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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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Related in: MedlinePlus

(a) Myelinated and unmyelinated nerve fibers in contralateral sciatic nerves (SNs). No demyelination was detected. Mitochondrial swelling and hyperplasia were seldom observed in axons. Chromatin in Schwann cells was uniform. Nerve fibers were compact and well organized (×500); (b) High magnification image of a contralateral SN showing uniform chromatin in Schwann cells, regularly arranged myelinatednerve fibers, and no observable demyelination or mitochondria swelling (×5000).
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Figure 7: (a) Myelinated and unmyelinated nerve fibers in contralateral sciatic nerves (SNs). No demyelination was detected. Mitochondrial swelling and hyperplasia were seldom observed in axons. Chromatin in Schwann cells was uniform. Nerve fibers were compact and well organized (×500); (b) High magnification image of a contralateral SN showing uniform chromatin in Schwann cells, regularly arranged myelinatednerve fibers, and no observable demyelination or mitochondria swelling (×5000).

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) Myelinated and unmyelinated nerve fibers in contralateral sciatic nerves (SNs). No demyelination was detected. Mitochondrial swelling and hyperplasia were seldom observed in axons. Chromatin in Schwann cells was uniform. Nerve fibers were compact and well organized (×500); (b) High magnification image of a contralateral SN showing uniform chromatin in Schwann cells, regularly arranged myelinatednerve fibers, and no observable demyelination or mitochondria swelling (×5000).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 7: (a) Myelinated and unmyelinated nerve fibers in contralateral sciatic nerves (SNs). No demyelination was detected. Mitochondrial swelling and hyperplasia were seldom observed in axons. Chromatin in Schwann cells was uniform. Nerve fibers were compact and well organized (×500); (b) High magnification image of a contralateral SN showing uniform chromatin in Schwann cells, regularly arranged myelinatednerve fibers, and no observable demyelination or mitochondria swelling (×5000).
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