Considerations for Lumbar Medial Branch Nerve Radiofrequency at Spinal Motion Segments Adjacent to a Fusion Construct.

Instrumented lumbar spinal fusion is common and results in biomechanical changes at adjacent spinal segments that increase facet load bearing. This can cause facet-mediated pain at levels adjacent to the surgical construct. Medial branch nerve radiofrequency ablation (RFA) exists as a treatment for some cases. It is important to acknowledge that the approach and instrumentation used during some specific lumbar fusion approaches will disrupt the medial branch nerve(s). Thus, the proceduralist must consider the fusion approach when determining which medial branch nerves are necessary to anesthetize for diagnosis and then to potentially target with RFA. This article discusses the relevant technical considerations for preparing for RFA to denervate lumbosacral facet joints adjacent to fusion constructs.

Multifidus dysfunction and restorative neurostimulation: a scoping review.

OBJECTIVE: Chronic low back pain (CLBP) is multifactorial in nature, with recent research highlighting the role of multifidus dysfunction in a subset of nonspecific CLBP. This review aimed to provide a foundational reference that elucidates the pathophysiological cascade of multifidus dysfunction, how it contrasts with other CLBP etiologies and the role of restorative neurostimulation. METHODS: A scoping review of the literature. RESULTS: In total, 194 articles were included, and findings were presented to highlight emerging principles related to multifidus dysfunction and restorative neurostimulation. Multifidus dysfunction is diagnosed by a history of mechanical, axial, nociceptive CLBP and exam demonstrating functional lumbar instability, which differs from other structural etiologies. Diagnostic images may be used to grade multifidus atrophy and assess other structural pathologies. While various treatments exist for CLBP, restorative neurostimulation distinguishes itself from traditional neurostimulation in a way that treats a different etiology, targets a different anatomical site, and has a distinctive mechanism of action. CONCLUSIONS: Multifidus dysfunction has been proposed to result from loss of neuromuscular control, which may manifest clinically as muscle inhibition resulting in altered movement patterns. Over time, this cycle may result in potential atrophy, degeneration and CLBP. Restorative neurostimulation, a novel implantable neurostimulator system, stimulates the efferent lumbar medial branch nerve to elicit repetitive multifidus contractions. This intervention aims to interrupt the cycle of dysfunction and normalize multifidus activity incrementally, potentially restoring neuromuscular control. Restorative neurostimulation has been shown to reduce pain and disability in CLBP, improve quality of life and reduce health care expenditures.

An incoherent HIFU transducer for treatment of the medial branch nerve: Numerical study and in vivo validation.

BACKGROUND: Chronic back pain due to facet related degenerative changes affects 4-6 million patients a year in the United States. Patients refractory to conservative therapy may warrant targeted injections of steroids into the joint or percutaneous medial branch nerve denervation with radiofrequency ablation. We numerically tested a novel noninvasive high intensity focused ultrasound transducer to optimize nerve ablation near a bone-soft tissue interface. METHODS: A transducer with 4 elements operating in an incoherent mode was modeled numerically and tested pre-clinically under fluoroscopic guidance. After 6 lumbar medial branch nerve ablations were performed in 2 pigs, they were followed clinically for 1 week and then sacrificed for pathological evaluation. RESULTS: Simulations show that the acoustic spot size in water at 6 dB was 14mm axial x 1.6mm lateral and 52mm axial x 1.6mm lateral for coherent and incoherent modes, respectively. We measured the size of N = 6 lesions induced in vivo in a pig model and compared them to the size of the simulated thermal dose. The best match between the simulated and measured lesion size was found with a maximum absorption coefficient in the cortical bone adjusted to 30 dB/cm/MHz. This absorption was used to simulate clinical scenarios in humans to generate lesions with no potential side effects at 1000 and 1500 J. CONCLUSION: The elongated spot obtained with the incoherent mode facilitates the targeting during fluoroscopic-guided medial branch nerve ablation.

The Occurrence of Dropped Head Syndrome After a Cervical Medial Branch Nerve Block in a Patient With Cervicothoracic Kyphotic Deformity: A Case Report.

Complications from medial branch blocks (MBBs) are rare when following proper procedural protocol. Dropped head syndrome (DHS) is characterized by profound muscle weakness in the cervical spine, resulting in a failure to maintain a level horizontal gaze and, in the worst cases, a chin-on-chest deformity. In this case report, we described DHS developing after cervical MBBs using short-acting anesthetic agents and subsequent management. A 69-year-old woman with a previous C6-C7 anterior cervical discectomy and fusion (ACDF) underwent bilateral posterior cervical MBBs targeting the C4-C5 and C5-C6 levels. Immediately following the injection, she reported a sudden inability to lift her head and was subsequently diagnosed with DHS. This condition continued with minimal improvement for over six months. After weighing the risks, the patient elected to avoid surgery, and she was provided a soft cervical collar and prescribed physical therapy. DHS is a debilitating condition more commonly associated with neurodegenerative conditions and inflammatory myopathy, which has received limited attention due to its rarity as a complication of cervical radiofrequency neurotomy. Surgery for this condition, when considered, typically involves long-segment posterior cervical instrumented fusion. Undergoing such a surgery is a complicated discussion that should consider patient clinical factors and preferences. The clinical impact of loss of strength in paraspinal musculature in this patient population is clearly deserving of further study.

