A Procedure for Mouse Dorsal Root Ganglion Cryosectioning.

High-quality mouse dorsal root ganglion (DRG) cryostat sections are crucial for proper immunochemistry staining and RNAscope studies in the research of inflammatory and neuropathic pain, itch, as well as other peripheral neurological conditions. However, it remains a challenge to consistently obtain high-quality, intact, and flat cryostat sections onto glass slides because of the tiny sample size of the DRG tissue. So far, there is no article describing an optimal protocol for DRG cryosectioning. This protocol presents a step-by-step method to resolve the frequently encountered difficulties associated with DRG cryosectioning. The presented article explains how to remove the surrounding liquid from the DRG tissue samples, place the DRG sections on the slide facing the same orientation, and flatten the sections on the glass slide without curving up. Although this protocol has been developed for cryosectioning the DRG samples, it can be applied for the cryosectioning of many other tissues with a small sample size.

Whole Central and Peripheral Nervous System Mice Dissection.

Animal models represent the workhorse of the neuroscience field. Despite this, today, there is still no step-by-step protocol to dissect a complete rodent nervous system, nor is there a complete schematic representing it that is freely available. Only methods to harvest the brain, the spinal cord, a specific dorsal root ganglion, and the sciatic nerve (separately) are available. Here, we provide detailed pictures and a schematic of the central and peripheral murine nervous system. More importantly, we outline a robust procedure to perform its dissection. The 30 min pre-dissection step allows isolating the intact nervous system within the vertebra with muscles free of viscera and skin. A 2-4 h dissection follows it under a micro-dissection microscope to expose the spinal cord and the thoracic nerves, and finally peel the whole central and peripheral nervous system off the carcass. This protocol represents a significant step forward in studying the anatomy and pathophysiology of the nervous system globally. For example, the dissected dorsal root ganglions from a neurofibromatosis type I mice model can be further processed for histology to unravel changes in tumor progression.

Alternative Dorsal Root Ganglion Neuromodulation Electrode Implantation: A Report of 2 Cases with 3 Different Techniques.

BACKGROUND AND STUDY AIMS: The traditional percutaneous placement of dorsal root ganglion (DRG) electrodes may not be eligible for every patient. In this tertiary spine surgery and interventional pain therapy center, alternative neurostimulation implantation techniques were developed and applied where standard percutaneous approaches failed or were contraindicated. CASE PRESENTATION: Three alternative implantation techniques can be used: (1) open surgical placement of DRG leads, (2) two-lead insertion via a lateral to medial transforaminal approach (level L3), and (3) percutaneous approach with two leads close to the spinal nerves L4 (peripheral nerve stimulation). RESULTS: The placement of the leads occurred without complications and resulted in similar expected outcomes as with the common percutaneous technique with long-term stable pain suppression at 7 months and 1 year. CONCLUSIONS: In patients in whom the DRG cannot be approached by the standard percutaneous approach, at least three alternatives may be used in experienced hands resulting in stable pain suppression of similar magnitude.

CT-Guided C2 Dorsal Root Ganglion Radiofrequency Ablation for the Treatment of Cervicogenic Headache: Case Series and Clinical Outcomes.

Cervicogenic headache is a secondary headache syndrome attributable to upper cervical spine pathology. Osteoarthritis of the lateral atlantoaxial joint with resultant C2 dorsal root ganglion irritation is an important and potentially treatable cause of cervicogenic headache. In this case series, we present 11 patients with cervicogenic headache who underwent C2 dorsal root ganglion thermal radiofrequency ablation. Radiologists should be familiar with this efficacious procedure and technical considerations to avoid complications.

Endoscopic Lateral Approach for Dorsal Root Ganglion Burst Stimulation: Technical Note and Illustrative Case Series.

INTRODUCTION: Dorsal root ganglion (DRG) stimulation demonstrated superiority over traditional spinal cord stimulation with better pain relief and greater improvement of quality of life. However, leads specifically designed for DRG stimulation are difficult to implant in patients who previously underwent spinal surgery and show epidural scarring at the desired site of implantation because of the reduced stiffness of the lead. Nevertheless, recurrent leg or arm pain after spinal surgery usually manifests as a single level radiculopathy, which should theoretically be amenable to DRG stimulation. MATERIALS AND METHODS: We present the percutaneous transforaminal placement of cylindrical leads through a lateral endoscopic approach for DRG stimulation in burst mode. RESULTS: We could successfully show that percutaneous transforaminal lead placement is feasible in three illustrative cases. CONCLUSION: This technical note combines two innovations, one linked to the other. The first innovation involves a novel endoscopic lateral transforaminal approach to insert a cylindrical lead to the DRG. Because this electrode is compatible with burst stimulation-enabled devices, a second innovation consists of the application of burst stimulation on the DRG.

