IR-Band Conversion of Target and Background Using Surface Temperature Estimation and Error Compensation for Military IR Sensor Simulation.

Military infrared (IR) imaging systems utilize one or more IR wavelength-bands, among short wavelength IR (SWIR), middle wavelength IR (MWIR), and long wavelength IR (LWIR) band. The IR image wavelength-band conversion which transforms one arbitrary IR wavelength-band image to another IR wavelength-band image is needed for IR signature modeling and image synthesis in the IR systems. However, the IR wavelength-band conversion is very challenging because absorptivity and transmittance of objects and background (atmosphere) are different according to the IR wavelength band and because radiation and reflectance characteristics of the SWIR are very different from the LWIR and MWIR. Therefore, the IR wavelength-band conversion in this paper applies to only IR targets and monotonous backgrounds at a long distance for military purposes. This paper proposes an IR wavelength-band conversion method which transforms one arbitrary IR wavelength-band image to another IR wavelength-band image by using the surface temperature estimation of an object and the error attenuation method for the estimated temperature. The surface temperature of the object is estimated by an approximated Planck's radiation equation and the error of estimated temperature is corrected by using the slope information of exact radiance along with the approximated one. The corrected surface temperature is used for generating another IR wavelength-band image. The verification of the proposed method is demonstrated through the simulations using actual IR images obtained by thermal equipment.

Changes in Neuroglial Activity in Multiple Spinal Segments after Caudal Epidural Pulsed Radiofrequency in a Rat Model of Lumbar Disc Herniation.

BACKGROUND: Herniated lumbar discs can induce sciatica by mechanical compression and/or chemical irritation. It was recently reported that neuroglial cellular activity after pulsed radiofrequency (PRF) application to a single dorsal root ganglion (DRG) attenuated neuroglial activity at the corresponding spinal dorsal horn. Recently, caudal epidural PRF has been used to manage neuropathic pain, but evidence of molecular changes after the administration of caudal epidural PRF to attenuate neuropathic pain is lacking, and it has not been determined whether caudal epidural PRF affects neuroglial activity at different spinal levels. OBJECTIVES: Using immunohistochemical methods in a rat model of lumbar disc herniation, the authors investigated the effects of caudal epidural PRF administration on pain-related behavior, on the activations of microglia and astrocytes in spinal cord, and on the expressions of calcitonin gene-related peptide (CGRP) and Transient receptor potential vanilloid 1(TRPV1) in the DRG at the L3, L4, L5, L6, and S1 levels. STUDY DESIGN: Controlled animal trial. SETTING: University hospital laboratory. METHODS: Forty-five Sprague-Dawley rats were randomly assigned to a sham-operated group (n = 10) or a nucleus pulposus (NP)-exposed group (n = 35). Rats in the NP-exposed group were further subdivided into a NP-exposed with sham stimulation group (the NP-nonPRF group; n = 13) or a NP exposed with caudal epidural PRF stimulation group (the NP-PRF group; n = 22). Pulsed radiofrequency was administered on postoperative day 10 (POD 10) by placing an electrode in the caudal epidural space through the sacral hiatus and administering 5 Hz of PRF current for 600 seconds (maximum tip temperature 42°C). Rats were tested for mechanical allodynia on POD 10 and on days 7 and 14 after caudal epidural PRF administration (post-PRF). At 14 days post-PRF, sections of the spinal cord from L3, L4, L5, L6, and S1 were immunostained for ionized calcium-binding adapter molecule 1 (Iba1) and glial fibrillary acidic protein (GFAP), and DRGs from the same levels were immunostained for CGRP and TRPV1. RESULTS: Mechanical withdrawal thresholds increased at 7 days post-PRF (P = 0.04), and the immunohistochemical expression of Iba1 in the L5 spinal dorsal horn and of CGRP in the L5 DRG were quantitatively reduced (P < 0.001) at 14 days post-PRF. Furthermore, the upregulations of Iba1 at L3, L4, L6, and S1 dorsal horns and CGRP at L6 DRG were also attenuated by caudal epidural PRF (P < 0.001). LIMITATION: We examined molecular changes only in ipsilateral lumbar regions and at 14 days post-PRF. CONCLUSION: Caudal epidural PRF reduced mechanical allodynia and downregulated microglia activity and CGRP expression at the lumbar disc herniated level and in adjacent lumbar spinal levels in a rat model of lumbar disc herniation.Key words: Caudal, pulsed radiofrequency, multisegmental, lumbar disc herniation, microglia, calcitonin gene-related peptide.

