Summary The drafting of guidelines and good clinical practices in every medical field is becoming a priority for all scientific societiesboth for medical-legal reasons and for the need to spread a common quality standard.
Pain therapy cannot be exempted from this even more so as it is still a "young" discipline without a "strong" core curriculum in Italy.
With this document Federdolore-SICD wants to open a discussion with other scientific societies, to start a platform that can outline the best indications of one of the most used techniques in all surgeries, SPOKE and HUB of pain therapy: epidural injections.
This document is a summary of the work of the Federdolore-SICD National secretary on this topic and aims to help improve the clinical practice of every pain therapist.
Riassunto La stesura di linee guida o di buone pratiche cliniche in ogni campo medico sta diventando una priorità per tutte le società scientifiche, sia per motivi medico-legali sia per esigenze di diffusione di uno standard qualitativo comune.
La terapia del dolore non può esimersi da questo, essendo una disciplina ancora giovane senza un ben delineato piano di studi e, in Italia, un forte “core curriculum”.
Con questo documento Federdolore-SICD vuole aprire una discussione con le altre società scientifiche, per avviare una piattaforma che possa delineare, alla luce delle evidenze in letteratura ma anche della comune pratica di chi opera quotidianamente nell'ambito della terapia del dolore, le migliori indicazioni di una delle tecniche maggiormente utilizzate in tutti gli ambulatori, SPOKE e HUB di terapia del dolore: l'iniezione peridurale.
Questo documento è la sintesi del lavoro del Direttivo Nazionale di Federdolore SICD su questo tema e vuole essere un aiuto a migliorare la pratica clinica di ogni terapista del dolore.
Key words Epidural blocks, good clinical practice, back pain, radiculopathy
Parole chiaveBlocco epidurale, buona pratica clinca, lombalgia, radicolopatia
This document presents the FEDERDOLORE-SICD scientific committee consensus on standards of good practice for performing epidural blocks for chronic pain treatment.
The drafting of guidelines (or good clinical practices) in the field of pain therapy, especially for interventional treatments, has always been hoped but is currently even more important for the recent legislative reforms.
It is the will of FEDERDOLORE-SICD to start a discussion with all the scientific societies involved in pain management to have common documents; the current paper aims to stimulate this discussion.
This document is relevant in the execution of single epidural blocks for the treatment of spinal pain at all levels with or without the presence of radicular pain.
Different specialists can perform epidural blocks, but current recommendations refer to specialists in anaesthesia who practice in pain therapy centres.
We want also to highlight that there is no national certification of adequate preparation to carry out analgesic techniques as there are no minimum numbers of procedures to be performed under tutoring before being defined as experts.
Epidural blocks with steroids have been documented to be effective (in the medium term) only in patients with radicular pain.1,2 It is correct to perform an epidural therapeutic block only after the patient has been treated with systemic corticosteroid therapy (if not contraindicated) with no improvement or limited and short time improvement.
Regardless of the existing evidence, it is essential that the doctor and the patient share the objectives and the reasons for which the procedure is carried out:
1. Anti-inflammatory treatment of radicular pathologies;
2. Anti-inflammatory treatment of ligament and other soft tissue pathologies within the vertebral canal;
3. Diagnosis of the level and the pain generating tissues;
4. Diagnosis of the presence of inflammatory pathology that lowers the threshold of nociceptors and makes the ectopic site more excitable.
In our opinion the lack of evidence about points 2, 3, 4 is due to the absence of scientific papers published with this purpose.
It is crucial that the patient is aware of the entity and duration of the possible benefits; they may vary according to the drug used and the therapeutic objective agreed upon.
The subsequent recommendations refer to the assessments that precede the execution of the technique, the environment and the methods of implementation of the technique.
The doctor-patient relationship has been and remains a keystone of care and an important part for achieving therapeutic success. For this reason, it is essential that the patient is carefully informed about the objectives of the procedure, the steps of the execution and about changes in the clinical conditions that may appear immediately or later.
It is necessary to give information, in addition to the possible benefits of the treatment, on the evolution of the pathology in the case of non-treatment and on the possible side effects, including the rarer and more serious ones, related to drugs (for steroids, delayed effects on glycemic control, blood pressure, GI and endocrine disorders).
No corticosteroid formulation has an indication for epidural administration, although there is widespread agreement in the international scientific community about their utility and safety; despite it, the patient must be informed that the drug used is for "off label" indication.3
Patient preparation and identification
Patient identification procedures according to WHO recommendations for surgical procedures must be followed.
It is important to reassess the site of the pain with the patient and review the instrumental examinations performed by the patient that document the location of the possible pathology or any anatomical abnormalities that may interfere with the execution of the procedure (eg: area of previous interventions if interlaminar access is expected, abnormal vessels or radicular cysts respectively for intraforaminal or caudal injections).
The presence of possible pregnancy must be excluded before the use of ionizing radiation.
Recent ASRA4 recommendations consider the epidural block a procedure with an intermediate risk if bleeding; therefore it is suggested to consider the opportunity to suspend the anticoagulant treatment in each patient and to value the possibility to execute the approach with less bleeding risk if possible. The risk of possible bleeding complications is more significant at cervical level.
Environment and tools
The epidural block must be performed in a protected environment, with biological pollution control, and with the possibility of monitoring patient blood pressure and O2 saturation during and after treatment for a time compatible with the possible onset of adverse events, depending on the type of drugs used.
The instruments for emergency intervention in the case of serious side effects such as cardiovascular and respiratory disorders must be present.1
The epidural block in the absence of radiological control instruments can be considered only in acute cases in which patients must be promptly treated also if in the lack of suitable equipment. This method cannot be regarded as a valid step in the patient's diagnosis or to support decisions on more invasive therapeutic options.
