Experimental Rat Model of Bony Defects in the Facet Joint Maintained with Bone Wax for the Study of Spinal Pain.

PURPOSE: Studies using experimental rat models for low back pain due to facet-joint defects are scarce. This study used a novel experimental rat model to determine whether bony defects induced by facetectomy could be maintained by bone wax, thus mimicking spondylolysis, and to analyze the effect of the facetectomy on rat behavior. PATIENTS AND METHODS: Twelve 10-week-old male Wistar rats weighing 300-350 g were divided into group A (n = 6) that underwent unilateral facetectomy of the right L5-6 facet joint and group B (n = 6) that additionally applied water-soluble bone wax at the facetectomy site. The difference in the left and right stride length, detected by the footprint test, and change in the left and right facet joint area were compared before and 4 weeks after the experiment. RESULTS: Even though the difference between the left and right stride lengths of groups A and B was not statistically significant, in contrast to group A, group B showed a shorter stride length on the right side (p = 0.22 and 0.46, in group A and group B, respectively). The right facet joint area, where the facetectomy was performed, was significantly smaller in group B 4 weeks after surgery, but not in group A (p = 0.50 and < 0.01, in group A and group B, respectively). CONCLUSION: Based on the results, we concluded that the bony defects, induced by facetectomy at the L5-6 facet joint, were maintained with bone wax. This study will provide an experimental model for bony defects in the facet joint.

Effect of Needle Tip Position on Contrast Media Dispersion Pattern in Transforaminal Epidural Injection Using Kambin's Triangle Approach.

PURPOSE: Dispersion of contrast media into the anterior epidural space is correlated with better outcomes after transforaminal epidural injection (TFEI). Needle tip position is an important factor affecting the pattern of contrast media dispersion. It is difficult to advance the needle medially to the interpedicle line with a conventional approach, especially in a severe spinal stenosis. But, with Kambin's triangle approach, the needle can be advanced more medially even in the severe stenosis. We aimed to compare contrast media dispersion patterns according to the needle tip position in TFEI with Kambin's triangle approach. PATIENTS AND METHODS: This single-center retrospective study analyzed fluoroscopic data of patients who underwent TFEI from March 2019 to July 2019. Data on the history of lumbar spinal fusion surgery and MRI findings were collected. The needle tip position was evaluated in three positions on fluoroscopic images (final anteroposterior [AP] view): extraforaminal (EF), lateral foramen (LF), and medial foramen (MF). Contrast media dispersion into the epidural space (epidural pattern) in the AP view was evaluated as a dependent variable. The relationship between the contrast media dispersion pattern and needle tip position was analyzed, and other factors affecting the contrast media dispersion pattern were identified. RESULTS: Ninety-eight TFEI cases were analyzed (51 LF, 35 MF, and 12 EF). An epidural pattern of dispersion was observed more frequently in the LF and MF groups than in the EF group. The LF and MF groups showed no significant difference in epidural pattern frequency. On logistic regression analysis, needle tip position emerged as a major factor influencing epidural pattern, while other factors including spine conditions had no significant effect. CONCLUSION: Positioning the needle tip medial to the pedicle helps in the spread of the contrast media into the epidural space during TFEI with Kambin's approach. Factors other than the needle tip position did not significantly affect the contrast media dispersion pattern.

Epiduroscopic laser neural decompression as a treatment for migrated lumbar disc herniation: Case series.

OBJECTIVE: Epiduroscopic laser neural decompression (ELND) is one of the more invasive techniques for managing patients with herniated lumbar disc. However, ELND can be used to treat, and diagnose the epidural pathology; indications for ELND remain controversial, especially, when applied in cases of large disc extrusion and migrated disc. This paper reports cases of patients that were satisfied with the ELND procedure for migrated lumbar disc herniation. METHODS: We reviewed the medical records of patients that received ELND for migrated lumbar disc in an outpatient clinic. The patients complained of low back pain with radicular pain with an intensity over 5 on a numeric rating scale (NRS) that had persisted for over 1 month. The Magnetic resonance imaging (MRIs) showed migrated lumbar disc herniation, and patients opted for ELND because they had previously experienced nerve blocks, and did not want to receive open surgery for their pain, even after the limitations of ELND were explained. RESULTS: Patients reported that their pain was dramatically reduced, and other discomfort symptoms, such as numbness, were also reduced after the procedure. In follow-up, all of the patients were satisfied with the results. CONCLUSION: We applied the ENLD procedure to mechanically, remove disc material that compressed the spinal nerve, and the patients were satisfied, and reported symptom relief. ELND was a sufficient treatment approach for lumbar migrated herniated disc for patients who did not want to undergo open spine surgery.

Facetoplasty Using Radiofrequency Thermocoagulation for Facet Joint Hypertrophy.