Comparative Effectivenesses of Pulsed Radiofrequency and Transforaminal Steroid Injection for Radicular Pain due to Disc Herniation: a Prospective Randomized Trial.

Transforaminal Epidural steroid injections (TFESI) have been widely adopted to alleviate and control radicular pain in accord with current guidelines. However, sometimes repeated steroid injections have adverse effects, and thus, this prospective randomized trial was undertaken to compare the effectivenesses of pulsed radiofrequency (PRF) administered to a targeted dorsal root ganglion (DRG) and TFESI for the treatment of radicular pain due to disc herniation. Subjects were recruited when first proved unsuccessful (defined as a score of > 4 on a visual analogue scale (VAS; 0-10 mm) and of > 30% according to the Oswestry Disability Index (ODI) or the Neck Disability Index (NDI)). Forty-four patients that met the inclusion criteria were enrolled. The 38 subjects were randomly assigned to receive either PRF (PRF group; n = 19) or additional TFESI (TFESI group; n = 19) and were then followed for 2, 4, 8, and 12 weeks. To evaluate pain intensity were assessed by VAS. ODI and NDI were applied to evaluate functional disability. Mean VAS scores for cervical and lumbar radicular pain were significantly lower 12 weeks after treatment in both study groups. NDI and ODI scores also declined after treatment. However, no statistically significant difference was observed between the PRF and TFESI groups in terms of VAS, ODI, or NDI scores at any time during follow-up. PRF administered to a DRG might be as effective as TFESI in terms of attenuating radicular pain caused by disc herniation, and its use would avoid the adverse effects of steroid.

Raster-stereographic evaluation of the effects of biomechanical foot orthoses in patients with scoliosis.

[Purpose] Little is known about the effects of biomechanical foot orthoses in scoliosis, as determined by raster stereography. The objective of this study was to investigate the effect of individually manufactured biomechanical foot orthoses on scoliosis angle, trunk imbalance, and pelvic obliquity by comparing them with general insoles by using DIERS formetric 4 dimensional in patients with scoliosis. [Subjects and Methods] Twenty-six patients with scoliosis were recruited at Yeungnam University Hospital and allocated equally to one of two groups, the biomechanical foot orthoses group or the control group. Parameters, such as, trunk rotation, imbalance, and scoliosis angle, were obtained using a DIERS formetric 4D. [Results] Scoliosis angle, pelvic obliquity, and trunk imbalance were significantly different between the two groups and improved in the biomechanical foot orthoses group with time, but no significant improvement in any parameter was observed in the control group. [Conclusion] Biomechanical foot orthoses could be effective in patients with scoliosis, and DIERS formetric 4D provides a useful method for evaluating scoliosis parameters.

Two-Year Outcome of Percutaneous Bipolar Radiofrequency Neurotomy of Sacral Nerves S2 and S3 in Spinal Cord Injured Patients with Neurogenic Detrusor Overactivity: A Randomized Controlled Feasibility Study.

