scholarly journals Increases in human motoneuron excitability after cervical spinal cord injury depend on the level of injury

2017 ◽  
Vol 117 (2) ◽  
pp. 684-691 ◽  
Author(s):  
Christine K. Thomas ◽  
Charlotte K. Häger ◽  
Cliff S. Klein
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Conduction Velocity ◽  
Spinal Injury ◽  
Cervical Spinal Cord ◽  
Motor Units ◽  
M Wave ◽  
Human Spinal Cord ◽  
Motoneuron Excitability ◽  
Cord Injury

After human spinal cord injury (SCI), motoneuron recruitment and firing rate during voluntary and involuntary contractions may be altered by changes in motoneuron excitability. Our aim was to compare F waves in single thenar motor units paralyzed by cervical SCI to those in uninjured controls because at the single-unit level F waves primarily reflect the intrinsic properties of the motoneuron and its initial segment. With intraneural motor axon stimulation, F waves were evident in all 4 participants with C4-level SCI, absent in 8 with C5 or C6 injury, and present in 6 of 12 Uninjured participants ( P < 0.001). The percentage of units that generated F waves differed across groups (C4: 30%, C5 or C6: 0%, Uninjured: 16%; P < 0.001). Mean (±SD) proximal axon conduction velocity was slower after C4 SCI [64 ± 4 m/s ( n = 6 units), Uninjured: 73 ± 8 m/s ( n = 7 units); P = 0.037]. Mean distal axon conduction velocity differed by group [C4: 40 ± 8 m/s ( n = 20 units), C5 or C6: 49 ± 9 m/s ( n = 28), Uninjured: 60 ± 7 m/s ( n = 45); P < 0.001]. Motor unit properties (EMG amplitude, twitch force) only differed after SCI ( P ≤ 0.004), not by injury level. Motor units with F waves had distal conduction velocities, M-wave amplitudes, and twitch forces that spanned the respective group range, indicating that units with heterogeneous properties produced F waves. Recording unitary F waves has shown that thenar motoneurons closer to the SCI (C5 or C6) have reduced excitability whereas those further away (C4) have increased excitability, which may exacerbate muscle spasms. This difference in motoneuron excitability may be related to the extent of membrane depolarization following SCI. NEW & NOTEWORTHY Unitary F waves were common in paralyzed thenar muscles of people who had a chronic spinal cord injury (SCI) at the C4 level compared with uninjured people, but F waves did not occur in people that had SCI at the C5 or C6 level. These results highlight that intrinsic motoneuron excitability depends, in part, on how close the motoneurons are to the site of the spinal injury, which could alter the generation and strength of voluntary and involuntary muscle contractions.

scholarly journals Locomotor Training After Human Spinal Cord Injury: A Series of Case Studies

2000 ◽  
Vol 80 (7) ◽  
pp. 688-700 ◽  
Author(s):  
Andrea L Behrman ◽  
Susan J Harkema
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Spinal Injury ◽  
Sensory Information ◽  
Locomotor Training ◽  
Overground Walking ◽  
Thoracic Spinal Cord ◽  
Human Spinal Cord ◽  
Thoracic Spinal ◽  
Cord Injury

AbstractMany individuals with spinal cord injury (SCI) do not regain their ability to walk, even though it is a primary goal of rehabilitation. Mammals with thoracic spinal cord transection can relearn to step with their hind limbs on a treadmill when trained with sensory input associated with stepping. If humans have similar neural mechanisms for locomotion, then providing comparable training may promote locomotor recovery after SCI. We used locomotor training designed to provide sensory information associated with locomotion to improve stepping and walking in adults after SCI. Four adults with SCIs, with a mean postinjury time of 6 months, received locomotor training. Based on the American Spinal Injury Association (ASIA) Impairment Scale and neurological classification standards, subject 1 had a T5 injury classified as ASIA A, subject 2 had a T5 injury classified as ASIA C, subject 3 had a C6 injury classified as ASIA D, and subject 4 had a T9 injury classified as ASIA D. All subjects improved their stepping on a treadmill. One subject achieved overground walking, and 2 subjects improved their overground walking. Locomotor training using the response of the human spinal cord to sensory information related to locomotion may improve the potential recovery of walking after SCI.

scholarly journals Multivariate Analysis of Acute Magnetic Resonance Imaging Predicts Neurological Improvements in Patients With Cervical Spinal Cord Injury After Early Surgical Decompression

Neurosurgery ◽  
2019 ◽  
Vol 66 (Supplement_1) ◽  
Author(s):  
Tomoo Inoue ◽  
Toshiki Endo ◽  
Shinsuke Suzuki ◽  
Hiroshi Uenohara ◽  
Teiji Tominaga
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Magnetic Resonance ◽  
Mr Imaging ◽  
Spinal Injury ◽  
Cervical Spinal Cord ◽  
Principal Component ◽  
Surgical Decompression ◽  
Cervical Spinal Cord Injury ◽  
Cord Injury

