Nerve Research Articles

Differential diagnosis of Guillain-Barré syndrome: steroid-responsive radiculopathy in Evans syndrome

Guillain-Barré syndrome is the most common acute inflammatory demyelinating peripheral nerve condition. Occasionally, other autoimmune conditions can mimic Guillain-Barré syndrome but may require different diagnostic workup and treatment. We report here two patients with Evans syndrome, a rare hematological autoimmune condition who developed a subacute inflammatory radiculopathy. Similarities and distinguishing clinical and diagnostic features are discussed.

Application of hip capsule peripheral nerve block in early analgesia in elderly patients with hip fracture

Application of hip capsule peripheral nerve block in early analgesia in elderly patients with hip fracture

Engineered Tools to Advance Cell Transplantation in the Nervous System Towards a Clinical Reality

Abstract Purpose of the Review The goal of this review is to highlight engineered tools for overcoming challenges in cell survival and engraftment for tissue regeneration and mitigation of neuropathic pain following cell transplantation for neural applications. Recent Findings There is a growing body of evidence supporting the safety of cell transplantation for the treatment of injuries to the brain, spinal cord, and peripheral nerves. However, the efficacy of these cell therapies is inconclusive, and the path forward remains unclear due to a lack of evidence of transplant survival and engraftment. Engineered biomaterials offer promising pre-clinical evidence of enhanced survival and engraftment of cells transplanted within the nervous system. Biomaterials have been used alone or in combination with drug and gene delivery to direct cell transplant outcomes and represent a future direction for clinical evaluation given pre-clinical survival rates that may eliminate reliance on systemic immunosuppression. Summary Biomaterial approaches under pre-clinical evaluation can support cell survival, localize cells in the injured tissue where they are needed, and enable tissue engraftment, yet have not advanced towards the clinic. Existing biomaterials provide passive support of survival during delivery and/or place a premium on supporting cell engraftment, but active remediation of tissue-local inflammation that inhibits transplant survival and leads to neuropathic pain has seen very little advancement in recent years. Combinatorial approaches capable of addressing challenges in both survival and engraftment of cell transplants in the nervous system represent an area for significant growth in the coming years.

Repeated intrathecal injections of peripheral nerve-derived stem cell spheroids improve outcomes in a rat model of traumatic brain injury

BackgroundTraumatic brain injury (TBI) is a major cause of disability and mortality worldwide. However, existing treatments still face numerous clinical challenges. Building on our prior research showing peripheral nerve-derived stem cell (PNSC) spheroids with Schwann cell-like phenotypes can secrete neurotrophic factors to aid in neural tissue regeneration, we hypothesized that repeated intrathecal injections of PNSC spheroids would improve the delivery of neurotrophic factors, thereby facilitating the restoration of neurological function and brain tissue repair post-TBI.MethodsWe generated PNSC spheroids from human peripheral nerve tissue using suspension culture techniques. These spheroids were characterized using flow cytometry, immunofluorescence, and reverse-transcription polymerase chain reaction. The conditioned media were evaluated in SH-SY5Y and RAW264.7 cell lines to assess their effects on neurogenesis and inflammation. To simulate TBI, we established a controlled cortical impact (CCI) model in rats. The animals were administered intrathecal injections of PNSC spheroids on three occasions, with each injection spaced at a 3-day interval. Recovery of sensory and motor function was assessed using the modified neurological severity score (mNSS) and rotarod tests, while histological (hematoxylin and eosin, Luxol fast blue staining) and T2-weighted magnetic resonance imaging analyses, alongside immunofluorescence, were conducted to evaluate the recovery of neural structures and pathophysiology.ResultsPNSC spheroids expressed high levels of Schwann cell markers and neurotrophic factors, such as neurotrophin-3 and Ephrin B3. Their conditioned medium was found to promote neurite outgrowth, reduce reactive oxygen species-mediated cell death and inflammation, and influence M1-M2 macrophage polarization. In the CCI rat model, rats receiving repeated triple intrathecal injections of PNSC spheroids showed significant improvements in sensory and motor function, with considerable neural tissue recovery in damaged areas. Notably, this treatment promoted nerve regeneration, axon regrowth, and remyelination. It also reduced glial scar formation and inflammation, while encouraging angiogenesis.ConclusionOur findings suggest that repeated intrathecal injections of PNSC spheroids can significantly enhance neural recovery after TBI. This effect is mediated by the diverse neurotrophic factors secreted by PNSC spheroids. Thus, the strategy of combining therapeutic cell delivery with multiple intrathecal injections holds promise as a novel clinical treatment for TBI recovery.

