An animal study is presented examining the effect of low level
laser (LLL) treatment on nerve regeneration following
axonotmesis. Twenty animals received a standardised injury to the right sciatic nerve using a time, load and length sequence (10 min, 150 N, 5 mm) known to cause extensive axonal degeneration of the rat sciatic nerve. The LLL treatment was administered using a hand-held
laser probe in light contact with the skin on the dorsal aspect of the hind leg overlying the site of the
axonotmesis injury to the sciatic nerve. A group of 10 animals were treated with 6J of LLL (GaAlAs 830 nm) daily for a period of 28 d. Ten more animals were treated daily with a
sham exposure setting and served as controls. Nerve function was assessed by a recognised method of walking tract print analysis; the "Sciatic Functional Index" (SFI), and nerve regeneration was assessed by recording the evoked compound action potentials (cAP) in the common peroneal nerve. At 21 d post-injury, the
laser-treated group had a significantly lower median SFI than the
sham laser-treated group, indicating that the real
laser treatment had improved functional recovery in the nerve. However, no differences were found between the evoked cAP parameters that were measured in the
laser-treated and
sham laser-treated groups. Histological examination reiterated the lack of difference between the two groups. Consequently, the effects of LLL on recovery must have occurred more peripherally to the point measured.