ABSTRACT
Objective To investigate biomechanical differences of two posterior occipitocervical internal fixation techniques for treating basilar invagination with atlantoaxial dislocation (BI-AAD). Methods Intra-articular cage + posterior occipital plate+C2 pedicle screw (Cage+C2PS+OP), and intra-articular cage+C1 lateral mass screw+C2PS (Cage+C1LMS+C2PS) models were established based on occipitocervical CT data of the BI-AAD and clinical operation scheme, and the stability of atlantoaxial joint and stress distribution characteristics of C2 endplate and implanted instruments under different motion states were analyzed. Results Compared with the Cage+C1LMS+C2PS model, the atlantoaxial range of motion ( ROM) under flexion, extension, lateral bending and axial rotation in the Cage+C2PS+OP model were reduced by 5. 26% , 33. 33% , 43. 75% , -5. 56% , and stress peak of screw-rod fixation system were reduced by 47. 81% , 60. 90% , 48. 45% , 39. 14% , respectively. Under two internal fixation modes, stresses of C2 endplate and cage were mainly distributed on the compressive side during the motion, and both the screw-bone interface and the caudal side of screw subjected to large loading. Conclusions Two internal fixation methods could provide similar stability. However, the stress concentration of screw-rod system was more obvious and the possibility of screw loosening and fracture was greater under Cage+ C1LMS+C2PS fixation.
ABSTRACT
Acute pain is a common complication after injury of a peripheral nerve but the underlying mechanism is obscure. We established a model of acute neuropathic pain via pulling a pre-implanted suture loop to transect a peripheral nerve in awake rats. The tibial (both muscular and cutaneous), gastrocnemius-soleus (muscular only), and sural nerves (cutaneous only) were each transected. Transection of the tibial and gastrocnemius-soleus nerves, but not the sural nerve immediately evoked spontaneous pain and mechanical allodynia in the skin territories innervated by the adjacent intact nerves. Evans blue extravasation and cutaneous temperature of the intact skin territory were also significantly increased. In vivo electrophysiological recordings revealed that injury of a muscular nerve induced mechanical hypersensitivity and spontaneous activity in the nociceptive C-neurons in adjacent intact nerves. Our results indicate that injury of a muscular nerve, but not a cutaneous nerve, drives acute neuropathic pain.
ABSTRACT
Objective@#To examine the effect of posterior reduction in atlantoaxial dislocation (AAD) associated with basilar invagination(BI) using Xuanwu occipital-cervical fusion system in single stage.@*Methods@#Thirty-seven AAD accompanied with BI cases treated at Department of Neurosurgery, Xuanwu Hospital, Capital Medical Universiy and the Second Hospital of Hebei Medical University were retrospective analyzed. There were 15 males and 22 females with age of (42.3±12.3) years (range: 18-69 years). All the cases had congenital osseous abnormalities, such as assimilation of atlas and abnormal cervical fusion. Anterior tissue was released through posterior route followed by cage implantation into facet joint and occipital-cervical fixation with cantilever technique. The clinical results were evaluated using Japanese Orthopedic Association scale(JOA) and the main radiological measurements including anterior atlantodental interval (ADI), the distance of odontoid tip above Chamberlain line, clivus-canal angle(CCA) and the length of syrinx were collected. The preoperative and postoperative JOA score and radiological measurements were compared by paired t-test.@*Results@#The mean JOA score of the patients increased from 10.5 to 14.4 at the one-year follow-up(t=14.3, P=0.00). Complete reduction of AAD and BI was achieved in 34 patients.The mean clivus-canal angle improved from (118.0±6.5) degrees preoperative to (143.7±5.0) degrees postoperative(t=6.2, P=0.00). Shrinkage of the syrinx was observed 1 week after surgery in 24 patients, and 6 months in 31 patients.Twenty-eight patients achieved bone fusion 6 months after surgery. All the patients achieved bone fusion 12 months after surgery. One-side vertebral artery occlusion was diagnosed in 1 case postoperatively for transient dizziness, and relieved in 2 weeks.Two patients developed moderate neck pain after surgery, and relieved in 1 month. No implant failure, spacer subsidence or infection was observed.@*Conclusions@#The treatment of AAD associated with BI using Xuanwu occipital-cervical fusion system from posterior approach in single stage is effective and safe. Cage implantation intraarticularly and fixation with cantilever technique achieve complete reduction in most cases.
ABSTRACT
In addition to restoration of bladder, bowel, and motor functions, alleviating the accompanying debilitating pain is equally important for improving the quality of life of patients with spinal cord injury (SCI). Currently, however, the treatment of chronic pain after SCI remains a largely unmet need. Electrical spinal cord stimulation (SCS) has been used to manage a variety of chronic pain conditions that are refractory to pharmacotherapy. Yet, its efficacy, benefit profiles, and mechanisms of action in SCI pain remain elusive, due to limited research, methodological weaknesses in previous clinical studies, and a lack of mechanistic exploration of SCS for SCI pain control. We aim to review recent studies and outline the therapeutic potential of different SCS paradigms for traumatic SCI pain. We begin with an overview of its manifestations, classification, potential underlying etiology, and current challenges for its treatment. The clinical evidence for using SCS in SCI pain is then reviewed. Finally, future perspectives of pre-clinical research and clinical study of SCS for SCI pain treatment are discussed.