Outcome Prediction by Diffusion Tensor Imaging (DTI) in Patients with Traumatic Injuries of the Median Nerve

Background/Objectives: The accurate quantification of peripheral nerve axonal regeneration after injury is critically important. Current strategies are limited to detecting early reinnervation. DTI is an MRI modality permitting the assessment of fractional anisotropy, which increases with axonal regeneration. The aim of this pilot study is to evaluate DTI as a potential predictive factor of clinical outcome after median nerve section and microsurgical repair. Methods: We included 10 patients with a complete section of the median nerve, who underwent microsurgical repair up to 7 days after injury. The follow-up period was 1 year, including the current strategy with clinical visits, the Rosén–Lundborg score and electroneuromyography. Additionally, DTI MRI of the injured wrist was planned 1, 3 and 12 months post-operatively and once for the contralateral wrist. Results: The interobserver reliability of DTI measures was almost perfect (ICC 0.802). We report an early statistically significant increase in the fractional anisotropy value after median nerve repair, especially in the region located distal to the suture. Meanwhile, Rosén–Lundborg score gradually increased between the third and sixth month, and continued to increase between the sixth and twelfth month. Conclusions: DTI outcomes three months post-operation could offer greater predictability compared to current strategies. This would enable faster decision-making regarding the need for a potential re-operation in cases of inadequate early reinnervation.

The Combination of Proteolytic Enzyme Supplementation, Acupuncture, and Osseous Manipulation for the Treatment of Traumatic Peripheral Nerve Injury: A Case Report

This report describes the treatment of peripheral nerve injury in a 43-year-old woman using a combination of proteolytic enzymes, acupuncture, and osseous manipulation as alternatives to conventional care. Her presenting symptoms include complete loss of sensation in the superolateral left thigh and a mass of fibrotic scar tissue in the area of injury. A holistic treatment plan was created to address the underlying mechanisms of the injury. Plant-based proteolytic enzymes, bromelain and papain, were used to address tissue inflammation and reduce scar tissue formation around the nerve, acupuncture was used to regenerate the superficial nerves, and osseous manipulations were provided for structural re-alignment. After 8 weeks of treatment, the patient reported significant reduction in the size of the fibrotic mass and complete resolution of sensory loss. The fibrotic mass of tissue reduced from 6 cm to 1 cm during the treatment course. Proteolytic enzymes have wide-ranging indications; however, they have not been well studied for peripheral nerve injury, which makes this a novel indication for this natural health product. This case report found the use of proteolytic enzymes, and acupuncture, effective in treating peripheral nerve injury and provides grounds for research to treat nerve-related injuries.

The reduction of imidazole propionate induced by intermittent fasting promotes recovery of peripheral nerve injury by enhancing migration of Schwann cells

