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Effect of pulsed radiofrequency on rat sciatic nerve chronic constriction injury: a preliminary study.

Li DY, Meng L, Ji N, Luo F - Chin. Med. J. (2015)

Bottom Line: Pulsed radiofrequency (PRF) application to the dorsal root ganglia can reduce neuropathic pain (NP) in animal models, but the effect of PRF on damaged peripheral nerves has not been examined.Ipsilateral MWT was significantly reduced and TWL significantly shorter compared to the contralateral side 14 days after CCI (both P = 0.000).In the PRF group, MWT was significantly higher and TWL significantly longer 14 days after the PRF treatment compared to before PRF treatment (both P = 0.000), while no such difference was observed in the sham group (P > 0.05).

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesiology and Pain Management, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China.

ABSTRACT

Background: Pulsed radiofrequency (PRF) application to the dorsal root ganglia can reduce neuropathic pain (NP) in animal models, but the effect of PRF on damaged peripheral nerves has not been examined. We investigated the effect of PRF to the rat sciatic nerve (SN) on pain-related behavior and SN ultrastructure following chronic constriction injury (CCI).

Methods: The analgesic effect was measured by hindpaw mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL). Twenty rats with NP induced by ligating the common SN were then randomly divided into a PRF treatment group and a sham group. The contralateral SN served as a control. The MWT and TWL were determined again 2, 4, 6, 8, 10, 12, and 14 days after the PRF or sham treatment. On day 14, ipsilateral and contralateral common SNs were excised and examined by electron microscopy.

Results: Ipsilateral MWT was significantly reduced and TWL significantly shorter compared to the contralateral side 14 days after CCI (both P = 0.000). In the PRF group, MWT was significantly higher and TWL significantly longer 14 days after the PRF treatment compared to before PRF treatment (both P = 0.000), while no such difference was observed in the sham group (P > 0.05). Electron microscopy revealed extensive demyelination and collagen fiber formation in the ipsilateral SN of sham-treated rats but sparse demyelination and some nerve fiber regrowth in the PRF treatment group.

Conclusions: Hyperalgesia is relieved, and ultrastructural damage ameliorated after direct PRF treatment to the SN in the CCI rat model of NP.

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(a) Ultrastructural damage to the sciatic nerve (SN), including demyelination, Wallerian degeneration, and axonal degeneration, following chronic constriction injury in sham-treated rats. Large clusters of collagen fibers were observed around severely disrupted myelin sheaths, and the numbers of axons and mitochondria were greatly reduced. Some nerve fibers were found to be loosely arranged adjacent to newly formed nerve fibers (original magnification ×500); (b) High magnification image showing extensive demyelination in the SN of a sham group rat. Microfilaments and microtubules in axons had disappeared (original magnification ×5000). ← Wallerian degeneration.
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Figure 5: (a) Ultrastructural damage to the sciatic nerve (SN), including demyelination, Wallerian degeneration, and axonal degeneration, following chronic constriction injury in sham-treated rats. Large clusters of collagen fibers were observed around severely disrupted myelin sheaths, and the numbers of axons and mitochondria were greatly reduced. Some nerve fibers were found to be loosely arranged adjacent to newly formed nerve fibers (original magnification ×500); (b) High magnification image showing extensive demyelination in the SN of a sham group rat. Microfilaments and microtubules in axons had disappeared (original magnification ×5000). ← Wallerian degeneration.

Mentions: The changes in SN ultrastructure following CCI, PRF, and sham treatment are shown in Figures 5–7. SN ligation resulted in severe mechanical damage to axons and Wallerian degeneration as measured 14 days after sham treatment [Figure 5a and b]. In contrast, ipsilateral SN fibers from PRF-treated rats exhibited loosely arranged axon bundles [Figure 6a and b] and the majority of myelinated and unmyelinated nerve fibers appeared normal. Most of the myelin sheaths retained structural integrity. The macrophages appeared in close proximity to nerve fibers with severe myelin sheath lesions and contained engulfed necrotic tissue and cholesterol crystals while collagen fibers were rarely seen. Abnormal features in PRF group axons included extensive mitochondrial hyperplasia with fragmented cristae and vacuole formation [Figure 6c and d]. In contralateral SNs from both groups, the laminar-like structure of myelin sheaths was well-defined, and subcellular structures were clearly visible in both Schwann cells and axons. Mitochondrial swelling and hyperplasia were seldom observed in contralateral axons [Figure 7a and b].