Utilizing pre-operative MR imaging and adapting optimal needle puncture approach to improve radiofrequency ablation fraction of thoracic dorsal root ganglia.

This experimental study evaluates the location of thoracic dorsal root ganglions (DRGs) through magnetic resonance imaging (MRI) scans, and evaluates the radiofrequency ablation (RFA) fraction of different puncture approaches on distinct DRG locations. Eight normal adult corpse specimens were used as thoracic spine specimens. An MRI examination was performed on each specimen using the following MRI sequences: STIR T2WI, fs-FRFSE T2WI, and 3D FIESTA-c. Then thoracic spine specimens (n = 14) were divided into three groups for RFA: Group A, using a transforaminal approach irrespective of DRG location; Group B, using a transforaminal, trans-lateral-zygapophysial or translaminar approach according to the DRG location; and Group C using a combination of puncture approaches. The quality of visualization of thoracic DRGs on STIR T2WI, fs-FRFSE T2WI, and 3D FIESTA-c scans were 53.5% (77/144), 88.2% (127/144), and 93.1% (134/144), respectively. In group A, the RFA fractions of the extraforaminal DRGs (N = 29), intraforaminal DRGs (N = 12) and intraspinal DRGs (N = 7) via a transforaminal approach were 72.6 ± 18.9%, 54.2 ± 24.8% and 32.9 ± 28.1% respectively. In group B, RFA of extraforaminal DRGs via a transforaminal approach (N = 43) or a trans-lateral zygapophysial approach (N = 45) led to ablation fractions of 71.9 ± 15.2% and 72.0 ± 17.9%, respectively; RFA of intraforaminal DRGs via a transforaminal approach (N = 14) or a translaminar approach (N = 16) led to ablation fractions of 57.1 ± 18.0% and 52.5 ± 20.6%, respectively; RFA of intraspinal DRGs via a transforaminal approach (N = 12) or a translaminar approach (N = 14) led to ablation fractions of 34.8 ± 24.6% and 71.8 ± 16.0%, respectively. In group C, the combined approach led to an ablation fraction for extraforaminal DRGs (N = 69) of 82.5 ± 14.1%, for intraforaminal DRGs (N = 39) of 81.5 ± 11.8%, and for intraspinal DRGs (N = 36) of 80.8 ± 13.3%. MRI can accurately assess DRG location before RFA. Adopting different and combined puncturing approaches tailored to different DRG locations can significantly increase the DRG RFA fraction.

Magnetic Resonance Neurography for Evaluation of Dorsal Root Ganglion Morphology.

BACKGROUND: In this study, the morphologic characteristics and anatomic position of the dorsal root ganglion (DRG) were measured and analyzed in healthy people using magnetic resonance neurography (MRN), which provided an anatomical reference for minimally invasive spinal surgery. METHODS: From January 2018 to December 2019, 20 healthy adult volunteers (10 male and 10 female volunteers between 20 and 65 years old) were scanned and imaged by 3.0 T magnetic resonance imaging combined with neuroimaging technology. Here, the position of the DRG was located, and the shape and size of the DRG, as well as its distance to the upper pedicle, were measured. RESULTS: All volunteers provided satisfactory MRN scans of the L1-S1 lumbar DRG. According to the spatial position of the DRG, the morphology of the DRG can be divided into the intervertebral foramen type (81.01%), intraspinal type (16.01%), extraforaminal type (0.8%), and mixed type (2.0%). CONCLUSIONS: The intervertebral foramen type and Intraspinal type were observed to be the main distribution forms of lumbar DRG. Due to the downward movement of lumbar segments, the position of the DRG was noted to gradually move to the spinal canal while its volume gradually increased. In addition, the distance from the upper pedicle was found to decrease gradually. MRN imaging can clearly show the shape, location, and adjacent relationship of the DRG, providing effective imaging guidance for the minimally invasive lumbar techniques.

