Anatomical Observation and Clinical Significance of the Medial Branch of the Lumbar Dorsal Rami.

STUDY DESIGN: Anatomical study. OBJECTIVE: This study aimed to elaborate on the anatomical characteristics of the medial branch of the lumbar dorsal rami and to discuss its possible clinical significance. SUMMARY OF BACKGROUND DATA: Radiofrequency ablation targeting the medial branch of the lumbar dorsal rami has been increasingly used in the clinical management of facetogenic low back pain (FLBP). Nonetheless, attention is also being given to complications such as atrophy of the lumbar soft tissues and muscles. Therefore, a more detailed understanding of the innervation pattern on the facet joint may improve the precision of nerve ablation therapy for FLBP. METHODS: An anatomical study of eight human specimens was carried out. The anatomic characteristics of the medial branch were observed and recorded. RESULTS: The medial branch originates from the lumbar dorsal rami, running close to the root of the posterolateral side of the superior articular process of the inferior cone. When passed through the mamillo-accessory ligament, it turns direction to the medial and caudal side, running in the multifidus muscle. In our study, each medial branch sent out two to five branches along the way. All the medial branches in L1-L4 gave off one to two small branches when crossing the facet joint and innervated the joint of the lower segment. Nineteen medial branches (23.75%) gave off recurrent branches to innervate the joint at the upper segment. CONCLUSION: The anatomical features of the medial branch remain similar in each lumbar segment. There are two types of joint branches, including the articular fibers that emanate from the medial branch as it runs along the medial border of the facet joint and the recurrent branch from the medial branch that innervates the upper facet joint. Moreover, an anastomotic branch was found in the medial branches between different segments.

Multifidus Denervation After Radiofrequency Ablation of the Medial Nerve Alters the Biomechanics of the Spine-A Computational Study.

Radiofrequency ablation of the medial branch is commonly used to treat chronic low back pain involving facet joints, which accounts for 12% to 37% of the total cases of chronic low back pain. An adverse effect of this procedure is the denervation of the multifidus muscle, which may lead to its atrophy which can affect the spine and possibly disc degeneration. This study aims to quantify changes in joint angles and loading caused by multifidus denervation after radiofrequency ablation. AnyBody model of the torso was used to evaluate intervertebral joints in flexion, lateral bending, and torsion. Force-dependent kinematics was used to calculate joint angles and forces. These dependent variables were investigated in intact multifidus, unilateral, and bilateral ablations of L3L4, L4L5, and L5S1 joints. The results showed pronounced angular joint changes, especially in bilateral ablations in flexion, when compared with other cases. The same changes' trend from intact to unilaterally then bilaterally ablated multifidus occurred in joint angles of lateral bending. Meanwhile, joint forces were not adversely affected. These results suggest that multifidus denervation after radiofrequency ablation affects spinal mechanics. Such changes may be associated with abnormal tissue deformations and stresses that can potentially alter their mechanobiology and homeostasis, thereby possibly affecting the health of the spine.

Anatomic-Topographic Investigation of the Branches of the Dorsal Ramus of Thoracic Spinal Nerves.

INTRODUCTION: Percutaneous radiofrequency facet denervation (PRFD) by thermocoagulation is a useful treatment for nonspecific thoracic pain syndrome. To guarantee that maximal thermal lesion is applied to the nerve, it is essential to have precise knowledge of the topography of the thoracic dorsal branches of the spinal nerves. This special anatomy was investigated, and the results were compared with the existing technique for PRFD, where the active needle tip is placed in the junction of the superior articular process and the transverse process. METHODS: Twenty thoracic spines of cadavers (10 females and 10 males) embalmed according to Thiel's method were bilaterally dissected. After careful removal of skin and subcutaneous fat tissue, the lateral and medial branches were traced centrally. In addition, the articular branch to the thoracic facet joint was traced peripherally. The distance of the medial branch to the inferior articular process at the level of the nerve passing the superior costotransverse ligament was measured. RESULTS: The dorsal branch bifurcates into lateral and medial branches medial to the superior costotransverse ligament. The medial branch runs laterally first to pass in between two parts of the intertransverse ligament running dorsally and to turn medially superficial to this ligament. The zygapophysial branch always originated from the medial branch passing the inferior articular process laterally by running caudally to turn medially and send branches to the capsule of the zygapophyseal joint. The distance of the medial branch lateral to the inferior articular process was constantly 3 mm. CONCLUSIONS: The current technique of PRFD at the thoracic spine targets the medial branch distal to the separation of the articular branch, rendering the lesion ineffective at denervating the zygapophyseal joint. For selective thermocoagulation of the articular branches of the thoracic zygapophyseal joint, a new technique should be developed. We propose an anatomically informed needle position that can now be confirmed clinically.

