Evaluation of corticospinal excitability in cervical myelopathy, before and after surgery, with transcranial magnetic stimulation: a pilot study

Purpose

A pilot study to examine the impact of cervical myelopathy on corticospinal excitability, using transcranial magnetic stimulation, and to investigate whether motor evoked potential (MEP) and silent period (SP) recruitment curve (RC) parameters can detect changes in corticospinal function pre- and post-surgery.

Methods

We studied six cervical myelopathy patients undergoing surgery and six healthy controls. Clinical and functional scores and neurophysiological parameters were examined prior to and 3 months following the surgery.

Results

MEP latencies for abductor pollicis brevis (APB) and tibialis anterior (TA) muscles and central motor conduction time were prolonged pre- and post-surgery; SP durations were differentially altered. There were significant differences in parameters of RCs for (1) MEP area in APB (max values, S50) and TA (slope) between controls and patients pre- and post-surgery and (2) SP duration in APB (max values) between patients pre-surgery and controls.

Conclusions

The findings of this pilot study suggest an uncoupling of excitatory and inhibitory pathways, which persists at 3 months following cord decompression. RCs for MEP and SP at 3 months provide more information on the functional status of the cord and prompts for a longer term follow-up.     

Study of the silent period following motor evoked potential by magnetic stimulation method

During the voluntary contraction of target muscles, a silent period is observed immediately after the motor evoked potential (MEP) is elicited by transcranial magnetic stimulation. In this study, the silent period was recorded from bilateral abductor digiti minimi (ADM) and abductor hallucis (AH) in 30 normal healthy subjects (120 extremities) and 30 patients with cervical myelopathy (120 extremities). In normal subjects, the silent period was 142.3±41.0 ms (mean±SD) for ADM, and 83.6±42.3 ms for AH. When stimulus intensity was increased from 60% to 95%, the length of the silent period increased, reaching almost maximal level. The length of the silent period correlated with stimulus intensity, but not with the contraction force of voluntary muscles. In patients with cervical myelopathy, the silent period was 69.2±27.8 ms (mean±SD) for ADM and 48.3±17.0 ms for AH, significantly shorter than in the normal subjects. We believe that the length of the silent period can be a useful parameter for indicating the function of the spinal inhibitory system. This work was presented, in part, at the 9th Annual Orthopaedic Research Meeting of the Japanese Orthopaedic Association, Kobe, Japan, 7–8 October 1994, and at the Xth International Congress of EMG and Clinical Neurophysiology, Kyoto, Japan, 15–19 October 1995.     

Does image guidance decrease pedicle screw-related complications in surgical treatment of adolescent idiopathic scoliosis: a systematic review update and meta-analysis

European Spine Journal - Surgical treatment of severe adolescent idiopathic scoliosis (AIS) with posterior spinal instrumentation and fusion with pedicle screws is common, requiring careful screw...     

Screws versus hooks: implant cost and deformity correction in adolescent idiopathic scoliosis

Objective  

To compare the costs of two spinal implants—hook and hybrid constructs and pedicle screw constructs—in posterior spinal fusion for adolescent idiopathic scoliosis (AIS) as they relate to intraoperative deformity correction.     

经颅刺激运动诱发电位联合体感诱发电位监测在特发性脊柱侧凸矫形手术中应用的研究

背景：特发性脊柱侧凸手术治疗中神经功能障碍是最应受到关注的并发症,术中神经功能监测可帮助早期发现可能的神经功能损伤。目的：分析联合应用经颅刺激运动诱发电位（TcMEP）和体感诱发电位（SEP）的多模式术中神经功能监测在特发性脊柱侧凸矫形手术中对预测医源性神经功能损害的作用。方法：在特发性脊柱侧凸矫形手术中,运用TcMEP和（或）SEP进行神经功能监测。MEP监测采用经颅刺激C3、C4,记录外周肌源性MEP,SEP监测采用刺激双侧胫后神经,记录电极采用Cz—CPz。阳性诊断标准：与基线相比,MEP波幅下降75％,SEP波幅下降50％。结果：112例特发性脊柱侧凸患者中,联合MEP、SEP监测的检出率为100％。MEP监测阳性6例,假阳性1例。1例出现一过性神经功能障碍。MEP的监测敏感性为100％,特异性为99％;SEP监测敏感性50％,特异性为100％;联合MEP、SEP监测的敏感性、特异性均为100％。结论：特发性脊柱侧凸矫形手术中MEP＋SEP的术中神经功能监测可提高监测敏感性及特异性,可预测术中神经功能损伤事件的发生。MEP是多模式监测的基础,SEP是重要补充。单独应用MEP监测在特发性脊柱侧凸患者手术中有应用前景。     