Effect of Dorsal Root Ganglion Retraction in Endoscopic Lumbar Decompressive Surgery for Foraminal Pathology: A Retrospective Cohort Study of Interlaminar Contralateral Endoscopic Lumbar Foraminotomy and Discectomy versus Transforaminal Endoscopic Lumbar Foraminotomy and Discectomy.

OBJECTIVE: Postoperative dysesthesia (POD) is a common complication in surgery involving foraminal diseases, including lumbar foraminal or extraforaminal herniated nucleus pulposus (HNP). Minimal dorsal root ganglion (DRG) retraction is key to preventing POD. We compared the clinical results, safety, and efficacy between the paraspinal transforaminal approach requiring DRG retraction and the interlaminar contralateral approach without DRG retraction for foraminal and extraforaminal diseases. METHODS: A retrospective cohort study was performed of 50 patients who underwent uniportal transforaminal endoscopic lumbar foraminotomy and discectomy (TELD) and 50 patients who underwent anuniportal interlaminar contralateral endoscopic lumbar foraminotomy and discectomy (ICELF) because of lumbar foraminal HNP. The operated levels, combined degenerative diseases, postoperative complications, and POD were analyzed. The visual analog scale (VAS) pain scores, modified Oswestry Disability Index, and MacNab criteria for evaluating pain disability and response were analyzed. RESULTS: In the ICELF group (total, n = 7, 14%), there were 5 (10%) and 2 (4%) patients with POD grade 1 and 2, respectively. In the TELD group (total, n = 13, 26%), there were 7 (14%), 5 (10%), and 1 (2%) patients with POD grade 1, 2, and 3, respectively. The overall occurrence rate of grade 2 and greater POD was higher in the TELD group (n = 6, 12%) than in the ICELF group (n = 2, 4%). In the ICELF group, 3 of 9 patients (33%) with combined canal structure deforming diseases had POD, of whom none had POD of grade 2 and greater. In the TELD group, 4 of 7 patients (57%) with combined canal structure deforming diseases had POD, of whom all had POD of grade 2 and greater. Two surgical groups showed favorable clinical outcomes with the visual analog scale, Oswestry Disability Index, and MacNab criteria. CONCLUSIONS: Both TELD and ICELF were found to treat foraminal or extraforaminal HNP with good clinical outcomes. ICELF might have a lower POD rate in complicated cases such as adjacent segment disease, degenerative spondylolisthesis, and isthmic spondylolisthesis. This surgical procedure could be an alternative in complicated cases or in patients with an anatomically limited L5-S1 level. However, the procedure is technically challenging to perform.

Microsurgical DREZotomy for Treatment of Brachial Plexus Avulsion Pain.

A 63-year-old man with a history of motorcycle accident 42 years ago suffered a left brachial plexus avulsion (BPA). Neuropathic pain in his left upper limb was felt in the C6-C7-C8 dermatomes. The rationale for performing "DREZotomy" is to preferentially interrupt the nociceptive inputs in the lateral part of the dorsal root entry zone (DREZ).1-3 For pain with complete deafferentation, as observed in BPA, the aim is to destroy the hyperactive nociceptive neurons deep in the apex of the dorsal horn (DH).4 Surgery is performed under general anesthesia, with the patient in prone position. Once the dura mater is opened, the arachnoid needs extensive dissection to open the dorsolateral and lateral spinal cisterns.5 In cases of BPA, the dorsolateral sulcus may be difficult to identify. Three anatomic elements can facilitate its recognition. Firstly, the remaining intact rootlets (above and below the avulsed segments) allow us to roughly localize the dorsolateral sulcus by joining these cranial and caudal normal rootlets. Secondly, blood vessels running on the spinal cord penetrate into the dorsolateral sulcus and often delineate the sulcus. Thirdly, scarring can be seen along the sulcus with small holes where the rootlets used to penetrate the cord. DREZotomy is performed using a graduated sharp bipolar instrument to allow precise microcoagulations of the DH. Preoperative surgical planning helps the surgeon by giving the angle between the DH and median plane.6 In the immediate postoperative period, the patient described the complete disappearance of neuropathic pain in his left upper limb, persistent at last follow-up (1 year) (Video 1).

