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Thoracic sympathetic nuclei ischemia: Effects on lower heart rates following experimentally induced spinal subarachnoid hemorrhage. Neurochirurgie 2020; 66:155-161. [PMID: 32387429 DOI: 10.1016/j.neuchi.2019.12.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 12/09/2019] [Accepted: 12/26/2019] [Indexed: 11/24/2022]
Abstract
BACKGROUND The neuropathological mechanism of heart rhythm disorders, following spinal cord pathologies, to our knowledge, has not yet been adequately investigated. In this study, the effect of the ischemic neurodegeneration of the thoracic sympathetic nuclei (TSN) on the heart rate (HR) was examined following a spinal subarachnoid hemorrhage (SSAH). METHODS This study was conducted on 22 rabbits. Five rabbits were used as a control group, five as SHAM, and twelve as a study group. The animals' HRs were recorded via monitoring devices on the first day, and those results were accepted as baseline values. The HRs were remeasured after injecting 0.5 cc of isotonic saline for SHAM and 0.5 cc of autolog arterial blood into the thoracic spinal subarachnoid space at T4-T5 for the study group. After a three-week follow-up with continuous monitoring of their HRs, the rabbit's thoracic spinal cords and stellate ganglia were extracted. The specimens were evaluated by histopathological methods. The densities of degenerated neurons in the TSN and stellate ganglia were compared with the HRs. RESULTS The mean HRs and mean degenerated neuron density of the TSN and stellate ganglia in control group were 251±18/min, 5±2/mm3, and 3±1/mm3, respectively. The mean HRs and the mean degenerated neuron density of the TSN and stellate ganglia were detected as 242±13/min, 6±2/mm3, and 4±2/mm3 in SHAM (P>0.05 vs. control); 176±19/min, 94±12/mm3, and 28±6/mm3 in the study group (P<0.0001 vs. control and P<0.005 vs. SHAM), respectively. CONCLUSIONS SAH induced TSN neurodegeneration may have been responsible for low HRs following SSAH. To date this has not been mentioned in the literature.
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Characterization of spinal subarachnoid bleeding associated to graded traumatic spinal cord injury in the rat. Spinal Cord 2014; 52 Suppl 2:S14-7. [DOI: 10.1038/sc.2014.93] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2014] [Revised: 03/31/2014] [Accepted: 05/05/2014] [Indexed: 11/08/2022]
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Jones CF, Lee JHT, Kwon BK, Cripton PA. Development of a large-animal model to measure dynamic cerebrospinal fluid pressure during spinal cord injury. J Neurosurg Spine 2012; 16:624-35. [DOI: 10.3171/2012.3.spine11970] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
Spinal cord injury (SCI) often results in considerable permanent neurological impairment, and unfortunately, the successful translation of effective treatments from laboratory models to human patients is lacking. This may be partially attributed to differences in anatomy, physiology, and scale between humans and rodent models. One potentially important difference between the rodent and human spinal cord is the presence of a significant CSF volume within the intrathecal space around the human cord. While the CSF may “cushion” the spinal cord, pressure waves within the CSF at the time of injury may contribute to the extent and severity of the primary injury. The objective of this study was to develop a model of contusion SCI in a miniature pig and establish the feasibility of measuring spinal CSF pressure during injury.
Methods
A custom weight-drop device was used to apply thoracic contusion SCI to 17 Yucatan miniature pigs. Impact load and velocity were measured. Using fiber optic pressure transducers implanted in the thecal sac, CSF pressures resulting from 2 injury severities (caused by 50-g and 100-g weights released from a 50-cm height) were measured.