Peripheral nerve injury (PNI) accompanied with sensory and motor dysfunction has serious effect on the quality of life of patients. Intermittent fasting (IF), as a dietary pattern, has rarely been reported to influence imidazole propionate (ImP), a microbial metabolite, in vivo. To date, the link between ImP and PNI is unknown. This study aimed to explore the impact of ImP on the recovery after PNI and determine whether IF could reduce the concentration of ImP in vivo. Sciatic nerve injury rat model and RSC96 cells were utilized with 16s RNA seq, HE staining, CCK-8 assay, Western blot (WB), Transmission electron microscopy (TEM), immunofluorescence, transwell and scratch wound healing assays as read outs. WB, TEM, transwell and wound healing assay showed an inhibitory effect of ImP on autophagy and migration of Schwann cells. This negative effect on migration was reversed by rapamycin. Detection of p-Erk and p-mTOR confirmed that the MAPK/Erk/mTOR pathway was involved in this process. In vivo, IF changed the composition of gut microbiome, including bacteria related to ImP production and reduced the concentration of ImP in serum. In sum, IF influenced the composition of gut microbiome and reduced the concentration of ImP in vivo. The reduction of ImP promoted migration of SCs through enhancing autophagy which involved MAPK/Erk/mTOR pathway.

Exploring the Utility of High-Resolution Ultrasonography and Color Doppler of Peripheral Nerves in Monitoring Response to Treatment in Leprosy Patients: A Prospective, Observational Study.

Diagnosis and monitoring of nerve function impairment (NFI) presents an ongoing challenge in global leprosy control. This was a prospective, observational study in leprosy patients receiving treatment with cutaneous and neurological examinations done every 3 months for 1 year. High-resolution ultrasonography and color Doppler (HRUS-CD) was performed in all patients at baseline, completion of treatment, and anytime during the study period if a patient had deterioration of nerve function noted clinically. All peripheral nerves were assessed, and parameters studied were cross-sectional area (CSA), length of thickening, endoneural flow signals (ENFS), and distortion in fascicular symmetry. Of 54 treatment-naive leprosy patients, loss of sensation was noted in 37 (68.5%), paresthesia in 20 (37.0%), and neuropathic pain in 7 (12.9%) at baseline presentation. At end of treatment of leprosy, maximum improvement in NFI across all clinical criteria was seen in ulnar and radial nerves (P <0.05). The number of impairments on HRUS-CD decreased consistently, significantly for ulnar (P = 0.009 right ulnar, P = 0.012 left ulnar) and right radial (P = 0.025) nerves, and significant improvements in CSA and ENFS were seen across multiple nerves, which correlated with improvement in NFI as well. Abnormal HRUS-CD findings in the target nerves were significantly associated with multibacillary cases (odds ratio [OR]: 4.33; 95% CI: 0.62-30.31), those in reaction (OR: 9.42; 95% CI: 1.51-58.66), and those older than 40 years (OR: 3.14; 95% CI: 0.49-19.93). This study provides objective evidence of improvement in NFI with anti-leprosy treatment, supporting integration of HRUS-CD imaging in monitoring nerve involvement in leprosy.

Representation of bulk water flow in the goldfish (Carassius auratus) midbrain.

With the mechanosensory lateral line system, fish and semi-aquatic amphibians detect water movements and pressure gradients. Hydrodynamic information picked up by the lateral line receptors is relayed via peripheral nerves to the lateral line brainstem and from there to the midbrain torus semicircularis. Most prior electrophysiological studies of the lateral line were done under still-water conditions, even though natural environments encountered by fish include bulk-flow. Flow velocity and direction sensing are likely important to fish as they navigate variable, turbulent environments, but to date, only few studies have gathered information on the processing of bulk water flow by midbrain units. Here, we recorded from lateral line units in the torus semicircularis while presenting various bulk flow velocities in anterior-to-posterior and posterior-to-anterior flow directions. We studied (1) the temporal spike patterns of mechanosensory midbrain units, (2) the processing of bulk water flow velocity by these units, and (3) the processing of bulk water flow direction. We found that midbrain mechanosensory units alter their discharge rate during bulk water flow - some units responded to flow by increasing their discharge rate but did not vary this rate significantly with flow velocity, while others exhibited increasing discharge rates with increasing flow velocity. Units directly coding for flow direction were not found.

Pediatric Charcot-Marie-Tooth disease and peripheral nerve blocks:a retrospective cohort study of 25 patients.

