Applicative value of T2 mapping in evaluating lumbosacral nerve root injury induced by lumbosacral disc herniation.

BACKGROUND: To alleviate the damage caused by nerve root entrapment mediated by lumbosacral disc herniation (LDH), an imaging method that allows quantitative evaluation of the lumbosacral nerve injury is necessary. PURPOSE: To investigate the diagnostic value of magnetic resonance (MR) T2 mapping in nerve root injury caused by LDH. MATERIAL AND METHODS: A total of 70 patients with unilateral sciatic nerve pain and 35 healthy volunteers were divided into three groups: LDH with nerve root entrapment; LDH without nerve root entrapment; and 35 healthy volunteers. All participants underwent 3.0-T MR with T1-weighted (T1W) imaging, T2-weighted (T2W) imaging, and T2-mapping images. T2 was measured and observed with the left and right nerve roots of the L4-S1 segments in healthy volunteers; the differences between the three groups were compared. T2 and the relaxation rate of nerve root injury were analyzed. RESULTS: T2 showed significant differences among the three groups (F = 89.494; P = 0.000), receiver operating characteristic curve revealed that the T2 relaxation threshold was 79 ms, the area under curve (AUC) area was 0.86, sensitivity was 0.77, and specificity was 0.74; the T2 relaxation rate was 1.06, the AUC area was 0.88, sensitivity was 0.74, and specificity was 0.85. CONCLUSION: T2 mapping could quantitatively evaluate the nerve root injury with lumbar disc degeneration. Hence, it can be used for the clinical evaluation of nerve root entrapment caused by LDH.

Botulinum Toxin Type A for Lumbar Sympathetic Ganglion Block in Complex Regional Pain Syndrome: A Randomized Trial.

BACKGROUND: The present study was designed to test the hypothesis that botulinum toxin would prolong the duration of a lumbar sympathetic block measured through a sustained increase in skin temperature. The authors performed a randomized, double-blind, controlled trial to investigate the clinical outcome of botulinum toxin type A for lumbar sympathetic ganglion block in patients with complex regional pain syndrome. METHODS: Lumbar sympathetic ganglion block was conducted in patients with lower-extremity complex regional pain syndrome using 75 IU of botulinum toxin type A (botulinum toxin group) and local anesthetic (control group). The primary outcome was the change in the relative temperature difference on the blocked sole compared with the contralateral sole at 1 postoperative month. The secondary outcomes were the 3-month changes in relative temperature differences, as well as the pain intensity changes. RESULTS: A total of 48 participants (N = 24/group) were randomly assigned. The change in relative temperature increase was higher in the botulinum toxin group than in the control group (1.0°C ± 1.3 vs. 0.1°C ± 0.8, respectively; difference: 0.9°C [95% CI, 0.3 to 1.5]; P = 0.006), which was maintained at 3 months (1.1°C ± 0.8 vs. -0.2°C ± 1.2, respectively; P = 0.009). Moreover, pain intensity was greatly reduced in the botulinum toxin group compared with the control group at 1 month (-2.2 ± 1.0 vs. -1.0 ± 1.6, respectively; P = 0.003) and 3 months (-2.0 ± 1.0 vs. -0.6 ± 1.6, respectively; P = 0.003). There were no severe adverse events pertinent to botulinum toxin injection. CONCLUSIONS: In patients with complex regional pain syndrome, lumbar sympathetic ganglion block using botulinum toxin type A increased the temperature of the affected foot for 3 months and also reduced the pain.

Lumbar plexus safe working zones with lateral lumbar interbody fusion: a systematic review and meta-analysis.