Results
The median peak impact loads were 54 N and 132 N for the 50-g and 100-g injuries, respectively. At a nominal 100 mm from the injury epicenter, the authors observed a small negative pressure peak (median −4.6 mm Hg [cranial] and −5.8 mm Hg [caudal] for 50 g; −27.6 mm Hg [cranial] and −27.2 mm Hg [caudal] for 100 g) followed by a larger positive pressure peak (median 110.5 mm Hg [cranial] and 77.1 mm Hg [caudal] for 50 g; 88.4 mm Hg [cranial] and 67.2 mm Hg [caudal] for 100 g) relative to the preinjury pressure. There were no significant differences in peak pressure between the 2 injury severities or the caudal and cranial transducer locations.
Conclusions
A new model of contusion SCI was developed to measure spinal CSF pressures during the SCI event. The results suggest that the Yucatan miniature pig is an appropriate model for studying CSF, spinal cord, and dura interactions during injury. With further development and characterization it may be an appropriate in vivo largeanimal model of SCI to answer questions regarding pathological changes, therapeutic safety, or treatment efficacy, particularly where humanlike dimensions and physiology are important.
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Affiliation(s)
- Claire F. Jones
- 1Orthopaedic and Injury Biomechanics Laboratory, Departments of Mechanical Engineering and Orthopaedics,
- 2International Collaboration on Repair Discoveries, and
| | - Jae H. T. Lee
- 2International Collaboration on Repair Discoveries, and
| | - Brian K. Kwon
- 2International Collaboration on Repair Discoveries, and
- 3Combined Neurosurgical and Orthopaedic Spine Program, Department of Orthopaedics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Peter A. Cripton
- 1Orthopaedic and Injury Biomechanics Laboratory, Departments of Mechanical Engineering and Orthopaedics,
- 2International Collaboration on Repair Discoveries, and
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Maikos JT, Qian Z, Metaxas D, Shreiber DI. Finite element analysis of spinal cord injury in the rat. J Neurotrauma 2008; 25:795-816. [PMID: 18627257 DOI: 10.1089/neu.2007.0423] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A three-dimensional (3D) finite element model (FEM) that simulates the Impactor weight-drop experimental model of traumatic spinal cord injury (SCI) was developed. The model consists of the rat spinal cord, with distinct element sets for the gray and white matter, the cerebrospinal fluid (CSF), the dura mater, a rigid rat spinal column, and a rigid impactor. Loading conditions were taken from the average impact velocities determined from previous parallel weight-drop experiments employing a 2.5-mm-diameter, 10-g rod dropped from either 12.5 or 25 mm. The mechanical properties were calibrated by comparing the predicted displacement of the spinal cord at the impact site to that measured experimentally. Parametric studies were performed to determine the sensitivity of the model to the relevant material properties, loading conditions, and essential boundary conditions, and it was determined that the shear modulus had the greatest influence on spinal cord displacement. Additional simulations were performed where gray and white matter were prescribed different material properties. These simulations generated similar drop trajectories to the homogeneous model, but the stress and strain distributions better matched patterns of acute albumin extravasation across the blood-spinal cord barrier following weight-drop SCI, as judged by a logit analysis. A final simulation was performed where the impact site was shifted laterally by 0.35 mm. The off-center impact had little effect on the rod trajectory, but caused marked shifts in the location of stress and strain contours. Different combinations of parameter values could reproduce the impactor trajectory, which suggests that another experimental measure of the tissue response is required for validation. The FEM can be a valuable tool for understanding the injury biomechanics associated with experimental SCI to identify areas for improvement in animal models and future research to identify thresholds for injury.
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Affiliation(s)
- Jason T Maikos
- Department of Biomedical Engineering, Rutgers, the State University of New Jersey, Piscataway, New Jersey 08854, USA
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Abstract
Most human spinal cord injuries involve contusions of the spinal cord. Many investigators have long used weight-drop contusion animal models to study the pathophysiology and genetic responses of spinal cord injury. All spinal cord injury therapies tested to date in clinical trial were validated in such models. In recent years, the trend has been towards use of rats for spinal cord injury studies. The MASCIS Impactor is a well-standardized rat spinal cord contusion model that produces very consistent graded spinal cord damage that linearly predicts 24-h lesion volumes, 6-week white matter sparing, and locomotor recovery in rats. All aspects of the model, including anesthesia for male and female rats, age rather than body weight criteria, and arterial blood gases were empirically selected to enhance the consistency of injury.