BACKGROUND: Little research has been expended on the use of bipolar radiofrequency (RF) lesioning of sacral nerves in spinal cord injured (SCI) patients with neurogenic detrusor overactivity (NDO), and no study has been undertaken to demonstrate its long-term effect. OBJECTIVE: To investigated the effect of bipolar RF ablation of the second and third sacral nerves over 2 years in SCI patients with NDO. STUDY DESIGN: A prospective, randomized controlled feasibility study. SETTING: The outpatient clinic of a single academic medical center in Korea. METHODS: Ten SCI patients with NDO were recruited. These patients were randomly assigned to 2 groups; the intervention group (n = 5) and the control group (n = 5). Control group members received optimized conventional treatment. International Consultation on Incontinence Questionnaire (ICIQ), 3-day voiding diary, and the urinary incontinence quality of life scale (I-QOL) data were obtained at baseline and at 6, 12, and 24 months after intervention. Urodynamic study (UDS) was performed at baseline and 24 months after intervention. In the intervention group, percutaneous bipolar RF neurotomy was performed on both S2 and S3 nerves in each patient. RESULTS: Frequency of urinary incontinence and ICIQ and IQOL scores showed significant effects for time and for the group x time interaction (P < 0.05). Daily mean volume of urinary incontinence showed only a significant group effect. In UDS parameters, comparisons of values at baseline and at 24 months revealed all variables showed significant intergroup differences (P < 0.05). LIMITATION: A small number of patients was recruited. CONCLUSION: Percutaneous bipolar RF ablation of sacral nerves S2 and S3 effectively reduces urinary incontinence and improves quality of life (QoL) in SCI patients with NDO and the effects lasted over 2 years.

The effects of biomechanical foot orthoses on the gait patterns of patients with malalignment syndrome as determined by three dimensional gait analysis.

[Purpose] The biomechanical effects of foot orthoses on malalignment syndrome have not been fully clarified. This experimental investigation was conducted to evaluate the effects of orthoses on the gait patterns of patients with malalignment syndrome. [Subjects and Methods] Ten patients with malalignment syndrome were recruited. For each participant, kinematic and kinetic data were collected under three test conditions: walking barefoot, walking with flat insoles in shoes, and walking with a biomechanical foot orthosis (BFO) in shoes. Gait patterns were analyzed using a motion analysis system. [Results] Spatiotemporal data showed the step and stride lengths when wearing shoes with flat insoles or BFO were significantly greater than when barefoot, and that the walking speed when wearing shoes with BFO was significantly faster than when walking barefoot or with shoes with flat insoles. Kinetic data, showed peak pelvic tilt and obliquity angle were significantly greater when wearing BFO in shoes than when barefoot, and that peak hip flexion/extension angle and peak knee flexion/extension and rotation angles were significantly greater when wearing BFO and flat insoles in shoes than when barefoot. [Conclusion] BFOs can correct pelvic asymmetry while walking.

ISSLS Prize Winner: Consensus on the Clinical Diagnosis of Lumbar Spinal Stenosis: Results of an International Delphi Study.

STUDY DESIGN: Delphi. OBJECTIVE: The aim of this study was to obtain an expert consensus on which history factors are most important in the clinical diagnosis of lumbar spinal stenosis (LSS). SUMMARY OF BACKGROUND DATA: LSS is a poorly defined clinical syndrome. Criteria for defining LSS are needed and should be informed by the experience of expert clinicians. METHODS: Phase 1 (Delphi Items): 20 members of the International Taskforce on the Diagnosis and Management of LSS confirmed a list of 14 history items. An online survey was developed that permits specialists to express the logical order in which they consider the items, and the level of certainty ascertained from the questions. Phase 2 (Delphi Study) Round 1: Survey distributed to members of the International Society for the Study of the Lumbar Spine. Round 2: Meeting of 9 members of Taskforce where consensus was reached on a final list of 10 items. Round 3: Final survey was distributed internationally. Phase 3: Final Taskforce consensus meeting. RESULTS: A total of 279 clinicians from 29 different countries, with a mean of 19 (±SD: 12) years in practice participated. The six top items were "leg or buttock pain while walking," "flex forward to relieve symptoms," "feel relief when using a shopping cart or bicycle," "motor or sensory disturbance while walking," "normal and symmetric foot pulses," "lower extremity weakness," and "low back pain." Significant change in certainty ceased after six questions at 80% (P < .05). CONCLUSION: This is the first study to reach an international consensus on the clinical diagnosis of LSS, and suggests that within six questions clinicians are 80% certain of diagnosis. We propose a consensus-based set of "seven history items" that can act as a pragmatic criterion for defining LSS in both clinical and research settings, which in the long term may lead to more cost-effective treatment, improved health care utilization, and enhanced patient outcomes. LEVEL OF EVIDENCE: 2.

