Axonal Sprouting Following Incomplete Spinal Cord Injury: An Experimental Model

Abstract

Recovery of function following incomplete spinal cord injury may in part result from growth of new connections by spared descending pathways. It has been difficult to demonstrate such anatomical reorganization with traditional anatomic techniques. This study utilizes an immunocytochemical method to demonstrate axonal growth cones within the lumbar spinal cord in rats recovering from an incomplete midthoracic spinal cord injury. Adult rats underwent subtotal section of the midthoracic cord sparing the left lateral funiculus and a portion of the left ventral funiculus. Light microscope immunocytochemistry was performed on sections of lumbar spinal cord with antibodies to identify sprouting axons. These antibodies were used to determine the distribution of growth cones on both sides of the lumbar spinal cord in experimental and control animals. Growth cones were first observed three days after the spinal cord lesion. Specific labeling, similar in appearance to previous reports of growth cone identification, was apparent within the intermediate gray and ventral horns on both sides of the cord. These data support the hypothesis of collateral sprouting distal to the lesion site following incomplete spinal cord injury. It further supports the idea that recovery of function following incomplete spinal cord injury is, in part, mediated by spared descending pathways. (J Spinal Cord Med 1997; 20:200-206)     

Long-term impacts of different posterior operations on curvature,neurological recovery and axial symptoms for multilevel cervical degenerative myelopathy

Purpose

To investigate the long-term impacts of different posterior operations on curvature, neurological improvement and axial symptoms for multilevel cervical degenerative myelopathy (CDM), and to study the relationship among loss of cervical lordosis, recovery rate and axial symptom severity.

Methods

We retrospectively reviewed 98 patients with multilevel CDM who had undergone laminoplasty (Group LP, 36 patients), laminectomy (Group LC, 30 patients), or laminectomy with lateral mass screw fixation (Group LCS, 32 patients) between January 2000 and January 2005. Loss of curvature index (CI) was measured according to the preoperative and final follow-up radiographic parameters. The recovery rate was calculated based on the Japanese Orthopedic Association (JOA) score. Axial symptom severity was quantified by Neck Disability Index (NDI).

Results

Analysis of final follow-up data showed significant differences among the three groups regarding loss of CI (F = 41.46, P < 0.001) between preoperative and final follow-up JOA scores (P < 0.001), final follow-up JOA score (F = 7.81, P < 0.001), recovery rate (F = 12.98, P < 0.001) and axial symptom severity (χ² = 18.04, P < 0.001). Loss of CI showed negative association with neurological recovery (r = −0.555, P < 0.001) and positive correlation with axial symptom severity (r = 0.696, P < 0.001).

Conclusions

Excellent neurological improvement was obtained by LP and LCS for patients with multilevel CDM, while loss of CI in groups LP and LC caused a high incidence of axial symptoms. Loss of CI was correlated with poor neurological recovery and axial symptom severity. Lateral mass screw fixation can effectively prevent loss of postoperative cervical curvature and reduce incidence of axial symptoms.     

Mapping cortical hand motor representation using TMS: A method to assess brain plasticity and a surrogate marker for recovery of function after stroke?

ObjectiveStroke is associated with reorganization within motor areas of both hemispheres. Mapping the cortical hand motor representation using transcranial magnetic stimulation may help to understand the relationship between motor cortex reorganization and motor recovery of the affected hand after stroke.MethodsA standardized review of the pertinent literature was performed.ResultsWe identified 20 trials, which analyzed the relationship between the extent and/or location of cortical hand motor representation using transcranial magnetic stimulation and motor function and recovery of the affected hand. Several correlations were found between cortical reorganization and measures of hand motor impairment and recovery.ConclusionA better understanding of the relationships between the extent and location of cortical hand motor representation and the motor impairment and motor recovery of the affected hand after stroke may contribute to a targeted use of non-invasive brain stimulation protocols. In the future motor mapping may help to guide brain stimulation techniques to the most effective motor area in an affected individual.     