Melatonin and adolescent idiopathic scoliosis: The present evidence

IntroductionAdolescent idiopathic scoliosis (AIS) is a multifactorial condition with genetic predisposing factors, and several causes have been put forward for its aetiopathogenesis, including possible hormonal dysfunction. Melatonin seems to play significant role in AIS.MethodsA systematic search in different database, to July 2021, was performed to define the role of melatonin in the pathophysiology of adolescent idiopathic scoliosis. Eight suitable studies were identified.ResultsThe concentration and rhythm of melatonin secretion can play an important role by influencing the pathogenesis of adolescent idiopathic scoliosis.ConclusionsAlthough there are many alterations of melatonin in subjects with adolescent idiopathic scoliosis, the many variables present do not allow to establish a direct cause–effect relationship.Level of evidenceLevel IV.     

Molekulare und genetische Aspekte der idiopathischen Skoliose

Spinal deformities, and particularly scoliosis, are the most frequent forms of orthopedic deformities in children and adolescents. About 1–6% of the population has scoliosis. This disorder leads to severe spinal deformities and predominantly affects adolescent girls. Although the multifactorial origin of adolescent idiopathic scoliosis (AIS) is broadly recognized, the genetic causes of AIS are still largely unknown. Our previous studies suggested a generalized dysfunction of melatonin transduction (the hormone that is primarily produced in the brain and epiphysis). In the meantime we have demonstrated that such a defect of signal transduction is caused by chemical alterations, which inactivate the function of the inhibitory G protein-coupled melatonin receptors. This discovery has led to the development of the first blood test to detect children without symptoms who are at risk of developing scoliosis. Since a single function (cellular reaction to melatonin) is determined, the unique advantage of this test is that it can be performed without knowledge of mutations in defective genes that could provoke the onset of AIS.     

青少年特发性脊柱侧凸与神经源性脊柱侧凸患者椎体和椎间盘的楔形变及其临床意义

目的:观察青少年特发性脊柱侧凸(adolescent idiopathic scoliosis,AIS)与神经源性脊柱侧凸(neurological scoliosis,NS)患者的椎体和椎间盘的楔形变情况,探讨其临床意义。方法:对35例AIS患者和31例NS患者(继发于Chiari畸形)应用Cobb法测量胸椎和腰椎每个侧凸范围内顶椎及其上、下各两个椎体和相应椎间盘的楔变角,计算其占整个侧凸角度的百分比(楔变率),得出侧凸范围内5个椎体的平均楔变率和4个椎间盘的平均楔变率。应用SPSS10.0统计软件进行统计分析,组间比较采用单因素方差分析。结果:相同病因、相同侧凸部位、相同Cobb角分组情况下,椎体与椎间盘的楔变率存在显著性差异(P0.05)。相同病因、相同侧凸部位,Cobb角60°组的椎体楔变率和椎间盘楔变率与Cobb角≥60°组比较均无显著性差异(P0.05)。相同侧凸部位、相同Cobb角分组,AIS组椎体和椎间盘的楔变率分别与NS组比较均无显著性差异(P0.05)。结论:AIS与NS患者椎体与椎间盘的相对楔形变方式相同,AIS患者的椎体楔形变可能是继发的。在治疗脊柱侧凸时,即便是较小角度的脊柱侧凸,都应该考虑到其存在椎体和椎间盘的楔形变。     