Lidocaine-Associated CNS Toxicity at Therapeutic Dosage: A Case Report and Literature Review.

Lidocaine is a commonly used anesthetic. High doses or intravenous administration of lidocaine, as well as other local anesthetics, may result in systemic effects involving the cardiovascular and neurologic systems. Typically, effects are dependent on the serum concentrations of the offending agent. This is a case where a patient presented with symptoms of systemic lidocaine toxicity despite therapeutic dosage and an undetectable serum lidocaine concentration. A 47-year-old Caucasian male received a lumbar medial branch injection of lidocaine and presented with symptoms of perioral numbness, seizure-like activity, and confusion. The patient had a workup, including a CT head without acute findings and an undetectable serum lidocaine level. Due to symptoms consistent with systemic local anesthetic toxicity, intravenous lipid emulsion (ILE) was administered with resolution and without recurrence of symptoms. There should be a low threshold of suspicion for local anesthetic systemic toxicity when patients have neurologic or cardiovascular symptoms following exposure. Toxicity may be present despite therapeutic dosages and low serum concentrations. ILE may be beneficial and should be considered.

End-on versus parallel radiofrequency lesioning for neurotomy of the cervical medial branch nerves: a study protocol of a prospective, randomized, double-blind clinical trial: the "EndPaRL" study.

BACKGROUND: Cervical facet joint disease is a common source of neck pain and its prevalence increases with aging. Conservative multimodal management options (e.g., strengthening of neck muscles, non-steroidal anti-inflammatory medications, massage, and thermal modalities) often fail to relieve pain. Cervical medial branch nerve (CMBN) radiofrequency neurotomy (RFN) is an effective minimally invasive technique for treating chronic neck pain secondary to facet joint disease. An end-on approach for this procedure has been proposed that may be technically easier and require less time while reducing post-procedural discomfort. The protocol presented here is for a study that aims to compare the efficacy of a new end-on approach using multi-tined cannulae, against the conventional parallel technique that employs straight cannulae for RFN of the CMBN in patients with chronic neck pain due to cervical facet joint disease. METHODS: A multicentre randomized, non-inferior, active comparator-controlled trial will be conducted with two parallel groups and blinding of participants and outcome assessor. The study will include 72 adults with chronic neck pain secondary to facet joint disease who are candidates for RFA of the CMBN. Participants will be randomized to either the conventional parallel or the end-on approach in a 1:1 ratio. The intensity of pain and pain-related domains (function, quality of life, sleep, adverse effects of the interventions, analgesic intake) will be measured at 1, 3, 6, and 12 months after the procedure. DISCUSSION: Neck pain secondary to cervical facet joint disease is prevalent and RFA of the CMBN is a validated treatment for relieving it. The conventional parallel technique can be technically challenging, and it can be associated with adverse effects while the newer end-on approach has the potential of being a simpler technique with less adverse effects. This trial will be the first non-inferiority study to compare the clinical efficacy of the end-on approach against the conventional parallel approach for RFN of CMBN in patients with chronic neck pain due to cervical facet joint disease. TRIAL REGISTRATION: ClinicalTrials.gov NCT05818774. Registered on April 20, 2023.

Chronic Low Back Pain: The Therapeutic Benefits of Diagnostic Medial Branch Nerve Blocks.

BACKGROUND: Chronic low back pain (CLBP) is an extremely prevalent disease, whose etiology is often multifactorial. Facet joint arthropathy is one of the most common causes of CLBP. Facet joints are innervated by the medial branches of the primary and adjacent level dorsal rami and are, therefore, key potential targets for the symptomatic management of CLBP. A lumbar medial branch nerve block (MBB) procedure is often used to assist in the diagnosis of facet mediated CLBP. For unclear reasons, some patients experience protracted relief of CLBP after diagnostic MBBs alone. OBJECTIVE: To describe the phenomenon of protracted relief of CLBP after diagnostic MBBs and search for predictors of this response. STUDY DESIGN: A retrospective chart review of patients who underwent MBB procedures by a single practitioner, over a 2 year period, was conducted. SETTING: All patients were seen at the Montefiore Multidisciplinary Pain Program, Bronx, NY. METHODS: Data from follow up visits was used to categorize patient's response to MBBs as having no relief (NR), transient relief (TR) or protracted relief (PR). Patient demographics and characteristics were collected, and a multivariate analysis investigating associations with PR was conducted. RESULTS: 146 patients met inclusion criteria. 41 patients (28%) had NR, 54 (37%) had TR, and 51 (35%) had PR. CLBP symptom duration of < 6 months (P = 0.013) and unilateral back pain symptoms (P = 0.0253) were significantly associated with PR after MBB. LIMITATION: This is a retrospective study with a relatively small sample size conducted on patients belonging to a single practitioner. Outcomes were based largely on subjective patient satisfaction scores. CONCLUSIONS: In select patients, MBB may produce protracted relief of CLBP symptoms. The authors present distinct hypotheses which may help explain the therapeutic effects of diagnostic MBB procedures.