Optic nerve injury demonstrated by MRI with STIR sequences

We studied nine patients with optic nerve injury associated with closed head trauma by magnetic resonance imaging (MRI) with short inversion time inversion recovery (STIR) sequences on 11 occasions from 4 days to 14 years after the injury: three studies were within 17 days and eight over 4 months to 14 years. MRI revealed abnormal high signal in 10 of the 11 injured nerves. MRI 4 days after the injury showed no abnormality.     

右美托咪啶对老年骨科手术患者全麻恢复期质量的影响

目的 评价右美托咪啶对老年骨科手术患者全麻恢复期质量的影响.方法 择期行骨科手术患者60例,ASA分级Ⅰ～Ⅲ级,年龄≥65岁,采用随机数字表法,将其随机分为3组(n=20):对照组(C组)、右美托咪啶0.25 μg/kg组(D1组)和右美托咪啶0.50 μg/kg组(D2组).C组、D1组和D2组分别于麻醉诱导前15 min静脉输注生理盐水、右美托咪啶0.25 μg/kg和0.50μg/kg( 15 ml),输注时间15 min.3组均采用全身麻醉,于切皮前即刻静脉注射氟比洛芬酯1 mg/kg.记录自主呼吸恢复时间、苏醒时间、拔除气管导管时间及全麻恢复期不良反应的发生情况,采用词语等级量表评分法(VRS)评估苏醒5min时疼痛程度.结果 与C组比较,D1组和D2组躁动、呛咳、心血管事件发生率和VRS评分降低,镇痛有效率升高,D2组苏醒时间和拔除气管导管时间延长(P＜0.05);与D1组比较,D2组苏醒时间和拔除气管导管时间延长(p＜0.05),VRS评分、镇痛有效率及不良反应发生率比较差异无统计学意义(P＞0.05).结论 全麻诱导前静脉输注右美托咪啶0.25μg/kg可改善老年骨科手术患者全麻恢复期的质量.     

振荡电场对脊髓损伤大鼠运动功能恢复和轴突再生的影响

目的:探讨振荡电场对脊髓损伤大鼠运动功能恢复和轴突再生的影响。方法:改良Allen′s打击法建立90只SD大鼠脊髓损伤模型,随机分为实验组和对照组,两组均置入刺激电极。实验组施加振荡电场干预,对照组只置入振荡电场刺激器而不给予干预。电场强度600μV/mm,振荡周期为每15min极性交替变换,供电方式为感应式供电,工作方式为大鼠清醒状态下持续刺激至实验结束。建模成功后2周、6周、12周进行BBB评分、运动诱发电位评价脊髓神经传导情况(MEP潜伏期差和波幅差);HE染色行组织学观察,神经丝蛋白(NF200)、胶质纤维酸性蛋白(GFAP)免疫组化染色,观察轴突再生情况、行轴突计数、胶质瘢痕形成和星形胶质细胞突起夹角测量,两组间比较行t检验。结果:实验组和对照组比较,2周时,BBB评分、MEP波幅差和轴突计数无差异(P>0.05),但右下肢MEP潜伏期差缩短(P<0.05)。6周和12周时,BBB评分、MEP潜伏期差和波幅差、轴突计数和星形胶质细胞突起夹角测定两组间均有显著差异(P<0.05)。12周时HE染色观察两组可见损伤部位脊髓空洞及瘢痕形成;NF染色实验组可见较多神经纤维通过损伤区;GFAP染色发现两组间IOD值测定无显著差异。结论:振荡电场可以促进脊髓损伤大鼠的脊髓传导功能改善和后肢运动功能恢复,电场作用时间需达6周以上。大鼠后肢运动功能恢复可能与振荡电场促进轴突再生、诱导其定向生长,促进星形胶质细胞线性排列等有关。     

Ketamine and midazolam is an inappropriate preinduction combination in uncooperative children undergoing brief ambulatory procedures

