techniques [21].

Further, most recent guidelines highlighted the strong recommendation that when considering chronic non-cancer pain treatment, optimization of non-opioid and non-pharmacologic therapy, if viable, is mandatory and preferable rather than a trial of opioid medications [22]. Unfortunately, the role of interventional techniques is still poorly outlined in some diffuse pain syndromes such as LBP or osteoarthritis (OA). This is mostly due to methodologic concerns, although worldwide, these procedures are scheduled and performed daily [23, 24].

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