Radiofrequencies in low back pain PDTA - Pathos

If the doctor deems it appropriate to activate the diagnostic/therapeutic procedure, he sets up the procedure, has consent signed and sets the date of the procedure. Whoever performs the first procedure must verify indications, clinic, current therapy, allergies and assumes responsibility for the act, identifies the metamere concerned or type of procedure (e.g. caudal infiltration instead of interlaminar epidural) trying to follow the indications (see specific chapters of the various procedures). You must comply with the agreed protocols, make the surgical file reporting useful data (in the PI non-progression of the m.d.c., pain to direct the 2nd procedure (2nd PI, coblation, RFG, PDS, SCS, referral to neurosurgeon) or the passage to another PDTA It is essential to mark the procedure precisely on the TA folder as recommended by the flow-chart, when possible it is useful to acquire and archive the images.

Those who carry out the first post-procedural check-up evaluate the diagnostic/therapeutic response of the procedure considering the various parameters: pain relief, (NRS, PR) duration over time, quality of life (Oswestry), reduction of drugs and use of rescue dose, leave written documentation indicating the next step to the procedure (another IP, coblation, peridoscopy, SCS, etc.) and program all the subsequent steps. Any subsequent maneuvers must be scheduled after 15-20 days to give the cortisone-deposit time to act. In the operational flow-chart of the LBP we start from procedures of low complexity (IP, block FA) and proceed, based on the response, to procedures of medium complexity or high technology (SCS, PDS). Sometimes patients arrive who have already undergone diagnostic/therapeutic procedures (e.g. intraforaminal by neuroradiologists) so they can go directly to more advanced procedures.

In radiculopathy PDTA, the use of RFG and PDS can potentially give an "intermediate" response compared to SCS, so they can be used in cases where SCS seems disproportionate to the patient's symptoms or clinical conditions (elderly patient, patient with doubtful compliance, in canal stenoses). The use of RF in various applications (disc coblation, RF FA, RF S-J, RFG) can be decisive or in any case long-lasting responses but it is expected that they can be repeated or follow one another because they act on different structures; International data emerge in which procedures with RF or PDS can recover the progressive loss of efficacy also of SCS.

Our case studies lead us to identify 3 types of patients:

Although from 23 to 48% of patients with lumbosciatica due to herniated disc heal spontaneously, around 70% continue to have symptoms after a year, which is why analgesic therapy is often necessary.4 We must not forget that the first step of a therapeutic approach is the pharmacological one and only after its failure are interventional methods proposed.

The World Health Organization (WHO) in 1996 proposed a pain rating scale (initially only for cancer pain) and subsequently also adopted as a guideline for the treatment of musculoskeletal pain.

Codeine is a prodrug and only 10% of the administered codeine is transformed into morphine, as such it exerts the analgesic effect. The demethylation at the cytochrome level is carried out by the 2D6 -CYP 450 enzyme of which there is a large genetic polymorphism. 7-10% of Caucasian subjects are genetically lacking in this enzyme (called poor metabolizers), in these subjects the drug is practically ineffective due to the lack of transformation into morphine. On the other hand, the opposite situation is recorded in about 15-20 million Europeans where there is a duplication of 2D6 (called ultra rapid metabolizers), therefore acute toxicity effects are possible in these subjects (e.g. nausea, hallucinations, hyperalgesia, etc.) also strict.

Tramadol is an analgesic drug whose mechanism of action is mainly due to an increase in serotonergic neurotransmission in the central nervous system. The pharmacodynamics of tramadol is not limited to an increase in serotonergic neurotransmission, in fact this active principle also acts by inhibiting the reuptake of norepinephrine and interacting with mu-receptors as a weak agonist. The recommended daily dose is between 50-100 mg orally four times a day, but taking into account the dual mechanism of action, careful titration of the drug is suggested to prevent the typical side effects (nausea, vomiting, convulsions.) Given its emetic effect, it is practice the association with an antiemetic and particular attention must be paid to the possible association with the antiemetics metoclopramide and ondasentron.. Ondasetron, being a serotonergic antagonist, may block the analgesic activity of tramadol. Unfortunately, tramadol is the drug most frequently involved in inappropriate or contraindicated drug combinations responsible for adverse drug reactions, even fatal.6

The third step includes drugs such as morphine, oxycodone, buprenorphine, fentanyl and tapentadol and their use is indicated when the pain intensity is severe, at least greater than or equal to 6 on the NRS scale.