BACKGROUND: We prospectively studied the effects of intramuscular (i.m.) ketamine alone, or combined with midazolam, on mask acceptance and recovery in young children who were uncooperative during induction of anaesthesia. METHODS: The Institutional Review Board (IRB) approval was obtained to study 80 children, 1-3 years, scheduled for bilateral myringotomies and tube insertion (BMT). Mask induction was attempted in all the children. Those who were uncooperative were randomly assigned to one of the four preinduction treatment groups: group I, ketamine 2 mg.kg(-1); group II, ketamine 2 mg.kg(-1) combined with midazolam 0.1 mg.kg(-1); group III, ketamine 2 mg.kg(-1) with midazolam 0.2 mg.kg(-1); or group IV, ketamine 1 mg.kg(-1) with midazolam 0.2 mg.kg(-1). Anaesthesia was continued with nitrous oxide and halothane by facemask. RESULTS: Children in all treatment groups achieved satisfactory sedation in less than 3 min following the administration of the preinduction drug(s). Compared with patients who received halothane induction (comparison group), the use of ketamine alone did not significantly (P > 0.0167, a Bonferroni corrected significance level) delay recovery and discharge times (18.8 +/- 2.5 and 82.5 +/- 30.7 min vs 12.6 +/- 4.6 and 81.0 +/- 33.8 min, P = 0.030 and P = 0.941, respectively). Patients who received ketamine/midazolam combinations, however, had significantly longer recovery and discharge times vs halothane (32.3 +/- 14.0 and 128.0 +/- 36.6 min, P = 0.001, P = 0.007, respectively). These times were so clinically unacceptable, that the study had to be terminated with only 17 patients receiving study drugs. CONCLUSIONS: It is concluded that ketamine/midazolam combination is not appropriate for preinduction of anaesthesia in paediatric ambulatory patients because of unacceptably prolonged recovery and delayed discharge times.     

Postural stability in altered and unaltered sensory environments following fatiguing exercise of lower extremity joints

Investigations of postural recovery following controlled external perturbations have provided models for healthy and pathological balance behavior. Less work, however, has investigated postural responses related to internal perturbations of the balance system. In this study, lower extremity joint (knee, or ankle) and overall fatigue of the dominant leg provided the internal perturbations to the balance system. Postural sway was examined during unilateral dominant leg standing before and immediately following fatiguing exercise, as well as at 10, 20, and 30 min post-fatigue activity. Sway was measured in both firm and sway-referenced support surface (external perturbation) conditions. Both joint-localized fatigue and overall fatigue were found to induce impairments in postural control, which were further exacerbated by external postural perturbations. Follow-up pairwise comparisons indicated that these impairments persisted at 10 and 30 min post-fatigue. No differences in postural sway were found between fatigue locations or across any interactions between sway and fatigue location. The results indicated that muscular fatigue imposed a prolonged internal perturbation to postural control, regardless of any individual or combined joint fatigue localization. This global effect, combined with the prolonged impairment in postural response, provides support for critical contributions from a central mechanism to postural deficits due to fatigue.     

双水平气道正压无创通气用于老年患者全麻恢复期的呼吸支持

目的研究双水平气道正压(BiPAP)通气在老年患者全麻恢复期呼吸支持的可行性。方法30例择期手术的老年患者随机分为BiPAP组与对照组,每组15例。在术前、拔管后、吸氧或无创通气1h后三个时点比较血液动力学、动脉血气分析参数和呼吸动力学指标。结果两组患者血液动力学的各项指标在各时点差异无显著意义;BiPAP组无创通气1h后PaCO2较拔管后降低,与对照组吸氧1h后比PaCO2低;拔管后两组患者PaO2较术前降低,BiPAP组吸氧1h可提高PaO2。BiPAP无创通气1h后,VTi、VE、Cdyn升高,RAWm降低;而对照组吸氧1h后较拔管后无明显改善。结论老年患者短期BiPAP面罩支持无创通气耐受性好,对血液动力学无明显影响,可以改善通气和氧合,降低气道阻力,提高肺顺应性。