Can therapeutic ultrasound influence the regeneration of peripheral nerves?

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J Neurosci Methods. 2005 Mar 30;142(2):185-92.

Can therapeutic ultrasound influence the regeneration of peripheral nerves?

Raso VV, Barbieri CH, Mazzer N, Fasan VS.

Departamento de Biomecanica, Medicina e Reabilitacao do, Aparelho Locomotor,

Faculdade de Medicina de Ribeirao Preto, USP, Campus Universitario, 14049-900

Ribeirao Preto, SP, Brazil.

An experimental study of the influence of the therapeutic ultrasound on the

regeneration of the sciatic nerve submitted to a controlled crush injury was

carried out in rats. Twenty female Wistar rats weighing 250g on average were

used and divided into two groups of 10 animals each, respectively, submitted to:

(1) crush injury followed by ultrasound irradiation and (2) crush injury only.

Under general anaesthesia the sciatic nerve was exposed on the right thigh and

crushed with a device especially developed and built for this purpose, with a

15,000g constant load for 10min, affecting a 5mm-long segment of the nerve

proximal to its bifurcation. Pulsed ultrasound irradiation (1:5, 1MHz,

0.4W/cm(2), 2min duration) was started the day after the operation and repeated

for 10 consecutive days. The sciatic functional index (SFI) was evaluated at

weekly intervals up to the third week, when the animal was killed for histologic

and nerve fiber density studies of the sciatic nerve carried out on the lesion

site and on the segments immediately proximal and distal to it. The SFI

progressively improved for both treated and untreated nerves but in a more

marked and significant way for the treated nerves (73 and 55%, respectively).

Nerve fiber density did no return to normal in either case but was significantly

higher in the treated nerves, with predominance of small diameter thin myelin

sheath fibers typical of nerve regeneration in the treated nerves, as opposed to

large diameter thin myelin sheath fibers in the untreated nerves. The authors

conclude that low intensity therapeutic ultrasound enhances nerve regeneration,

as demonstrated with significance on the 21st postoperative day.

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