Clinical evaluation of transforaminal epidural steroid injection in patients with gadolinium enhancing spinal nerves associated with disc herniation.

BACKGROUND: Transforaminal epidural steroid injection (TFESI) of corticosteroid is frequently employed to mitigate the painful and disabling symptoms of lumbar disc herniation. However, the treatment outcome of TFESI in patients with radicular pain and inflamed neural structures as assessed by contrast-enhanced magnetic resonance imaging (MRI) has not been forthcoming. OBJECTIVES: To investigate functional improvement and pain reduction following TFESI in patients found to have nerve inflammation as evidenced by gadolinium-enhanced (MRI). STUDY DESIGN: Retrospective assessment. SETTING: Tertiary spinal intervention center, Daegu, Korea. METHODS: Thirty-seven patients were selected by strict inclusion criteria. Patients were classified into enhancing and non-enhancing groups as evidenced by gadolinium-enhanced MRI. The enhancing group was further divided into pre-dorsal roog ganglion (DRG) only enhanced group and pre-DRG and post-DRG enhanced group. Clinical outcomes were evidenced by numeric rating scale (NRS) and Oswestry disability index (ODI) at pretreatment, one week, and 4 weeks after treatment. RESULTS: The improvement of NRS and ODI in the enhanced group was greater than those of the non-enhanced group, at one week and 4 weeks after TFESI (P < 0.05). However there was no significant difference in improvement of NRS and ODI between pre-DRG only enhanced group and pre-DRG and post-DRG enhanced group at one week and 4 weeks after TFESI. LIMITATIONS: Retrospective chart review with a small sample size. CONCLUSION: The improvement of NRS and ODI in the enhanced group was significantly greater than those of the non-enhanced group after TFESI. Radicular pain and functional impairment in the presence of gadolinium enhancing spinal neural structures and lumbar disc herniation may be more responsive to TFESI than patients without enhancing neural structures.

Effectiveness of intra-articular steroid injection for atlanto-occipital joint pain.

OBJECTIVES: The aims of this study were to evaluate the role of intra-articular joint injection for atlanto-occipital (AO) joint pain and to determine pain referral sites from that joint. DESIGN: Prospective observational study. METHOD: We evaluated 29 patients with chronic refractory neck pain and/or headache, and limited range of lateral bending with rotation at the AO joint on physical examination. Of the 24 patients who consented to undergo diagnostic injections, 20 patients had at least 50% relief from pain and underwent two AO intra-articular injections of mixture of local anesthetic and steroid approximately 1 week apart. Patients completed pain drawings, visual analog scales (VASs) for pain, and neck disability index (NDI) for level of function. Patients were evaluated for 2 months after the first injection. RESULT: There was headache in 14/20 (70%), posterior neck pain (PNP) in 20, and referred pain in 17 (85%). The average VAS values for headache, PNP, and other referred pains were reduced significantly from 5.64, 5.70, and 5.41, respectively, before treatments to 0.64, 2.30, and 1.71, respectively, two months after injection (P < 0.01). The average NDI value was reduced significantly from 39.95% at pretreatment to 20.40% at 2 months after treatment (P < 0.01). CONCLUSION: AO intra-articular steroid injection appears effective for the short-term control of chronic refractory pain arising from the AO joint.

Attenuation of spinal cord injury-induced astroglial and microglial activation by repetitive transcranial magnetic stimulation in rats.

Spinal cord injury (SCI) causes not only loss of sensory and motor function below the level of injury but also chronic pain, which is difficult and challenging of the treatment. Repetitive transcranial magnetic stimulation (rTMS) to the motor cortex, of non-invasive therapeutic methods, has the motor and sensory consequences and modulates pain in SCI-patients. In the present study, we studied the effectiveness of rTMS and the relationship between the modulation of pain and the changes of neuroglial expression in the spinal cord using a rat SCI-induced pain model. Elevated expressions of Iba1 and GFAP, specific microglial and astrocyte markers, was respectively observed in dorsal and ventral horns at the L4 and L5 levels in SCI rats. But in SCI rats treated with 25 Hz rTMS for 8 weeks, these expressions were significantly reduced by about 30%. Our finding suggests that this attenuation of activation by rTMS is related to pain modulation after SCI. Therefore, rTMS might provide an alternative means of attenuating neuropathic pain below the level of SCI.

