Effects of Anatomical Site and Loading Rate on Tensile Behavior of Fiber Bundles Isolated From Nerve Roots

2016 ◽  
Author(s):  
Atsutaka Tamura ◽  
Mizuki Sakaya ◽  
Takao Koide
Keyword(s):  
Fold Increase ◽  
Spinal Nerve ◽  
Tensile Behavior ◽  
Fiber Bundles ◽  
Anatomical Site ◽  
Human Body Model ◽  
Spinal Level ◽  
Nerve Roots ◽  
Thoracic Spinal ◽  
Significant Difference

The present study has investigated the characteristics of the tensile behavior of fiber bundles isolated from the spinal nerve roots. By conducting a series of uniaxial stretching tests at three different velocities, 0.2, 2, and 20 mm/s, we found a significant difference (P < 0.05) in failure strain (∼0.15), linear portion of elastic modulus (∼20 MPa), and tensile strength (∼2 MPa) between low (0.2 mm/s) and high (20 mm/s) loading rates. However, it was revealed that mechanical properties of fiber bundles were resultantly on the order of the same magnitude, indicating that their mechanical responses were relatively insensitive to a strain rate irrespective of a 100-fold increase in the applied stretching velocities. It was also confirmed that the “spinal level effect” does exist in the nerve roots, i.e., a fiber bundle isolated from the thoracic spinal level is the strongest in mechanical strength compared to that of the cervical and lumbar spinal levels (P < 0.01), which suggests we should pay more close attention to an anatomical site where excised samples are obtained. The mechanical data obtained here will be useful to improve a mathematical human body model and to assess the potential injury in crash simulations relevant to whiplash associated disorder.

Dynamic Tensile Behavior of Fiber Bundles Isolated From Spinal Neve Roots: Effects of Anatomical Site and Loading Rate on Mechanical Strength

2018 ◽  
Vol 1 (3) ◽  
Author(s):  
Atsutaka Tamura ◽  
Mizuki Sakaya
Keyword(s):  
Mechanical Strength ◽  
Fold Increase ◽  
Fiber Bundles ◽  
Anatomical Site ◽  
Spinal Level ◽  
Mechanical Responses ◽  
Thoracic Spinal ◽  
Significant Difference ◽  
Lumbar Spinal ◽  
Neural Fiber

We found a significant difference (P < 0.05) between the linear portion of the elastic modulus (∼20 MPa) and tensile strength (∼2 MPa) at the 0.2 mm/s (low: 0.01 s−1), 2 mm/s (medium: 0.11 s−1), and 20 mm/s (high: 1.11 s−1) loading rates by performing a series of uniaxial stretching tests. However, the mechanical properties of the neural fiber bundles were resultantly of the same magnitude, indicating that their mechanical responses were relatively insensitive to a given strain rate regardless of a 100-fold increase in the applied stretching velocities. We also confirmed that a “spinal level effect” exists in the nerve roots, i.e., a fiber bundle isolated from the lumbar spinal level is weaker in mechanical strength compared to that from the cervical and thoracic spinal levels (P < 0.05), suggesting that closer attention should be paid to an anatomical site from which test samples are excised.

Dynamic Tensile Behavior of Fiber Bundles Freshly Isolated From Nerve Roots

2017 ◽  
Author(s):  
Atsutaka Tamura ◽  
Jun-ichi Hongu ◽  
Tomomi Yamamoto ◽  
Takao Koide
Keyword(s):  
Stress Relaxation ◽  
Nerve Root ◽  
Traffic Accidents ◽  
Mechanical Damage ◽  
Tensile Behavior ◽  
Elastic Response ◽  
Fiber Bundles ◽  
Human Body Model ◽  
Nerve Roots ◽  
Time Constants