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Affiliation(s)
- Wise Young
- W.M. Keck Center for Collaborative Neuroscience, Rutgers State University of New Jersey, 604 Allison Rd., Piscataway, NJ 08854-8082, USA.
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Martin D, Schoenen J, Delrée P, Gilson V, Rogister B, Leprince P, Stevenaert A, Moonen G. Experimental acute traumatic injury of the adult rat spinal cord by a subdural inflatable balloon: methodology, behavioral analysis, and histopathology. J Neurosci Res 1992; 32:539-50. [PMID: 1527800 DOI: 10.1002/jnr.490320409] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We describe an experimental model to produce closed traumatic injuries to the spinal cord of adult rats. This model uses an inflatable balloon that is introduced in the dorsal subdural space and moved to a location rostral to the laminectomy site. The spinal cord trauma can be graded by varying either the duration of compression or the volume of saline used to inflate the balloon. The locomotor deficit of animals with various degrees of injury has been assessed at increasing delays after trauma. The parameters generating transient or definitive deficits of varying intensity were defined. Some injured animals underwent nuclear magnetic resonance imaging. Detailed histopathological studies demonstrated that the extent of the spinal lesion was significantly correlated with the physical parameters of compression and with the severity of the behavioral deficit.
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Affiliation(s)
- D Martin
- Department of Neurosurgery, University of Liège, Belgium
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Cameron T, Prado R, Watson BD, Gonzalez-Carvajal M, Holets VR. Photochemically induced cystic lesion in the rat spinal cord. I. Behavioral and morphological analysis. Exp Neurol 1990; 109:214-23. [PMID: 2165913 DOI: 10.1016/0014-4886(90)90076-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The present study describes the production of a spinal cord lesion which is initiated by vascular occlusion resulting from the interaction between the photosensitizing dye erythrosin B and an argon laser beam. The lesion has characteristics similar to those of the central cavity thought to lead to the production of post-traumatic syringomyelia (PTS) in humans. The present study examines the behavioral and morphological characteristics of this injury over a 28-day period. Histological analysis revealed a cavity extending from the dorsal horns to lamina VIII, with some lateral and ventral pathways being spared. The cavity volume reached a maximum 7 days after lesion induction. Behavioral changes were assessed using six different tests of motor and reflex function (motor function, climbing, waterbath, inclined plane, withdrawal to pain, and withdrawal to extension). Lesioned animals exhibited flaccid paralysis for 3-5 days, which resolved afterward. The photochemically induced cavity should provide a reproducible model for examining the effects of cystic spinal cord injury on locomotor and reflex function.
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Affiliation(s)
- T Cameron
- Department of Biomedical Engineering, University of Miami, Florida
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Holtz A, Nyström B, Gerdin B, Olsson Y. Neuropathological changes and neurological function after spinal cord compression in the rat. J Neurotrauma 1990; 7:155-67. [PMID: 2258946 DOI: 10.1089/neu.1990.7.155] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
As part of a series of experimental investigations of the effects of various pharmacological agents on the outcome of compressive spinal cord trauma in the rat, the time course of the cell changes in the cord at the site of and distal to the compression was studied at the light microscopic level. The degree of compression used with the present model results in a transient paraparesis that recovers almost completely over a period of 3 weeks as judged by the inclined plane technique. The most significant morphological findings were as follows. Initially (1 and 24 h after the impact) there was pronounced swelling and hemorrhage at the compression site, chiefly in the gray matter of the cord. On day 4 there was severe necrosis in the same region, with numerous macrophages and leukocytes. Rats killed after 21 days showed either minor residual signs of necrosis or essentially normal tissue architecture. Surprisingly, necrosis with delayed onset also developed in the dorsal columns, involving the pyramidal tracts. This necrosis was detected in animals killed after 9 and 21 days but not in those observed after 4 days or earlier. The longitudinal tracts of the white matter showed reduced staining in paraffin sections of the compression site. Epon sections revealed splits in the myelin sheaths and enlarged periaxonal spaces as early as 1 h after the impact. The alterations in the longitudinal tracts persisted throughout the 21-day observation period and extended down to L2-L4. There was gradual functional recovery, documented by the inclined plane test. Preinjury values were almost reached on day 21, although the cord still showed some morphological damage. In individual animals, no relation was found between degree of function as tested by inclined plane and extent of morphologic injury. Additional functional and morphological methods obviously are needed in future investigations of the effects of treatments on the outcome of compressive spinal cord injury.