Neurophysiological mechanism of the unloading reflex as a prognostic factor in the early stages of idiopathic adolescent scoliosis

This paper presents a new neurophysiological method of evaluating the risk of progression in idiopathic scoliosis in the early stages of the disease, by investigating the unloading reflex in paraspinal muscles. The study included 394 patients with scoliosis and 70 healthy children. Latency of the unloading reflex and repeatability of the rebound and silent period were analysed for each reflex evoked. Prolonged latency and minimal number of cycles are the most important factors in the evaluation of progressive idiopathic scoliosis. The method can be used to detect progressive idiopathic scoliosis in the early stages of the disease. The high sensitivity of the method means it can be used as a basis on which to take an early decision to perform surgery.     

Multisurgeon assessment of surgical decision-making in adolescent idiopathic scoliosis: curve classification, operative approach, and fusion levels.

STUDY DESIGN: A multisurgeon assessment of curve classification, selection of operative approach, and fusion levels via a case study presentation. OBJECTIVES: To evaluate the ability of a group of scoliosis surgeons, not involved in the development of a new classification system, to accurately choose the corresponding curve classification of adolescent idiopathic scoliosis (AIS) cases and to evaluate the variability in the selection of operative approaches and both proximal and distal fusion levels in accordance with the new classification system in operative adolescent idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Recent evaluations using the King method for classifying AIS has shown poor intraobserver and interobserver reliability. A new, comprehensive classification system of AIS has been developed, but the result of a scoliosis surgeon's ability to apply the objective classification is unknown. In the surgical treatment of AIS, there are three choices for the operative approach (anterior, posterior, or both) and multiple choices for the selection of fusion levels. METHODS: During an AIS roundtable discussion at a spinal surgery meeting, 28 scoliosis surgeons were presented seven cases of operative AIS via good quality slides. Standard preoperative radiographs and clinical photographs were presented, and the reviewers were asked to classify the cases by a new classification system, choose their preferred surgical approach, and classify both proximal and distal fusion levels. RESULTS: For the seven cases presented, 84% of the curve types, 86% of lumbar modifiers, and 90% of sagittal thoracic modifiers were classified by the reviewers as described in the new classification. The case study found widely variable operative approaches and fusion levels chosen by the reviewers. There was an average of five different proximal (range, 4-8) and four different distal (range, 3-5) fusion levels chosen by the reviewers for each case. CONCLUSIONS: This case study assessment found a relatively high rate (84-90%) of agreement in curve classification of the individual components of a new classification system of AIS. This suggests the ability of a group of scoliosis surgeons to identify the specific criteria necessary for this new classification system of AIS. In addition, the high variability in selection of both operative approach and fusion levels confirms the current lack of standardized treatment paradigms. This further reinforces the need for a method to critically and objectively evaluate these variable treatments to determine the "best" radiographic and clinical results.     

Curve correction effect of rigid spinal orthosis in different recumbent positions in adolescent idiopathic scoliosis (AIS): a pilot MRI study

In this pilot cross-sectional study, the effectiveness of rigid spinal orthoses in the correction of spinal curvature of 14 patients with moderate adolescent idiopathic scoliosis (AIS) at different recumbent positions (supine, prone, right and left decubitus) was investigated. Using magnetic resonance (MR) imaging and multi-planar reconstruction technique, evaluation of the scoliotic spine in the coronal, sagittal and axial planes and the effect of spinal orthosis on AIS at different recumbent positions was studied. There was significant reduction of coronal Cobb's angle (p < 0.05) with bracing at all four recumbent positions and the maximal reduction was found in the prone position (18% reduction). The sagittal Cobb's angle was only significantly reduced at the supine position while the axial rotation did not change significantly in all positions.     

Preserved cutaneous silent period in cervical root avulsion

Objective: Brachial plexus injuries are usually severe and involve the entire brachial plexus, sometimes occurring with root avulsions. Imaging and electrodiagnostic studies are an essential part of the lesion evaluation; however, the results sometimes show a discrepancy. The cutaneous silent period (SP) is a spinal inhibitory reflex mediated by small-diameter A-delta nociceptive fibers. The aim of the study was to determine if cutaneous SP testing may serve as a useful aid in evaluation of brachial plexus injury and/or in the diagnosis of root avulsion.

