Earticle

Knee osteoarthritis is one of the leading causes of disability and pain in the world. Genicular nerve radiofrequency ablation (RFA) is an effective interventional procedure for chronic knee pain due to knee osteoarthritis, and recently, cooled RFA has been introduced into the genicular nerve RFA. This narrative review summarized the relevant neuroanatomy and randomized controlled trials regarding conventional and cooled genicular nerve RFA. The effectiveness of conventional and cooled genicular nerve RFA has been observed in several randomized controlled studies. Recent cadaveric studies have improved our understanding of knee joint innervation, including variability in the location of the genicular nerves, leading to a debate regarding the ideal target locations for genicular nerve RFA. Genicular nerve cooled RFA, which produces larger spherical-shaped lesions than conventional genicular nerve RFA, is expected to show a better outcome by effectively creating a lesion on genicular nerves even when an anatomical variation and additionally targeting other additional knee joint nerves.

Myoclonus is defined as the involuntary muscle contractions that occur suddenly, irregularly, and asymmetrically. It is classified into various types based on the anatomical site of origin or etiology. Among them, spinal myoclonus refers to movement disorders originating from the spinal cord, which can be caused by conditions such as tumors, infections, degenerative diseases, trauma, or spinal compression. Although rare, neuraxial anesthesia, including spinal and epidural anesthesia, is known to induce spinal myoclonus. Cervical epidural steroid injection is a commonly used conservative treatment for radicular pain originating from the cervical spine. The incidence of complications following epidural steroid injections is reported to be relatively low. However, there have been rare cases reported of segmental spinal myoclonus occurring after epidural steroid injections. Here, we present a case of segmental spinal myoclonus that occurred after cervical epidural steroid injection in a patient with cervical disc herniation. We aim to share this case and discuss the management strategies when such complications arise.

The mechanisms of pain in spinal cord injury are very diverse, including peripheral and central neuropathy, muscle spasticity or spasm, secondary musculoskeletal pain due to overuse or atrophy, chronic central sensitization, and visceral pain. More effective treatment is possible if you carefully listen to the patient's medical history and pain pattern. We introduce a 54-year-old male patient who became paraplegic due to spinal cord injury 13 years ago and has been receiving morphine through an intrathecal drug delivery pump since 7 years ago. He mainly complained of severe breakthrough pain accompanied by flexor spasm, which improved significantly after changing administration from morphine to baclofen. Baclofen is FDAapproved for not only spasticity but also for flexor spasm and concomitant pain. Therefore, intrathecal administration of baclofen in patients with spinal cord injury may have a dramatic effect on pain.

Fibrous dysplasia (FD) is a benign bone tumor, which is prone to deformities, fractures, and results in pain. The etiology of FD has been linked to G protein mutation. FD can cause a wide spectrum of symptoms depending on the degree of involvement or comorbidity. We report a case of FD diagnosed at the pain clinic. A 37-year-old male visited the pain clinic with upper back and chest pain. The patient suffered from throbbing and burning sensation on his back for 12 years, and it has worsened since 3 years ago. We performed three times of erector spinae plane block at one-month interval and prescribed medications under the diagnosis of intercostal neuralgia. His pain improved over few weeks, however, the symptoms had a pattern of wax and wane with a numerical rating scale(0 = no pain, 10 = worst pain imaginable) ranging from 2 to 8 during the 6-month follow-up. We decided to perform chest CT and 3 phase bone scan(3PBS) concerned about potential lesions or malignancies. Chest CT and 3PBS showed recent and multiple old fracture of ribs, and a focal radioactive uptake in the right temporal skull. After discussing with a radiologist, thoracic and neuro-surgeon, his lesions were presumed as FD. We planned to continue managing of his pain, and will consider further multidisciplinary care if needed.

Chronic hip pain is common with advancing age and can cause significant functional limitation. It can be caused by osteoarthritis, rheumatoid arthritis, and post-total hip arthroplasty pain. Conventional radiofrequency (RF) treatment of articular branches of the obturator and femoral nerve is emerging as a potential option for patients with chronic hip osteoarthritis refractory to conservative management. A 58-year-old female patient presented with right-sided hip pain. Despite receiving medical treatment with anticonvulsants and NSAIDs, the patient's pain was not effectively relieved. As a result, conventional RF ablation was performed, consisting of three procedures spaced seven months apart. Following the procedure, the patient experienced significant pain relief, with rating on numeric rating scale (NRS) decreasing to 2 for a duration of 5 months. In conclusion, conventional RF of the articular sensory branches of the femoral nerve and obturator nerve at the hip joint is a potential option for reduction of chronic hip pain.