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Affiliation(s)
- A Holtz
- Department of Neurosurgery, University Hospital, Uppsala, Sweden
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Abstract
Three models of inducing spinal trauma in experimental animals--weight-dropping model, severance-by-knife model, and laceration-type-lesions model--are reviewed critically. Contributions by these models in understanding paraplegia in anatomical and pathological terms are brought out. Important distinctions between subthreshold traumas vs. threshold and suprathreshold traumas, transient and permanent paraplegic syndrome, and regeneration of served axonal fibers vs. prevention of development of permanent paraplegia, are stressed while evaluating each model of spinal trauma. Conceptual contributions by these three models and their bearing on the potential clinical applications are discussed.
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Affiliation(s)
- G D Das
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
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Sutton CH. Graded spinal cord injuries produced in rabbits with non-invasive microwave hyperthermia. THE JOURNAL OF THE AMERICAN PARAPLEGIA SOCIETY 1988; 11:41-9. [PMID: 2978418 DOI: 10.1080/01952307.1988.11735794] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The use of non-invasive microwave energy to produce spinal cord injuries with intraspinal hyperthermia was studied in experimental animals. Lesions were produced with external beam microwave irradiation at 915 MHz in rabbits, using intraspinal temperature levels from 40 to 43 degrees C., and periods of heating ranging from 15 to 60 minutes. The parameters which determined thermal dose were the degree of temperature elevation in the spinal cord relative to the body core and the duration of that elevation. Thermal dose-response relationships were established by monitoring intraspinal temperatures during heating using an epidural thermistor probe at T8. Animals were examined 48 hours after lesion production and assigned a neurological grade. Injuries were grouped clinically according to their degree of relative functional severity as minimal, mild, moderate, or severe. Evaluation of spinal cord integrity was carried out by recording cortical somatosensory evoked responses (SER) following sciatic nerve stimulation. Increased SER latencies were first observed after heating the spinal cord to 41 degrees for 60 minutes. Impulse transmission was absent after heating to 42 degrees for 30 minutes, a thermal dose which produced complete paraplegia. Morphologically, lesion size and configuration were directly related to the thermal dose used in their production. Low thermal doses produced white matter edema limited to the posterior columns, while larger doses resulted in demyelination, retrograde neuronal changes, and infarction of the dorsal half of the cord. High thermal doses also produced foci of hemorrhage in the gray and white matter of the dorsal cord. These studies suggest that reproducible spinal cord injuries with predictable levels of neurological severity can be produced by noninvasive microwave heating.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- C H Sutton
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI
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Watson BD, Prado R, Dietrich WD, Ginsberg MD, Green BA. Photochemically induced spinal cord injury in the rat. Brain Res 1986; 367:296-300. [PMID: 3697704 DOI: 10.1016/0006-8993(86)91606-9] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
We have developed in the rat a minimally invasive model of reproducible spinal cord injury initiated photochemically. With the exposed spinal column intact, 560 nm irradiation of the translucent dorsal surface induces excitation of the systemically injected dye, rose Bengal, in the spinal cord microvasculature. The resultant photochemical reaction leads to vascular stasis. Histopathological changes at 7 days include hemorrhagic necrosis of the central gray matter, edematous pale-staining white matter tracts and vascular congestion. At the level of cord irradiation (T8) the entire cord thickness is necrosed except for the periphery of the anterior funiculus. Voluntary motor function is consistently lost in the subacute phase of injury.