Viscoelasticity of the nerve root may play a significant role in biomechanical stability of the spine. To date, however, relatively few studies have been conducted to characterize and elucidate this complex mechanical behavior. Thus, a series of tensile stress relaxation tests with a ramp-hold phase was performed using fiber bundles isolated from the nerve roots. In addition, the current study presents the application of a curve fitting technique, i.e., a stress relaxation response of the fiber bundles was theoretically predicted based on the measured data obtained at moderate to sub-traumatic loading conditions. To do that, a least squares optimization method was employed, and we revealed that this technique is applicable to reasonably predict even an instantaneous “elastic” response as well as subsequent slow stress decay of the neural fiber bundles. The resultant fitted coefficients also suggested that the viscoelastic tensile behavior of the nerve root is mainly dominated by the long-term time constants (100–1000 s) rather than the short-term time constants (0.1–1 s). Since a mathematical human body model is a powerful tool to investigate injury mechanisms involving high-contact sports and traffic accidents, our results will be useful in predicting potential spinal injuries and alleviating mechanical damage of the nerve roots, while preventing neck/low back pain due to such traumatic events.

Spinal Nerve Origins of the Muscular Branches of the Radial Nerve

Neurosurgery ◽  
2012 ◽  
Vol 70 (6) ◽  
pp. 1438-1441 ◽  
Author(s):  
Lei Zhang ◽  
Cheng-Gang Zhang ◽  
Zhen Dong ◽  
Yu-Dong Gu
Keyword(s):  
Brachial Plexus ◽  
Radial Nerve ◽  
Compound Muscle Action Potential ◽  
Electrophysiological Study ◽  
Spinal Nerve ◽  
Posterior Interosseous Nerve ◽  
Triceps Brachii ◽  
Nerve Roots ◽  
Extensor Pollicis Longus ◽  
Significant Difference

Abstract BACKGROUND: In injuries of the lower brachial plexus, finger flexion can be restored by nerve or tendon transfer. However, there is no technique that can guarantee good recovery of finger and thumb extension. OBJECTIVE: To determine the spinal nerve origins of the muscular branches of the radial nerve and identify potential intraplexus donor nerves for neurotization of the posterior interosseous nerve in patients with lower brachial plexus injuries. METHODS: An intraoperative electrophysiological study was carried out during 16 contralateral C7 nerve transfers. The compound muscle action potential of each muscle innervated by the radial nerve was recorded while the C5-T1 nerves were individually stimulated. RESULTS: The triceps brachii muscle primarily received root contributions from C7. The C5 and C6 nerve roots displayed greater amplitudes for the brachioradialis and supinator muscles compared with those of the C7, C8, and T1 nerve roots (P &lt; .05). The extensor carpi radialis branch was innervated by C5, C6, and C7, and no significant differences were detected between them (P &gt; .05). The amplitudes obtained for the extensor digitorum communis branch were the largest from C7 and C8, without a significant difference between them (P &gt; .05), whereas the amplitudes of the extensor carpi ulnaris and extensor pollicis longus were largest from the C8 root (P &lt; .05). CONCLUSION: The supinator muscle branch is likely the best donor nerve for the repair of lower brachial plexus injuries affecting muscles that are innervated by the posterior interosseous nerve.

Intraspinal characteristics of thoracic spinal nerve roots anomalies

2019 ◽  
Vol 34 (1) ◽  
pp. 72-75
Author(s):  
Zora Haviarová ◽  
Viktor Matejčík ◽  
Roman Kuruc ◽  
Ján Líška ◽  
Filip Halgaš
Keyword(s):  
Spinal Nerve ◽  
Spinal Nerve Roots ◽  
Nerve Roots ◽  
Thoracic Spinal

737 Prediction of drop out in an adjunctive light treatment trial in patients with non-seasonal depression and evening chronotype

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A287-A288
Author(s):  
Joey W Chan ◽  
Y K Wing ◽  
S P Lam ◽  
Shirley Xin Li ◽  
J Zhang
Keyword(s):  
Clinical Characteristics ◽  
Red Light ◽  
Bright Light ◽  
Fold Increase ◽  
Light Therapy ◽  
Light Treatment ◽  
Drop Out ◽  
Sleep Diary ◽  
Significant Difference ◽  
Seasonal Depression