UNLABELLED: Lumbar spinal stenosis is one of most common pathologic conditions affecting the lumbar spine. Pain and/or disability in the low back and lower extremities with or without neurogenic claudication may occur as a result of compression of dural sac contents or nerve roots in the narrowed space. Bulging and protrusion, facet joint hypertrophy, and disc herniation combined with osteophytes and arthritic changes of facet joints can be the cause of lumbar spinal stenosis. Medical/interventional treatment may be considered as an initial treatment for patients with mild symptoms of lumbar spinal stenosis. Surgery is usually considered when medical/interventional treatment has failed. Even though surgery has been considered to be the definitive treatment for spinal stenosis conventionally, it has potential problems including general anesthesia related complications and failed back surgery syndrome. For that reason, minimally invasive techniques such as percutaneous endoscopic lumbar discectomy (PELD), epiduroscopic laser neural decompression (ELND), and nucleoplasty with radiofrequency have been developed as alternatives to surgery.The authors present a case of treating lumbar spinal stenosis by using radiofrequency thermocoagulation. Radiofrequency therapy is used for spinal pain, usually in forms of neurotomy or nucleoplasty. The patient in this case had leg pain with neurogenic claudication caused by lumbar spinal stenosis from facet joint hypertrophy. His pain did not respond to conservative treatment including epidural steroid injection, but he didn't want to get surgery. As an alternative to surgery, we applied radiofrequency thermocoagulation with high temperatures of electrode to the hypertrophied facet joint for the decompressing of the spinal nerve and the patient's pain was improved without any complications after the treatment. KEY WORDS: Low back pain, neurogenic claudication, lumbar spinal stenosis, facet joint hypertrophy, radiofrequency thermocoagulation, minimally invasive technique.

The Extent of Tissue Damage in the Epidural Space by Ho / YAG Laser During Epiduroscopic Laser Neural Decompression.

BACKGROUND: Lasers have recently become very useful for epiduroscopy. As the use of lasers increases, the potential for unwanted complications with direct application of laser energy to nerve tissue has also increased. Even using the lowest laser power to test for nerve stimulation, there are still risks of laser ablation. However, there are no studies investigating tissue damage from laser procedures in the epidural space. OBJECTIVE: This is a study on the risks of Ho/YAG laser usage during epiduroscopy. STUDY DESIGN: Observatory cadaver study. SETTING: Department of anatomy and clinical research institute at the University Hospital. METHODS: We used 5 cadavers for this study. After removing the dura and nerve root from the spinal column, laser energy from a Ho/YAG laser was applied directly to the dura and nerve root as well as in the virtual epidural space, which mimicked the conditions of epiduroscopy with the dura folded. Tissue destruction at all laser ablation sites was observed with the naked eye as well as with a microscope. Specimens were collected from each site of laser exposure, fixed in 10% neutral formalin, and dyed with H/E staining. RESULTS: Tissue destruction was observed in all laser ablation sites, regardless of the length of exposure and the power of the laser beam. LIMITATIONS: A cadaver is not exactly the same as a living human because dura characteristics change and tissue damage can be influenced by dura thickness according to the spinal level. CONCLUSION: Even with low power and short duration, a laser can destroy tissue if the laser beam makes direct contact with the tissue.

Exogenously applied muscle metabolites synergistically evoke sensations of muscle fatigue and pain in human subjects.

NEW FINDINGS: What is the central question of this study? Can physiological concentrations of metabolite combinations evoke sensations of fatigue and pain when injected into skeletal muscle? If so, what sensations are evoked? What is the main finding and its importance? Low concentrations of protons, lactate and ATP evoked sensations related to fatigue. Higher concentrations of these metabolites evoked pain. Single metabolites evoked no sensations. This suggests that the combination of an ASIC receptor and a purinergic P2X receptor is required for signalling fatigue and pain. The results also suggest that two types of sensory neurons encode metabolites; one detects low concentrations of metabolites and signals sensations of fatigue, whereas the other detects higher levels of metabolites and signals ache and hot. The perception of fatigue is common in many disease states; however, the mechanisms of sensory muscle fatigue are not understood. In mice, rats and cats, muscle afferents signal metabolite production in skeletal muscle using a complex of ASIC, P2X and TRPV1 receptors. Endogenous muscle agonists for these receptors are combinations of protons, lactate and ATP. Here we applied physiological concentrations of these agonists to muscle interstitium in human subjects to determine whether this combination could activate sensations and, if so, to determine how the subjects described these sensations. Ten volunteers received infusions (0.2 ml over 30 s) containing protons, lactate and ATP under the fascia of a thumb muscle, abductor pollicis brevis. Infusion of individual metabolites at maximal amounts evoked no fatigue or pain. Metabolite combinations found in resting muscles (pH 7.4 + 300 nm ATP + 1 mm lactate) also evoked no sensation. The infusion of a metabolite combination found in muscle during moderate endurance exercise (pH 7.3 + 400 nm ATP + 5 mm lactate) produced significant fatigue sensations. Infusion of a metabolite combination associated with vigorous exercise (pH 7.2 + 500 nm ATP + 10 mm lactate) produced stronger sensations of fatigue and some ache. Higher levels of metabolites (as found with ischaemic exercise) caused more ache but no additional fatigue sensation. Thus, in a dose-dependent manner, intramuscular infusion of combinations of protons, lactate and ATP leads to fatigue sensation and eventually pain, probably through activation of ASIC, P2X and TRPV1 receptors. This is the first demonstration in humans that metabolites normally produced by exercise act in combination to activate sensory neurons that signal sensations of fatigue and muscle pain.