The effects of ischemia on long-tract neural conduction in the spinal cord

1979 ◽  
Vol 50 (5) ◽  
pp. 639-644 ◽  
Author(s):  
Arthur I. Kobrine ◽  
Delbert E. Evans ◽  
Hugo V. Rizzoli
Keyword(s):  
Spinal Cord ◽  
Blood Flow ◽  
Spinal Cord Ischemia ◽  
Evoked Response ◽  
Content Type ◽  
Neural Conduction ◽  
Progressive Development ◽  
Normal Blood Flow ◽  
Lower Limits ◽  
Hydrogen Clearance

✓ In this experiment, the effects of ischemia on neural conduction in the monkey spinal cord were studied. In six monkeys generalized ischemia of the spinal cord was created by bleeding the animals to a hypotensive level below the lower limits of autoregulation in the spinal cord. The progressive development of spinal cord ischemia was documented by blood-flow measurement using the hydrogen clearance method. Physiological integrity of the spinal cord was monitored and recorded by the spinal evoked response. The spinal evoked response did not disappear until at least 10 minutes of profound ischemia. At levels of ischemia 20% to 25% of normal blood flow, the spinal evoked response was unchanged. It is concluded that long-tract neural conduction in the spinal cord is relatively resistant to the effects of ischemia.

Experimental acute balloon compression of the spinal cord

1979 ◽  
Vol 51 (6) ◽  
pp. 841-845 ◽  
Author(s):  
Arthur I. Kobrine ◽  
Delbert E. Evans ◽  
Hugo V. Rizzoli
Keyword(s):  
Spinal Cord ◽  
Blood Flow ◽  
Spinal Cord Ischemia ◽  
Evoked Response ◽  
Physical Injury ◽  
Thoracic Spinal Cord ◽  
Content Type ◽  
Balloon Compression ◽  
Thoracic Spinal ◽  
Flow Changes

✓ Acute balloon compression of the thoracic spinal cord for 15, 7, 5, 3, and 1 minute in monkeys caused immediate disappearance of the spinal evoked response and complete focal ischemia of the compressed segment in all animals. Only the animals in the 1-minute group, however, demonstrated return of the evoked response. These data, coupled with data from previous experiments of slow balloon compression of the spinal cord and spinal cord ischemia, suggest that the major pathological substrate for neural dysfunction after balloon compression of the spinal cord, be it acute or slow, is physical injury of the neural membrane, irrespective of blood flow changes. These findings also suggest that the ability of that membrane to recover is related to rapidity and length of time of compression. Focal changes in blood flow do not appear to be significant in this mechanism.

Effects of the 21-aminosteroid U74006F on posttraumatic spinal cord ischemia in cats

1988 ◽  
Vol 68 (3) ◽  
pp. 462-465 ◽  
Author(s):  
Edward D. Hall
Keyword(s):  
Spinal Cord ◽  
Blood Flow ◽  
Sodium Succinate ◽  
Spinal Cord Ischemia ◽  
Intravenous Dose ◽  
Content Type ◽  
Methylprednisolone Sodium Succinate ◽  
Surprising Effect ◽  
Surgical Preparation ◽  
Dorsolateral Funiculus