The Guidelines on pain management suggest, having verified the intensity of the pain, to start the therapy with the most suitable drug. Therefore, if the patient complains of chronic pain of intensity 8 on the NRS scale, drug therapy must be started from the last step, skipping the second.7 In our experience, when using an opioid it is essential to start from the lowest dosages and increase very gradually, always using prophylaxis for nausea and constipation, as well as accurate information to the patient.

Tapentadol is a recently synthesized molecule, it has affinity on the µ-opioid receptors and simultaneously an inhibition action on the reuptake of norepinephrine and serotonin. Tapentadol exerts its analgesic effects directly without any pharmacologically active metabolites. Patients should start treatment with this drug with the lowest possible dosage and then increase it to the dose that allows you to control the painful symptoms. Treatment is usually started with doses between 50-200 mg/day. It is a very manageable drug that allows its use even in patients with mild-moderate renal insufficiency and mild liver damage. The most frequent side effects consist of nausea, dizziness, headache and constipation and the latter can be combated by taking a laxative together with tapentadol. Withdrawal symptoms may occur following sudden discontinuation of tapentadol treatment and should therefore be discontinued gradually. Several studies support greater or equal clinical efficacy of tapentadol in the treatment of LBP compared to other strong opioids such as oxycodone, and greater or equianalgesia of tapentadol is achieved with an incidence of side effects half that of oxycodone. (better gastrointestinal tolerability).8.9

Before starting treatment with opioid drugs, as well as before applying a patient to variably complex interventional methods (as discussed below), it is necessary to request a psychological evaluation as well as, in some selected cases, to entrust the management of drug therapy to the SERT (drug addiction services). This in order to avoid, in fragile subjects, the phenomenon of addiction. The SERT is a free public service of the NHS in which professionals such as doctors, nurses, educators, social workers and psychologists work. Applicants are required to provide personal data as drugs considered by Italian law as narcotics (buprenorphine, methadone, gamma-hydroxybutyrate) may be dispensed with. At the time of dispensing, a certificate is issued, in the form of a self-adhesive or paper label, which allows possession of the molecule for therapeutic purposes. Some facilities use the recognition of the patient, the prescribing doctor and the drug dispenser through an identification code. The SERTs implement interventions of information, prevention, harm reduction, support, orientation, and treatment of addictions for both patients and their relatives. They ascertain the psychophysical state of health of the subject, defining individual therapeutic programs to be implemented directly or in agreement with social recovery structures, and periodically evaluate the progress and results of treatment and intervention programs on individual drug addicts with reference to clinical aspects psychological and social.

Continuing along the path, followed by the application of low, medium or high complexity methods that allow us to implement the interventional possibilities available to us. Low complexity methods have a low cost compared to medium and high complexity methods even if the benefit is lower both in quantitative and qualitative terms. Epidural space injections of a mixture of anesthetic and cortisone have good scientific evidence in treating LBP caused by herniated discs but poor scientific evidence in treating LBP due to degenerative disc disease. They are very effective in the short term but not in the long term. The facet joint blocks do not have a long-term benefit, however they can be repeated over time if they are effective (good pain relief) without particular complications. Sacroiliac block is the most common therapy in the treatment of LBP due to sacroiliitis.10

Among the methods of medium complexity, radiofrequency consists of high-frequency electromagnetic waves supplied through a needle with a visible tip or with an electrocatheter, which locally generate an electric field with relative heat production. (Figure 3)  Pulsed radiofrequency (RFP) maintains the electrode tip temperature between 40-42°C throughout the procedure, enabling neuromodulation of the dorsal roots and preventing cell destruction. Needle RFP is performed by positioning the needle transforaminal near the nerve root in its post-ganglionic position under radiological control and confirmed by injection of contrast medium. Lead RFP is performed with lead insertion through the hiatus, radiological confirmation, peridurography, and neurostimulation. RFP appears to cause microscopic and intracellular damage (eg, mitochondrial and cytoskeletal edema, microfilament and microtubule disorganization, myelin rearrangement) after applying an electric field to the dorsal ganglion with a mild thermal effect. Furthermore, it would influence in the medium term the gene expression of c-fos, TNF ? and IL-6 involved in the mechanism of neural inflammation and maintenance of nerve root hypersensitivity. The goal is to reduce inflammation and restore nerve function, with benefits that can last for some time depending on the pathology and duration of treatment. It is an outpatient therapy that is performed in day surgery lasts a few minutes and is performed on the patient awake, in the prone position. The RFP is applied in a particular way for some specific pathologies such as: chronic pain in the pelvis-perineal area, LBP especially with irradiation to the lower limbs, arthrosis, some types of disc degeneration and recurrence  after surgery, FBSS, mono or pluriradiculopathies, root canals. Following the therapy, postural gymnastics and/or physiotherapy exercises are usually recommended to obtain even better results.

