Objectives

In order to elucidate the influence of sympathetic nerves on lumbar radiculopathy, we investigated whether sympathectomy attenuated pain behaviour and altered the electrical properties of the dorsal root ganglion (DRG) neurons in a rat model of lumbar root constriction.

The December 2014 Spine Roundup. 360 . looks at: surgeon outcomes;. complications and scoliosis surgery; is sequestrectomy enough in lumbar disc prolapse?; predicting outcomes in lumbar disc herniation; sympathectomy has a direct effect on the dorsal root ganglion; and distal extensions of fusion in adolescent idiopathic scoliosis

Purpose: Upper cervical spine stabilization in children can be challenging due to anatomic abnormalities such as incomplete posterior elements, vertebral artery variability and small patient size. Several techniques have been described for stabilization of the upper cervical spine, each with its own advantages and disadvantages. Since the introduction of the technique by Harms, many authors have shown C1 lateral mass screws to be safe and effective in the stabilization of the upper cervical spine in adults. No large series of paediatric C1 lateral mass screw fixation has been reported in the literature. The purpose of this study was to describe the indications, technique, and outcomes of C1 lateral mass screw fixation in a consecutive series of 11 paediatric patients. Method: A database generated retrospective review of all patients who underwent C1 lateral mass screw fixation as part of an upper cervical spine stabilization construct was performed. In all patients the C2 dorsal root ganglion was sacrificed. Patient demographics and clinical outcomes were obtained through chart review. Radiographs immediately post-operatively, at six-weeks, three-months, and final follow-up were reviewed. Results: Eleven consecutive paediatric patients underwent bilateral C1 lateral mass screw fixation for a variety of conditions including C1-C2 instability, deformity, congenital malformation, trauma, as well as revision surgery. The average age was 10 years (range 4 to 16 years) with a mean follow-up of 11 months (range 6 – 18 months). There were no iatrogenic vertebral artery, hypoglossal nerve or spinal cord injuries. All 11 patients had solid fusion clinically and radiographically, with no loss of fixation. The C2 dorsal root ganglion was sacrificed in all patients with resulting minor occipital parasthaesia that progressively diminished in severity. Conclusion: This is the largest series of consecutive patients reported in the literature to date showing that the technique is safe and effective, with acceptable morbidity when applied to the paediatric population. We believe that C1 lateral mass screws offer significant advantages over traditional fixation techniques when the C1 vertebra is to be included in an upper cervical instrumented construct

Introduction. In degenerative disorders of the spine such as disc herniation, intervertebral discs can affect neural tissue, which may result in pain as demonstrated in both basic science and clinical investigations. Previous in vitro and in vivo studies have shown that notochordal cells and chondrocyte-like cells in nucleus pulposus affect nervous tissue differently. The aim of the present study was to evaluate the morphology of spinal neural tissue in an in vivo rat model following application of cells derived from nucleus pulposus. Material and method. A disc herniation model in rats (n=58) was used. The L4 nerve root was exposed to a) nucleus pulposus (3mg), b) notochordal cells (25,000 cells) or c) chondrocyte-like cells (25,000 cells). Four control groups were included: 1) application of nucleus pulposus (3 mg) and mechanical displacement of the spinal nerve complex, 2) sham operated animals, 3) application of cell diluent (50 μl) and 4) naïve animals. Seven days after surgery the L4 nerve roots with their dorsal root ganglion were harvested and prepared for blinded neuropathological examinations using light microscopy. Results. Damage and loss of myelinated nerve fibers as well as epineural granulation tissue were most pronounced in the group that had been subjected to nerve root displacement and application of nucleus pulposus. There was significantly less nerve fiber damage in all other groups. The number of myelinated nerve fibers with enlarged outer Schwann cell compartment was significantly higher in all experimental groups as compared to naïve animals, except for animals in which the nerve root complex had been exposed to cell diluent, notochordal cells and chondrocyte-like cells. Discussion and Conclusion. This is the first examination nerve root and dorsal root ganglion morphology after exposure to notochordal cells and chondrocyte-like cells in an in vivo model. The results indicate that application of notochordal cells and chondrocyte-like cells, per se, do not structurally affect the myelinated nerve fibers compared to naïve animals. However, one cannot exclude that there may be physiological effects of notochordal cells and chondrocyte-like cells on nerve tissue in vivo although no morphological differences were observed with the present method. The findings in the present study support previous observations that mechanical nerve tissue displacement and application of nucleus pulposus can induce pronounced morphological nerve tissue changes. However, the combination of mechanical nerve tissue displacement and application of notochordal cells and/or chondrocyte-like cells was not tested. In conclusion, the present study suggests that mechanical nerve tissue displacement is a prerequisite for the induction of morphological changes following application of disc tissue and its components on neural tissue. Summary. The effects of notochordal cells and chondrocyte-like cells on spinal nerve tissue might be dependent on concurrent mechanical nerve tissue deformation