PURPOSE: Significant risk of injury to the lumbar plexus and its departing motor and sensory nerves exists with lateral lumbar interbody fusion (LLIF). Several cadaveric and imaging studies have investigated the lumbar plexus position with respect to the vertebral body anteroposterior plane. To date, no systematic review and meta-analysis of the lumbar plexus safe working zones for LLIF has been performed. METHODS: This systematic review was conducted according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Relevant studies reporting on the position of the lumbar plexus with relation to the vertebral body in the anteroposterior plane were identified from a PubMed database query. Quantitative analysis was performed using Welch's t test. RESULTS: Eighteen studies were included, encompassing 1005 subjects and 2472 intervertebral levels. Eleven studies used supine magnetic resonance imaging (MRI) with in vivo subjects. Seven studies used cadavers, five of which performed dissection in the left lateral decubitus position. A significant correlation (p < 0.001) existed between anterior lumbar plexus displacement and evaluation with in vivo MRI at all levels between L1-L5 compared with cadaveric measurement. Supine position was also associated with significant (p < 0.001) anterior shift of the lumbar plexus at all levels between L1-L5. CONCLUSIONS: This is the first comprehensive systematic review and meta-analysis of the lumbar neural components and safe working zones for LLIF. Our analysis suggests that the lumbar plexus is significantly displaced ventrally with the supine compared to lateral decubitus position, and that MRI may overestimate ventral encroachment of lumbar plexus.

Magnetic resonance imaging-guided lumbar nerve root infiltrations: optimization of an in-house protocol.

BACKGROUND: For the treatment of radicular pain, nerve root infiltrations can be performed under MRI guidance in select, typically younger, patients where repeated CT exams are not desirable due to associated radiation risk, or potential allergic reactions to iodinated contrast medium. METHODS: Fifteen 3 T MRI-guided nerve root infiltrations were performed in 12 patients with a dedicated surface coil combined with the standard spine coil, using a breathhold PD sequence. The needle artifact on the MR images and the distance between the needle tip and the infiltrated nerve root were measured. RESULTS: The distance between the needle tip and the nerve root was 2.1 ± 1.4 mm. The visual artifact width, perpendicular to the needle long axis, was 2.1 ± 0.7 mm. No adverse events were reported. CONCLUSION: This technical note describes the optimization of the procedure in a 3 T magnetic field, including reported procedure time and an assessment of targeting precision.

Does the L5 spinal nerve move? Anatomical evaluation with implications for postoperative L5 nerve palsy.

PURPOSE: While palsy of the L5 nerve root due to stretch injury is a known complication in complex lumbosacral spine surgery, the underlying pathophysiology remains unclear. The goal of this cadaveric study was to quantify movement of the L5 nerve root during flexion/extension of the hip and lower lumbar spine. METHODS: Five fresh-frozen human cadavers were dissected on both sides to expose the lumbar vertebral bodies and the L5 nerve roots. Movement of the L5 nerve root was tested during flexion and extension of the hip and lower lumbar spine. Four steps were undertaken to characterize these movements: (1) removal of the bilateral psoas muscles, (2) removal of the lumbar vertebral bodies including the transforaminal ligaments from L3 to L5, (3) opening and removing the dura mater laterally to visualize the rootlets, and (4) removal of remaining soft tissue surrounding the L5 nerve root. Two metal bars were inserted into the sacral body at the level of S1 as fixed landmarks. The tips of these bars were connected to make a line for the ruler that was used to measure movement of the L5 nerve roots. Movement was regarded as measurable when there was an L5 nerve excursion of at least 1 mm. RESULTS: The mean age at death was 86.6 years (range 68-89 years). None of the four steps revealed any measurable movement after flexion/extension of the hip and lower lumbar spine on either side (< 1 mm). Flexion of the hip and lower lumbar spine revealed lax L5 nerve roots. Extension of the hip and lower lumbar spine showed taut ones. CONCLUSION: Significant movement or displacement of the L5 nerve root could not be quantified in this study. No mechanical cause for L5 nerve palsy could be identified so the etiology of the condition remains unclear.

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.

Direct anterior decompression of L4 and L5 nerve root in sacral fractures using the pararectus approach: a technical note.