Technical Considerations of Endoscopic Kambin's Triangle Lumbar Interbody Fusion.

The performance of transforaminal endoscopic lumbar interbody fusion through a Kambin's triangle approach requires significant modifications when compared to a traditional transforaminal discectomy. Indeed, due to the inherently limited field of view, small working corridor, and need to deploy an adequately sized interbody graft, there are several important technical adaptations which can help improve the efficacy of this approach. In this manuscript, the technical aspects of a percutaneous, endoscopic interbody fusion are discussed in detail.

Dysethesia due to irritation of the dorsal root ganglion following lumbar transforaminal endoscopy: Analysis of frequency and contributing factors.

BACKGROUND: New onset of acute dysethetic leg pain due to irritation of the dorsal root ganglion (DRG) following uneventful recovery from an expertly executed lumbar transforaminal endoscopic decompression is a common problem. Its incidence and relation to any risk factors that could be mitigated preoperatively are not well understood. METHODS: We performed a multicenter frequency analysis of DRG irritation dysesthesia in 451 patients who underwent lumbar transforaminal endoscopic decompression for herniated disc and foraminal stenosis. The 451 patients consisted of 250 men and 201 women with an average age of 55.77 ± 15.6 years. The average follow-up of 47.16 months. The primary clinical outcome measures were the modified Macnab criteria. Chi-square testing was employed to analyze statistically significant associations between increased dysesthesia rates, preoperative diagnosis, the surgical level(s), and surgeon technique. RESULTS: At final follow-up, Excellent (183/451; 40.6 %) and Good (195/451; 43.2 %) Macnab outcomes were observed in the majority of patients (378/451; 83.8 %). The majority of study patients (354; 78.5 %) had an entirely uneventful postoperative recovery without any DRG irritation, but 21.5 % of patients were treated for it in the immediate postoperative recovery period with supportive care measures including activity modification, transforaminal epidural steroid injections, non-steroidal anti-inflammatories, gabapentin, or pregabalin. There was no statistically significant difference in dysesthesia rates between lumbar levels from L1 to S1, or between single (DRG rate 21.8 %) or two-level (DRG rate 20.2 %) endoscopic decompression (p = 0.742). A statistically significantly higher incidence of postoperative dysesthesia was observed in patients who underwent decompression for foraminal stenosis (38/103; 27 %), and recurrent herniated disc (7/10; 41.2 %; p = 0.039). There were also statistically significant variations in dysesthesia rates between the seven participating clinical study sites ranging from 11.6%-33% (p = 0.002). Unrelenting postoperative dysesthetic leg pain due to DRG irritation was statistically associated with less favorable long-term clinical outcomes with DRG rates as high as 45 % in patients with a Fair and 61.3 % in patients with Poor Macnab outcomes (p < 0.0001). CONCLUSIONS: Postoperative dysesthesia following transforaminal endoscopic decompression should be expected in one-fifth of patients. There was no predilection for any lumbar level. Foraminal stenosis and recurrent herniated disc surgery are risk factors for higher dysesthesia rates. There was a statistically significant variation of dysesthesia rates between participating centers suggesting that the surgeon skill level is of significance. Severe postoperative dysesthesia may be a predictor of Fair of Poor long-term Macnab outcomes.

Microsurgery versus Medical Treatment for Neuropathic Pain Caused by Foraminal Extraforaminal Lumbar Disc Herniation: An Observational Study.

AIM: To investigate the incidence of neuropathic pain (NP) in patients with foraminal/extraforaminal lumbar disc herniation (FEFLDH), the prognosis of NP and the effect of microsurgery on patients treatment. MATERIAL AND METHODS: Two patient groups with FEFLDH were investigated: the surgery group underwent surgical treatment, and the medical-treated group received medical treatment. Patients were diagnosed with NP when the Self-Administered Leeds Assessment of Neuropathic Symptoms and Signs (S-LANSS) pain scale was ≥ 12 points. The NP scores were evaluated during patient admission and at 1, 6 and 12 months postoperation or during medical treatment. RESULTS: The surgery group included 37 patients (18 women, 19 men); FEFLDHs were localised at the L3-4 (n=9), L4-5 (n=23) and L5-S1 (n=5) levels. NP was detected in 16 patients before surgery (43%). The medical-treated group included 46 patients (19 women, 27 men); FEFLDHs were localised at the L2-3 (n=7), L3-4 (n=12) and L4-5 (n=27) levels. NP was detected in 20 patients before medical treatment (43%). The most common neuropathic symptom for patients was a burning sensation. NP was found more common in patients who were of at advanced age ( > 65 years) (p=0.019), had a longer clinical duration (p=0.007) or had a foraminal disc herniation (p=0.038). CONCLUSION: Chronic compression of the dorsal root ganglion by FEFLDH is a significant cause of NP. If surgical treatment is delayed for FEFLDH, the risk of persistent NP may increase.