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Khan M, Griebel R, Rozdilsky B, Politis M. Hemorrhagic changes in experimental spinal cord injury models. Can J Neurol Sci 1985; 12:259-62. [PMID: 4052887 DOI: 10.1017/s0317167100047120] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Early hemorrhagic changes in the spinal cord were compared in three experimental spinal cord injury models in the rat in order to determine the nature and consistency of spinal cord hemorrhage following specific and quantitated forces of injury. The spinal cords were injured by weight-dropping, aneurysm clip and extradural balloon compression techniques. Hemorrhagic changes were assessed quantitatively by the image analyser at 1 and 3 hours after injury. Tissue damage was assessed by determining the percentage of total cross sectional area containing hemorrhage. The extent of hemorrhage at site of injury in the clip and balloon preparations was equal, but several times lower in the weight-drop induced injury. Within each experimental group no appreciable differences were observed at the site of injury between the 1 and 3 hours preparations. The variability of damage within experimental groups was most in the weight-dropping and balloon and least in the clip preparations. Differences were also indicated with respect to the distribution of hemorrhage in grey versus white matter. These findings may be of significance when functional recovery is considered in various experimental acute spinal cord injury models.
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Abstract
Allen's weight-drop method for producing experimental spinal cord injuries was improved by placing a curved stainless steel plate anterior to the spinal cord to provide a smooth, hard surface for the receipt of posterior cord impact. In addition, an electronic circuit was used to ensure that cord injury was produced by a single impact, thereby enhancing the reproducibility of the injury mechanism. Using a spinal cord injury model with these modifications, the author found that the recovery of hindlimb function and the histopathological appearance of the injured cord 6 weeks after upper lumbar injury were closely related to injury magnitude. The curve of functional recovery versus injury magnitude has a sharp transition centered at 10 gm X 15 cm, and indicates that an injury of 10 gm X 20 cm produces a "threshold" lesion suitable for the future evaluation of spinal cord treatment methods.
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Abstract
The 'Allen technique', a weight-drop procedure introduced in 1911, remains the most widely used technique for experimental spinal cord contusion. Control of injury severity in this procedure is achieved by alteration of the height from which the standardized weight (usually 20 g) is dropped. It has not been possible in this technique to independently vary the amount of cord compression and the initial velocity of compression, since both are related to drop-weight kinetic energy. Our approach uses a constrained stroke pneumatic impactor to afford independent control of these two parameters. Mechanical testing of the device has verified the accuracy and repeatability of impact velocity and cord compression. More importantly, a pilot series at 2 m/s contact velocity with a range of compression has demonstrated neurophysiologically distinct levels of spinal cord injury as a function of compression. This includes a 'moderate' functional injury with impaired and delayed neuronal conduction through the injury site. Such a 'moderate' injury, at the threshold between recovery and permanent cord dysfunction, is particularly promising for the study of mechanisms underlying progressive post-contusion pathology; 'moderate' injury has not been reproducibly generated in weight-drop techniques.
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Dolan EJ, Tator CH, Endrenyi L. The value of decompression for acute experimental spinal cord compression injury. J Neurosurg 1980; 53:749-55. [PMID: 7441334 DOI: 10.3171/jns.1980.53.6.0749] [Citation(s) in RCA: 144] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A clip compression method was used to produce acute spinal cord compression injury in rats. The force and duration of the spinal cord compression were independently varied, and functional recovery of the cord was assessed using the inclined plane technique. Mathematical modeling produced a curve defining the relationship between force, duration, and functional recovery for each week after injury. The study clearly showed the beneficial effect of decompression and that increasing either the force or duration of compression, or both, caused a reduction in recovery.
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