PURPOSE: To describe a new surgical technique for neurolysis and decompression of L4 and L5 nerve root entrapment after vertical sacral fractures via the pararectus approach for acetabular fractures, and to present four case examples. PATIENTS AND METHODS: We retrospectively evaluated four patients suffering radiculopathy from entrapment of the L4 or L5 nerve root in vertical sacral fractures between January and December 2016. The mean follow-up period after surgery was 18 (range 7-27) months. All patients underwent direct decompression and neurolysis of the L4 and L5 nerve roots via the single-incision, intrapelvic, extraperitoneal pararectus approach. RESULTS: In all patients, the L4 and L5 nerve root was successfully visualized and decompressed, proving feasibility of the pararectus approach for this indication. No patient presented with a neural tear. Complete neurologic recovery was present in one patient at last follow-up; two patients had incomplete recovery of their radiculopathy; and one patient had no improvement after nerve root decompression. CONCLUSIONS: The pararectus approach allows for sufficient visualisation and direct decompression and neurolysis of the L4 and L5 nerve root entrapped in vertical sacral fractures. Although neurologic recovery was not achieved in all patients in this small case series, the approach may be a suitable alternative to posterior approaches and other anterior approaches such as the lateral window of the ilioinguinal approach.

A digital anatomic investigation of the safe triangle areas for L1-5 percutaneous minimally invasive discectomy.

PURPOSE: To reconstruct the three-dimensional safe triangle areas at L1-5 based on the computed tomography digital data, analyze the safe scopes for the puncture location and angles, and provide anatomic references for percutaneous lumbar discectomy. METHODS: Computed tomography data from patients and control group were imported from the database and anatomical reference parameters were measured in Mimics software. The rebuilt model was rotated clockwise along the M-axis to measure the inscribed circle radius of the safe triangle at different angles. Based on the outer diameter of the largest cannula, the safe angles were calculated. The distances between points on the projection of safe triangle-inscribed circle and the upper lumbar spinous process were measured. Similarly, while the safe triangle was on the left side, the model was contra-rotated to measure all the parameters. RESULTS: There was no significant difference between the patient and control group in both the least distance between the selected anatomical reference locations and the safe triangle-inscribed circle radius at L4-5. According to the series which had a largest cannula of 2.5 mm, the safe puncture angles increased with the descending disc levels. The optimal angles were 40°-45° for L1-2, 45°-50° for L2-3, 50° for L3-4, and 55° for L4-5 separately. The differences between genders in the distances of paired reference points were significant. CONCLUSIONS: Individual safe localization of the percutaneous puncture could be obtained by analyzing the three-dimensional relationship between the puncture localization and anatomical landmarks.

The nerve root sedimentation sign in diagnosis of lumbar spinal stenosis.

BACKGROUND: The nerve root sedimentation sign is a magnetic resonance (MR) sign, shown to be present in central lumbar spinal stenosis. The lack of sedimentation of the nerve roots to the dorsal part of the dural sac is consistent with the positive nerve root sedimentation sign. PURPOSE: To validate the reliability of the nerve root sedimentation sign in diagnosis of different grades of lumbar spinal canal stenosis. MATERIAL AND METHODS: This study was a retrospective review of 101 consecutive MR imaging (MRI) studies obtained on patients with clinically suspected lumbar canal stenosis. Based on the minimum anteroposterior (AP) diameter of the dural sac the study sample was classified into two groups: a group with morphological lumbar spinal stenosis; and the group of patients free from stenosis (AP > 12 mm). Patients with stenosis were further subclassified based on its severity: severe stenosis (AP ≤ 10 mm); and moderate stenosis (AP > 10 mm to ≤ 12 mm). RESULTS: Positive sedimentation sign was identified in 81% of patients with severe lumbar spinal stenosis and 14% of patients with moderate stenosis. No patients without lumbar spinal stenosis had a positive nerve root sedimentation sign. Of patients with a positive nerve root sedimentation sign, 89% presented with neurological claudication. CONCLUSION: The nerve root sedimentation is a useful tool for identification of patients with both severe clinical and morphological lumbar spinal stenosis; however, its performance in the diagnosis of patients with moderate morphological spinal stenosis is poor.