✓ The ability of a single intravenous dose of the 21-aminosteroid U74006F to affect the development of posttraumatic spinal cord ischemia was examined in pentobarbital-anesthetized cats. After surgical preparation, each animal received a 300 gm-cm contusion injury to the exposed L-3 vertebral segment, followed by a single bolus injection of vehicle or U74006F (3 or 10 mg/kg) at 30 minutes postinjury. Spinal cord white matter blood flow (SCBF) was measured by hydrogen clearance in the dorsolateral funiculus in the center of the injured segment before and at various times up to 4 hours after injury. In vehicle-treated cats, there was a progressive decline in SCBF over the course of the experiment. By 4 hours postinjury, SCBF had decreased from a preinjury value of 15.9 ± 2.4 ml/100 gm/min (mean ± standard error of the mean) to 5.8 ± 0.8 ml/100 gm/min, representing a decline of 63.5%. In contrast, the SCBF measured 4 hours postinjury in cats that were treated with a single 10-mg/kg dose of U74006F was 13.6 ± 1.7 ml/100 gm/min (p < 0.001 vs. vehicle). Animals that received a 3-mg/kg intravenous dose of U74006F displayed a drop in SCBF equal to that of vehicle-treated cats. However, when a 3-mg/kg dose of U74006F was given to four vehicle-treated cats at the end of the experiment, a partial reversal of ischemia was recorded. Blood flow increased within 30 minutes from a mean of 4.5 ± 0.8 to 7.4 ± 1.0 ml/100 gm/min or an increase of 64.4% (p < 0.05). This rather surprising effect of U74006F in reversing posttraumatic ischemia once it has developed significantly is not shared by a 30-mg/kg intravenous dose of methylprednisolone sodium succinate (MP), although MP has previously been shown to attenuate the posttraumatic drop in SCBF when given before the SCBF drop occurs. The mechanism of action of U74006F in antagonizing posttraumatic ischemia development is believed to involve the ability of the compound to inhibit iron-dependent lipid peroxidation in central nervous system tissue.

The effect of hypothermia on regional spinal cord blood flow in rats

1989 ◽  
Vol 70 (5) ◽  
pp. 780-784 ◽  
Author(s):  
Toshihisa Sakamoto ◽  
William W. Monafo
Keyword(s):  
Spinal Cord ◽  
Blood Flow ◽  
Cord Blood ◽  
Spinal Cord Ischemia ◽  
Control Level ◽  
Normal Group ◽  
Spinal Cord Blood Flow ◽  
Content Type ◽  
Arterial Blood ◽  
Anesthetized Rats

✓ Spinal cord ischemia may accompany surgical procedures on the aorta or vertebral column. Regional spinal cord blood flow (SCBF) was measured at five vertebral levels in the spinal cords of pentobarbital-anesthetized rats based on the distribution of intravenously injected carbon-14-labeled butanol. In seven normal rats, mean SCBF (± standard error of the mean) ranged from 52.7 ± 5.4 to 68.5 ± 4.9 ml ⋅ min−1 ⋅ 100 gm−1 (depending on the level, being lowest at the thoracic levels) and mean arterial blood pressure (MABP) was 126 mm Hg. Corporal hypothermia (mean rectal temperature 28.1° ± 0.6°C) was induced by cold exposure in seven other rats, and SCBF, measured immediately thereafter, was significantly elevated at all five levels by 52% to 69% compared to the normal group. However, MABP was elevated in the hypothermic group to 165 ± 4 mm Hg (p < 0.0001). Therefore, in seven additional hypothermic rats, MABP was maintained at the control level by withdrawal of arterial blood as necessary. In these animals, SCBF at all levels was still significantly elevated compared with the normal group and the values were nearly identical to those measured in the hypertensive hypothermic rats. It was concluded that hemodynamic autoregulation of SCBF is impaired in the presence of moderate systemic hypothermia in pentobarbital-anesthetized rats.

Local blood flow, oxygen tension, and oxygen consumption in the rat spinal cord

1983 ◽  
Vol 58 (4) ◽  
pp. 516-525 ◽  
Author(s):  
Nariyuki Hayashi ◽  
Barth A. Green ◽  
Mayra Gonzalez-Carvajal ◽  
Joseph Mora ◽  
Richard P. Veraa
Keyword(s):  
Spinal Cord ◽  
Blood Flow ◽  
Oxygen Consumption ◽  
White Matter ◽  
Oxygen Tension ◽  
Tissue Oxygen ◽  
Spinal Cord Blood Flow ◽  
Content Type ◽  
Hydrogen Clearance ◽  
Tissue Oxygen Consumption

✓ A reliable and reproducible microelectrode technique provided consistent simultaneous measurements of local spinal cord blood flow (local SCBF), tissue oxygen tension (TO2), and tissue oxygen consumption (TO2C) in the rat. Local SCBF was measured by the hydrogen clearance technique, local TO2 was measured polarographically, and local TO2C was calculated from the declining slope of local TO2 following temporary arrest of local SCBF. Mean local TO2 values varied only slightly between gray and white matter, while local TO2C and SCBF maintained a 3 to 1 ratio between gray and white matter areas. Measurements were also made of these parameters in specific white matter tracts and laminae of Rexed. Local white matter SCBF was relatively homogeneous throughout the ventral, lateral, and dorsal funiculi. Gray matter blood flow was more variable with topography. The highest local SCBF was recorded in areas rich in internuncial neurons. The somatic motor regions had values slightly higher than recorded in sensory regions.