Effect of pulsed radiofrequency on rat sciatic nerve chronic constriction injury: a preliminary study.

Li DY, Meng L, Ji N, Luo F - Chin. Med. J. (2015)

(a) Ultrastructural damage to the sciatic nerve (SN), including demyelination, Wallerian degeneration, and axonal degeneration, following chronic constriction injury in sham-treated rats. Large clusters of collagen fibers were observed around severely disrupted myelin sheaths, and the numbers of axons and mitochondria were greatly reduced. Some nerve fibers were found to be loosely arranged adjacent to newly formed nerve fibers (original magnification ×500); (b) High magnification image showing extensive demyelination in the SN of a sham group rat. Microfilaments and microtubules in axons had disappeared (original magnification ×5000). ← Wallerian degeneration.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4836261&req=5

Figure 5: (a) Ultrastructural damage to the sciatic nerve (SN), including demyelination, Wallerian degeneration, and axonal degeneration, following chronic constriction injury in sham-treated rats. Large clusters of collagen fibers were observed around severely disrupted myelin sheaths, and the numbers of axons and mitochondria were greatly reduced. Some nerve fibers were found to be loosely arranged adjacent to newly formed nerve fibers (original magnification ×500); (b) High magnification image showing extensive demyelination in the SN of a sham group rat. Microfilaments and microtubules in axons had disappeared (original magnification ×5000). ← Wallerian degeneration.
Mentions: The changes in SN ultrastructure following CCI, PRF, and sham treatment are shown in Figures 5–7. SN ligation resulted in severe mechanical damage to axons and Wallerian degeneration as measured 14 days after sham treatment [Figure 5a and b]. In contrast, ipsilateral SN fibers from PRF-treated rats exhibited loosely arranged axon bundles [Figure 6a and b] and the majority of myelinated and unmyelinated nerve fibers appeared normal. Most of the myelin sheaths retained structural integrity. The macrophages appeared in close proximity to nerve fibers with severe myelin sheath lesions and contained engulfed necrotic tissue and cholesterol crystals while collagen fibers were rarely seen. Abnormal features in PRF group axons included extensive mitochondrial hyperplasia with fragmented cristae and vacuole formation [Figure 6c and d]. In contralateral SNs from both groups, the laminar-like structure of myelin sheaths was well-defined, and subcellular structures were clearly visible in both Schwann cells and axons. Mitochondrial swelling and hyperplasia were seldom observed in contralateral axons [Figure 7a and b].

Bottom Line: Pulsed radiofrequency (PRF) application to the dorsal root ganglia can reduce neuropathic pain (NP) in animal models, but the effect of PRF on damaged peripheral nerves has not been examined.Ipsilateral MWT was significantly reduced and TWL significantly shorter compared to the contralateral side 14 days after CCI (both P = 0.000).In the PRF group, MWT was significantly higher and TWL significantly longer 14 days after the PRF treatment compared to before PRF treatment (both P = 0.000), while no such difference was observed in the sham group (P > 0.05).

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesiology and Pain Management, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China.

ABSTRACT

Background: Pulsed radiofrequency (PRF) application to the dorsal root ganglia can reduce neuropathic pain (NP) in animal models, but the effect of PRF on damaged peripheral nerves has not been examined. We investigated the effect of PRF to the rat sciatic nerve (SN) on pain-related behavior and SN ultrastructure following chronic constriction injury (CCI).

Methods: The analgesic effect was measured by hindpaw mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL). Twenty rats with NP induced by ligating the common SN were then randomly divided into a PRF treatment group and a sham group. The contralateral SN served as a control. The MWT and TWL were determined again 2, 4, 6, 8, 10, 12, and 14 days after the PRF or sham treatment. On day 14, ipsilateral and contralateral common SNs were excised and examined by electron microscopy.

Results: Ipsilateral MWT was significantly reduced and TWL significantly shorter compared to the contralateral side 14 days after CCI (both P = 0.000). In the PRF group, MWT was significantly higher and TWL significantly longer 14 days after the PRF treatment compared to before PRF treatment (both P = 0.000), while no such difference was observed in the sham group (P > 0.05). Electron microscopy revealed extensive demyelination and collagen fiber formation in the ipsilateral SN of sham-treated rats but sparse demyelination and some nerve fiber regrowth in the PRF treatment group.

Conclusions: Hyperalgesia is relieved, and ultrastructural damage ameliorated after direct PRF treatment to the SN in the CCI rat model of NP.

Show MeSH
Related in: MedlinePlus