Interleukin-6 contributes to initiation of neuronal regeneration program in the remote dorsal root ganglia neurons after sciatic nerve injury.

To assess the potential role of IL-6 in sciatic nerve injury-induced activation of a pro-regenerative state in remote dorsal root ganglia (DRG) neurons, we compared protein levels of SCG-10 and activated STAT3, as well as axon regeneration in IL-6 knockout (IL-6ko) mice and their wild-type (WT) counterparts. Unilateral sciatic nerve compression and transection upregulated SCG-10 protein levels and activated STAT3 in DRG neurons not only in lumbar but also in cervical segments of WT mice. A pro-regenerative state induced by prior sciatic nerve lesion in cervical DRG neurons of WT mice was also shown by testing for axon regeneration in crushed ulnar nerve. DRG neurons from IL-6ko mice also displayed bilaterally increased levels of SCG-10 and STAT3 in both lumbar and cervical segments after sciatic nerve lesions. However, levels of SCG-10 protein in lumbar and cervical DRG of IL-6ko mice were significantly lower than those of their WT counterparts. Sciatic nerve injury induced a lower level of SCG-10 in cervical DRG of IL-6ko than WT mice, and this correlates with significantly shorter regeneration of axons distal to the crushed ulnar nerve. These results suggest that IL-6 contributes, at the very least, to initiation of the neuronal regeneration program in remote DRG neurons after unilateral sciatic nerve injury.

Dorsal Root Entry Zone Lesion for Neuropathic Pain Due to Thoracolumbar Spine Fracture: Long-Term Result.

OBJECTIVE: To retrospectively evaluate long-term efficacy and safety of dorsal root entry zone (DREZ) lesion for treatment of neuropathic pain within the lower extremities and perineal region after thoracolumbar spine fracture. METHODS: Forty-two patients were treated with posterior laminectomy under general anesthesia. The DREZ regions of the spinal cord segments were ablated under a microscope. Data regarding pain relief, pain variation over time, and postoperative complications were collected. The relationship between injured spinal column segment, spinal cord, nerve root, and pain territory were analyzed retrospectively. RESULTS: Spinal column injury segments were located between T12 and L4. Pain territories were distributed between the T11 and S5 dermatomes with varying ranges, at an average of 2-6 segments higher than the spinal cord injury segments. Pain relief rate was 100% in 21 patients (50.0%) and was over 50% in 14 patients (33.3%). Eighteen patients (42.9%) developed temporary tingling in the upper edge of the spinal cord lesion segment after surgery. Of the 4 patients with unilateral lower extremity pain, 2 developed postoperative persistent pain in the contralateral lower extremity. CONCLUSIONS: For patients with neuropathic pain of the lower extremities and/or the perineal region after thoracolumbar spine fracture, pain within the lower extremities was mostly because of nerve root injury. Pain in the perineal region caused by L1 fracture was attributed to spinal cord injury segmental pain. Nerve root injury pain had a good prognosis after DREZ lesion; the effect of DREZ lesion for spinal cord injury segmental pain may be uncertain.

Electro-acupuncture-induced neuroprotection is associated with activation of the IGF-1/PI3K/Akt pathway following adjacent dorsal root ganglionectomies in rats.