Background. Foraminal stenosis is often encountered in patients undergoing decompression for spinal stenosis. Given the increased resection of facets and the presence of the more sensitive dorsal root ganglion, it is hypothesized that patients with foraminal stenosis have poorer postoperative outcomes. Methods. Thirty-one patients undergoing decompression without fusion for lumbar spinal stenosis were evaluated. The degree of foraminal stenosis was determined by 2 independent reviewers for absence of fat around the nerve roots. ImageJ digital imaging software was also used to evaluate the foraminal area. Patients with foraminal stenosis were compared with those without using the Oswestry Disability Index (ODI) and a numerical pain scale for back and leg pain at a minimum of 1 year follow-up. Results. Twenty patients in the foraminal stenosis group were compared with 11 without foraminal stenosis. There were no significant differences between the 2 groups regarding age, sex, comorbidities, number of levels operated on, preoperative ODI, back pain or leg pain scores. The foraminal area was significantly smaller in the foraminal stenosis group. Patients without foraminal stenosis reported significant improvements in ODI (mean 26.0), back pain (mean 3.1) and leg pain scores (mean 5.5). Patients with foraminal stenosis reported significant improvements in ODI (mean 18.8) and leg pain (mean 2.5) but not in back pain (mean 0.3). Comparing the 2 groups, the patients with foraminal stenosis had significantly less improvement in back pain (p = 0.02) and leg pain (p = 0.02). Conclusion. The results of this study suggest that presence of foraminal stenosis is a negative predictor for successful outcome following decompression surgery. This may be related to the increased instability that occurs when a foraminotomy is required. Spinal fusion may reduce this effect, and further study is required. NO DISCLOSURES

Radiofrequency (RF) lesions have been used for over 25 years in the treatment of intractable pain of spinal origin. The conventional understanding of this technique is that the heat which is produced in the tissue surrounding the electrode tip causes destruction of nervous tissue, which in turn reduces the input of noxious nerve stimuli and alleviates pain. Neuropathic pain is usually a contra-indication to the use of RF nerve lesioning. For treatment of patients with severe radicular pain we use pulsed radiofrequency who has been recently described as a technique to apply a relatively high voltage near a nerve but without the usual effects of rise in temperature or subsequent nerve injury. This study reports the effect of pulsed RF in 21 patients with severe radicular pain who had previously failed to respond to conventional therapy. Patients and Methods: From December 2000 to August 2001, 18 patients underwent pulsed RF Rhizotomy of Dorsal Root Ganglion (DRG) of segmental N. Root of the painful dermatome. Out of them, 16 passed treatment in the lumbar area and 2 in the neck. The age of the patients ranged from 20 to 75 years (m=55.7 years). Male/female ratio was 1.4/1. 50% was previously operated (discectomy, laminectomy). No complications were seen either in the procedure or in the follow-up. Results: Out of 21 patients, 3 (14.3%) did not respond to treatment. In the remaining 18 patients Rhizotomy was successful at 3 months follow-up. Mean VAS score before procedures was 8.85 (range 7–10), after treatment 3.8 (range 0–10). Conclusion: Pulsed RF treatment is a safe, simple procedure to control radicular, neuropathic pain in the cervical, thoracic and lumbar regions. Advantages of this method:. It is non-destructive procedure and it can therefore be used for different indication which were not suitable for conventional RF. Post-procedure discomfort does occur but it is less pronounced than following conventional RF. Although permanent sensory loss is a rare complication of RF it does occur. Pulsed RF does not have this complication