While low back pain is predominantly attributed to benign musculoskeletal disorders, rare cases may involve serious conditions, necessitating careful differential diagnosis. A 70-year-old male patient presented of back pain and bilateral leg pain that had persisted for 5 months. The patient had no history of cancer. The imaging assessment revealed previous compression fractures in L1 and lumbar spinal stenosis at L3, 4, 5. To alleviate the symptoms, the patient underwent caudal epidural block and balloon decompressive epidural neuroplasty, which provided moderate pain relief. After 9 months, however, the patient reported worsening of pre-existing symptoms and the onset of nocturnal left flank pain. A follow-up imaging assessment revealed metastatic spinal tumor with an additional pathologic compression fracture in prostate cancer was confirmed as the primary source of the metastatic spinal tumor,

Spinal nerve root metastases are extremely rare and have only been reported as individual cases, while metastases to non-primary sites are common in malignant tumors. Metastatic breast cancer often spreads to bones, liver, lungs, and brain. Among these, the bones metastasized by cancer cells include commonly the rib, vertebra, pelvis, and long bone in arm or leg. We report here a rare case that breast cancer metastasized S1-3 nerve roots. An involving patient showed thick nerve roots at the sacral intervertebral regions, which was a strong enhancement in contrast-enhanced magnetic resonance imaging. Based on a pathological examination, primary lesions of the patient were revealed as breast cancer and additional multiple metastases were founded within the brain. The clinical process was characterized by worsening radiculopathy, especially intractable pain. Radiological appearance may be similar to neurogenic tumors of lesions in the intervertebral region, because of an enlargement of the nerve root and its marked contrast enhancement. Local tumor control and pain relief can be performed through radiation therapy, but it is only palliative treatment. Thus, a metastatic possibility of malignant neoplasm should be considered in patients with radiological sign of radiculopathy.

Objectives : Spinal cord stimulation (SCS) is a last-resort treatment for patients with chronic neuropathic pain. The mechanism underlying SCS and pain relief is not yet fully understood. Because the inflammatory balance between pro-and anti-inflammatory molecules in the spinal nociceptive network is pivotal in the development and maintenance of neuropathic pain, the working mechanism of SCS is suggested to be related to the modulation of this balance. The aim of this systematic review is to summarize and understand the effects of different SCS paradigms on the central inflammatory balance in the spinal cord. Materials and methods : A systematic literature search was conducted using MEDLINE, Embase, and PubMed. All articles studying the effects of SCS on inflammatory or glial markers in neuropathic pain models were included. A quality assessment was performed on predetermined entities of bias. Results : A total of 11 articles were eligible for this systematic review. In general, induction of neuropathic pain in rats results in a proinflammatory state and at the same time an increased activity/expression of microglial and astroglial cells in the spinal cord dorsal horn. Conventional SCS seems to further enhance this proinflammatory state and increase the messenger RNA expression of microglial markers, but it also results in a decrease in microglial protein marker levels. High-frequency and especially differential targeted multiplexed SCS can not only restore the balance between pro- and anti-inflammatory molecules but also minimize the overexpression/activation of glial cells. Quality assessment and risk of bias analysis of the studies included make it clear that the results of these preclinical studies must be interpreted with caution. Conclusions : In summary, the preclinical findings tend to indicate that there is a distinct SCS paradigm-related effect in the modulation of the central inflammatory balance of the spinal dorsal horn.

