Avaliação qualitativa e quantitativa das lesões agudas por esmagamento do nervo isquiático do rato

Abstract

Nervos isquiáticos de ratos esmagados com cargas diferentes foram estudados com o auxílio da microscopia de luz. Pesos de 500 g, 1.000 g, 5.000 g, 10.000 g, e 15.000 g foram utilizados por 10 minutos num dispositivo portátil especialmente desenvolvido para este estudo. As análises morfológicas e morfométricas das fibras mielínicas mostraram que a lesão produzida às fibras neurais e ao tecido neural foi diretamente proporcional à carga aplicada e que uma carga de 500 g é suficiente para produzir um dano severo, com lesão importante das estruturas do endoneuro.

O ultrassom terapêutico na medula espinhal acelera a regeneração do nervo ciático de ratos

“…In this investigation, the injury was produced with deadweight equipment, developed in our laboratory and employed in previous investigations. 28 With this equipment, the applied load does not decrease with time, favoring high reproducibility in controlled crush injuries. Ultrasonic irradiation was employed with parameters of current use in clinical practice, including lower potency (0.16 W/cm 2 ), which is more adequate for stimulation of nerve regeneration, according to results obtained in investigations in which the irradiation was applied at the lesion site, 22,34 the small area irradiated (1.43 cm 2 ), which enabled the concentration of waves on the spinal column, and the low frequency (1 MHz), which is better suited to reach the deepest tissues, as is the case of the spinal cord and of the sensory ganglion, protected by the vertebrae.…”

“…The right sciatic nerve was approached through a rectilinear longitudinal cutaneous incision on the lateral surface of the thigh and exposed all along its length, from the emergence underneath the gluteus maximus muscle up to its trifurcation at knee level. To produce the crush injury, we employed a portable deadweight device, [28][29][30] assembled with a load of 5,000 g. (Figure 1) With the nerve exposed, the animal was positioned in the device and the load was applied for 10 minutes, covering a segment measuring 5mm in length located 5mm below the nerve emergence point. 15,28 After production of the injury, the animal was removed from the crush device, the nerve was positioned in its anatomical bed and the surgical wound was sutured.…”

Efeito do laser de baixa intensidade (660 nm) na regeneração do nervo isquiático lesado em ratos

“…Vários parâmetros, como comprimento de onda, densidade de energia, modo do pulso e potência do laser, estão sendo utilizados para estimular a regeneração e acelerar a recuperação funcional do nervo periférico 15,16,28,[39][40][41][42] . Em geral as publicações cujo tratamento utilizou o laser de emissão contínua apresentaram resultados positivos na regeneração nervosa periféri-ca, podendo ser esse modelo a primeira escolha para tal na regeneração 43 .…”

Uma nova pinça regulável para a produção de lesões por esmagamento do nervo ciático do rato

“…Described mechanisms range from applying external compression with a tourniquete 14 , to a direct nerve approach and the application of some kind of crushing instrument, such as microsurgical or watchmaker pinches 8 or even sutures with surgical wires 15 and some types of machines. 7,9,16 In a series of previous studies, the authors hereof used a universal assay machine 9,10,12 or a dead-load machine 17 , always with predetermined and controlled loads throughout the time established for producing it. Despite of the reliability of the results achieved with both machines, its use itself is relatively difficult, because an anesthetized animal with exposed sciatic nerve must be taken there and adapted on the accessories enabling its use in order to manipulate such a small anatomical structure.…”

“…The universal assay machine has the additional disadvantage of gradually reducing the applied load, with crushed nerve accommodation, requiring continuous adjustments in order to keep it at the planned levels. The dead-load machine solves this problem 17 , but it is a robust instrument. After using both kinds of machines, the authors of the present study envisaged the possibility of obtaining the same results with a much simpler and user-friendly device, which is an adjustable crush-maker pinch for in loco use, without the need of transferring and adapting the animals as happened with previously employed machines.…”