Ultrasound-Guided Procedures in the Cervical Spine.

Cervical pain is a common symptom among the general population. When conservative strategies fail to provide pain relief, cervical spine injections may be considered. Compared with cervical surgery, cervical injections have low major complications and, with the right indication, have demonstrated good results. Traditionally, these types of procedures have been performed under fluoroscopy; however, in recent years, ultrasound has become a more common imaging modality to guide spinal injections. Although ultrasound presents an excellent quality image for soft tissue and allows ​the observation of vascular tissues, nerves, and the contour of bone surfaces, the cervical region has a complicated neurovascular network and a comprehensive understanding of the cervical sonoanatomy should remain as the basis before one can plan cervical ultrasound-guided intervention. This paper aims to show the advantages of ultrasound in facilitating the performance of cervical spine procedures, including facet joint injections, medial branch blocks, and selective nerve root blocks; analyze the sonoanatomy and landmarks of commonly intervened cervical structures; and illustrate how these procedures can be performed safely and precisely under ultrasound guidance.

In vivo measurements of medial branch nerve depth and adjacent osseous structures for ablation of facet-related back pain: Predictors for patient candidacy.

BACKGROUND: Medial branch (MB) targeting during RF ablation for facetogenic back pain is usually performed with flouroscopic guidance yet no specific measurements on the target depth have been published. In order to understand candidacy for other potential ablation methods, we sought to determine the actual MB depth and measurements of adjacent osseous structures. METHODS: CT scans without contrast of the lumbar spine performed in the supine position were retrospectively analyzed in 100 patients. Axial slices less than or equal to 2.5 mm with sagittal and coronal reformations were evaluated. The following distances were measured bilaterally at the L2-L5 levels: The depth from the skin to the MB nerve (anatomic target for RF ablation) at a 15° angulation, the smallest width of the pedicle, and the length, height and width of the transverse process. Age, gender, weight, height, and BMI were correlated with the above measurements. RESULTS: The average distance and 95% CI from skin-to-MB in mm at a 15°angle to the skin increased as the lumbar level increased measuring 64.4 (62.4-66.5) at L2, 72.0 (69.7-74.3) at L3, 79.2 (76.9-81.6) at L4, and 79.1 (76.7-81.5) at L5. The average thickness of the pedicles also increased as the lumbar level increased measuring 9.2 mm at L2 and 16.1 mm at L5. Body weight, lumbar level, and female gender were associated with increased MB depth. Taller stature was associated with more superficial MB depth. We eliminated mild interaction effects between height, weight, and gender by substituting BMI for height and weight without affecting r2. Linear regression revealed the following equation: MB Depth (mm) = 2.2*BMI + 4.9*lumbar vertebral level + 3.6 (if female) - 5.4, which fit the data well (P<0.001, r2 = 0.60). CONCLUSIONS: Our results demonstrate that the MB resides 107 mm or less in depth when measured at a 15° angulation from the skin in > 95% of patients and the distance increases as the lumbar level increases.

Survey of sonoanatomic distances for lumbar medial branch nerve blocks in healthy volunteers.

BACKGROUND: The precise knowledge of anatomy and the region of transverse process (TP) and superior articular processes (AP) and their distance from the skin are important in blocking and treating lumbar facet syndrome. Evaluation of these anatomic distances from 3rd and 5th lumbar vertebrae in both sides and in different body mass index (BMI) in healthy volunteers might improve knowledge of ultrasound (US) lumbar medial branch nerve blocks (LMBB). METHODS: Bilateral US in the 3rd and 5th lumbar vertebrae of 64 volunteers carried out and the distance between skin to TP and skin to AP was measured. These distances were compared on both sides and in different BMI groups. The analysis was done using SPSS 11. Analysis of variance was used to compare the means at three vertebral levels (L3-L5) and different BMI groups. P values less than 0.05 were considered statistically significant. The paired t-test was used to compare the mean distance between skin to TP and skin to AP on both sides. RESULTS: The distance between skin to TP and skin to AP of 3rd vertebrae to 5th vertebrae was increased in both right and left sides (P < 0.001) from up to down. The mean distance from skin to TP were greater on the left side compared to the right in all three vertebral levels from L3 to L5 (P values 0.014, 0.024, and 0.006 respectively). The mean distance from skin to TP and the skin to AP was statistically significant in different BMI groups (P < 0.001). CONCLUSIONS: We found many anatomic distances which may increase awareness of US guided LMBB.