The myodural bridge (MDB) connects the suboccipital musculature to the spinal dura mater (SDM) as it passed through the posterior atlanto-occipital and the atlanto-axial interspaces. Although the actual function of the MDB is not understood at this time, it has recently been proposed that head movement may assist in powering the movement of cerebrospinal fluid (CSF) via muscular tension transmitted to the SDM via the MDB. But there is little information about it. The present study utilized dogs as the experimental model to explore the MDB’s effects on the CSF pressure (CSFP) during stimulated contractions of the suboccipital muscles as well as during manipulated movements of the atlanto-occiptal and atlanto-axial joints. The morphology of MDB was investigated by gross anatomic dissection and by histological observation utilizing both light microscopy and scanning electron microscopy. Additionally biomechanical tensile strength tests were conducted. Functionally, the CSFP was analyzed during passive head movements and electrical stimulation of the suboccipital muscles, respectively. The MDB was observed passing through both the dorsal atlanto-occipital and the atlanto-axial interspaces of the canine and consisted of collagenous fibers. The tensile strength of the collagenous fibers passing through the dorsal atlanto-occipital and atlanto-axial interspaces were 0.16 ± 0.04 MPa and 0.82 ± 0.57 MPa, respectively. Passive head movement, including lateral flexion, rotation, as well as flexion–extension, all significantly increased CSFP. Furthermore, the CSFP was significantly raised from 12.41 ± 4.58 to 13.45 ± 5.16 mmHg when the obliques capitis inferior (OCI) muscles of the examined specimens were electrically stimulated. This stimulatory effect was completely eliminated by severing the myodural bridge attachments to the OCI muscle. Head movements appeared to be an important factor affecting CSF pressure, with the MDB of the suboccipital muscles playing a key role this process. The present study provides direct evidence to support the hypothesis that the MDB may be a previously unappreciated significant power source (pump) for CSF circulation.

Background : The Best Practices in Pain Management from the U.S. Department of Health and Human Services (HHS) describes interventional techniques as part of a continuum. Epidural injections are commonly utilized modalities in managing low back and lower extremity pain. Epidural injections were initially administered in 1901 where the first descriptions of caudal epidural with local anesthetic for low back pain appeared. Since then, multiple developments have occurred. Currently, epidural injections are provided by caudal, interlaminar, and transforaminal approaches. The comparative effectiveness of each modality has been studied. However, comparative assessment has been sparse. Objectives : To assess the efficacy of 3 routes of administration of epidural injections for lumbar disc herniation. Study Design : A systematic review and meta-analysis of randomized controlled trials (RCTs) of transforaminal, interlaminar and caudal epidural injections in managing chronic low back and lower extremity pain due to lumbar disc herniation. Methods : RCTs with a placebo control or an active control design, performed under fluoroscopic guidance, with at least 6 months of follow-up are included. The outcome measures were pain relief and functional status improvement. Significant improvement was defined as 50% or greater pain relief and functional status improvement. Data extraction and methodological quality assessment were performed. Evidence was summarized utilizing principles of best evidence synthesis. Results : A total of 21 trials were included. Of these, 7 studied caudal epidural injections, whereas transforaminal epidural injections were studied in 12 trials, and lumbar interlaminar epidural injections were studied in 10 trials, which all met inclusion criteria. Based on qualitative and quantitative analysis, which included conventional dual-arm and single-arm analysis for interlaminar epidural injections, and single-arm analysis for caudal and transforaminal epidural injections, and the approach to the epidural space, there is Level I evidence for local anesthetic and steroids, Level II for local anesthetic alone for transforaminal and interlaminar approaches, and Level II for the caudal approach with steroids or local anesthetic alone for shortand long-term relief. Limitations : There is a paucity of literature with intermediate or long-term relief of at least 6 months with appropriate outcome parameters. Conventional dual-arm meta-analysis was feasible only for interlaminar epidural injections. Conclusion : Epidural injections with local anesthetic and steroids showed Level I evidence for transforaminal and interlaminar approaches, whereas with local anesthetic alone Level II evidence was demonstrated. In contrast, caudal epidural injections showed Level II evidence with local anesthetic with steroids or local anesthetic alone.