Anatomical Topographical Investigation of the Medial Branch of the Dorsal Thoracic Branch of the Spinal Nerve in the Segments T10-T12.

INTRODUCTION: The zygapophyseal joints represent one possible cause for back pain. Therefore, many interventions are targeting the denervation of the facet joints. The aim of this study is to describe the course of the medial branch of the dorsal branch of the spinal nerve and its articular branches to the zygapophyseal joints in the segments T10-T12. METHODS: The medial branches in the thoracic segments T10-T12 were dissected in 20 Thiel embalmed cadavers. An Eschenbach magnifying glass (4.0× magnification) was used during dissection preserving the articular branches. The topography and the branching pattern of the medial branches was observed. RESULTS: The course of the nerves in the segments T10-T12 differed from each other because of the different osseous anatomy of each segment. The medial branch at the segment T10 crossed the tip of the transverse process in 28 of the 40 hemivertebral specimens. In the remaining cases it passed superior to the transverse process. At T11 the medial branch ran constantly through an osteofibrous canal. At the segment T12 the medial branches showed a similar course to the medial branches in the lumbar region. In many cases two articular branches, which arose from the medial branch were identified. CONCLUSIONS: The results of this study show a considerable anatomic variety at the segment T10. It also demonstrates that the transverse process is an important landmark to encounter the medial branch. Furthermore, the possibility of a double innervation of the facet joints should always be considered.

Localization of Nerve Growth Factor Expression to Structurally Damaged Cartilaginous Tissues in Human Lumbar Facet Joint Osteoarthritis.

Purpose: Nerve Growth Factor (NGF) is a pivotal mediator of chronic pain and plays a role in bone remodelling. Through its high affinity receptor TrkA, NGF induces substance P (SP) as key downstream mediator of pain and local inflammation. Here we analysed NGF, TrkA and SP tissue distribution in facet joint osteoarthritis (FJOA), a major cause of chronic low back pain. Methods: FJOA specimens (n=19) were harvested from patients undergoing intervertebral fusion surgery. Radiologic grading of FJOA and spinal stenosis, followed by immunohistochemistry for NGF, TrkA and SP on consecutive tissue sections, was performed in ten specimens. Explant cultures (n=9) were used to assess secretion of NGF, IL-6, and SP by FJOA osteochondral tissues under basal and inflammatory conditions. Results: NGF was predominantly expressed in damaged cartilaginous tissues (80%), occasionally in bone marrow (20%), but not in osteochondral vascular channels. NGF area fraction in cartilage was not associated with the extent of proteoglycan loss or radiologic FJOA severity. Consecutive sections showed that NGF and SP expression was localized at structurally damaged cartilage, in absence of TrkA expression. SP and TrkA were expressed in subchondral bone marrow in both presence and absence of NGF. Low level NGF, but not SP secretion, was detected in four out of eighteen FJOA explants under both basal or inflammatory conditions (n=2 each). Conclusion: NGF is associated with SP expression and structural cartilage damage in osteoarthritic facet joints, but not with radiologic disease severity. NGF tissue distribution in FJOA differs from predominant subchondral bone expression reported for knee OA.

Cooled-radiofrequency neurotomy for the treatment of chronic lumbar facet (zygapophyseal) joint pain: A retrospective study.