The aim of the present study was to investigate the putative role and underlying mechanisms of insulin­like growth factor 1 (IGF­1) in mediating neuroplasticity in rats subjected to partial dorsal root ganglionectomies following electro­acupuncture (EA) treatment. The rats underwent bilateral removal of the L1­L4 and L6 dorsal root ganglia (DRG), sparing the L5 DRG, and were subsequently subjected to 28 days of EA treatment at two paired acupoints, zusanli (ST 36)­xuanzhong (GB 39) and futu (ST 32)­sanyinjiao (SP 6), as the EA Model group. Rats that received partial dorsal root ganglionectomies without EA treatment served as a control (Model group). Subsequently, herpes simplex virus (HSV)­IGF­1, HSV­small interfering (si) RNA­IGF­1 and the associated control vectors were injected into the L5 DRG of rats in the EA Model group. HSV­IGF­1 transfection enhanced EA­induced neuroplasticity, which manifested as partial recovery in locomotor function, remission hyperpathia, growth of DRG­derived spared fibers, increased expression of phosphorylated (p­) phosphatidylinositol 3­kinase (PI3K) and Akt, and increased pPI3K/PI3K and pAkt/Akt expression ratios. By contrast, HSV­siRNA­IGF­1 treatment attenuated these effects induced by HSV­IGF­1 transfection. The results additionally demonstrated that HSV­IGF­1 transfection augmented the outgrowth of neurites in cultured DRG neurons, and interference of the expression of IGF­1 retarded neurite outgrowth. Co­treatment with a PI3K inhibitor or Akt siRNA inhibited the aforementioned effects induced by the overexpression of IGF­1. In conclusion, the results of the present study demonstrated the crucial roles of IGF­1 in EA­induced neuroplasticity following adjacent dorsal root ganglionectomies in rats via the PI3K/Akt signaling pathway.

Nanoimprinted Anisotropic Topography Preferentially Guides Axons and Enhances Nerve Regeneration.

Surface topography has a profound effect on the development of the nervous system, such as neuronal differentiation and morphogenesis. While the interaction of neurons and the surface topography of their local environment is well characterized, the neuron-topography interaction during the regeneration process remains largely unknown. To address this question, an anisotropic surface topography resembling linear grooves made from poly(ethylene-vinyl acetate) (EVA), a soft and biocompatible polymer, using nanoimprinting, is established. It is found that neurons from both the central and peripheral nervous system can survive and grow on this grooved surface. Additionally, it is observed that axons but not dendrites specifically align with these grooves. Furthermore, it is demonstrated that neurons on the grooved surface are capable of regeneration after an on-site injury. More importantly, these injured neurons have an accelerated and enhanced regeneration. Together, the data demonstrate that this anisotropic topography guides axon growth and improves axon regeneration. This opens up the possibility to study the effect of surface topography on regenerating axons and has the potential to be developed into a medical device for treating peripheral nerve injuries.

Differential response of pineal microglia to surgical versus pharmacological stimuli.

Microglial cells are one of the interstitial elements of the pineal gland (PG). We recently reported the pattern of microglia colonization and activation, and microglia-Pax6+ cell interactions during normal pineal ontogeny. Here, we describe the dynamics of microglia-Pax6+ cell associations and interactions after surgical or pharmacological manipulation. In adult rats, the superior cervical ganglia (SCG) were exposed, and either bilaterally excised (SCGx) or decentralized (SCGd). In the SCGx PGs, the density of Iba1+ microglia increased after surgery and returned to sham baseline levels 13 days later. Pineal microglia also responded to SCGd, a more subtle denervation. The number of clustered Iba1+ /PCNA+ /ED1+ microglia was higher 4 days after both surgeries compared to the sham-operated group. However, the number of Pax6+ /PCNA- cells and the percentage of Pax6+ cells contacted by and/or phagocytosed by microglia increased significantly only after SCGx. Separate groups of rats were treated with either bacterial lipopolysaccharides (LPS) or doxycycline (DOX) to activate or inhibit pineal microglia, respectively. Peripheral LPS administration caused an increase in the number of clustered Iba1+ /PCNA+ /ED1+ microglial cells, and in the percentage of Pax6+ cells associated with and/or engulfed by microglia. In the LPS-treated PGs, we also noted an increase in the number of PCNA+ cells that were Iba1- within the microglial cell clusters. The density of Pax6+ cells did not change after LPS treatment. DOX administration did not influence the parameters analyzed. These data suggest that pineal microglia are highly receptive cells capable of rapidly responding in a differential manner to surgical and pharmacological stimuli.

Percutaneous dorsal root ganglion block for treating lumbar compression fracture-related pain.