Effect of Intradiscal Methylene Blue Injection for the Chronic Discogenic Low Back Pain: One Year Prospective Follow-up Study.

OBJECTIVE: To evaluate the efficacy of intradiscal methylene blue (MB) injection in patients with chronic discogenic low back pain. METHOD: Twenty patients with discogenic low back pain (4 males, 16 females; mean age 45.6 years) refractory to conservative management were recruited. All subjects underwent MB injection in target lumbar intervertebral discs confirmed by provocative discography. The clinical outcome was assessed by visual analog scale (VAS) and Oswestry disability index (ODI) at baseline and 1, 3, 6 and 12 months after treatment. Successful outcome was described as minimum of 2 points reduction in pain intensity compared with the baseline. RESULTS: VAS and ODI significantly decreased after one injection. The average VAS and ODI were reduced significantly from 5.1 and 38.0 at baseline to 3.2 and 27.4 at 3 months after injection (p<0.05). However, the mean score of VAS at 12 month follow-up was 4.5 and we could not observe any difference between 12 months after injection and pretreatment. Eleven of twenty patients (55%) reported successful outcomes after intradiscal MB injection at 3 month follow up and the average VAS was reduced by 3.3±1.1 (p<0.05). At the time of 12 month follow up, pain had relapsed in 6 patients who have had satisfactory effect at 3 month follow up. Successful outcome was maintained in only 5 patients (20%) for 1 year. CONCLUSION: The intradiscal MB injection is a short-term effective minimally invasive treatment indicated for discogenic back pain but it may lose its effectiveness long-term.

The validation of ultrasound-guided lumbar facet nerve blocks as confirmed by fluoroscopy.

STUDY DESIGN: This is a prospective study. PURPOSE: To develop a methodological approach for conducting ultrasound-guided lumbar facet nerve block by defining essential ultrasound-guided landmarks in order to assess the feasibility of this method. OVERVIEW OF LITERATURE: The current role of ultrasound guidance for musculoskeletal intervention treatments has been reported upon in previous literature. METHODS: Ultrasound-guided facet nerve block was done in 95 segments for 50 patients with chronic back pain by facet arthropathy. After the surface landmarks of the spinous process and iliac crest line were confirmed, longitudinal facet views were obtained by a curved array transducer to identify the different spinal segments. The spinous process and facet joint with transverse process were delineated by transverse sonograms at each level and the target point for the block was defined as lying on the upper edge of the transverse process. The needle was inserted toward the target point. After a contrast injection, the placement of the needle and contrast was checked by fluoroscopy. RESULTS: Eighty-seven segments (91.6%) could be guided successfully to the right facet nerve block by using ultrasound. After fluoroscopic control, 8 needles had to be corrected because of problems with other segments (3 cases) and lamina placements (5 cases). For the 42 patients who underwent successful block by ultrasound, however, the mean visual analogue score for back pain was improved from 6.2 ± 0.9 before the block to 4.0 ± 1.0 after the block (p = 0.001). CONCLUSIONS: Ultrasound-guided longitudinal facet view and the surface landmarks of the spinous process and iliac crest line seems to be a promising guidance technique for the lumbar facet nerve block technique.

Pulsed radiofrequency application reduced mechanical hypersensitivity and microglial expression in neuropathic pain model.

