Contribution to the study of the spinal cord changes during experimental model of the acute spinal cord injury

THESES

Contribution to the study of the spinal cord changes during experimental model of the acute spinal cord injury (Abstract)^*. Thesis. Campinas, 2004

Manoel Baldoino Leal Filho

^{Correspondence}

This study reports an experience with 58 Wistar adult rats who sustained acute midthoracic spine cord injury due to Fogarty's balloon-compression technique. This experience was approved by the institutional animal care and use committee (CEEA-IB-Unicamp).

In the first step all the animals, sham and experimentals, were anesthetized with intraperitoneal pentobarbital 60 mg/Kg. The catheter was inserted into dorsal epidural space through a small hole made in the ligamentum flavum, advanced cranially to midthoracic spinal level, and inflated with 20 microlitres of saline only in the experimental group. The present study was performed to investigate the relationship between the spine cord injury and the time of compression (5, 15, 30 or 60 seconds). Quantitative neurological outcome was presented with 4, 24 and 48 hours from the compression to characterize the graduation of injury in different groups. The poor outcome occured with 60 seconds compression independentely of the time of neurological examination. Some animals died suddenly with pulmonary edema and a second step investigation was done to elucidate it. The aim of this second study was to show a model of neurogenic pulmonary edema due to thoracic spine injury using a Fogarty's balloon containing 20 microlitres of saline during 60 seconds of compression (n = 17). There were used two different group of anesthesics to compare the influence of the drugs on the pulmonary edema and three groups were constituted: sham (1), compression / pentobarbital, 60 mg/Kg (2) and compression / xylasin, 10 mg/Kg / ketamin, 75 mg/Kg (3).

The results indicated that there were differences between the groups. In rats with pentobarbital anesthesia systolic blood pressure doubled the baseline value during compression, whereas this effect was less pronounced in the xylasine/ketamine group. The pulmonary index (100 x wet lung weight / bodyweight) was 0.395± 0.018 in sham (1), rose to 0.499±0.060 in (3), and was maximum under group 2 (0.639±0.14; p=0.0018). Histologic examination of the spinal cord showed parenchymal ruptures and acute hemorrhage. Comparison of the pulmonary index with morphometric evaluation of edema fluid-filled alveoli by light microscopy in paraffin sections, showed that relevant intra-alveolar edema occured only for index values above 0.55. On electron microscopy, endothelial alterations, and signs of damage of the alveolar lining cells were found.

The present study showed that the anesthesic drug pentobarbital was very important for the formation of the lung edema. The present experience suggests that the pulmonary edema induced by spinal compression is of neurogenic nature, that the anesthesic drug used had an important participation in the genesis of edema and that it is a good method to produce neurogenic pulmonary edema.

Key words: spinal cord injury, trauma, neurogenic lung edema.

*

Contribuição ao estudo das alterações da medula espinhal em modelo experimental de lesão traumática na fase aguda (Resumo). Tese de Doutorado. Universidade Estadual de Campinas, UNICAMP (Área de Ciências Médicas, Neurologia). Orientador: Antonio Guilherme Borges Neto.

Publication Dates

• Publication in this collection
  13 Apr 2005
• Date of issue
  Mar 2005