Charcot-Marie-Tooth (CMT) disease is an inherited neurologic disorder characterized by progressive peripheral neuropathies. The use of peripheral nerve blocks (PNB) in patients with CMT disease has been controversial because of concerns about exacerbating existing neurologic impairments and the "double hit" hypothesis. We aimed to assess the use of PNB in pediatric patients with CMT disease undergoing orthopedic surgery to address the limited data available in the literature on this topic. In this retrospective cohort study, we included all pediatric patients with CMT disease scheduled for orthopedic surgery receiving PNB at our centre. All of the patients had preoperative neurologic exams and received one or more ultrasound-guided regional anesthesia techniques. Data extracted included details of anesthesia technique, surgical procedure, opioid consumption, and pain scores during the first three postoperative days. We also reviewed any complications such as neurologic deficits and local anesthetic toxicity. We used descriptive statistics to summarize the findings. We included 25 patients, 14 of whom (56%) presented with pre-existing neurologic deficits, primarily in the lower extremities. Postoperative assessments revealed no new neurologic impairments in 24/25 (96%) patients, with only one patient experiencing a nerve injury possibly related to the surgical procedure. Opioid consumption was low in the postanesthesia care unit and on the day of surgery. No additional complications were noted in the first 72hr after surgery. Despite concerns, PNB showed favourable outcomes in a pediatric cohort with CMT disease, with low opioid consumption and pain scores and minimal complications during follow-up. These findings match previous reports of adult patients with CMT disease and suggest that the benefits of PNB may outweigh the perceived risks in pediatric patients with CMT disease.

Diagnostic Capability of Ultrasonography in Evaluating Peripheral Nerve Injuries of the Brachial Plexus.

The purpose of this study is to determine the diagnostic capability of ultrasonography (US) in patients with suspected brachial plexus injury (BPI) to the terminal nerves by comparing physical examination (PE) findings with US, electromyography (EMG), and magnetic resonance imaging (MRI) reports. All patients at a single institution who underwent US for peripheral nerve injury of the brachial plexus and terminal nerves resulting in sensory-motor deficits from October 1, 2017 to October 31, 2023 were identified. A retrospective chart review was performed. Each PE, US, EMG, and MRI reports were given an overall rating: "normal" or "abnormal." Terminal nerves (musculocutaneous, axillary, radial, ulnar, medial) were individually assessed as "normal" or "abnormal." The interobserver agreement between reports was calculated using Cohen kappa. Specificity and sensitivity analyses were performed to determine diagnostic accuracy and were reported with 95% confidence intervals (CI). A total of 120 patients were included. Most injuries were traumatic in nature (78.8%) and were low-energy (53.8%). When each imaging modality was compared with the PE findings, EMG had the highest interobserver agreement (Cohen kappa = 0.18), followed by US (Cohen kappa = 0.10), and last MRI (Cohen kappa = 0.07). The US had the highest sensitivity (0.92, CI = 0.85, 0.96) among the 3 imaging modalities (Table 2). On US, the ulnar nerve was most commonly abnormal (n = 84, 70.0%). Ultrasonography serves as a useful adjunct in the workup of patients with suspected peripheral BPI and is reliable in localizing the pathology of injured terminal nerves in the brachial plexus.

Enhancing facial nerve regeneration with scaffold-free conduits engineered using dental pulp stem cells and their endogenous, aligned extracellular matrix.