ABSTRACT: Cooled-radiofrequency (CRFA) is a newer technique and may have some theoretical advantages over traditional radiofrequency ablation (TRFA). In this study, we aimed to investigate the efficacy and safety of CRFA for the treatment of lumbar facet joint-mediated pain. In this retrospective study, we evaluated 185 CRFA performed on 105 patients. All patients with axial lower back who received the preliminary diagnosis of lumbar facet joint-mediated pain and refractory to conservative therapy underwent diagnostic medial branch blocks. CRFA was recommended to those patients who responded favorably to two sets of diagnostic medial branch blocks. Pain scores in numeric rating scale (NRS) were recorded pre-treatment and post-treatment at different time-points. The primary outcome measure was to report descriptive NRS score and average % improvement from baseline at each time point. A significant pain relief was determined by a decrease of ≥50% of mean NRS. Secondary outcome measure was the time to repeat treatment with subsequent CRFA. Adverse events were also recorded.Primary outcome measure determined as the improvement in NRS, for at least 50% or more, was achieved in both 1st (4-8 weeks) and 2nd (>2-6 months) follow-up (FU) with 60.5% and 53.6% reduction in NRS respectively. Our subgroup analysis comparing the younger (<50) and older (≥50) age groups showed superior pain relief with CRFA in the older (≥50) age group, both in the 1st (4-8 weeks) and 2nd (>2-6 months) FU time points (63.4% and 58.4% reduction in NRS, respectively). Cooled-radiofrequency ablation is an effective and safe procedure for the treatment of chronic lumbar facet joint related pain. The duration of pain relief was comparable to traditional radiofrequency ablation as reported in the literature.

Tolerability and Feasibility of X-ray Guided Non-Invasive Ablation of the Medial Branch Nerve with Focused Ultrasound: Preliminary Proof of Concept in a Pre-clinical Model.

Four to six million patients a year in the United States suffer from chronic pain caused by facet joint degeneration. Thermal ablation of the affected facet joint's sensory nerve using radiofrequency electrodes is the therapeutic standard of care. High-intensity focused ultrasound (HIFU) is a novel technology enabling image-guided non-invasive thermal ablation of tissue. Six pigs underwent fluoroscopy-guided HIFU of the medial branch nerve and were followed up for 1 wk (two pigs), 1 mo (two pigs) and 3 mo (two pigs). At the end of each follow-up period, the animals were sacrificed, and targeted tissue was excised and evaluated with computed tomography scans as well as by macro- and micropathology. No significant adverse events were recorded during the procedure or follow-up period. All targets were successfully ablated. X-Ray-guided HIFU is a feasible and promising alternative to radiofrequency ablation of the lumbar facet joint sensory nerve.

Lumbar medial branch cryoneurolysis under ultrasound guidance: initial report of five cases.

AIMS: To assess the feasibility and preliminary results of ultrasound guided medial branch cryoneurolysis in the management of facet joint syndrome. MATERIAL AND METHODS: Between March 2017 and August 2017, a total of 20 patients underwent medial branch blocks, 12 of which were positive. Five patients chose to participate in the study and 8 medial branch cryoneurolysis were performed. The primary endpoint of the study was the feasibility of the procedure. The secondary endpoint was the efficacy on pain assessed over the following year after the procedure. RESULTS: Technical feasibility of cryoneurolysis under ultrasound guidance was 100%. Accurate needle positioning at the accurate target in the angle between the posterior aspect of the transverse process and the lateral aspect of the facet joint was achieved in all cases. Needle progression could be depicted with US guidance in all cases. Mean pre-procedural Visual Analogue Scale and Oswestry disability Index scores were 6.8 (range 5-8) and 20.6 (range 12- 31), respectively. Follow up showed a decrease of Visual Analogue Scale score at one month (1.75, range 0-7), and at three months (1.75 range 0-3), Mean self-reported improvement at 6 months was 76% (60- 100%) and 77% at 12 months (50-100%). We report one case of failure at one month. No complications were noted during or after the procedure. CONCLUSION: Our findings suggest that ultrasound is a valid imaging modality to perform lumbar medial branch cryoneurolysis. Initial results show that cryoneurolysis under ultrasound guidance appears as a safe and effective procedure in patients suffering for facet joint pain.

Two-Needle Technique for Lumbar Radiofrequency Medial Branch Denervation: A Technical Note.