Introduction Far lateral disc prolapse (also known as foraminal or extreme lateral prolapse) make up 10% of all disc herniations. In addition, far lateral disc prolapses tend to affect more proximal levels more frequently than do prolapses in the posterolateral location and they are often associated with greater radicular symptoms than typical posterolateral herniations, most likely due to involvement of the dorsal root ganglion. Surgery for far lateral disc protrusions has been associated with a less favourable outcome, perhaps due to delays in diagnosis, inadequate preoperative imaging, and postoperative instability as a result of excessive bony and facet resection during the surgical approach. Methods Twelve patients with far lateral disc herniations operated on by the senior author (RPW) fulfilled the criteria of having both pre- and postoperative Oswestry Disability Index (ODI) scores recorded at each clinic visit. Results of these cases and those of a cohort of age and sex matched patients undergoing standard posterolateral discectomy undertaken by the same surgeon were analyzed. The presence of radiculopathy pre- and postoperatively, workers compensation status, return to work, length of stay and complications, as well as any prior intervention in the form of nerve root sleeve blocks or surgery were recorded. Results Both groups were well matched in terms of age and sex. Follow up ranged from 4 to 18 months. Herniations at more proximal levels (L2/3 and L3/4) were seen more frequently in the far lateral group than in the posterolateral group. Six patients in the far lateral group had preoperative nerve root sleeve blocks compared with one in the posterolateral group. Two patients in each group had had previous (different level) surgery. Patients in each group had similar preoperative ODI scores. Both groups demonstrated a reduction in the preoperative ODI compared with the preoperative score. The mean improvement was 24 (range −26 to +62) for the far lateral group and 22 (range −6 to +46). There was no significant difference between the groups. Discussion The results of this study are encouraging with respect to surgical treatment of far lateral discs. Recent literature has questioned the efficacy of surgical intervention for this pathology. These results show that with carefully selected patients results are comparable with standard posterolateral discectomy

Summary Statement. TRPA1 antagonist reduced spontaneous excitatory postsynaptic currents of substantia gelatinosa neuron in spinal cord dorsal horn by in vivo patch-clamp analysis. TRPA1 may act as a mediator of excitatory synaptic transmission. Introduction. Little is known about the pathophysiological mechanisms of radicular pain. The substantia gelatinosa (SG) in the spinal cord dorsal horn receives primary afferent inputs, which predominantly convey nociceptive sensations. Nociceptive information is modified and integrated in the SG, suggesting that the SG may be a therapeutic target for treating radicular pain. Electrophysiological study using in vivo patch-clamp recording from SG neurons is a useful method to analyze functional properties in synaptic transmission. Transient receptor potential ankyrin 1 (TRPA1) has been widely identified in the central and peripheral nervous system such as peripheral nociceptor, dorsal root ganglion (DRG), and spinal cord dorsal horn, and is considered that they are involved in synaptic transmission of pain. However, it is still unknown about its functional role and mechanism of pain transmission in spinal cord dorsal horn. The purpose of this study is to investigate changes in excitatory synaptic transmission of SG neurons with TRPA1 antagonist and to clarify the potential role of TRPA1 in the rat spinal cord dorsal horn using in vivo patch-clamp analysis. Methods. Male Sprague-Dawley rat were divided into three experimental groups. In the root constriction (RC) group, the right L5 spinal root was ligated proximal to the DRG. The root was exposed only in the sham operation group, and no procedure was performed in the control group. In order to evaluate the excitability of the substantia gelatinosa neuron in the dorsal horn, we recorded excitatory postsynaptic currents (EPSCs) using in vivo whole-cell patch-clamp methods in each groups. Also, to clarify the function of TRPA1, we observed the change of EPSCs with application of TRPA1 antagonist (HC030031). Statistical significance was determined as P < 0.05 using Student's paired t test and one-way analysis of variance (ANOVA) followed by a Tukey–Kramer test. Results. Spontaneous EPSCs (sEPSCs) were increased in the RC group more than in the sham and control group. With application of HC030031, the frequency and amplitude of sEPSCs were significantly reduced in all three groups. The relative frequency and the relative amplitude were 81% and 89% in the RC group, 81% and 94% in the control group, 70% and 88% in the sham group, respectively. There was no statistical significant difference among the three groups. Discussion. The mechanism of synaptic transmission via TRPA1 in the spinal cord dorsal horn is considered that activated TRPA1 cause Ca. 2+. influx into presynaptic terminal and glutamate release from synaptic vesicle onto SG neuron. In the present study, sEPSCs were significantly reduced by TRPA1 antagonist not only in the RC group but also in the control group and sham group, which indicating that some TRPA1 were activated consistently in the rat spinal cord dorsal horn. It is considered that TRPA1 act as a mediator of excitatory transmission, thus, suppressing the activity of TRPA1 may lead to pain relief

