Neurophysiological identification of long sensory and motor tracts within the spinal cord

Examination of repaired spinal cord tracts has usually required separate groups of animals for anterograde and retrograde tracing owing to the incompatibility of techniques such as tissue fixation. However, anterograde and retrograde labeling of different animals subjected to the same repair may not allow accurate examination of that repair strategy because widely variable results can occur in animals subjected to the same strategy. We have developed a reliable method of labeling spinal cord motor tracts bidirectionally in the same animal using DiI, a lipophilic dye, to anterogradely label the corticospinal tract and Fluoro-Gold (FG) to retrogradely label cortical and brainstem neurons of several spinal cord motor tracts in normal and injured adult rats. Other tracer combinations (lipophilic dyes or fluorescent dextrans) were also investigated but were less effective. We also developed methods to minimize autofluorescence with the DiI/FG technique, and found that the DiI/FG technique is compatible with decalcification and immunohistochemistry for several markers relevant for studies of spinal cord regeneration. Thus, the use of anterograde DiI and retrograde FG is a novel technique for bidirectional labeling of the motor tracts of the adult spinal cord with fluorescent tracers and should be useful for demonstrating neurite regeneration in studies of spinal cord repair. (J Histochem Cytochem 49:1111–1122, 2001)

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Reorganization of descending motor tracts in the rat spinal cord

European Journal of Neuroscience ◽

10.1046/j.1460-9568.2002.02243.x ◽

2002 ◽

Vol 16 (9) ◽

pp. 1761-1771 ◽

Cited By ~ 133

Author(s):

Olivier Raineteau ◽

Karim Fouad ◽

Florence M. Bareyre ◽

Martin E. Schwab

Keyword(s):

Spinal Cord ◽

Rat Spinal Cord ◽

Motor Tracts

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Clinico-pathological evidence that axonal loss underlies disability in progressive multiple sclerosis

Multiple Sclerosis Journal ◽

10.1177/1352458510364992 ◽

2010 ◽

Vol 16 (4) ◽

pp. 406-411 ◽

Cited By ~ 102

Author(s):

Emma C Tallantyre ◽

Lars Bø ◽

Omar Al-Rawashdeh ◽

Trudy Owens ◽

Chris H Polman ◽

...

Keyword(s):

Multiple Sclerosis ◽

Spinal Cord ◽

Progressive Multiple Sclerosis ◽

Axonal Loss ◽

Motor Disability ◽

Human Spinal Cord ◽

Axonal Pathology ◽

Motor Tracts ◽

First Time

Growing evidence suggests that axonal degeneration rather than demyelination is the pathological substrate underlying chronic, irreversible disability in multiple sclerosis. However, direct evidence linking clinical disability measured in vivo with corresponding post-mortem measures of axonal pathology is lacking. Our objective in this study was to investigate the relationship between motor disability accumulated by patients with multiple sclerosis during life and the degree of axonal loss observed in their descending motor tracts after death. Human spinal cord derived at autopsy from 45 patients with multiple sclerosis was investigated. The medical records of each patient were reviewed by a multiple sclerosis neurologist to determine the degree of motor disability reached before death. Spinal cord sections were stained immunohistochemically. The degree of demyelination and the number of surviving corticospinal tract axons were measured in each patient. Patients who had accumulated higher levels of motor disability prior to death demonstrated fewer surviving corticospinal axons. Motor disability did not correlate with degree of demyelination. This study provides for the first time, direct clinico-pathological evidence that axonal loss is the pathological substrate of established disability in multiple sclerosis.

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Regulatory Forum Opinion Piece*: Effective Sectioning of Spinal Cord during Regulatory-type Nonclinical Toxicity Studies

Toxicologic Pathology ◽

10.1177/0192623317720120 ◽

2017 ◽

Vol 45 (5) ◽

pp. 580-583 ◽

Cited By ~ 3

Author(s):

Brad Bolon

Keyword(s):