Ligamental compartments and their relation to the passing spinal nerves are detectable with MRI inside the lumbar neural foramina.

PURPOSE: Intraforaminal ligaments (IFL) in lumbar neural foramina (NF) and their relation to the lumbar spinal nerves (SN) are addressed. METHOD: Giemsa- and PAS-stained plastinated body slices of 15 lumbar spines were made and compared to MRI and CT data acquired of the same fresh specimens. We dissected one fixed lumbar spine to discuss our results with previous literature. Macroscopic pathophysiological changes and operational interventions at these lumbar spines were excluded. RESULTS: In the NF, thin medial IFL touch the SN. As a second compartment, intermedial vertical IFL are seen. A third lateral horizontal compartment of IFL is formed by thick cranial and caudal ligaments. Ligaments of the second and third compartments have no direct contact with the SN. From medial to lateral, the IFL thicken. All compartments are 3D reconstructed. If compartments of the IFL have no direct contact with the SN seen in the slices, a connection was noticed after dissection. CONCLUSION: Manual dissection seems to be inappropriate for a detailed study of the IFL. The lateral and intermedial compartments being free of the SN may transmit power and protect the SN, while the thin medial IFL may lead the SN passing the NF under physiological conditions. We conclude from the close topographical relation that the IFL may be relevant in foraminal stenosis. Any herniation in the NF presses IFL to the SN. Therefore, we think the IFL themselves could cause neurogenic claudication in case of their non-physiological turnover. Visualisation of IFL seems to be possible by using MRI. These slides can be retrieved under Electronic Supplementary Material.

Effect of Ultrasound-Guided Intercostal Nerve Block Versus Fluoroscopy-Guided Epidural Nerve Block in Patients With Thoracic Herpes Zoster: A Comparative Study.

OBJECTIVES: To compare the efficacy of a conventional fluoroscopy-guided epidural nerve block and an ultrasound (US)-guided intercostal nerve block in patients with thoracic herpes zoster (HZ). METHODS: This work was a comparative study of 38 patients with thoracic HZ pain and a chest wall herpetic eruption, aged 18 years or older, with pain intensity of 5 or greater on a numeric rating scale (NRS) for less than a 1-month duration. Patients were consecutively enrolled and assigned to 2 groups in which the intervention was either the US-guided intercostal nerve block or the fluoroscopy-guided epidural nerve block approach with the addition of a 5-mL mix of 2.5 mg of dexamethasone plus 0.5% lidocaine. The primary outcome measure was the NRS score reduction for the pain. Secondary outcomes included the duration of treatment, number of repeated injections until the final visit, and proportion of patients with pain relief after the first and final visits. RESULTS: All patients within both intervention groups showed significant pain relief on the NRS at the final follow-up point (P < .05). There was no significant difference in the mean value of NRS improvement based on the intervention type. There was also no statistically significant difference in the duration of treatment and the frequency of injection for pain relief. CONCLUSIONS: These findings showed that both the US-guided intercostal nerve block and the fluoroscopy-guided epidural nerve block were effective in patients with thoracic HZ. Compared data showed no significant differences in the pain reduction, duration of treatment, and frequency of injection. The US-guided intercostal nerve block, which is more accessible than the fluoroscopy-guided epidural nerve block, might be an alternative option for thoracic HZ.

Third primary branch of the posterior ramus of the spinal nerve at the thoracolumbar region: a cadaveric study.

