Creation of an intramedullary cavity by hemorrhagic necrosis removal 24 h after spinal cord contusion in rats for eventual intralesional implantation of restorative materials

Effect of Durotomy versus Myelotomy on Tissue Sparing and Functional Outcome after Spinal Cord Injury

Various surgical strategies have been developed to alleviate elevated intraspinal pressure (ISP) following acute traumatic spinal cord injury (tSCI). Surgical decompression of either the dural (durotomy) or the dural and pial (myelotomy) lining of the spinal cord has been proposed. However, a direct comparison of these two strategies is lacking. Here, we compare the histological and functional effects of durotomy alone and durotomy plus myelotomy in a rodent model of acute thoracic tSCI. Our results indicate that tSCI causes local tissue edema and significantly elevates ISP (7.4 ± 0.3 mmHg) compared with physiological ISP (1.7 ± 0.4 mmHg; p < 0.001). Both durotomy alone and durotomy plus myelotomy effectively mitigate elevated local ISP (p < 0.001). Histological examination at 10 weeks after tSCI revealed that durotomy plus myelotomy promoted spinal tissue sparing by 13.7% compared with durotomy alone, and by 25.9% compared with tSCI-only (p < 0.0001). Both types of decompression surgeries elicited a significant beneficial impact on gray matter sparing (p < 0.01). Impressively, durotomy plus myelotomy surgery increased preservation of motor neurons by 174.3% compared with tSCI-only (p < 0.05). Durotomy plus myelotomy surgery also significantly promoted recovery of hindlimb locomotor function in an open-field test (p < 0.001). Interestingly, only durotomy alone resulted in favorable recovery of bladder and Ladder Walk performance. Combined, our data suggest that durotomy plus myelotomy following acute tSCI facilitates tissue sparing and recovery of locomotor function. In the future, biomarkers identifying spinal cord injuries that can benefit from either durotomy alone or durotomy plus myelotomy need to be developed.

High-resolution Micro-CT Myelography to Assess Spinal Subarachnoid Space Changes After Spinal Cord Injury in Rats

BACKGROUND AND PURPOSE

The spinal subarachnoid space (SSAS) is vital for neurologic function. Although SSAS alterations are known to occur after spinal cord injury (SCI), there is a lack of high-resolution imaging studies of the SSAS after SCI in rodents. Therefore, the aim here was to assess changes in the SSAS of rats subjected to graded SCI, using high-resolution micro-CT myelography.

METHODS

Long-Evans adult rats were subjected to mild or severe spinal cord contusion at T9. Imaging studies of SSAS features were carried out in injured rats at acute (day 1) and subacute (day 15) stages postinjury, as well as in control rats, using high-resolution micro-CT myelography with a contrast-enhanced digital subtraction protocol. We studied a total of 33 rats randomly allocated into five experimental groups. Micro-CT myelograms were assessed by expert observers using both qualitative and quantitative criteria.

RESULTS

Qualitative and quantitative analyses showed that SCI induces changes in the SSAS that vary as a function of both injury severity and time elapsed after injury. SSAS blockage was the main alteration detected. Moreover, the method used here allowed fine details to be observed in small animals, such as variations in the preferential pathways for contrast medium flow, neuroimaging nerve root enhancement, and leakage of contrast medium due to tearing of the dural sac.

CONCLUSION

Micro-CT myelography provides high-resolution images of changes in the SSAS after SCI in rats and is a useful tool for further experimental studies involving rat SCI in vivo.

Local Serpin Treatment via Chitosan-Collagen Hydrogel after Spinal Cord Injury Reduces Tissue Damage and Improves Neurologic Function