Spinal Cord ◽

Nervous System ◽

White Matter ◽

Best Practices ◽

Gray Matter ◽

Vertical Plane ◽

Toxicity Studies ◽

Regulatory Guidelines ◽

Motor Tracts ◽

Regulatory Type

Regulatory guidelines for nonclinical neurotoxicity testing require spinal cord evaluation but do not specify a trimming scheme. The Society of Toxicologic Pathology (STP) “best practices” for nervous system sampling during nonclinical general toxicity studies recommend that spinal cord be assessed in both longitudinal/oblique and transverse sections. This article defines possible longitudinal/oblique orientations, describes their benefits and challenges, and provides an expert recommendation regarding suitable trimming planes. Longitudinal parasagittal (LP) sections follow a vertical plane just lateral to the midline, revealing sensory and motor tracts but little gray matter. Longitudinal horizontal sections transect only sensory or motor tracts and variable quantities of gray matter. Oblique vertical (OV) sections angle across the spinal cord from side to side. Oblique transverse (OT) sections slant through from top (dorsal [posterior]) to bottom (ventral [anterior]). Compared to longitudinal planes, oblique orientations demonstrate considerably more gray matter and white matter. Current STP “best practices” explicitly recommend the LP and OV options; the OT orientation also will yield suitable sections while permitting assessment of anatomic symmetry. Selection among the LP, OT, and OV planes should be at the discretion of the study pathologist. The bilaterally symmetrical OT sections likely will be analyzed most easily by nonneuropathologists.

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Spinal Cord Mapping as an Adjunct for Resection of Intramedullary Tumors: Surgical Technique with Case Illustrations

Neurosurgery ◽

10.1097/00006123-200211000-00015 ◽

2002 ◽

Vol 51 (5) ◽

pp. 1199-1207 ◽

Cited By ~ 62

Author(s):

Alfredo Quinones-Hinojosa ◽

Mittul Gulati ◽

Russell Lyon ◽

Nalin Gupta ◽

Charles Yingling

Keyword(s):

Spinal Cord ◽

Evoked Potentials ◽

Motor Evoked Potentials ◽

Cervical Spinal Cord ◽

Tumor Resection ◽

Neurological Deficits ◽

Electromyographic Activity ◽

Intramedullary Spinal Cord ◽

Motor Tracts ◽

Stimulation Of

Abstract OBJECTIVE Resection of intramedullary spinal cord tumors may result in transient or permanent neurological deficits. Intraoperative somatosensory evoked potentials (SSEPs) and motor evoked potentials are commonly used to limit complications. We used both antidromically elicited SSEPs for planning the myelotomy site and direct mapping of spinal cord tracts during tumor resection to reduce the risk of neurological deficits and increase the extent of tumor resection. METHODS In two patients, 3 and 12 years of age, with tumors of the thoracic and cervical spinal cord, respectively, antidromically elicited SSEPs were evoked by stimulation of the dorsal columns and were recorded with subdermal electrodes placed at the medial malleoli bilaterally. Intramedullary spinal cord mapping was performed by stimulating the resection cavity with a handheld Ojemann stimulator (Radionics, Burlington, MA). In addition to visual observation, subdermal needle electrodes inserted into the abductor pollicis brevis-flexor digiti minimi manus, tibialis anterior-gastrocnemius, and abductor halluces-abductor digiti minimi pedis muscles bilaterally recorded responses that identified motor pathways. RESULTS The midline of the spinal cord was anatomically identified by visualizing branches of the dorsal medullary vein penetrating the median sulcus. Antidromic responses were obtained by stimulation at 1-mm intervals on either side of the midline, and the region where no response was elicited was selected for the myelotomy. The anatomic and electrical midlines did not precisely overlap. Stimulation of abnormal tissue within the tumor did not elicit electromyographic activity. Approaching the periphery of the tumor, stimulation at 1 mA elicited an electromyographic response before normal spinal cord was visualized. Restimulation at lower currents by use of 0.25-mA increments identified the descending motor tracts adjacent to the tumor. After tumor resection, the tracts were restimulated to confirm functional integrity. Both patients were discharged within 2 weeks of surgery with minimal neurological deficits. CONCLUSION Antidromically elicited SSEPs were important in determining the midline of a distorted cord for placement of the myelotomy incision. Mapping spinal cord motor tracts with direct spinal cord stimulation and electromyographic recording facilitated the extent of surgical resection.