Comparison of hydrogen clearance and 14C-antipyrine autoradiography in the measurement of spinal cord blood flow after severe impact injury

1980 ◽  
Vol 52 (6) ◽  
pp. 801-807 ◽  
Author(s):  
David F. Cawthon ◽  
Howard J. Senter ◽  
William B. Stewart
Keyword(s):  
Spinal Cord ◽  
Blood Flow ◽  
White Matter ◽  
Cord Blood ◽  
Flow Patterns ◽  
Spinal Cord Blood Flow ◽  
Content Type ◽  
Thoracic Cord ◽  
Impact Injury ◽  
Hydrogen Clearance

✓ Spinal cord blood flow was measured by two different techniques in normal and traumatized cat spinal cord. Flow was measured in the thoracic cord after severe (500 gm-cm) impact injury at T-6. Blood flow was measured sequentially at two sites for 7 hours after trauma using the hydrogen clearance technique, and spatially at many sites but at selected times by means of the 14C-antipyrine autoradiographic method. The two techniques gave similar results. Control white-matter blood flow in the lateral funiculus was 11.13 ± 1.29 ml/min/100 gm in the hydrogen clearance series, and 11.07 ± 3.16 gm blood/min/100 gmin the antipyrine series. Following injury, blood flow remained in the control range until 1 hour after trauma, when ischemia became the major pattern. From 4 to 8 hours following trauma, several categories of flow patterns emerged. In one group of animals, white-matter blood flow returned to control levels at some points along the length of cord surveyed, but remained depressed at adjacent cord levels. In another category of animals, most sites in the white matter had flows approaching control levels by 7 to 8 hours. In yet another group, all sites examined, although a limited number, showed ischemia. In contrast, gray-matter ischemia appeared earlier (25% of control levels at 1 hour), had a sharper focus, and persisted in the period examined. The differences in blood flow between gray and white matter and the longitudinal variation in white-matter flow suggested that the hydrogen clearance method should be verified by autoradiography for accuracy of spatial flow patterns.

Spinal cord blood flow as affected by changes in systemic arterial blood pressure

1976 ◽  
Vol 44 (1) ◽  
pp. 12-15 ◽  
Author(s):  
Arthur I. Kobrine ◽  
Thomas F. Doyle ◽  
Hugo V. Rizzoli
Keyword(s):  
Spinal Cord ◽  
Blood Flow ◽  
Cord Blood ◽  
Spinal Cord Blood Flow ◽  
Content Type ◽  
Arterial Blood ◽  
Wide Range ◽  
Blood Pressures ◽  
Infusion Of Norepinephrine ◽  
Hydrogen Clearance

✓ The authors used the hydrogen clearance method to measure focal spinal cord blood flow (SCBF) in the rhesus monkey over a wide range of mean arterial blood pressures (MAP) in an attempt to test the hypothesis of autoregulation. The MAP was either lowered by bleeding or raised by the intravenous infusion of norepinephrine or angiotensin. The SCBF remained constant and in the normal range with an MAP of 50 to 135 mm Hg, indicating the presence of autoregulation. Below 50 mm Hg, SCBF fell passively with further decreases in MAP. At MAP values above 135 mm Hg, vasodilatation occurred which resulted in a breakthrough of autoregulation and marked increases in SCBF with further increases in the MAP.