Methods: In 19 patients with traumatic brachial plexus injury (15 males, age 18–62 years) we performed a clinical examination, CT myelography and neurophysiological testing. A needle EMG was obtained from muscles supplied by C5-T1 myotomes. Cutaneous SP was recorded after painful stimuli were delivered to the thumb (C6 dermatome), middle (C7) and little (C8) fingers while subjects maintained voluntary contraction of intrinsic hand muscles.

Results: Electrodiagnostic and imaging studies confirmed root avulsion (partial or total) maximally involving C5, C6 roots in 12 patients, whereas only in 4 of them the cutaneous SP was partially absent. In the remaining subjects, the cutaneous SP was preserved.

Conclusion: In brachial plexopathy even with plurisegmental root avulsion, the cutaneous SP was mostly preserved. This method cannot be recommended as a reliable test for diagnosis of single root avulsion; however, it can provide a quick physiological confirmation of functional afferent A-delta fibers through damaged roots and/or trunks. The clinicians may add this test to the diagnosis of spinal cord dysfunction.     

Extreme long-term outcome of operatively versus conservatively treated patients with adolescent idiopathic scoliosis

European Spine Journal - We report on outcomes of surgically versus (vs) non-surgically treated patients with moderate adolescent idiopathic scoliosis (AIS) after minimum of 29&nbsp;years. AIS...     

The aetiology of idiopathic scoliosis: biomechanical and neuromuscular factors

The aetiology of adolescent idiopathic scoliosis (AIS) remains an enigma. In the literature there are two opinions: one believes a deviating growth pattern is responsible for the condition – patients with AIS tend to be growing faster/be taller – while the other opinion assumes that the growth pattern is normal, but its presence is necessary to allow the development of the scoliosis. We discuss the two stage hypothesis: the natural history of AIS involves an initial stage in which a small curve develops due to a small defect in the neuromuscular control system and a second stage during adolescent growth in which the scoliotic curve is exacerbated by biomechanical factors. Received: 4 March 1999 Revised: 27 January 2000 Accepted: 4 February 2000     

褪黑素受体1A基因多态性与青少年特发性脊柱侧凸相关性研究

目的研究褪黑素受体1A基因（MTNR1A）多态性与青少年特发性脊柱侧凸（AIS）发生发展的关系。方法共纳入226例AIS患者及277例正常对照者。记录AIS患者组最大Cobb角。采用PCR-RFLP的方法对MTNR1A基因启动子区域多态性位点rs2119882进行基因分型。结果AIS患者组MTNR1A基因多态性位点rs2119882的基因型及等位基因分布与正常对照组比较没有明显差异。在AIS组内,多态性位点rs2119882不同基因型所对应的最大Cobb角没有明显差异。结论MTNR1A基因rs2119882位点多态性与AIS的发生发展都没有关系。     

Restoration of thoracic kyphosis in adolescent idiopathic scoliosis with patient-specific rods: did the preoperative plan match postoperative sagittal alignment?

European Spine Journal - To determine if the planned sagittal profile for thoracic kyphosis (TK) restoration was achieved after adolescent idiopathic scoliosis (AIS) surgery using a novel hybrid...     

青少年脊柱侧弯的研究进展

【摘要】〓脊柱侧弯类型包括功能性脊柱侧弯及结构性脊柱侧弯。特发性脊柱侧弯属结构性脊柱侧弯,约占全部脊柱侧弯80%左右,是临床中最常见的结构性脊柱侧弯。青少年特发性脊柱侧弯(AIS)影响了约0.5%~3%的学生,由于中国的教育发展,中小学生的学习压力不断增加,相信AIS发病率可能进一步升高。脊柱侧弯的预后关键在于早期发现,早期干预。早期发现的最有效途径应该是普查,且早期畸形不明显亦无脊柱结构的变化,易于矫正。     

Preoperative radiological and electrophysiological evaluation in 100 adolescent idiopathic scoliosis patients