BACKGROUND: Radiofrequency ablation (RFA) of the medial branches of the dorsal rami has been reported to relieve facet joint-related back pain for 6 months to 1 year in 60% of patients. Although providing benefit in a significant proportion of patients, there remains a group of patients who do not experience any pain relief from RFA or experience only benefit from the ablation for a short period. Failure of RFA has been attributed to technical failure of coagulating the nerve or coagulation of a minimal section of the nerve, allowing for early reinnervation. Increasing the success rate and duration of relief may require techniques that increase the likelihood of successful nerve ablation over a relevant distance by maximizing lesion size. OBJECTIVES: The aim of this technical note is to detail a modification to the current commonly used lumbar medial branch radiofrequency (RF) denervation approach to increase lesion size. STUDY DESIGN: This is a technical report describing a novel two-needle approach to lumbar RF medial branch denervation. SETTING: Large private interventional pain management institute. METHODS: A dual needle placement of two 10-mm active tip RF cannulas separated by 6 mm is used to optimally contact the superior articular process (SAP) from its ventral to dorsal borders, which encompasses the anticipated course of the medial branch nerves. RESULTS: The described technique creates a lesion that we estimate to be 11.0-mm wide and 11.6-mm long along the course of the medial branch adjacent to the SAP ensuring adequate coverage and treatment. LIMITATIONS: This report does not encompass a systematic evaluation of the clinical safety and efficacy of the two-needle RFA approach. Future studies will have to assess the long-term efficacy and safety of the approach. CONCLUSIONS: The detailed two-needle approach to lumbar RF medial branch denervation appears to be promising in terms of projected treatment success by coagulating a large volume of tissue, in a cost- and time-efficient manner.

Tarsal tunnel syndrome caused by posterior facet talocalcaneal coalition: A case report.

RATIONALE: Tarsal tunnel syndrome (TTS) is a compressive neuropathy of the posterior tibial nerve and its branches. Tarsal coalition is defined as a fibrous, cartilaginous, or osseous bridging of 2 or more tarsal bones. TTS with tarsal coalition is uncommon. Here, we present a rare example of successful surgical management of TTS with posterior facet talocalcaneal coalition. PATIENT CONCERNS: A 74-year-old woman presented with hypoesthesia, numbness, and an intermittent tingling sensation on the plantar area over the right forefoot to the middle foot area. The hypoesthesia and paresthesia of the right foot began 6 years previously and were severe along the lateral plantar aspect. The symptoms were mild at rest and increased during daily activities. Tinel sign was positive along the posteroinferior aspect of the medial malleolus. DIAGNOSIS: Lateral ankle radiography showed joint-space narrowing and sclerotic bony changes with a deformed C-sign and humpback sign. Oblique coronal and sagittal computed tomography revealed an irregular medial posterior facet, partial coalition, narrowing, and subcortical cyst formation of the posterior subtalar joint. Magnetic resonance imaging showed an abnormal posterior talocalcaneal coalition compressing the posterior tibia nerve. Electromyography and nerve conduction velocity studies were performed, and the findings indicated that there was an incomplete lesion of the right plantar nerve, especially of the lateral plantar nerve, around the ankle level. INTERVENTIONS: Surgical decompression was performed. Intraoperatively, the lateral plantar nerve exhibited fibrotic changes and tightening below the posterior facet talocalcaneal coalition. The coalition was excised, and the lateral plantar nerve was released with soft-tissue dissection. OUTCOMES: The patient's symptoms of tingling sensation and hypoesthesia were almost relieved at 4 months postoperatively, but she complained of paresthesia with an itching sensation when the skin of the plantar area was touched. The paresthesia had disappeared almost completely at 8 months after surgery. She had no recurrence of symptoms at the 1-year follow-up. LESSONS: The TTS with tarsal coalition is rare. Supportive history and physical examination are essential for diagnosis. Plain radiographs and computed tomography or magnetic resonance imaging are helpful to determine the cause of TTS and verify the tarsal coalition. After diagnosis, surgical excision of the coalition may be appropriate for management with a good outcome.

Cost-Effectiveness of Radiofrequency Denervation for Patients With Chronic Low Back Pain: The MINT Randomized Clinical Trials.