Abstract INTRODUCTION Patients with cervical spinal cord injury (SCI) show different clinical outcomes. There is a significant association between the acute magnetic resonance (MR) imaging of cervical SCI and neurological recovery of cervical SCI. We speculated that principal component analysis (PCA), a dimension reduction procedure, would detect clinically predictive patterns in complex MR imaging and predict neurological improvements assessed by the American Spinal Injury Association Impairment Scale (AIS) and Japanese Orthopaedic Association (JOA) score. METHODS We performed a retrospective analysis of 50 patients with cervical SCI who underwent early surgical decompression less than 48 h after the trauma. We analyzed 7 types of MR imaging assessments: axial grade assessed by the Brain and Spinal Injury Center score (BASIC), longitudinal intramedurallry lesion length, spinal cord signal intensity on T1 and T2 weighted image, maximum canal compromise, maximum spinal cord compression, Subaxial Cervical Spine Injury Classification System. PCA was applied on these multivariate data to identify factors that contribute to recovery after cervical SCI following surgery. AIS conversion was evaluated at 6 mo. RESULTS Nonlinear principal component (PC) evaluation detected 2 features of MR imaging. PCA revealed PC 1 (40.6%) explaining the intramedullary signal abnormalities that were negatively associated with postoperative AIS conversion. PC2 (18.5%) suggested extrinsic morphological variables, but did not predict outcomes. The BASIC score revealed the significant overall predictive value for AIS conversion at six months (AUC 0.86). This result suggested that the intramedullary signal abnormalities reflect delayed neurological improvements even after early surgical decompressions in patients with cervical SCI. CONCLUSION PCA could be a useful data-mining tool to show the complex relationships between acute MR imaging findings in cervical SCI. This study emphasized the importance of multivariable intramedullary MR imaging as clinical outcome predictors.

scholarly journals Epidemiological Characteristics of Spinal Cord Injury in Northwest China: A Single Hospital-based Study

2020 ◽  
Author(s):  
ZhiMeng Wang ◽  
Peng Zou ◽  
Jun-Song Yang ◽  
Ting-ting Liu ◽  
Leilei Song ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Traffic Accidents ◽  
Spinal Injury ◽  
Cervical Spinal Cord ◽  
Northwest China ◽  
Female Ratio ◽  
Hospitalization Period ◽  
Cord Injury ◽  
Epidemiological Characteristics

Abstract Background : While the cities in China in which spinal cord injury (SCI) studies have been conducted previously are at the forefront of medical care, northwest China is relatively underdeveloped economically, and the epidemiological characteristics of SCI have rarely been reported in this region. Methods : The SCI epidemiological survey software developed was used to analyze the data of patients treated with SCI from 2014 to 2018. The sociodemographic characteristics of patients, including name, age, sex, and occupation, were recorded. The following medical record data, obtained from physical and radiographic examinations, were included in the study: data on the cause of injury, fracture location, associated injuries, and level of injury. Neurological function was evaluated using the American Spinal Injury Association (ASIA) impairment scale. In addition, the treatment and complications during hospitalization were documented. Results : A total of 3,487 patients with SCI with a mean age of 39.5±11.2 years were identified in this study, the male to female ratio was 2.57:1. The primary cause of SCI was falls (low falls 47.75%, high falls 37.31%), followed by traffic accidents (8.98%) and impact with falling objects (4.39%). Of all patients, 1,786 patients (51.22%) had complications and other injuries. According to the ASIA impairment scale, the numbers of grade A, B, C, and D injuries were 747 (21.42%), 688 (19.73%), 618 (17.72%), and 1434 (41.12%), respectively. During the hospitalization period, a total of 1,341 patients experienced complications, with an percentage of 38.46%. Among all complications, pulmonary infection was the most common (437, 32.59%), followed by hyponatremia (326, 24.31%), bedsores (219, 16.33%), urinary tract infection (168, 12.53%), deep venous thrombosis (157, 11.71%), and others (34, 2.53%). Notably, among 3,487 patients with SCI, only 528 patients (15.14%) received long-term rehabilitation treatment. Conclusion : The incidence of SCI in northwest China was on the rise with higher proportion in males, fall and the MCVs were the primary causes of SCI. The occupations most threatened by SCI are farmers and workers. The investigation and analysis of the epidemiological characteristics of SCI in respiratory complications are important factors leading to death after SCI, especially when the SCI occurs in the cervical spinal cord. Finally, the significance of SCI rehabilitation should be addressed.

Twitch and Tetanic Properties of Human Thenar Motor Units Paralyzed by Chronic Spinal Cord Injury

2006 ◽  
Vol 96 (1) ◽  
pp. 165-174 ◽  
Author(s):  
C. K. Häger-Ross ◽  
C. S. Klein ◽  
C. K. Thomas
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Cervical Spinal Cord ◽  
Motor Units ◽  
Total Force ◽  
Force Output ◽  
Relative Contribution ◽  
Control Units ◽  
Cord Injury ◽  
Contraction Times

Little is known about how human motor units respond to chronic paralysis. Our aim was to record surface electromyographic (EMG) signals, twitch forces, and tetanic forces from paralyzed motor units in the thenar muscles of individuals ( n = 12) with chronic (1.5–19 yr) cervical spinal cord injury (SCI). Each motor unit was activated by intraneural stimulation of its motor axon using single pulses and trains of pulses at frequencies between 5 and 100 Hz. Paralyzed motor units ( n = 48) had small EMGs and weak tetanic forces ( n = 32 units) but strong twitch forces, resulting in half-maximal force being achieved at a median of only 8 Hz. The distributions for cumulative twitch and tetanic forces also separated less for paralyzed units than for control units, indicating that increases in stimulation frequency made a smaller relative contribution to the total force output in paralyzed muscles. Paralysis also induced slowing of conduction velocities, twitch contraction times and EMG durations. However, the elevated ratios between the twitch and the tetanic forces, but not contractile speed, correlated significantly with the extent to which unit force summated in response to different frequencies of stimulation. Despite changes in the absolute values of many electrical and mechanical properties of paralyzed motor units, most of the distributions shifted uniformly relative to those of thenar units obtained from control subjects. Thus human thenar muscles paralyzed by SCI retain a population of motor units with heterogeneous contractile properties because chronic paralysis influenced all of the motor units similarly.

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