Introduction: C1-2 polyaxial screw-rod fixation is a relatively new technique. While recognising the potential for inadvertent vertebral artery injury there have been few reports in the literature outlining all the possible complications. Aim:To review all cases of C1 lateral mass screw insertion with emphasis on the evaluation of the potential structures at risk during the procedure. Methods: We retrospectively reviewed all patients in our unit who has C1 lateral mass screw insertion over a 2 year period. The C1 lateral mass screw was inserted as part of an atlantoaxial stabilisation or incorporated into a modular occiput/subaxial construct. Outcome measures included clinical and radiological parameters. Clinical indicators included age, gender, neurologic status, surgical indication and the number of levels stabilised. Intraoperative complications including blood loss, vertebral artery injury or dural tears were recorded. Radiological indicators included post-operative plain radiographs to assess sagittal alignment and to check for screw malposition or construct failure. Results: A total of 18 C1 lateral mass screws were implanted in 9 patients. There were 3 male and 6 female patients who had C1 lateral mass screws inserted in this tertiary referral centre. Two patients had atlantoaxial stabilisation of a C2 odontoid fracture. There were 4 patients with rheumatoid arthritis whose C1 lateral mass screws were inserted as part of an occipitocervical or subaxial cervical stabilisation. The other pathologies included trauma and spinal tumours. There was no vertebral artery injury and no cerebrospinal fluid leak. Three patients developed post operative occipital neuralgia. This neuralgia was transient in one of the patients having settled at 6-week follow up. In the other 2 patients the neuralgia was unresolved at the time of latest follow up but was adequately controlled with appropriate pain management. Post operatively no patient had radiographic evidence of construct failure and all demostrated excellent sagittal alignment. Conclusion: It has been reported that the absence of threads on the upper portion of the long shank screw may protect against neural irritation. However insertion of the C1 lateral mass screw necessitates careful caudal retraction of the C2 dorsal root ganglion. The insertion point for the C1 lateral mass screw is at the junction of the C1 posterior arch and the midpoint of the posterior inferior part of the C1 lateral mass. Two patients in our series suffered occipital neuralgia post insertion of the C1 lateral mass screws. This highlights the potential for C2 nerve root irritation during and after the insertion of the C1 lateral mass screw

Osteoarthritis (OA) is a highly prevalent degenerative joint disorder characterized by joint pain and physical disability. Aberrant subchondral bone induces pathological changes and is a major source of pain in OA. In the subchondral bone, which is highly innervated, nerves have dual roles in pain sensation and bone homeostasis regulation. The interaction between peripheral nerves and target cells in the subchondral bone, and the interplay between the sensory and sympathetic nervous systems, allow peripheral nerves to regulate subchondral bone homeostasis. Alterations in peripheral innervation and local transmitters are closely related to changes in nociception and subchondral bone homeostasis, and affect the progression of OA. Recent literature has substantially expanded our understanding of the physiological and pathological distribution and function of specific subtypes of neurones in bone. This review summarizes the types and distribution of nerves detected in the tibial subchondral bone, their cellular and molecular interactions with bone cells that regulate subchondral bone homeostasis, and their role in OA pain. A comprehensive understanding and further investigation of the functions of peripheral innervation in the subchondral bone will help to develop novel therapeutic approaches to effectively prevent OA, and alleviate OA pain.

Cite this article: Bone Joint Res 2022;11(7):439–452.

Aims

Pigment epithelium-derived factor (PEDF) is known to induce several types of tissue regeneration by activating tissue-specific stem cells. Here, we investigated the therapeutic potential of PEDF 29-mer peptide in the damaged articular cartilage (AC) in rat osteoarthritis (OA).

The June 2012 Research Roundup³⁶⁰ looks at: platelet-rich plasma; ageing, bone and mesenchymal stem cells; cytokines and the herniated intervertebral disc; ulcerative colitis, Crohn’s disease and anti-inflammatories; the effect of NSAIDs on bone healing; osteoporosis of the fractured hip; herbal medicine and recovery after acute muscle injury; and ultrasound and the time to fracture union.

The June 2012 Spine Roundup³⁶⁰ looks at: back pain; spinal fusion for tuberculosis; anatomical course of the recurrent laryngeal nerve; groin pain with normal imaging; the herniated intervertebral disc; obesity’s effect on the spine; the medicolegal risks of cauda equina syndrome; and intravenous lidocaine use and failed back surgery syndrome.