OBJECTIVES: To evaluate the cost-effectiveness of radiofrequency denervation when added to a standardized exercise program for patients with chronic low back pain. METHODS: An economic evaluation was conducted alongside 3 pragmatic multicenter, nonblinded randomized clinical trials (RCTs) in The Netherlands with a follow up of 52 weeks. Eligible participants were included between January 1, 2013, and October 24, 2014, and had chronic low back pain; a positive diagnostic block at the facet joints (n = 251), sacroiliac (SI) joints (n = 228), or a combination of facet joints, SI joints, and intervertebral discs (n = 202); and were unresponsive to initial conservative care. Quality-adjusted life-years (QALYs) and societal costs were measured using self-reported questionnaires. Missing data were imputed using multiple imputation. Bootstrapping was used to estimate statistical uncertainty. RESULTS: After 52 weeks, no difference in costs between groups was found in the facet joint or combination RCT. The total costs were significantly higher for the intervention group in the SI joint RCT. The maximum probability of radiofrequency denervation being cost-effective when added to a standardized exercise program ranged from 0.10 in the facet joint RCT to 0.17 in the SI joint RCT irrespective of the ceiling ratio, and 0.65 at a ceiling ratio of €30 000 per QALY in the combination RCT. CONCLUSIONS: Although equivocal among patients with symptoms in a combination of the facet joints, SI joints, and intervertebral discs, evidence suggests that radiofrequency denervation combined with a standardized exercise program cannot be considered cost-effective from a societal perspective for patients with chronic low back pain originating from either facet or SI joints in a Dutch healthcare setting.

The efficacy and safety of cooled-radiofrequency neurotomy in the treatment of chronic thoracic facet (zygapophyseal) joint pain: A retrospective study.

Anatomic course of medial branches in the thoracic spine is significantly different. Cooled RFA (CRFA) is a newer technique that can create a larger spherical lesion with a potential to compensate for the anatomic variability of the medial branches in the thoracic spine. Our retrospective study aimed to investigate the efficacy and the adverse effects of the CRFA in the treatment of thoracic facet-related pain.For this retrospective study, we evaluated 40 CRFA performed on 23 patients. The patients with diagnosis of thoracic facet joint-related pain underwent CRFA. Pain scores in numeric rating scale (NRS) were recorded at pretreatment and posttreatment at different time-points. The primary outcome measure was to report descriptive NRS score and average % improvement from baseline at each time point. A significant pain relief was determined by a decrease of ≥ 50% of mean NRS. Secondary outcome measure was the time to repeat treatment with subsequent CRFA. Adverse events were also recorded.Improvement of average pain level was 20.72% in the 1st follow-up (FU) (4-8 weeks), 53% in the 2nd FU (2-6 months), and 37.58% in the 3rd FU (6-12 months). Subgroup analysis was done based on age cutoff (age in years ≤ 50 versus >50), and pretreatment NRS (≤7 versus >7). Patients with age ≤50 and NRS score >7 experienced the best pain relief in the 2nd FU period (2-6 months). The patients with age > 50 and NRS pain level ≤7 showed steadily increased benefit both in the 2nd FU (2-6 months) and 3rd FU (6-12 months).This is the first clinical study to evaluate the efficacy and adverse effects of CRFA in the thoracic spine for facet joint-related pain. Our results suggest that CRFA procedure is an effective treatment modality for thoracic facet-related pain. Our subgroup analysis demonstrated that the pain relief and duration varies with the age and the pretreatment pain levels.

Radiofrequency facet joint denervation efficiency based on the severity of spondylarthrosis and in osteoporotic vertebral compression fractures. A retrospective study.