Abstract Introduction Drop out during treatment hampers therapeutic effect of interventions. The current study examines the possible predictors of drop out during the five-week light treatment in patients with unipolar non-seasonal depression and evening-chronotype. Methods Baseline characteristics including demographics, sleep diary parameters, light treatment prescribed, and early clinical outcomes changes were compared between the Drop out and Non drop out group. Logistic regression analysis was used to examine predictors for drop out. All data were analyzed in a modified intention to treat analysis with last observation carried forward approach. Results A total of 91 subjects (Female 79%, 46.3 ± 11.8 years old) were included in the analysis. There was no significant difference in the baseline demographic and clinical characteristics between the Drop out and Non drop out group. There was also no significant difference in the improvement of clinical parameters over the first week among the two groups. However, treatment non-adherence (in terms of compliance of less than 80% of prescribed duration) over the first treatment week predicts a five-fold increase in risk of drop out during light therapy. (OR: 5.85, CI: 1.414–24.205, p=0.015) after controlling for potential confounders including age, gender, treatment group, patient expectation, and treatment-emergent adverse events. Conclusion This study found that baseline clinical characteristics including depression severity and improvement of depressive symptoms in the initial week did not differ between the Drop out and Non drop out group. The drop out was also not affected by the type of light (dim red versus bright red light), indirectly supporting dim red light as a valid placebo in bright light therapy trial. Treatment adherence is the early phase of light treatment is an important predictor of drop out. Support (if any):

Enlarged spinal nerve roots in RASopathies: Report of two cases

2021 ◽  
Vol 64 (4) ◽  
pp. 104187
Author(s):  
Leoni Chiara ◽  
Tedesco Marta ◽  
Talloa Dario ◽  
Verdolotti Tommaso ◽  
Onesimo Roberta ◽  
...  
Keyword(s):  
Spinal Nerve ◽  
Spinal Nerve Roots ◽  
Nerve Roots

Lumbosacral intersegmental epispinal axons and ectopic ventral nerve rootlets

1987 ◽  
Vol 67 (2) ◽  
pp. 269-277 ◽  
Author(s):  
Wesley W. Parke ◽  
Ryo Watanabe
Keyword(s):  
Nerve Root ◽  
Sensory Nerve ◽  
Conus Medullaris ◽  
Spinal Nerve ◽  
Nerve Fibers ◽  
Ventral Horn ◽  
Spinal Nerve Roots ◽  
Nerve Roots ◽  
Content Type ◽  
Almost All

✓ An epispinal system of motor axons virtually covers the ventral and lateral funiculi of the human conus medullaris between the L-2 and S-2 levels. These nerve fibers apparently arise from motor cells of the ventral horn nuclei and join spinal nerve roots caudal to their level of origin. In all observed spinal cords, many of these axons converged at the cord surface and formed an irregular group of ectopic rootlets that could be visually traced to join conventional spinal nerve roots at one to several segments inferior to their original segmental level; occasional rootlets joined a dorsal nerve root. As almost all previous reports of nerve root interconnections involved only the dorsal roots and have been cited to explain a lack of an absolute segmental sensory nerve distribution, it is believed that these intersegmental motor fibers may similarly explain a more diffuse efferent distribution than has previously been suspected.

Validation of a locally derived serum calcium adjustment equation: relationship with total 25(OH) vitamin D and PTH levels

2016 ◽  
Vol 70 (1) ◽  
pp. 69-74 ◽  
Author(s):  
Jonathan Joseph Scargill ◽  
John Mark Guy
Keyword(s):  
Vitamin D ◽  
Fold Increase ◽  
Reference Interval ◽  
Albumin Concentration ◽  
Vitamin D Levels ◽  
Significant Difference ◽  
25 Oh Vitamin D ◽  
New Equation ◽  
The Uk ◽  
Adjustment Equation