PURPOSE: Spinal column procedures require an accurate understanding of neural pathways relative to the anatomic structure. Since Bogduk's report in 1982, it has been known that the human lumbar posterior ramus of the spinal nerve (PRSN) comprise not two but three primary branches at least in some lumbar segments. The purpose of the current study was to examine the existence of the three primary branches in the thoracic and lumbar segments. METHODS: In this study, we investigated the anatomy of the human PRSN in the thoracic and lumbar segments. Ventral dissection was performed in eight cadavers to determine the anatomy of the PRSN between T1 and L5. RESULTS: At the distal end of a given PRSN, the PRSN divided into three primary branches-medial, intermediate and lateral-in 196 out of 272 segments in the thoracic and lumbar regions in eight cadavers. The medial branch supplied the spinalis compartment, and reached the skin. The lateral branch supplied the iliocostalis muscle compartment, and reached skin. The intermediate branch supplied the longissimus muscle and the area between the medial and the lateral branch, which was a seemingly shorter branch. CONCLUSION: The triplication of the primary branch of the PRSN is considered not uncommon. The third branch should be recognized in the literature and in textbooks.

Chemical lumbar sympathectomy in the treatment of recalcitrant erythromelalgia.

OBJECTIVE: Erythromelalgia is highly disabling and treatment is often very challenging. There have been solitary case reports that it might benefit from sympathectomy. This study sought to evaluate the short-term and long-term efficacy of chemical lumbar sympathectomy (CLS) for treatment of recalcitrant erythromelalgia and try to identify a CLS-responsive subset. METHODS: Patients with recalcitrant erythromelalgia were recruited from a tertiary hospital over a 10-year period. L3 to L4 CLS was performed using 5% phenol. The pain intensity score (visual analog scale [VAS] 0-10) was assessed before CLS and at 1 day, 1 week, 3 months, 6 months, 1 year, and 2 years after CLS. A VAS decrease of 90%-100% is defined as complete response, 60%-89% as major partial response. Relapse was defined by a return of a VAS score of 5 or higher. SCN9A gene mutations were screened. RESULTS: Thirteen patients were enrolled, with a median age of 15 years. The mean follow-up was 6.2 ± 3.8 years. SCN9A gene mutation was identified in five patients having family histories. The VAS was 8.2 ± 2.0 at baseline; it decreased to 4.9 ± 2.7 at 1 day and 1.9 ± 3.0 at 1 week after CLS. Nine patients (69.2%) achieved complete response at 1 week after CLS, including three patients with SCN9A gene mutation. Among the three complete response patients having the gene mutation, two reverted to major partial response and one relapsed at 2 years after CLS. Among the six complete response patients without mutation, five maintained complete response and one relapsed. Among the four patients who did not achieve complete response, one patient died at 3.5 months and one patient had an amputation performed at 4 months after CLS. CONCLUSIONS: CLS provides a valid option for the treatment of recalcitrant erythromelalgia. It takes about 1 week to achieve full efficacy. Relapse may occur, especially in patients with an SCN9A gene mutation.

Intradiscal ozone therapy for lumbar disc herniation.

The rationale behind intradiscal O2-O3 therapy is the pain elicited by the mechanical compression of the nerve root, which is associated with periganglionic and periradicular inflammation. This study aimed to determine the effect of intradiscal ozone injection on pain score and satisfaction of patients with low back pain (LBP) secondary to disc herniation. Patients with LBP diagnosed with disc herniation were enrolled in this clinical trial. After prepping and draping the area, intradiscal injection of ozone/oxygen mixture (10 ml, 25µg/ml) was performed under fluoroscopy guide (c-arm). Pain score and patient satisfaction were assessed prior to the injection (baseline) and 1, 3, 6, 12 and 24 months after the injection. Sixty three patients (24 males, 39 females) with mean age of 53.3 ±2.0 y enrolled in the study. The mean±standard deviation (SD) of pain score before intervention was 6.968 ±0.11. Pain score was reduced to 4.25±0.19 at 1 month, 4.33±0.20 at 3 months, 4.87 ±0.21 at 6 months and 5.22 ±0.20 at 24 months. According to the modified MacNab scale success of pain relief was as follows: excellent: 4 (6.3%), good: 17 (26.98 %), sufficient: 13 (20.63 %), poor: 13 (20.63 %), no result: 11 (17.46%), negative: 4 (6.3 %). Intradiscal ozone therapy was determined to provide improved outcomes in patients with single level of bulging and protrusion.