OBJECTIVE: Pulsed radiofrequency (PRF) procedure has been used in clinical practice for the treatment of chronic neuropathic pain conditions without neuronal damage. The purpose of this study was to investigate the changes in pain response and glial expression after the application of PRF on a dorsal root ganglion (DRG) in a neuropathic pain model. DESIGN: A neuropathic pain model (14 female Sprague-Dawley [SD] rats; 200-250 g) was made by a unilateral L5 spinal nerve ligation (SNL) and transection on the distal side of the ligation. The development of mechanical and cold hypersensitivity on the hindpaw was established postoperative day 9 (POD 9). The rats were then randomly assigned to the PRF (+) and the PRF (-) groups. Furthermore, PRF (2 bursts/s, duration = 20 milliseconds, output voltage = 45 V) was applied on the ipsilateral DRG for 180 seconds, with a maximum temperature of 42°C, at POD 10. Pain behaviors were tested throughout the 12 days after PRF. We also examined the changes of the spinal glial expression by immunohistochemistry. RESULTS: Significant reduction of mechanical hypersensitivity in the PRF (+) group was observed from day 1 after a single PRF procedure and was maintained throughout the following 12 days. Immunoreactivity for OX42 in the ipsilateral dorsal horn also decreased compared with that of the PRF (-) group. However, cold hypersensitivity and glial fibrillary acidic protein (GFAP) immunoreactivity in the dorsal horn was not affected by a PRF procedure. CONCLUSIONS: Our result demonstrated that the mechanical hypersensitivity, induced by L5 SNL, was attenuated by a PRF procedure on the ipsilateral DRG. This analgesic effect may be associated with an attenuation of the microglial activation in the dorsal horn.

Differences of ground reaction forces and kinematics of lower extremity according to landing height between flat and normal feet.

The study compared lower extremity kinematics and kinetics between male subjects with flat and normal feet when landing on both feet from platforms at different heights. Ten subjects with a flat feet arch and 10 subjects with a normal foot arch were recruited. They performed a double limb drop landing from 20, 40, and 60 cm onto a force-plate. A three-dimensional motion analysis system, force plates, and electromyography were used to analyze lower extremity kinetic and kinematic data. The GRF and angle of sagittal plane significantly increased with landing height in the flat foot group. In particular, hip joint angles at a height of 60 cm were significantly greater. The electromyography values were significantly higher for the tibialis anterior and vastus lateralis muscles, but were significantly lower in the abductor hallucis, gastrocnemius, and biceps femoris muscles in the flat foot group. GRF, joint angles, and muscle activity patterns in the lower extremities increases more with height in flat footed individuals than in people with a normal foot arch. Flat feet may aggravate the risk of shock on landing from a height; this might be ameliorated by a compensatory strategy at the hip joints to facilitate load distribution.

Long-term effect of pulsed radiofrequency on chronic cervical radicular pain refractory to repeated transforaminal epidural steroid injections.

OBJECTIVE: The article aims to evaluate the long-term effectiveness and safety of pulsed radiofrequency (PRF) on the dorsal root ganglion (DRG) in patients with chronic cervical radicular pain refractory to repeated transforaminal epidural steroid injections (TFESIs). DESIGN: This is a prospective observational study. METHODS: We retrospectively reviewed data on 112 subjects who had received repeated TFESIs for cervical radicular pain. Twenty-nine of those 112 patients continued to complain of persistent cervical radicular pain, despite an average of three repeated TFESIs. Among 29 patients with sustained arm pain of over 4 on the numerical rating scale (NRS), a total of 21 patients were included prospectively. Those 21 patients underwent PRF on the symptomatic cervical DRG and were evaluated carefully for neurologic deficits and side effects. The clinical outcomes were measured via NRS for arm pain before treatment, and 1, 3, 6, and 12 months after treatment. Successful pain relief was defined as a 50% or more reduction in the NRS score as compared with the pretreatment score. After 12 months, patients' satisfaction levels with treatment were determined. RESULTS: Fourteen of the 21 patients (66.7%) after cervical PRF stimulation reported pain relief of 50% or more at the 3-month and 12-month follow-up periods, respectively. Fifteen of the 21 patients (71.4%) were satisfied with their outcome at 12 months' posttreatment. No serious adverse effects were observed. CONCLUSION: Application of PRF to the DRG appears to be an effective and relatively safe intervention technique for chronic cervical radicular pain refractory to repeated TFESIs.

Changes in expression of mRNA for interleukin-8 and effects of interleukin-8 receptor inhibitor in the spinal dorsal horn in a rat model of lumbar disc herniation.