The use of fluoroscopy is recommended to confirm the correct position of the needle but, above all, to demonstrate the diffusion of the solution injected through the use of a contrast iodinated agent5-9 (the use of contrast medium can be excluded only in allergic patients in whom the effect of the anaesthetic can be considered to demonstrate the achievement of the structures involved in the genesis of pain).
The use of ultrasounds, by expert personnel, can be acceptable to visualize the correct introduction of the needle at the level of the sacral hiatus, to identify the level at which the epidural block is performed and to measure the depth of the epidural space (when it is possible to obtain an adequate visualization of the anatomical structures);10 a combined technique with ultrasound and nerve stimulator can be used for peri-radicular blocks. The demonstration of the correct diffusion of the drug within the vertebral canal with ultrasound is lacking.
Prevention of infections
The procedure must be performed by adequate asepsis measures for all staff present in the room (cuff, mask, sterile gloves after appropriate hand hygiene) and the patient (preparation of the sterile field with disinfectants containing iodopovidone or chlorhexidine).1
The staff must be adequately trained in the preparation of suitable material, resuscitation techniques and the management of radiological instruments.10
There is widespread agreement on the use of corticosteroids in the solution injected in the epidural space even if no one of the corticosteroids present on the market in Italy is indicated for this route of administration. A local anaesthetic is often added to the steroid.11-13
About the choice of the corticosteroid to be used, there has been much discussion due to the publication of cases of medullary or cerebral infarction secondary to epidural blocks, mainly through the cervical transforaminal route.14 The hypothesis, never demonstrated, is that the formulations of particulate corticosteroids can give rise to vascular obstruction due to the aggregation of molecules larger than red blood cells (triamcinolone, betamethasone) or packaging (methylprednisolone);15,16 also the presence of bulking agents such as polyglycol and benzoic acid (present only in depo-formulation) has been taken into consideration for the potential neurotoxicity.
The use of formulations of small molecules (dexamethasone) was therefore recommended, which seems to have the same efficacy as slow-release formulations, although a higher number of administrations may be necessary for obtaining the same effectiveness.17,18
It has been suggested that the dosage of methylprednisolone administered does not exceed 3 mg/kg to prevent excessive water and sodium retention. The typical doses are 12-18 mg of betamethasone and 80-120 mg of methylprednisolone, but also a reduced dose of methylprednisolone to 40 mg seem to have comparable efficacy.19
The volume of solution injected varies according to the approach used and is summarized in Table 1.20,21
The solvent can be saline or a local anesthetic at no motor blocking concentrations: lidocaine 0.5%, bupivacaine 0.125-0.25%, ropivacaine 0.2%.
The interlaminar access allows to inject the drug close to the level of suspected pathology, but the drugs mainly spread in the posterior epidural space and often doesn't reach the lateral or anterior space that are the leading locations of pathology.22,23 Often the spread is unilateral and larger volumes of medication, if compared with the intraforaminal approach, are needed for adequate distribution. The use of contrast medium is recommended to document the spread of the injected solution.
At cervical level the interlaminar approach is considered less risky for vascular and other adverse effects if compared with the transforaminal technique; also if accomplished between C6 and T1 (where the epidural space is wider and where the presence of yellow ligament is indisputable) 3 ml of solution have been shown to be sufficient to reach even the most rostral vertebral segments.24
At the lumbar level, to reach the anterior epidural space, at least 5 ml of solution are required.
Intraforaminal or transforaminal block
The intraforaminal technique is considered the most precise technique to inject the drugs at the affected root and to reach the anterior epidural space.25
A higher risk of vascular events burdens intraforaminal injection (spinal cord or cerebral ischemia, for cervical-level blockages) not only caused by intravascular injection (especially of particulate steroids, see above) but also to the formation of thrombi due to a lesion of the vessel wall. The risk is exceptionally high at the cervical level, where there are no safe areas of foramen relative to the absence of vessels (the technique would, therefore, be avoided). The risk of pneumothorax is also present, at the dorsal level.26,27
If an intraforaminal epidural is performed at cervical or thoracic levels despite recommendations, the use of contrast medium and fluoroscopy is mandatory.
In the lumbar region, the Kambin triangle is considered safe for vessel puncture; the boundaries of the Kambin’s triangle are the superior endplate of the inferior vertebral body (base of the triangle), the superior articulating facet (the height of the triangle), and the exiting superior nerve root (the hypotenuse of the triangle).28
Though the volume of drug injected is usually 3 ml, it appears that higher amounts (8 ml) give better results.29
The caudal epidural approach is considered safe and effective for pathologies involving the lower lumbar roots and sacral roots and seems to favor the distribution of the drug towards the anterior epidural space.30,31 The injected volume ranges from 10 to 20 ml or more.
Block with catheter
The use of a catheter for the administration of epidural drugs has the purpose of optimally reaching targets that are difficult to achieve due to anatomical changes or the presence of scars. The use of the catheter may be indicated in patients in whom the presence of laminectomy contraindicates a targeted interlaminar approach or at the level of the cervical epidural space to reach specific roots even if, in this case, it has not been demonstrated a greater efficacy from the use of a catheter.32
Recording and data storage
It is essential to record the data related to the injection site, the injected drugs, the spread of the contrast medium in the vertebral canal and the effect of the anesthetic, if used.
Conflict of interests
The authors certify the scientific work was conducted without conflicts of interests and that they actively contributed to its realization.