Altered blood flow and secondary injury in experimental spinal cord trauma

1978 ◽  
Vol 49 (4) ◽  
pp. 569-578 ◽  
Author(s):  
Howard J. Senter ◽  
Joan L. Venes
Keyword(s):  
Spinal Cord ◽  
Blood Flow ◽  
Pharmacological Intervention ◽  
Secondary Injury ◽  
Thoracic Spinal Cord ◽  
Content Type ◽  
Thoracic Spinal ◽  
Dorsolateral Funiculus ◽  
Altered Blood ◽  
Hydrogen Clearance

✓ A modification of the hydrogen clearance technique was used to study blood flow in the dorsolateral funiculus of traumatized thoracic spinal cord in cats. The results of this study show that ischemia occurred in all animals both at the level of trauma, and 1 cm below the site of trauma. There was, however, a period of over 1 hour after trauma during which blood flow was maintained at both sites. This investigation not only confirms the presence of ischemia in the lateral funiculus of the injured spinal cord but suggests that a period of time exists in the posttraumatic period during which pharmacological intervention may alter the ischemic response and possibly prevent secondary injury resulting from the ischemia.

Local spinal cord blood flow in experimental traumatic myelopathy

1975 ◽  
Vol 42 (2) ◽  
pp. 144-149 ◽  
Author(s):  
Arthur I. Kobrine ◽  
Thomas F. Doyle ◽  
Albert N. Martins
Keyword(s):  
Spinal Cord ◽  
Blood Flow ◽  
Normal Range ◽  
Spinal Cord Blood Flow ◽  
Content Type ◽  
Lateral Funiculus ◽  
Experimental Spinal Cord Injury ◽  
Cord Injury ◽  
Before And After ◽  
Hydrogen Clearance

✓ Focal blood flow was measured in the lateral funiculus and center of the spinal cord in the rhesus monkey both before and after a 600 gm-cm injury at T-10. Measurements made by the hydrogen clearance technique showed that blood flow in the lateral funiculus more than doubled within 4 hours after injury, returned to normal by 8 hours, and remained in the normal range for 24 hours. At no time was a hypoperfusion in the lateral funiculus present. Blood flow in the center of the spinal cord, at the level of the lesion, began to fall within 1 hour following injury and continued to fall for 4 hours. These data challenge the notion that spreading ischemia of the white matter is an important factor in the pathophysiology of experimental spinal cord injury.

Local blood flow, oxygen tension, and oxygen consumption in the rat spinal cord

1983 ◽  
Vol 58 (4) ◽  
pp. 526-530 ◽  
Author(s):  
Nariyuki Hayashi ◽  
Barth A. Green ◽  
Mayra Gonzalez-Carvajal ◽  
Joseph Mora ◽  
Richard P. Veraa
Keyword(s):  
Spinal Cord ◽  
Blood Flow ◽  
Oxygen Consumption ◽  
Oxygen Tension ◽  
Tissue Oxygen ◽  
Local Blood Flow ◽  
Rat Spinal Cord ◽  
Spinal Cord Blood Flow ◽  
Content Type ◽  
Tissue Oxygen Consumption

✓ Using a reliable and reproducible microelectrode technique, consistent simultaneous measurements of local spinal cord blood flow (SCBF), tissue oxygen tension, and tissue oxygen consumption were made at cervical, thoracic, and lumbar levels in the rat spinal cord. These observations showed that the metabolic state is maintained constant along the cord, despite significant variations in vasculature. The physiological and anatomical aspects of these findings are discussed.

Percutaneous flexible bipolar epidural neuroelectrode for spinal cord stimulation

1984 ◽  
Vol 60 (6) ◽  
pp. 1317-1319 ◽  
Author(s):  
Alfred G. Kaschner ◽  
Wilhelm Sandmann ◽  
Heinz Larkamp
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Epidural Space ◽  
Somatosensory Evoked Potentials ◽  
Spinal Cord Stimulation ◽  
Spinal Cord Ischemia ◽  
Aortic Occlusion ◽  
Content Type ◽  
Fine Print

✓ This article describes a new flexible bipolar neuroelectrode which is inserted percutaneously into the epidural space for segmental spinal cord stimulation. This electrode was used in experiments with dogs and monkeys for recording cortical somatosensory evoked potentials in order to identify intraoperative spinal cord ischemia during periods of aortic occlusion.

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