STUDY DESIGN: Autologous nucleus pulposus obtained from coccygeal intervertebral discs was grafted on the proximal of L5 dorsal root ganglion. Pain behavior, mRNA expression of Interleukin-8 (IL-8), and immunohistochemical changes were assessed. OBJECTIVE: The purpose of this study is to investigate temporal changes of IL-8 expression in the spinal cord and dorsal root ganglion and the pain-related behaviors with time course and to elucidate whether repertaxin (IL-8 receptor inhibitor) attenuates pain-related behaviors in a rat model of lumbar disc herniation. SUMMARY OF BACKGROUND DATA: Inflammatory mediators like cytokines and chemokines have been implicated in radicular pain because of disc herniation. IL-8, known as CXCL8, is a chemokine, which has been reported to be associated with painful degenerative disc disorders and chronic inflammatory pain states. METHODS: Lumbar disc herniated rat model was made by implantation of the autologous nucleus pulposus, harvested from the coccygeal vertebra of each tail, on the left L5 nerve root just proximal to the dorsal root ganglion. Rats were tested for mechanical allodynia and thermal hyperalgesia at 2 days before surgery, and on days 1, 5, 10, 20, 30, 40, 50, and 60 postoperatively. Experimental group was intrathecally injected with the IL-8 receptor inhibitor at L5 level on postoperative day 10. Mechanical allodynia of the plantar surface of both hindpaw was tested on 30 minutes, 1, 3 hours, 1, 3, 5, and 10 days after administration. For the staining of astrocytes and microglia, immunohistochemical study was done 20 days after surgery. RESULTS: Mechanical allodynia in ipsilateral hindpaw developed 1 day after surgery and lasted until 60 days and thermal withdrawal latency decreased significantly on the ipsilateral side 10 days after surgery and gradually increased through day 60. The IL-8 receptor inhibitor attenuated the mechanical allodynia caused by nucleus pulposus when it was administered on postoperative day 10 and reduced microglial activation and phosphorylated form of mitogen-activated protein kinase (pERK) expression in the spinal dorsal horn. CONCLUSION: IL-8 might be a potential therapeutic target in chronic radicular neuropathic pain because of disc herniation, CXCL8 inhibitor could be one of its promising therapeutic agents.

Abnormal spontaneous activities on needle electromyography and their relation with pain behavior and nerve fiber pathology in a rat model of lumbar disc herniation.

STUDY DESIGN: This longitudinal experimental study was conducted to investigate electrophysiologic characteristics, pain behavior, and histological changes in a rat model of lumbar disc herniation. OBJECTIVE: To observe abnormal spontaneous activity (ASA) on needle electromyography (EMG) and to determine its relation with neuropathic pain behavior and histological changes longitudinally in a rat model of lumbar disc herniation. SUMMARY OF BACKGROUND DATA: Needle EMG is generally performed to determine the existence and the degree of radiculopathy caused by disc herniation. The local application of autologous nucleus pulposus to the spinal nerve has been shown to induce neuropathic pain. However, little is known about the relations between neuropathic pain and abnormal EMG findings and the manner in which they change with time in rat models of lumbar disc herniation. METHODS: Twenty-five Sprague-Dawley rats were randomly assigned to either sham or experimental groups. In the experimental group, autologous nucleus pulposus was grafted on the left L5 dorsal root ganglion. All rats were evaluated for mechanical allodynia and thermal hyperalgesia and underwent needle EMG examinations before and on days 1, 5, 10, 20, 30, 40, and 50 after surgery. Morphologic changes of L5 spinal nerves and of sciatic nerves were assessed by toluidine blue staining on days 1, 5, and 50 after surgery. RESULTS: A dramatic decrease in mechanical withdrawal threshold and in thermal withdrawal latency was observed on day 1 after surgery, and these changes persisted until day 50 after surgery. ASAs on needle EMG were observed on day 1 (33%), peaked on day 5 (93%), and gradually decreased from day 10 (69%) to day 40 (18%) after surgery. Pathologic findings of nerve fibers, such as swelling of myelin sheaths, demyelination, and degeneration of axoplasms were observed from day 1. These findings were exaggerated on day 5 and then diminished but were still evident on day 50. CONCLUSION: Neuropathic pain and pathologic changes in spinal nerve fibers probably remain even after ASAs in EMG have disappeared in our rat model of lumbar disc herniation. These results provide baseline data concerning the natural courses of electrophysiologic findings and of radicular pain in patients with intervertebral disc herniation.