BACKGROUND: The pain of acute compression fracture in the lumbar spine may be refractory to conservative treatment, and surgery is not an optimal choice for the elderly or infirm individuals. Moreover, even vertebroplasty can cause many side effects such as chemical leak, adjacent segment instability, and residual pain. Percutaneous dorsal root ganglion block (PDRGB) possibly is an alternative therapeutic option. In this study, we evaluated the efficacy of pain relief and the rate of adjacent level compression fracture in patients with acute compression fracture of the lumbar spine. METHODS: We retrospectively reviewed 40 patients with lumbar compression fracture from 2013 to 2015. The patients were treated with navigation-assisted CT-guided PDRGB with steroid at the pathological level and at the adjacent level above and below. Therapeutic response was evaluated using the Numerical Rating Scale (NRS); and an optimal, acceptable, and unfavorable outcome were analyzed. RESULTS: Among the 40 patients treated, initial pain relief on the first day was dramatic, and the average NRS did not change significantly up to the first-year follow-up. The highest percentage of a good outcome, at 90% (37.5% with an optimal outcome, 52.5% with an acceptable outcome), was reported at 1 week postoperatively. The percentage of optimal outcomes increased even at the 1-year follow-up. No adjacent compression fracture was found in the group treated with PDRGB alone at the 1-year follow-up. CONCLUSIONS: PDRGB is a simple, safe, and minimally invasive procedure that showed immediate and prolonged improvement of pain in lumbar osteoporotic compression fracture patients who failed conservative treatment or had residual pain after vertebroplasty. However, continuous medication for osteoporosis was still required.

Flexible microelectrode array for interfacing with the surface of neural ganglia.

OBJECTIVE: The dorsal root ganglia (DRG) are promising nerve structures for sensory neural interfaces because they provide centralized access to primary afferent cell bodies and spinal reflex circuitry. In order to harness this potential, new electrode technologies are needed which take advantage of the unique properties of DRG, specifically the high density of neural cell bodies at the dorsal surface. Here we report initial in vivo results from the development of a flexible non-penetrating polyimide electrode array interfacing with the surface of ganglia. APPROACH: Multiple layouts of a 64-channel iridium electrode (420 µm2) array were tested, with pitch as small as 25 µm. The buccal ganglia of invertebrate sea slug Aplysia californica were used to develop handling and recording techniques with ganglionic surface electrode arrays (GSEAs). We also demonstrated the GSEA's capability to record single- and multi-unit activity from feline lumbosacral DRG related to a variety of sensory inputs, including cutaneous brushing, joint flexion, and bladder pressure. MAIN RESULTS: We recorded action potentials from a variety of Aplysia neurons activated by nerve stimulation, and units were observed firing simultaneously on closely spaced electrode sites. We also recorded single- and multi-unit activity associated with sensory inputs from feline DRG. We utilized spatial oversampling of action potentials on closely-spaced electrode sites to estimate the location of neural sources at between 25 µm and 107 µm below the DRG surface. We also used the high spatial sampling to demonstrate a possible spatial sensory map of one feline's DRG. We obtained activation of sensory fibers with low-amplitude stimulation through individual or groups of GSEA electrode sites. SIGNIFICANCE: Overall, the GSEA has been shown to provide a variety of information types from ganglia neurons and to have significant potential as a tool for neural mapping and interfacing.

Creating a Strain Relief Loop during S1 Transforaminal Lead Placement for Dorsal Root Ganglion Stimulation for Foot Pain: A Technical Note.

Chronic neuropathic pain is often refractory to conventional medical treatments and leads to significant disability and socio-economic burden. Dorsal root ganglion (DRG) stimulation has recently emerged as a treatment for persistent neuropathic pain, but creating a strain relief loop at the S1 level has thus far been a challenging technical component of DRG lead placement. We describe a refined technique for strain relief loop formation at the S1 level using a transforaminal approach that we employed in a 45-year-old patient with intractable foot pain. We successfully placed a strain relief loop in the sacral space in a predictable and easily reproducible manner using a transforaminal anchorless approach. The patient experienced a decrease in visual analog pain score (85%), and improvement in function during the trial period, and proceeded with permanent implantation. The described sacral transforaminal strain relief loop formation technique appears to be a more reliable and predictable technique of DRG lead placement in the sacrum than those previously documented.