Spinal cord injury (SCI) results in massive secondary damage characterized by a prolonged inflammation with phagocytic macrophage invasion and tissue destruction. In prior work, sustained subdural infusion of anti-inflammatory compounds reduced neurological deficits and reduced pro-inflammatory cell invasion at the site of injury leading to improved outcomes. We hypothesized that implantation of a hydrogel loaded with an immune modulating biologic drug, Serp-1, for sustained delivery after crush-induced SCI would have an effective anti-inflammatory and neuroprotective effect. Rats with dorsal column SCI crush injury, implanted with physical chitosan-collagen hydrogels (CCH) had severe granulomatous infiltration at the site of the dorsal column injury, which accumulated excess edema at 28 days post-surgery. More pronounced neuroprotective changes were observed with high dose (100 µg/50 µL) Serp-1 CCH implanted rats, but not with low dose (10 µg/50 µL) Serp-1 CCH. Rats treated with Serp-1 CCH implants also had improved motor function up to 20 days with recovery of neurological deficits attributed to inhibition of inflammation-associated tissue damage. In contrast, prolonged low dose Serp-1 infusion with chitosan did not improve recovery. Intralesional implantation of hydrogel for sustained delivery of the Serp-1 immune modulating biologic offers a neuroprotective treatment of acute SCI.

Myelotomy promotes locomotor recovery in rats subjected to spinal cord injury: A meta-analysis of six randomized controlled trials

OBJECTIVE:

To investigate the effects of myelotomy on locomotor recovery in rats subjected to spinal cord injury.

DATA SOURCES:

Electronic databases including PubMed, Science Citation Index, Cochrane Library, China National Knowledge Infrastructure, Chinese Journals Full-text Database, China Biology Medicine disc, and Wanfang Database were searched to retrieve related studies published before September 2017. The MeSH terms (the Medical Subject Headings) such as “myelotomy”, “spinal cord injuries”, “rats”, “randomized controlled trial” and all related entry terms were searched.

DATA SELECTION:

Randomized controlled trials using myelotomy for the treatment of acute spinal cord injury in rats were included. Basso, Beattie, and Bresnahan scores were adopted as the evaluation method. RevMan Software (version 5.3) was used for data processing. The χ² and I² tests were used to assess heterogeneity. Using a random-effects model, a subgroup analysis was conducted to analyze the source of the heterogeneity.

OUTCOME MEASURES:

Basso, Beattie, and Bresnahan scores were observed 1–6 weeks after spinal cord injury.

RESULTS:

Six animal trials were included, using a total of 143 lab rats. The included trials were divided into two subgroups by injury degrees (moderate or severe). The pooled results showed that, 1–6 weeks after spinal cord injury, the overall Basso, Beattie, and Bresnahan score was significantly higher in the myelotomy group than in the contusion group (weighted mean difference (WMD) = 0.60; 95% confidence interval (CI): 0.23–0.97; P = 0.001; WMD = 2.10; 95% CI: 1.56–2.64; P < 0.001; WMD = 2.65; 95% CI: 1.73–3.57; P < 0.001; WMD = 1.66; 95% CI: 0.80–2.52; P < 0.001; WMD = 2.09; 95% CI: 0.92–3.26, P < 0.001; WMD = 2.25; 95% CI: 1.06–3.44, P < 0.001). The overall heterogeneity was high (I² = 85%; I² = 95%; I² = 94%; I² = 88%; I² = 91%; I² = 89%). The results in the moderate injury subgroup showed that Basso, Beattie, and Bresnahan scores were significantly higher in the myelotomy group than in the contusion group (WMD = 0.91, 95% CI: 0.52–1.3, P < 0.001; WMD = 2.10; 95% CI: 1.56–2.64, P < 0.001; WMD = 2.65; 95% CI: 1.73–3.57, P < 0.001; WMD = 2.50, 95% CI: 1.72–3.28, P < 0.001; WMD = 3.29, 95% CI: 2.21–4.38, P < 0.001; WMD = 3.27; 95% CI: 2.31–4.23, P < 0.001). The relevant heterogeneity was low. However, there were no significant differences in Basso, Beattie, and Bresnahan scores between the myelotomy and contusion groups in the severe injury subgroup at 2 and 3 weeks after the injury (P = 0.75; P = 0.92).

CONCLUSION:

To date, this is the first attempt to summarize the potential effect of myelotomy on locomotor recovery in rats with spinal cord injury. Our findings conclude that myelotomy promotes locomotor recovery in rats with spinal cord injury, especially in those with moderate injury.