Changes in spinal cord expression of fractalkine and its receptor in a rat model of disc herniation by autologous nucleus pulposus.

STUDY DESIGN: Behavior, mRNA and immunohistochemical assessment of the expression of fractalkine (CX3CL1) and its receptor (CX3CR1) in a rat model of disc herniation by autologous nucleus pulposus (NP) implantation. OBJECTIVE: To evaluate the changes in expression of fractalkine and its receptor in the spinal cord and their association with pain behavior in a rat model of disc herniation. SUMMARY OF BACKGROUND DATA: Chemokines have recently been implicated in the pathophysiology of neuropathic pain. They mediate astrocytic migration and microglial proliferation, which are involved in the regulation of nociceptive transmission. Fractalkine is a chemokine, which participates in the mechanisms of neuropathic pain as a mediator of neuron-glia interactions. METHODS: Sixty-six rats (NP-treated = 47, sham = 19) were implanted with autologous NP (approximately 3 mg) on the left L5 nerve root, just proximal to the dorsal root ganglion and tested for thermal hyperalgesia and mechanical allodynia before surgery and on days 1, 5, 10, 20, and 30 after surgery. The changes of expression of fractalkine and its receptor in the spinal cord were studied using real time PCR and immunohistochemistry. RESULTS: Rats developed ipsilateral mechanical allodynia at day 1 and bilateral thermal hyperalgesia at day 5 after surgery, and these changes in sensitivity persisted throughout the observation period. The expression of mRNA for fractalkine in the spinal cord was increased by day 5 and remained upregulated for the duration of the experiment. The immunostaining for fractalkine increased in neurons and astrocytes and that for the fractalkine receptor increased in microglia in the dorsal horn ipsilateral to the disc herniation. CONCLUSION: Our results indicate that autologous implantation of NP induces thermal hyperalgesia and mechanical allodynia, and leads to an upregulation of fractalkine and its receptor in spinal neurons and glia, implicating fractalkine in association with radicular pain.

Short-term effects of pulsed radiofrequency on chronic refractory cervical radicular pain.

OBJECTIVE: To evaluate the short-term effectiveness of pulsed radiofrequency on the dorsal root ganglion (DRG) in patients with chronic refractory cervical radicular pain. METHOD: Fifteen patients (13 males, 2 females; mean age, 55.9 years) with chronic radicular pain due to cervical disc herniation or foraminal stenosis refractory to active rehabilitative management, including transforaminal cervical epidural steroid injection and exercise, were selected. All patients received pulsed radiofrequency on the symptomatic cervical dorsal root ganglion and were carefully evaluated for neurologic deficits and side effects. The clinical outcomes were measured using a visual analogue scale (VAS) and a neck disability index (NDI) before treatment, one and three months after treatment. Successful pain relief was defined as a 50% or greater reduction in the VAS score as compared with the pre-treatment score. After three months, we categorized the patients' satisfaction. RESULTS: The average VAS for radicular pain was reduced significantly from 5.3 at pretreatment to 2.5 at 3 months post-treatment (p<0.05). Eleven of 15 patients (77.3%) after cervical pulsed RF stimulation reported pain relief of 50% or more at the 3 month follow-up. The average NDI was significantly reduced from 44.0% at pretreatment to 35.8% 3 months post-treatment (p<0.05). At 3 months post-treatment, eleven of fifteen patients (73.3%) were satisfied with their status. No adverse effects were observed. CONCLUSION: The results demonstrate that the application of pulsed radiofrequency on DRG might be an effective short-term intervention for chronic refractory cervical radicular pain. Further studies, including a randomized controlled trial with long-term follow-up, are now needed.