Muscle Control and Non-specific Chronic Low Back Pain.

OBJECTIVES: Chronic low back pain (CLBP) is the most prevalent of the painful musculoskeletal conditions. CLBP is a heterogeneous condition with many causes and diagnoses, but there are few established therapies with strong evidence of effectiveness (or cost effectiveness). CLBP for which it is not possible to identify any specific cause is often referred to as non-specific chronic LBP (NSCLBP). One type of NSCLBP is continuing and recurrent primarily nociceptive CLBP due to vertebral joint overload subsequent to functional instability of the lumbar spine. This condition may occur due to disruption of the motor control system to the key stabilizing muscles in the lumbar spine, particularly the lumbar multifidus muscle (MF). METHODS: This review presents the evidence for MF involvement in CLBP, mechanisms of action of disruption of control of the MF, and options for restoring control of the MF as a treatment for NSCLBP. RESULTS: Imaging assessment of motor control dysfunction of the MF in individual patients is fraught with difficulty. MRI or ultrasound imaging techniques, while reliable, have limited diagnostic or predictive utility. For some patients, restoration of motor control to the MF with specific exercises can be effective, but population results are not persuasive since most patients are unable to voluntarily contract the MF and may be inhibited from doing so due to arthrogenic muscle inhibition. CONCLUSIONS: Targeting MF control with restorative neurostimulation promises a new treatment option.

Anatomical evaluation of lumbar nerves using diffusion tensor imaging and implications of lateral decubitus for lateral transpsoas approach.

PURPOSE: Recently, lateral interbody fusion (LIF) has become more prevalent, and evaluation of lumbar nerves has taken on new importance. We report on the assessment of anatomical relationships between lumbar nerves and vertebral bodies using diffusion tensor imaging (DTI). METHODS: Fifty patients with degenerative lumbar disease and ten healthy subjects underwent DTI. In patients with lumbar degenerative disease, we studied nerve courses with patients in the supine positions and with hips flexed. In healthy subjects, we evaluated nerve courses in three different positions: supine with hips flexed (the standard position for MRI); supine with hips extended; and the right lateral decubitus position with hips flexed. In conjunction with tractography from L3 to L5 using T2-weighted sagittal imaging, the vertebral body anteroposterior span was divided into four equally wide zones, with six total zones defined, including an anterior and a posterior zone (zone A, zones 1-4, zone P). We used this to characterize nerve courses at disc levels L3/4, L4/5, and L5/S1. RESULTS: In patients with degenerative lumbar disease, in the supine position with hips flexed, all lumbar nerve roots were located posterior to the vertebral body centers in L3/4 and L4/5. In healthy individuals, the L3/4 nerve courses were displaced forward in hips extended compared with the standard position, whereas in the lateral decubitus position, the L4/5 and L5/S nerve courses were displaced posteriorly compared with the standard position. CONCLUSIONS: The L3/4 and L4/5 nerve roots are located posterior to the vertebral body center. These were found to be offset to the rear when the hip is flexed or the lateral decubitus position is assumed. The present study is the first to elucidate changes in the course of the lumbar nerves as this varies by position. The lateral decubitus position or the position supine with hips flexed may be useful for avoiding nerve damage in a direct lateral transpsoas approach. Preoperative DTI seems to be useful in evaluating the lumbar nerve course as it relates anatomically to the vertebral body.

Periprosthetic UHMWPE Wear Debris Induces Inflammation, Vascularization, and Innervation After Total Disc Replacement in the Lumbar Spine.