OBJECTIVES: Radiofrequency denervation of the facet joints is performed via a well-established method. Its primary, direct indication is a positive response to a nerve block injection (MBB). Our study aimed to find other, effective but indirect indication signs through the retrospective analysis of our patients treated earlier. PATIENTS AND METHODS: In our institute between 1 January, 2008 and 31 December, 2017 facet joint denervation has been performed in more than 2000 cases, and we included 529 patients in our retrospective study. We had separate groups for vertebral compression fractures and for spondylarthrosis of different severity (Grade 1; 2-3; 4), thus we assessed the postoperative condition of these patients using Visual Analoge Scale (VAS). The efficacy of the intervention was examined in every groups separately according to symptoms and previous spine surgeries. RESULTS: In view of our results, chronic lumbago and dorsalgia that are attributable to osteoporotic vertebral compression fracture are obvious indications if they do not respond to conservative therapy, as 76.8% of such patients remained asymptomatic for minimum 6 months (p = 0,000). Another indication is Grade 2 or 3 chronic spondylarthrosis without radicular involvement, since these groups reported a 51.4% success rate (asymptomatic for minimum 6 months) (p = 0,015). Long term pain relief is obviously impaired by the presence of radicular compression, as we were not able to decrease the pain of 97% of such patients. Our findings also suggest that the vast majority of those who have previously undergone spine surgery cannot benefit from the intervention. CONCLUSION: Based on this study, facet joint denervation can serve as an effective therapy supplement in a properly selected group of patients who do not respond to oral NSAIDs, exercise and physiotherapy. By this procedure we found we can reach long term benefit in the groups of osteoporotic vertebral fracture patients and patients with moderate spondylarthrosis. According to our results and the literature datas the properly patient selection for the indication of the RF ablation can be as effective as the controversial diagnostic nerve block injections.

Do Stabilization Exercises Increase the Effects of Lumbar Facet Radiofrequency Denervation?

AIM: To investigate the effects of lumbar stabilization exercises on pain severity, functional disability, and physical performance after two weeks following radiofrequency denervation in patients with lumbar facet joint syndrome (LFJS). MATERIAL AND METHODS: Thirty-nine patients diagnosed with LFJS and had radiofrequency denervation were assigned to study and control groups. The study group (n=20) received a six-week stabilization exercise program and was informed about spine biomechanics, while the control group (n=19) received only informations about spine biomechanics. Pain severity with visual analogue scale, perceived disability with Oswestry disability index, physical performance with physical performance tests and gait speed test were applied before and after radiofrequency denervation, and after six weeks of intervention program. RESULTS: Despite the similar improvements were shown in terms of all outcomes in both groups following radiofrequency denervation (p > 0.05), the improvements were more in favor of study group after six week intervention program (p < 0.05). CONCLUSION: These results indicate that radiofrequency denervation is effective in improving the pain, disability, and physical performance in patients with LFJS and this effect is further enhanced by the stabilization exercises following this procedure. Adding stabilization exercises to radiofrequency denervation yielded positive outcomes and these exercise are strongly advised in physiotherapy and rehabilitation program.

The Source and the Course of the Articular Branches to the T4-T8 Zygapophysial Joints.

OBJECTIVE: To define the source and the course of the articular branches to the midthoracic zygapophysial ("z") joints. DESIGN: Cadaveric dissection. SETTING: The Gross Anatomy Laboratory of the Duke University School of Medicine. SUBJECTS: Ten human cadaveric thoraces. METHODS: Gross and stereoscopic dissection of dorsal rami T4-T8 was performed bilaterally on 10 adult embalmed cadavers. The medial and lateral branches were traced to their origins from the dorsal rami, and the course of the articular nerves was documented through digital photography. Radio-opaque wire (20 gauge) was applied to the nerves. Fluoroscopic images were obtained to delineate their radiographic course with respect to osseous landmarks. RESULTS: Forty-eight inferior articular branches were identified. Three (6.3%) originated from the medial branch and 44 (91.7%) from the dorsal ramus. One was indeterminate. Fifty-one superior articular branches were identified. Eight (15.7%) originated from the medial branch and 43 (84.3%) from the dorsal ramus. In 12% of cases (6/50), there was side-to-side asymmetry in the origins of the articular branches. Nerves were commonly suspended in the intertransverse space. The articular branches contacted an osseous structure in only 39% of cases. As previously reported, a "descending branch" was not identified in any specimen. CONCLUSIONS: Articular branches to the T4-T8 z-joints have substantial inter- and intraspecimen variability of origin. They typically arise from the dorsal ramus rather than the medial branch and frequently do not contact any osseous structure to allow percutaneous needle placement.

A pilot cohort study of lumbar facet joint denervation in patients with chronic low-back pain.