Objective. Engineered nerve conduits must simultaneously enhance axon regeneration and orient axon extension to effectively restore function of severely injured peripheral nerves. The dental pulp contains a population of stem/progenitor cells that endogenously express neurotrophic factors (NTFs), growth factors known to induce axon repair. We have previously generated scaffold-free dental pulp stem/progenitor cell (DPSC) sheets comprising an aligned extracellular matrix (ECM). Through the intrinsic NTF expression of DPSCs and the topography of the aligned ECM, these sheets both induce and guide axon regeneration. Here, the capacity of bioactive conduits generated using these aligned DPSC sheets to restore function in critical-sized nerve injuries in rodents was evaluated.Approach. Scaffold-free nerve conduits were formed by culturing DPSCs on a substrate with aligned microgrooves, inducing the cells to align and deposit an aligned ECM. The sheets were then detached from the substrate and assembled into scaffold-free cylindrical tissues.Main results. In vitroanalyses confirmed that scaffold-free DPSC conduits maintained an aligned ECM and had uniformly distributed NTF expression. Implanting the aligned DPSC conduits across critical-sized defects in the buccal branch of rat facial nerves resulted in the regeneration of a fascicular nerve-like structure and myelinated axon extension across the injury site. Furthermore, compound muscle action potential and stimulated whisker movement measurements revealed that the DPSC conduit treatment promoted similar functional recovery compared to the clinical standard of care, autografts. Significance. This study demonstrates that scaffold-free aligned DPSC conduits supply trophic and guidance cues, key design elements needed to successfully promote and orient axon regeneration. Consequently, these conduits restore function in nerve injuries to similar levels as autograft treatments. These conduits offer a novel bioactive approach to nerve repair capable of improving clinical outcomes and patient quality of life.

Establishment of a Magnetically Controlled Scalable Nerve Injury Model.

Animal models of peripheral nerve injury (PNI) serve as the fundamental basis for the investigations of nerve injury, regeneration, and neuropathic pain. The injury properties of such models, including the intensity and duration, significantly influence the subsequent pathological changes, pain development, and therapeutic efficacy. However, precise control over the intensity and duration of nerve injury remains challenging within existing animal models, thereby impeding accurate and comparative assessments of relevant cases. Here, a new model that provides quantitative and off-body controllable injury properties via a magnetically controlled clamp, is presented. The clamp can be implanted onto the rat sciatic nerve and exert varying degrees of compression under the control of an external magnetic field. It is demonstrated that this model can accurately simulate various degrees of pathology of human patients by adjusting the magnetic control and reveal specific pathological changes resulting from intensity heterogeneity that are challenging to detect previously. The controllability and quantifiability of this model may significantly reduce the uncertainty of central response and inter-experimenter variability, facilitating precise investigations into nerve injury, regeneration, and pain mechanisms.

Single center experience with hourglass-like constriction neuropathy of suprascapular nerve.

Hourglass-like constriction (HGC) may occur in several peripheral nerves. However, data on the prognosis of motor weakness in patients with HGC of the suprascapular nerve (SSN) are limited compared with other nerves. Here, we aimed to describe the clinical and imaging features of HGC of the SSN. We retrospectively reviewed patients diagnosed with suprascapular neuropathy using magnetic resonance imaging (MRI) or electrodiagnostic studies over 16 years. After excluding extrinsic causes, patients with HGC of the SSN detected using MRI were included. Fourteen patients with HGC of the SSN were identified. MRI revealed that all HGCs were located between the origin of the SSN from the upper trunk of the brachial plexus and the suprascapular notch. Seven patients exhibited HGC precisely at the origin of the SSN from the brachial plexus. Four patients showed T2 hyperintensity of the SSN extending to the upper trunk of the brachial plexus or the extraforaminal cervical root. The initial treatments included observation (n = 1), steroid therapy (n = 12), suprascapular notch release (n = 1). Of the 12 patients with a sufficient follow-up period, nine fully recovered from motor weakness of the SSN with non-operative treatments. Six of the nine patients who recovered fully experienced their first clinical improvement more than 6 months after onset. Treatment strategies for HGC differ depending on the affected nerve. For HGC of the SSN, due to the high spontaneous recovery rate observed in our study, conservative management for at least 6 months should be initially considered.

Peripheral nerve stimulation for lower-limb postoperative recovery: A systematic review and meta-analysis of randomized controlled trials.

