Optimal time window of myelotomy in rats with acute traumatic spinal cord injury: a preliminary study

Abstract

Objectives: Pathophysiological mechanisms underlying spinal cord injury (SCI) partially involve edema and formation of a hematoma. Myelotomy seems to be a promising intervention. However, the appropriate timing of myelotomy is still unknown in SCI. Here we aimed to determine the timing of microsurgical myelotomy in an animal model of SCI. Methods: The SCI model was contusion-induced with a new york university impactor. Sixty-five adult female rats were randomly divided into the following groups: laminectomy alone (the 'sham group', SG), laminectomy plus contusion (the 'contusion group', CG) or laminectomy plus contusion followed by myelotomy at 8, 24 or 48 h (8 h-MTG [myelotomy-treated group], 24 h-MTG or 48 h-MTG). Functional recovery was evaluated via the open field test and the inclined plane test every week after SCI. The percentage of spared white matter area (SWMA) and ultrastructure characteristics of the injured dorsolateral spinal cord were determined on the 42nd day after SCI. Results: Compared with the CG, myelotomy at 8 h-MTG or 24 h-MTG greatly improved the BASSO-BEATTIE-BRESNAHAN scores (Po0.008), whereas the 48 h-MTG showed less efficacy (P ¼ 0.023). All myelotomy groups showed higher mean angle values in an inclined plane test (Po0.005) and had greater percentages of SWMA than the CG. Rats in the 24 h-MTG showed a higher intraaxonal fraction and myelin fraction than those in 48 h-MTG (Po0.005). Conclusion: Myelotomy up to 48 h after SCI improves recovery in rats. The potential time window of myelotomy may be between 8 and 24 h after SCI.

Myelotomy reduces spinal cord edema and inhibits aquaporin-4 and aquaporin-9 expression in rats with spinal cord injury

“…The findings are consistent with ours and other previous reports showing that myelotomy is an effective therapeutic measure for rats with SCI. 5,7,13 In addition, we found that myelotomy reduced SCI-induced edema in rats with SCI, which was accompanied by downregulation of AQP4 and AQP9 expression. Our study suggests that myelotomy may reduce edema in rats with SCI through the inhibition of AQP4 and AQP9 expression, thus improving locomotor functions.…”

“…Microsurgical myelotomy was performed under a Zeiss operating microscope (Oberkochen, Germay) as we previously described. 13 The original incision was disinfected and opened layer by layer. The spinal cord tissues with dark purple appearance were exposed.…”

“…13 In the present study, we aimed to investigate the effects of myelotomy performed 24 h after SCI on the expression of AQP4 and AQP9 and spinal cord edema in a rat model of moderate SCI.…”

Injectable Hydrogels for Spinal Cord Repair: A Focus on Swelling and Intraspinal Pressure

“…A few recent studies have suggested that increases in tissue pressure after SCI are associated with negative functional outcomes Varsos et al, 2015] ( fig. 1 a), and surgical alleviation of this pressure improves functional outcomes in both experimental animals [Yang et al, 2013] as well as patients . However, currently there are no clear clinical guidelines for monitoring and managing intraspinal pressure after SCI.…”

“…It is interesting to note that the resulting networks are fundamentally more inhomogeneous than step-growth polymerized hydrogels, containing hydrophobic 'pockets' throughout. Other noncovalent crosslinking includes the calcium-mediated crosslinking of alginate hydrogels [Prang et al, 2006;Ansorena et al, 2013;des Rieux et al, 2014;Grulova et al, 2015;Gunther et al, 2015;Pawar et al, 2015b] and self-assembly of amphiphilic polymers [Silva et al, 2004;Tysseling-Mattiace et al, 2008;Song et al, 2012;Yang et al, 2013], with both types of hydrogels reporting swelling of about 40%. Self-assembled hydrogels are often fabricated from designer polypeptides, which provides a high degree of control over network assembly as each amino acid is user specified.…”