Background : Background: Chronic low back pain is observed frequently after lumbar spinal surgery. Epidural fibrosis has been implicated in the etiology of persistent pain after back surgery. The incidence of epidural fibrosis increases as the number and extent of spinal surgery increases. Epidural fibrosis can be detected by conventional radiologic methods [eg, lumbosacral magnetic resonance imaging (MRI) with gadolinium], but these methods are insufficient to reveal the presence of epidural adhesions. Imaging of the epidural cavity using an epiduroscope is one of the best methods for visualizing the spinal cavity without damaging anatomic structures. Objectives : To evaluate the correlation between the type and number of surgery and the degree of epidural fibrosis and to compare epidural fibrosis in epiduroscopic and MRI findings in patients with failed back surgery syndrome(FBSS). Study design : A prospective trial. Setting : A university hospital. Methods : This study included 61 patients with persistent low back pain and/or radicular pain for at least 6 months, despite lumbar surgery and conservative treatment, and who accepted epiduroscopic imaging. All patients were evaluated in a physical examination using a visual analog scale (VAS) per the elapsed time after surgery. The patients were divided into 3 groups according to the number and type of surgeries. Epidural fibrosis was rated using MRI with gadolinium and epiduroscopy. Results : When the relationship between admission symptoms and epidural fibrosis was evaluated, MRI findings of fibrosis were found to be significantly higher in all patients with both lumbar and radicular pain symptoms at the confidence level of 95% (P = 0.001). The degree of fibrosis detected using epiduroscopy was grade 1 and 2 in almost all patients who presented with low back pain only, only radicular pain, or only distal paresthesia (P = 0.001). In the correlation analysis between the duration of the postoperative period (4.13 ± 2.97 years) and the degree of fibrosis detected using MRI and epiduroscopy, a statistically significant relationship was found at the confidence level of 95% (P < 0.05). As the number and extent of spinal surgeries increased, the incidence of MRI fibrosis increased, which is compatible with the literature (P = 0.001) There was a statistically significant relationship between the degree of fibrosis as detected using MRI and epiduroscopy at the confidence level of 95% (P < 0.05). Differently, we observed that 6 patients had grade 1 fibrosis as diagnosed using epiduroscopy, whereas none had fibrosis on MRI. Limitations : We did not have a control group. Further studies are required to demonstrate the relevance of these 2 imaging techniques (epiduroscopy and MRI) in terms of detecting epidural fibrosis in patients with FBSS. Conclusions : Epiduroscopic imaging seems to be more sensitive than MRI in detecting grade I epidural fibrosis in patients with FBSS. Thus, the possibility of low-grade epidural fibrosis as a source of pain after back surgery, should be kept in mind in normally reported MRIs. Treatment should be planned accordingly.

Background : Although fluoroscopy-guided interventional therapies have declined in recent years, radiation exposure remains a critical issue for both patients and medical staff. Radiation exposure varies according to the physicians’ experience, procedure time, patients’ body mass index (BMI), imaging techniques, and the type of procedure performed. Objective : The purpose of this study is to report procedure times and calculate the radiation doses for 4 different approaches of fluoroscopy-guided epidural injections per procedure and BMI to provide radiations doses for potential use in future dose reduction strategies. Study Design : Retrospective, observational study. Setting : A university hospital, pain management center. Methods : A retrospective evaluation was performed of patients who received epidural steroid injections between January 2015 and December 2020 in a university hospital interventional pain management center. This observational study was conducted with patients aged ≥ 18 who underwent 3,711 epidural injections including cervical interlaminar, lumbar interlaminar, lumbar transforaminal, and caudal approaches. If more than one level or bilateral injections were performed, total dose and times were divided by the number of sites injected to attain procedure time and mean dose per injection. Provided doses for each patient were also divided by patients’ BMI to obtain dose per BMI. Results : The highest radiation dose per procedure was found in caudal epidural injection with 0.218 mGy·m2, and the lowest dose was found in cervical interlaminar epidural injection with 0.057 mGy·m2. The radiation dose per procedure was 0.123 mGy·m2 for lumbar transforaminal and 0.191 mGy·m2 for lumbar interlaminar epidural injection. The shortest procedure time was determined in transforaminal (37.3 seconds) injections, and the longest was in lumbar interlaminar (46.7 seconds) injections. Caudal epidural injection also had the highest radiation dose per BMI which was 0.00749, and cervical interlaminar epidural injection had the lowest radiation dose per BMI, which was 0.00214. Limitations : Firstly, injections were performed by first- or second-year fellows in pain medicine. Moreover, patient-related factors (previous surgery, scoliosis, etc.) affecting radiation exposure were ignored. Conclusions : Radiation dose levels and procedure times of 4 approaches of epidural injections were obtained from 3,711 procedures performed in a university hospital pain medicine clinic. BMI of patients was taken into account with the dose levels of injections given per BMI. Multicenter research with standardized techniques will assure more reliable reference levels, which will guide pain physicians to self-assess their own levels of radiation exposure.