BACKGROUND: The pathophysiology and mechanisms driving the generation of unintended pain after total disc replacement (TDR) remain unexplored. Ultrahigh-molecular-weight polyethylene (UHMWPE) wear debris from TDRs is known to induce inflammation, which may result in pain. QUESTIONS/PURPOSES: The purpose of this study was to determine whether (1) periprosthetic UHMWPE wear debris induces immune responses that lead to the production of tumor necrosis factor-α (TNFα) and interleukin (IL)-1ß, the vascularization factors, vascular endothelial growth factor (VEGF) and platelet-derived growth factor-bb (PDGFbb), and the innervation/pain factors, nerve growth factor (NGF) and substance P; (2) the number of macrophages is associated with the production of the aforementioned factors; (3) the wear debris-induced inflammatory pathogenesis involves an increase in vascularization and associated innervation. METHODS: Periprosthetic tissues from our collection of 11 patients with contemporary TDRs were evaluated using polarized light microscopy to quantify UHMWPE wear particles. The major reason for revision (mean implantation time of 3 years [range, 1-6 years]) was pain. For control subjects, biopsy samples from four patients with degenerative disc disease with severe pain and autopsy samples from three normal patients with no history of back pain were also investigated. Immunohistochemistry and histology were used to identify secretory factors, macrophages, and blood vessels. Immunostained serial sections were imaged at ×200 magnification and using MATLAB and NIH ImageJ, a threshold was determined for each factor and used to quantify positive staining normalized to tissue sectional area. The Mann-Whitney U test was used to compare results from different patient groups, whereas the Spearman Rho test was used to determine correlations. Significance was based on p < 0.05. RESULTS: The mean percent area of all six inflammatory, vascularization, and innervation factors was higher in TDR tissues when compared with normal disc tissues. Based on nonparametric data analysis, those factors showing the most significant increase included TNFα (5.17 ± 1.76 versus 0.05 ± 0.03, p = 0.02), VEGF (3.02 ± 1.01 versus 0.02 ± 0.002, p = 0.02), and substance P (4.15 ± 1.01 versus 0.08 ± 0.04, p = 0.02). The mean percent area for IL-1ß (2.41 ± 0.66 versus 0.13 ± 0.13, p = 0.01), VEGF (3.02 ± 1.01 versus 0.34 ± 0.29, p = 0.04), and substance P (4.15 ± 1.01 versus 1.05 ± 0.46, p = 0.01) was also higher in TDR tissues when compared with disc tissues from patients with painful degenerative disc disease. Five of the factors, TNFα, IL-1ß, VEGF, NGF, and substance P, strongly correlated with the number of wear particles, macrophages, and blood vessels. The most notable correlations included TNFα with wear particles (p < 0.001, ρ = 0.63), VEGF with macrophages (p = 0.001, ρ = 0.71), and NGF with blood vessels (p < 0.001, ρ = 0.70). Of particular significance, the expression of PDGFbb, NGF, and substance P was predominantly localized to blood vessels/nerve fibers. CONCLUSIONS: These findings indicate wear debris-induced inflammatory reactions can be linked to enhanced vascularization and associated innervation/pain factor production at periprosthetic sites around TDRs. Elucidating the pathogenesis of inflammatory particle disease will provide information needed to identify potential therapeutic targets and treatment strategies to mitigate pain and potentially avoid revision surgery. LEVEL OF EVIDENCE: Level III, therapeutic study.

Management of an unusual sciatica.

PURPOSE: Extraforaminal entrapment of the L5 nerve root is uncommon, and its management can sometimes be very challenging. METHODS: We present the case of a 57-year-old female, complaining of a sciatica in her left leg, for 3 years, with no response to any kind of conservative treatment. MRI and CT scan revealed the presence of a large L5S1 strictly lateral osteophyte compressing the left L5 root in its extraforaminal path. RESULTS: The patient underwent a left anterior retroperitoneal approach with assistance from a vascular surgeon given the very close relation between the osteophyte and the left common iliac vein, lying just on top of it, osteophyte was removed in one piece with the use of an osteotome after retraction of the vessels. The patient progressively recovered from her left sciatic pain with a satisfactory clinical result at 1 year. CONCLUSION: Literature is sparse on the treatment of extraforaminal entrapment of the L5 nerve root; the current case shows a successful treatment strategy with the use of an anterior approach for direct vision of the lesion and good control of the vessels.