Patients undergoing lower-limb orthopedic surgery may experience multiple postoperative complications. Although peripheral nerve stimulation (PNS) is a promising non-pharmacological approach that has been used in lower-limb postoperative recovery, the clinical efficacy of PNS remains inconclusive. This study systematically searched three databases (PubMed, Embase, and Cochrane Library) for randomized controlled trials (RCTs) that examined the treatment effects of PNSs in patients who underwent lower-limb orthopedic surgery up to September 29, 2023. Two investigators independently identified studies, extracted data, and conducted meta-analyses with Review Manager 5.4. The outcomes were pain relief (measured by reductions in pain intensity and analgesic consumption) and functional improvements (range of motion [ROM] and length of hospitalization [LOH]). A total of 633 patients including 321 in the experimental groupsand 312 in the control groups from eight RCTs were included. PNS showed no significant effect on pain intensity, while analgesic consumption was marginally significantly reduced in the experimental group. Furthermore, no significant differences were observed regarding functional improvements in ROM or LOH after the intervention. Although PNS had no significant effect on pain relief or functional improvements, the intervention exhibited a marginally significant reduction in analgesic consumption. Future trials should be conducted with larger sample sizes, longer follow-up periods, and more varied stimulation parameters.

Using biothesiometer, Neuropathy Symptom Score, and Neuropathy Disability Score for the early detection of peripheral neuropathy: A cross-sectional study.

Patients with peripheral neuropathy could have damaged peripheral nerves, which leads to sensory and motor dysfunction. Diabetes, infections, and trauma are the major causes of peripheral neuropathy. Vibratory perception threshold (VPT) tools are commonly used to detect peripheral neuropathy. This study aims to determine the assessment of peripheral neuropathy through the different diagnostic tools in the community in Malaysia. A total number of 1283 participants were recruited from the seven retail pharmacies located in Selangor, Malaysia. The peripheral neuropathy test was conducted based on VPT tools on both feet using the digital biothesiometer. Following that, Neurological Symptom Score (NSS) and Neurological Disability Score (NDS) were taken from the participants to assess the neurological symptoms. Participants had an average age of 40.6 ± 12.9 years and were mostly of Chinese ethnicity (54.1%). The findings show that increasing age was associated with more severe peripheral neuropathy across the various assessment tools, but gender differences were found with the biothesiometer test and ethnicity has severity in the biothesiometer and disability scores. The sensitivity and specificity of the biothesiometer test were 0.63 and 0.84, respectively. The combined tool NSS and NDS had high specificity and a high positive predictive value, suggesting that it could be a reliable indicator of peripheral neuropathy when both scores are elevated. The findings show that the biothesiometer test, NSS, and NDS are considered screening VPT tools for diagnosing peripheral neuropathy. However, further evaluation and diagnostic testing are necessary in cases of a positive test result.

Vagus nerve stimulation recruits the central cholinergic system to enhance perceptual learning.

Perception can be refined by experience, up to certain limits. It is unclear whether perceptual limits are absolute or could be partially overcome via enhanced neuromodulation and/or plasticity. Recent studies suggest that peripheral nerve stimulation, specifically vagus nerve stimulation (VNS), can alter neural activity and augment experience-dependent plasticity, although little is known about central mechanisms recruited by VNS. Here we developed an auditory discrimination task for mice implanted with a VNS electrode. VNS applied during behavior gradually improved discrimination abilities beyond the level achieved by training alone. Two-photon imaging revealed VNS induced changes to auditory cortical responses and activated cortically projecting cholinergic axons. Anatomical and optogenetic experiments indicated that VNS can enhance task performance through activation of the central cholinergic system. These results highlight the importance of cholinergic modulation for the efficacy of VNS and may contribute to further refinement of VNS methodology for clinical conditions.