AimsMany clinical laboratories in the UK use a standard equation to adjust total calcium for albumin concentration. To assess the validity of this practice, we assessed the effect of the use of a traditional and locally derived calcium adjustment equation on parathyroid hormone (PTH) and 25(OH, hydroxy) vitamin D levels.MethodsSamples requested for calcium and albumin measurement over a 6 month period that met inclusion criteria were used to derive a calcium adjustment equation (n=60 941). The traditional and locally derived calcium adjustment equations were then applied to a second cohort of adult patients that underwent calcium measurement over a 1 year period (n=275 456). Patients were classified as hypocalcaemic, normocalcaemic or hypercalcaemic using a UK Pathology Harmony adjusted calcium reference interval (2.2–2.6 mmol/L).ResultsThe local calcium adjustment equation provided a 7.1-fold reduction in the prevalence of hypocalcaemia. Patients classified as hypocalcaemic using the locally derived equation had statistically significantly lower 25(OH) vitamin D and higher PTH levels. A 2.4-fold increase in the prevalence of hypercalcaemia was also observed using the new equation, but with no significant difference in 25(OH) vitamin D or PTH levels.ConclusionsA locally derived calcium adjustment equation reclassified the calcium status of 61 278 (22%) patients. Patients classified as hypocalcaemic by the locally derived equation had significantly lower 25(OH) vitamin D and significantly higher PTH values, providing evidence that use of this adjustment equation generates adjusted calcium results of greater clinical relevance. This study provides further and novel evidence that individual laboratories should determine local equations for adjusted calcium where possible.

scholarly journals Involvement of N-methyl-d-aspartate receptors in plasticity induced by paired corticospinal-motoneuronal stimulation in humans

2018 ◽  
Vol 119 (2) ◽  
pp. 652-661 ◽  
Author(s):  
Siobhan C. Dongés ◽  
Jessica M. D’Amico ◽  
Jane E. Butler ◽  
Janet L. Taylor
Keyword(s):  
Biceps Brachii ◽  
Motor Evoked Potentials ◽  
Controlled Study ◽  
Spinal Level ◽  
Double Blind ◽  
Double Blind Placebo ◽  
Human Spinal Cord ◽  
Significant Difference ◽  
Antidromic Potentials ◽  
Dependent Mechanism

Plasticity can be induced at human corticospinal-motoneuronal synapses by delivery of repeated, paired stimuli to corticospinal axons and motoneurons in a technique called paired corticospinal-motoneuronal stimulation (PCMS). To date, the mechanisms of the induced plasticity are unknown. To determine whether PCMS-induced plasticity is dependent on N-methyl-d-aspartate receptors (NMDARs), the effect of the noncompetitive NMDAR antagonist dextromethorphan on PCMS-induced facilitation was assessed in a 2-day, double-blind, placebo-controlled experiment. PCMS consisted of 100 pairs of stimuli, delivered at an interstimulus interval that produces facilitation at corticospinal-motoneuronal synapses that excite biceps brachii motoneurons. Transcranial magnetic stimulation elicited corticospinal volleys, which were timed to arrive at corticospinal-motoneuronal synapses just before antidromic potentials elicited in motoneurons with electrical brachial plexus stimulation. To measure changes in the corticospinal pathway at a spinal level, biceps responses to cervicomedullary stimulation (cervicomedullary motor evoked potentials, CMEPs) were measured before and for 30 min after PCMS. Individuals who displayed a ≥10% increase in CMEP size after PCMS on screening were eligible to take part in the 2-day experiment. After PCMS, there was a significant difference in CMEP area between placebo and dextromethorphan days ( P = 0.014). On the placebo day PCMS increased average CMEP areas to 127 ± 46% of baseline, whereas on the dextromethorphan day CMEP area was decreased to 86 ± 33% of baseline (mean ± SD; placebo: n = 11, dextromethorphan: n = 10). Therefore, dextromethorphan suppressed the facilitation of CMEPs after PCMS. This indicates that plasticity induced at synapses in the human spinal cord by PCMS may be dependent on NMDARs. NEW & NOTEWORTHY Paired corticospinal-motoneuronal stimulation can strengthen the synaptic connections between corticospinal axons and motoneurons at a spinal level in humans. The mechanism of the induced plasticity is unknown. In our 2-day, double-blind, placebo-controlled study we show that the N-methyl-d-aspartate receptor (NMDAR) antagonist dextromethorphan suppressed plasticity induced by paired corticospinal-motoneuronal stimulation, suggesting that an NMDAR-dependent mechanism is involved.

Sign in / Sign up

Export Citation Format

Share Document