INTRODUCTION: Radio-frequency (RF) denervation of the facet joints is a procedure aimed at the nociceptive median branch nerves of the lumbar dorsal rami. Pain signals from the facet joints are carried through these fibres; by ablating these fibres, central signalling can be prevented. This pilot study investigated the clinical effect and feasibility of the procedure at our institution, the Spine Centre of Southern Denmark. METHODS: Patients with at least 50% pain relief after initial medial branch diagnostic blocks were candidates for RF denervation. Patients were divided into two groups: 1) patients with at least 80% pain relief and 2) patients with between 50% and 79% pain relief after diagnostic blocks. Denervation was performed bilaterally on the three lowest facet joints in the lumbar spine. The primary outcome parameter was visual analogue scale (VAS). Follow-up questionnaires were answered after one week and after three, six and 12 months. RESULTS: For the whole sample, we found a mean reduction of 43 VAS points after one week. At three months, we found a mean reduction of 25 points. Six-month data showed a mean 19-point reduction. Twelve-month data showed a mean reduction of 17 points. Group 1 showed superior improvements at all follow-up points and after 12 months, we found a mean VAS reduction of 22 points for this group. CONCLUSIONS: This pilot cohort study found RF denervation of the facet joint to be a promising alternative for patients with chronic low-back pain. The effect persisted at the one-year follow-up; however, the effect diminished over time. FUNDING: The Danish Rheumatism Association, The A.P. Møller Foundation for the Advancement of Medical Science. TRIAL REGISTRATION: The study protocol was approved by the ethical committee of Southern Denmark with registration number S-20160070.

Incidence of Cervicogenic Headache Following Lower Cervical Radiofrequency Neurotomy.

BACKGROUND: The facet joints contribute to chronic cervical spine pain in an estimated 55% of chronic neck pain cases and can be treated with percutaneous radiofrequency neurotomy (PRN). Damage to surrounding structures during treatment or successful treatment of the primary pain source leading to unmasking could lead to new onset of pain, including cervicogenic headache (CGH). In this study, we aimed to define the incidence of headache in patients who have been previously treated with PRN for lower cervical facet pain. SETTING: All patients treated at a single academic institution's pain management clinic from 2014 to 2016 with cervical PRN were reviewed. METHODS: All patients treated at a single institution's pain management clinic from 2014 to 2016 were reviewed. Those treated with lower cervical PRN were identified, and incidence of CGH was described as a percentage of the study population. Patient age and pain scores between those with and without headaches following treatment were compared by unpaired T-tests. Gender, presence of comorbid disease and levels involved, quality of pain, exacerbating and alleviating factors, location of referred pain, and previous treatments between those with and without headaches following treatment were compared using chi-square tests. RESULTS: Among the 88 patients in the study group, 12 were found to have only moderate relief of their pretreatment pain as well as a new onset headache meeting the diagnostic criteria for cervicogenic headache. Compared to those without a headache after treatment, those diagnosed with cervicogenic headache were more likely to be female (P = 0.041), report a higher maximum pain level on presentation (P = 0.015), have a diagnosis of diabetes prior to presentation (P = 0.011), and have had the procedure performed at levels which included C3 (P = 0.013) (Table 1). LIMITATIONS: The limitations of this study include its single-center design, as this cohort may not be truly representative of the population of patients receiving cervical PRN as a whole, and as a result, these results may not be generalizable. Due to the small size of the cohort, more subtle differences in presenting signs and symptoms between those with and without headaches may not be detectable. Finally, as previously mentioned, the lack of data on some of the patients who presented with headache may have led to underdiagnosis of the true incidence of cervicogenic headache. Future work should look to re-examine the incidence of CGH in a larger cohort to validate the findings here and further define risk factors for post-procedural CGH. CONCLUSIONS: This retrospective review of all patients seen over 2 years in an academic pain clinic found a 13.6% incidence of cervicogenic headache following cervical radiofrequency neurotomy at levels C3-C7. This supports the possibility of the unmasking phenomenon following the procedure, though contributing mechanisms underlying this phenomenon may be multifactorial and require further study.IRB: This study was approved by the institution's Institutional Review Board (IRB2010601795). KEY WORDS: Cervical spine, facetogenic pain, percutaneous radiofrequency neurotomy, cervicogenic headache, chronic pain, zygapophysial joints, innervation convergence, retrospective chart review.