Abstract A041: Deciphering the bidirectional influences of sympathetic neurons and cancer associated fibroblasts and the resulting contributions to PDAC progression

Abstract The pancreatic ductal adenocarcinoma (PDAC) tumor microenvironment (TME) is innervated by a variety of peripheral nerves that are emerging as facilitators of tumor initiation, progression and metastasis. However, the influences of sympathetic nerves on the TME and how these bi-directional interactions can exacerbate PDAC progression remains unclear. Sympathetic nerves innervate both human and murine PDAC tumors and are frequently surrounded by abundant and heterogeneous cancer-associated fibroblasts (CAFs), which are known to play various crucial roles in PDAC progression. In our studies, we aim to elucidate the bidirectional CAF and sympathetic-neuron crosstalk that may promote tumor growth using a variety of in vitro coculture systems to model sympathetic-CAF interactions, as well as in vivo modeling of nerves in murine PDAC tumors. Our nerve-CAF cocultures reveal that CAFs closely and frequently interact with sympathetic nerves, and also enhance sympathetic nerve outgrowth. We further sequenced these cocultured conditions to evaluate intrinsic transcriptional changes that may be contributing to the enhanced nerve outgrowth. We identified several genes that may contribute to upregulated CAF adhesion, ECM deposition and neuroactive ligand-receptor interactions, which may also be supportive of the axon outgrowth and tumor cell growth. We are also currently characterizing human and murine PDAC samples that contain and lack sympathetic innervation to evaluate spatial phenotypic shifts within the TME. Collectively, our results suggest that this crosstalk between sympathetic neurons and CAFs may both enhance tumor innervation and tumor-promoting phenotypes in the TME, such as axonogenesis and fibrosis in PDAC. Citation Format: Ariana Sattler, Parham Diba, Tetiana Korzun, Marigold Kuykendall, Kevin MacPherson-Hawthorne, Mara Sherman, Teresa Zimmers, Sebnem E Eksi. Deciphering the bidirectional influences of sympathetic neurons and cancer associated fibroblasts and the resulting contributions to PDAC progression [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr A041.

Peripheral Nerve Blocks as a Predictor of Nerve Reconstruction Success After Major Limb Amputation

Peripheral Nerve Blocks as a Predictor of Nerve Reconstruction Success After Major Limb Amputation

10 kHz spinal cord stimulation improves metrics of spinal sensory processing in a male STZ rat model of diabetes

To explore why clinical 10 kHz spinal cord stimulation (10 kHz SCS) might improve neurological function in a model of painful diabetic neuropathy (PDN), the short-term behavioral, electrophysiological, and histological effects of 10 kHz SCS were studied using adult male streptozotocin (STZ)-induced diabetic Sprague-Dawley rats. Four testing groups were established: Naïve controls (N = 8), STZ controls (N = 7), STZ+Sham SCS (N = 9), and STZ+10 kHz SCS (N = 11). After intraperitoneal injection (60 mg/kg) of STZ caused the rats to become hyperglycemic, SCS electrodes were implanted in the dorsal epidural space over the L5-L6 spinal segments in the STZ+Sham SCS and STZ+10 kHz SCS groups and were stimulated for 14 days. The von Frey filament paw withdrawal threshold was measured weekly. At termination, animals were anesthetized and the electrophysiologic response of dorsal horn neurons (receptive field size, vibration, radiant warmth) of the ipsilateral foot was measured. Tissue from the plantar paw surface was obtained post-euthanization for intraepidermal nerve fiber density measurements. In comparison to other control groups, while no significant effect of 10 kHz SCS on peripheral intraepidermal nerve fiber density was observed, 10 kHz SCS ‘normalized’ the central neural response to vibration, receptive field, and paw withdrawal threshold, and elevated the neural response to tissue recovery from warm stimuli. These results suggest that short-term, low intensity 10 kHz SCS operates in the spinal cord to ameliorate compromised sensory processing, and may compensate for reduced peripheral sensory functionality from chronic hyperglycemia, thereby treating a broader spectrum of the sensory symptoms in diabetic neuropathy.