This is a prospective study of spinal magnetic resonance imaging (MRI), electrophysiological recordings, and neurological examinations of 100 patients admitted for surgery for adolescent idiopathic scoliosis (AIS), which was conducted to assess the prevalence of structural and functional abnormalities within the spinal cord in patients with clinically normal neurologic condition. In all patients the clinical diagnosis and intact neurological condition was ascertained by a spinal orthopedic surgeon. Full-length spinal axis MRI studies (T1/T2 sequences) and somato-sensory evoked potentials of the tibial nerves (tSSEPs) were preoperatively assessed by independent evaluators blinded to the patients' medical histories. Structural spinal cord abnormalities were found in three of 100 AIS patients on MR imaging. In one patient a Chiari malformation type 1 with an accompanying syringomyelia was diagnosed, which required a suboccipital decompression. In the other two patients small thoracic syringomyelias were diagnosed. Abnormalities of spinal cord function were detected in 68% of the 100 patients: tSSEP latencies corrected for body height were increased in 56% of the patients; pathological differences between tSSEPs on the left and right sides were present in 17% (12% in combination with a prolongation of the latency). The findings of this study indicate that MRI and electrophysiological examinations are essential to assess spinal cord abnormalities that are clinically not detectable in AIS patients. Even in patients with intact neurologic condition and clinically typical right-curved thoracic scoliosis, the possibility of intraspinal pathologies should be ruled out by MRI. It is especially important to detect structural pathologies like syringomyelia and Chiari malformation before proceeding with scoliosis surgery, as these conditions are associated with a higher neurological risk during scoliosis surgery. The electrophysiological recordings made in the present study, with the high number of pathological tSSEPs, are indicative of functional abnormalities with a subclinical involvement of the recorded neuronal pathways. The relevance of the latter findings is not yet clear, but pre-operative tSSEP examinations offer the possibility of assessing alterations in spinal cord function that are undetectable by clinical examination.     

Idiopathic scoliosis: etiological concepts and hypotheses

Scoliosis is diagnosed as idiopathic in 70 % of structural deformities affecting the spine in children and adolescents, probably reflecting our current misunderstanding of this disease. By definition, a structural scoliosis should be the result of some primary disorder. The goal of this article is to give a comprehensive overview of the currently proposed etiological concepts in idiopathic scoliosis regarding genetics, molecular biology, biomechanics, and neurology, with particular emphasis on adolescent idiopathic scoliosis (AIS). Despite the fact that numerous potential etiologies for idiopathic scoliosis have been formulated, the primary etiology of AIS remains unknown. Beyond etiology, identification of prognostic factors of AIS progression would probably be more relevant in our daily practice, with the hope of reducing repetitive exposure to radiation, unnecessary brace treatments, psychological implications, and costs-of-care related to follow-up in low-risk patients.     

青少年特发性脊柱侧凸女性患者瘦素基因启动子区-2548G/A基因多态性研究

目的:探讨瘦素基因启动子区-2548G/A(rs7799039)基因多态性与女性青少年特发性脊柱侧凸(adolescent idiopathic scoliosis,AIS)发生发展、异常生长模式及侧凸类型之间的相关性。方法:收集451例AIS女性患者及335例正常同龄女性青少年的静脉血标本,采用PCR-RFLP方法对两组的瘦素基因启动子区-2548G/A(rs7799039)多态性位点进行基因分型,比较两组间基因分型的差异,分析AIS组中基因分型与患者Cobb角和人体测量学指标的关系。结果:AIS组rs7799039位点基因型和等位基因频率与正常对照组之间无明显差异;在AIS组内,rs7799039位点不同基因型所对应的初诊Cobb角、校正身高、BMI、月经初潮年龄及Risser征均没有显著性差异;rs7799039位点等位基因多态性分布情况在不同侧凸类型AIS患者和对照组之间无统计学差异。结论:瘦素基因启动子区-2548G/A(rs7799039)基因多态性与女性AIS的发生发展、异常生长模式及不同侧凸类型之间都没有明显的相关性。