In fact, continuous radiofrequency refers to harmful percutaneous procedures aimed at causing neurolesions at the level of the Central and Peripheral somatosensory (mainly nociceptive) system. Radiofrequencies of clinical interest are 300-500 KHz. The radiofrequency signal is applied through an electrode isolated, except for its distal part called active tip around which the biological effects of interest, induced by the heat, take place. The total current entering the body is equal to the current leaving the body through a dispersion plate. Non-intranervous uses: medial branch sinus nerve neurotomy, sacroiliac joint neurotomy, spinal ganglia thermorhizotomy (not used), gray branch neurotomy (little used), sympathetic ganglia (cervical-lumbar), RF annuloplasty, coblation (RF bipolar). Uses within nervous tissue: trigeminal thermorhizotomy, percutaneous cervical cordotomy.

The exclusion criteria of this technique are the loss of 50% of the disc height, completely extruded or sequestered disc herniations, vertebral tumor or fracture, moderate or severe spinal stenosis, laceration of the disc annulus, degenerative instabilities. Coblation (C= controlled + Ablation) uses radiofrequency energy associated with a conductive medium to produce a plasma field made up of highly ionized particles in order to cause the breaking of organic molecular bonds in the tissue. Plasma is essentially a mixture of excited ions. Coblation therefore allows the nuclear material of the disk to be removed and channels to be created in the latter to allow the protrusion to re-enter. Potential complications are nerve injury, hemorrhaging, and discitis.12

The highly complex methods include medullary neurostimulation (SCS) based on selective electrical stimulation of the spinal cord by means of electrocatheters, implanted in the epidural space and connected to a pulse generator, in order to modify the perception of pain in the painful areas. The delivered electrical stimulus translates into the perception of a paresthesia by the patient (sensation similar to a "pins and needles") which replaces the painful sensation.

Epidurolysis consists in the positioning of a transacral peridural catheter armed for the administration of drugs (hyaluronidase, cortisone, local anesthetic and physiological solution) in the epidural space between the dura mater and the yellow ligament covering the internal part of the bone of the spinal canal, in order to obtain a "liberation" of the compressed nerve roots following a previous operation on the spine or due to adhesions formed following inflammatory / degenerative pathologies (post laminectomy syndrome, LBP, herniated discs, spinal stenosis). In fact, scar adhesions can contribute to the onset of radicular pain, by stretching or compressing the nerve roots. To act precisely on the root that causes the pain, it is possible to stimulate it electrically, so as to make the patient feel a tingling in the corresponding area (electroguided peridurolysis). The procedure, for which hospitalization is necessary, takes place in the operating room with sterile technique and under radiographic control (peridurography).

The benefit will appear gradually in the days following the intervention and may continue, depending on the severity of the clinical picture, for 3-6 months. The method can be repeated after at least 3 months. It is indicated to perform it after failure of conservative treatment with physical therapy, chiropractic, drug therapy, and fluoroscopy-guided epidural injections.

This study retrospectively analyzed some data collected routinely in the standard PDTA of the Pain Therapy Center of Varese and contained in the records of patients who performed medium/high complexity methods (RF and/or ESMT/ESMD implant) between January 2018 and in October 2020 in the Pain Therapy Center of Varese. The patients included in this study are 51, of which 21 males and 30 females, they are all adults (mean age 67±2.55) and 22 out of 51 patients are of working age (conventionally considered under 65 years). They are all patients diagnosed with LBP for at least 3 months and in whom conservative pharmacological therapy and low-complexity methods have failed to manage the symptoms. FBSS was diagnosed in 16 patients. In 80% of patients treated with medium/high complexity methods there were simultaneously several possible factors implicated in the genesis of LBP. Unlike other studies, patients diagnosed with depression were not excluded, who represent 3.4% of patients in our study. On the other hand, patients affected by LBP of tumor pathogenesis, nor patients undergoing ESM implantation with a diagnosis of vascular pathology/AOAI, were not considered. All interventional procedures of medium/high complexity were performed in Day Surgery at the Ospedale del Circolo in Varese.  Of these 51 patients, 14 had RF FA, 2 RF SJ, 11 coblation and 13 RF GAG, 11 had an ESM implanted. The latter underwent a clinical psychological evaluation before the operation. Finally, 2 patients are affected by multiple sclerosis and 1 only by post herpetic neuralgia. All the patients who underwent the procedure had to suspend their pre-operative anticoagulant and antiplatelet therapies in progress. In 99% of cases they took opioids for analgesic purposes, associated with NSAID . 33 out of 51 patients underwent repeated low complexity procedures (IP, IF SJ, IF FA, trigger points), with minimal temporary benefit. This confirms the fact that radiofrequencies constitute a method to be applied, according to a pyramid procedural model, in the treatment of more complex patients. For each of these five methods, a specific protocol was used, which represents the standard PDTA of the Pain Therapy Center of Varese, the result of experience gained over the years.