Ultrasound indications for chronic pain management: an update on the most recent evidence.

PURPOSE OF REVIEW: The ability of ultrasound to provide detailed anatomic visualization while avoiding radiation exposure continues to make it an appealing tool for many practitioners of chronic pain management. This review will present the most recent evidence regarding the use of ultrasound-guidance for the performance of interventional procedures in the treatment of chronic pain. RECENT FINDINGS: For a variety of different procedures, studies continue to compare ultrasound-guided techniques to commonly used fluoroscopic or landmark-based techniques. Small, randomized controlled trials are beginning to demonstrate that ultrasound-guided approaches to interventional pain procedures can be as well tolerated and effective as the traditionally used techniques, while providing some potential advantages in terms of decreased radiation exposure, avoidance of vascular structures, and in some cases, improved efficiency and decreased rates of adverse effects. SUMMARY: Despite continued interest in ultrasound-guided techniques for chronic pain management procedures, the evidence is still limited mainly to small, randomized trials and case series. For some procedures, such as stellate ganglion block and peripheral joint injections, recent evidence appears to be tilting in favor of ultrasound-guidance as the preferred technique, though fluoroscopy continues to be a much more reliable method for detection of intravascular uptake of injectate.

Microvascular oxygen partial pressure during hyperbaric oxygen in diabetic rat skeletal muscle.

Hyperbaric oxygen (HBO) is a major therapeutic treatment for ischemic ulcerations that perforate skin and underlying muscle in diabetic patients. These lesions do not heal effectively, in part, because of the hypoxic microvascular O2 partial pressures (PmvO2 ) resulting from diabetes-induced cardiovascular dysfunction, which alters the dynamic balance between O2 delivery (Q̇o2) and utilization (V̇o2) rates. We tested the hypothesis that HBO in diabetic muscle would exacerbate the hyperoxic PmvO2 dynamics due, in part, to a reduction or slowing of the cardiovascular, sympathetic nervous, and respiratory system responses to acute HBO exposure. Adult male Wistar rats were divided randomly into diabetic (DIA: streptozotocin ip) and healthy (control) groups. A small animal hyperbaric chamber was pressurized with oxygen (100% O2) to 3.0 atmospheres absolute (ATA) at 0.2 ATA/min. Phosphorescence quenching techniques were used to measure PmvO2 in tibialis anterior muscle of anesthetized rats during HBO. Lumbar sympathetic nerve activity (LSNA), heart rate (HR), and respiratory rate (RR) were measured electrophysiologically. During the normobaric hyperoxia and HBO, DIA tibialis anterior PmvO2 increased faster (mean response time, CONT 78 ± 8, DIA 55 ± 8 s, P < 0.05) than CONT. Subsequently, PmvO2 remained elevated at similar levels in CONT and DIA muscles until normobaric normoxic recovery where the DIA PmvO2 retained its hyperoxic level longer than CONT. Sympathetic nervous system and cardiac and respiratory responses to HBO were slower in DIA vs. CONT. Specifically the mean response times for RR (CONT: 6 ± 1 s, DIA: 29 ± 4 s, P < 0.05), HR (CONT: 16 ± 1 s, DIA: 45 ± 5 s, P < 0.05), and LSNA (CONT: 140 ± 16 s, DIA: 247 ± 34 s, P < 0.05) were greater following HBO onset in DIA than CONT. HBO treatment increases tibialis anterior muscle PmvO2 more rapidly and for a longer duration in DIA than CONT, but not to a greater level. Whereas respiratory, cardiovascular, and LSNA responses to HBO are profoundly slowed in DIA, only the cardiovascular arm (via HR) may contribute to the muscle vascular incompetence and these faster PmvO2 kinetics.