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Monitoring of Motor Tracts With Spinal Cord Stimulation

Spine ◽

10.1097/00007632-199407000-00019 ◽

1994 ◽

Vol 19 (13) ◽

pp. 1518-1524 ◽

Cited By ~ 33

Author(s):

Siavash S. Haghighi ◽

Donald H. York ◽

Robert W. Gaines ◽

John J. Oro

Keyword(s):

Spinal Cord ◽

Spinal Cord Stimulation ◽

Motor Tracts

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Nervous Structure of the Spinal Cord of the Young Larval Brook-Lamprey

Journal of Cell Science ◽

10.1242/jcs.s3-89.8.359 ◽

1948 ◽

Vol s3-89 (8) ◽

pp. 359-383

Author(s):

H. P. WHITING

Keyword(s):

Spinal Cord ◽

Motor Neuron ◽

Vital Staining ◽

Dorsal Funiculus ◽

Reliable Technique ◽

Lampetra Planeri ◽

Motor Tracts ◽

Primary Motor Neuron ◽

Vertebrate Embryos ◽

Similar Stage

1. A method for the study of the nervous system of vertebrate embryos by methylene blue vital staining is described. A reliable technique for rendering the preparations permanent is described. 2. An adaptation of the silver ‘on-the-slide’ method is given. 3. Three types of sensory intramedullary neuron are described in the spinal cord of recently hatched ammocoetes, or prides, of Lampetra planeri. All three are regarded as types of Rohon-Beard cell. 4. Four contemporary correlating types of cell are described in the cord: large internuncial neurons with a dendritic system which reaches the contralateral dorsal funiculus; cells of the Commissura Infima; oblique fibres, descending caudally from the sensory to the motor tracts; and small internuncial neurons with short dendrites. 5. The relations of the Miiller fibres in the trunk are described in part. 6. Two types of motor neuron have been found; the more fully developed corresponds to the primary motor neuron of aquatic larvae of other anamniote vertebrates. 7. The peripheral fibres of the somatic system of the trunk are described. 8. The neurological pattern revealed is compared with that in adult Lampetra: the divergences from the vertebrate pattern found in the cord of the adult are not found in the young ammocoete, which in this, as in so many respects, is a good prototype of gnathostome vertebrates. 9. The probable functional pattern is compared with that found in a similar stage of Amblystoma. Neurons of the correlating and motor system appear not to have been described before in ammocoetes less than 1 year old.

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Segmented quantitative diffusion tensor imaging evaluation of acute traumatic cervical spinal cord injury

British Journal of Radiology ◽

10.1259/bjr.20201000 ◽

2020 ◽

pp. 20201000

Author(s):

Mahmud Mossa-Basha ◽

Daniel J Peterson ◽

Daniel S Hippe ◽

Justin E Vranic ◽

Christoph Hofstetter ◽

...

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Diffusion Tensor Imaging ◽

White Matter ◽

Diffusion Tensor ◽

Cervical Spinal Cord ◽

Cervical Spinal Cord Injury ◽

Cord Injury ◽

Motor Tracts ◽

Normal Controls

Objectives: To evaluate segmented diffusion tensor imaging (DTI) white matter tract fractional anisotropy (FA) and mean diffusivity (MD) values in acute cervical spinal cord injury (CSCI). Methods: 15 patients with acute CSCI and 12 control subjects were prospectively recruited and underwent axial DTI as part of the spine trauma MRI. Datasets were put through a semi-automated probabilistic segmentation algorithm that analyzed white matter, motor and sensory tracts. FA and MD values were calculated for white matter, sensory (spinal lemniscal) and motor tracts (ventral/lateral corticospinal) at the level of clinical injury, levels remote from injury and in normal controls. Results: There were significant differences in FA between the level of injury and controls for total white matter (0.65 ± .09 vs 0.68 ± .07; p = .044), motor tracts (0.64 ± .07 vs 0.7 ± .09; p = .006), and combined motor/sensory tracts (0.63 ± .09 vs 0.69 ± .08; p = .022). In addition, there were significant FA differences between the level of injury and one level caudal to the injury for combined motor tracts (0.64 ± .07 vs 0.69 ± .05; p = .002) and combined motor/sensory tracts (0.63 ± .09 vs 0.7 ± .07; p = .011). There were no significant differences for MD between the level of injury and one level caudal to the injury or normal controls. Conclusion: Abnormalities in DTI metrics of DTI-segmented white matter tracts were detected at the neurological level of injury relative to normal controls and levels remote from the injury site, confirming its value in CSCI assessment. Advances in knowledge: Segmented DTI analysis can help identify microstructural spinal cord abnormalities in the setting of traumatic cervical spinal cord injury.

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