The aim of the study is to carry out a review of the clinical cases of patients in follow-up, in many cases already for 4-6 years, to verify the impact that the radiofrequency procedures they have undergone have within the PDTA in order to understand if:

1) Radiofrequencies may or may not be considered a valid therapeutic tool, capable of representing effective and targeted procedures on the individual patient, and at the same time having a limited economic impact (day surgery interventions with reduced hospitalization and complications, reduced biological risk, scarce invasiveness, short execution times), in a resource management framework that has as its current objective their adequate efficiency.

2)  Radiofrequencies may or may not be considered a valid advanced diagnostic tool in a II level Pain Therapy Centre, which allows us to screen the PG more precisely and initiate the patient towards a possible subsequent more reasoned clinical-therapeutic step and properly modulated. This also implies the possibility of applying more selected patients to procedures of even greater complexity or making an indication for NCH surgery if necessary.

The outcome of medium complexity methods was measured with the NRS pain scale and the ODI. These data were collected both in the preoperative visit before the medium/high complexity procedure and in the visit 3 weeks after surgery.

The NRS method is less discriminating than the VAS, but overcomes the obstacle of visual and motor coordination required to perform the latter and therefore offers greater possibilities of understanding on the part of the patient. For these reasons, we chose the NRS scale in our study over the VAS which, although it is a valid tool, is not always immediately understandable for the patient.

The ODI is an index that derives from the Owestry questionnaire and which measures functional impotence.

It is considered by many authors the gold standard for investigating the level of disability and the quality of life of a patient with LBP. On the basis of the percentage expressed, a qualitative-quantitative assessment of the disability can be made:

The study variables were described using the main descriptive statistics: mean, median and standard deviation for the quantitative variables, percentage frequencies for the qualitative variables.

The analysis of the association between quantitative variables (NRS-PRE/NRS-POST and ODI-PRE/ODI-POST) was conducted by means of the Wilcoxon test. The significance level considered was below p?0.05.

We divided the patients enrolled in our study into 3 categories based on the cross-analysis of comprehensive data on age, sex, duration of clinical follow-up at the Pain Therapy Center, previous procedures performed, diagnosis, pre- and post-procedure opioid use and any changes in the dosage of administration, type of medium/high intensity procedure performed and pre- and post-procedural pain assessment with ODI and NRS indices, and finally absence/presence of post-procedural benefit. (Figure 4)

The statistical results of the retrospective study we conducted demonstrate the significant role that radiofrequencies play within a complex PDTA as procedures of medium complexity. In fact, they allow patients to be subjected to further subsequent therapeutic steps to be selected more efficiently, especially if of high complexity, reducing their failures and optimizing the available resources. When the indication to carry out radiofrequency is given for a young patient of working age, this is often correlated to a more severe clinical symptomatological picture which implies a more serious pathology or a more disabling joint comorbidity. Consequently, the use of radiofrequencies is to be included in a path which, very reasonably, will involve the execution of multiple procedures from the simplest to the most complex, of the same type or of different types as well as more frequent over time. In the elderly patient, considering medium-long course pathologies and comorbidities, greater sedentary lifestyle, cessation of work, greater frailty and sensitivity to pharmacological therapies, radio frequencies are a valuable resource when effective, even if the benefit reported by the patient should be short term (1-2 months).

This is part of the perspective that they make possible a temporary state of well-being and pain relief for the patient, reducing or suspending the intake of drugs (often opioids) and give him back a better quality of life and greater autonomy in ADLs. Elderly and very elderly patients are unlikely to be considered candidates for highly complex procedures, such as, for example, the implantation of an ESM; this correlates both with an objective difficulty in the clinical and therapeutic management of these devices, and with the need for adequate resource efficiency.

The authors declare that the article is not sponsored and has been written in the absence of conflict of interest.