The histopathological and electron-microscopic examination of the stereotactic pulsed radiofrequency and conventional radiofrequency thermocoagulation lesions in rat brain.

Abstract

OBJECTIVE: Neurodestructive procedures have been used for treating intractable pain for a long time. Pulsed radiofrequency (RF) is a newly defined energy type. Pulsed RF may be used in the treatment of patients with some pain syndromes in whom the pain could not be controlled by the alternative techniques. The objective of the present study was to examine the histological and electron microscopical changes in rat brain after pulsed RF application. METHODS: Forty-five male rats were used in these experiments. Lesions were applied stereotactically to the target areas of the rat brains. Two different RF energy type were used as representative models of pulsed-RF and conventional-RF procedures. The rats were kept alive for 21 days and then killed. The effect of pulsed RF lesions on cerebral tissue ultrastructure was studied. RESULTS: In the pulsed RF group, intracytoplasmic edema, clarity of the mitochondrial cristas and opening in the cell membrane pores were observed on the electron microscopic examination. In the conventional RF group, these findings were more prominent. In the pulsed RF group, the ratio of the effected neurons was 5.5% on light microscopic examination. In the conventional RF group, the ratio of the effected neurons was 14.26% and central necrosis was observed additionally. DISCUSSION: Pulsed RF caused ultrastructural changes in the neurons. The pulsed RF may possibly cause a depression on the cell membrane potential by opening the cell membrane pores and resulting in the ion entrance into the cell cytoplasm and intracytoplasmic edema. However, it seems that all these changes were reversible.

AI evidence extraction

Main findings

After stereotactic pulsed RF application, electron microscopy showed intracytoplasmic edema, clearer mitochondrial cristae, and openings in cell membrane pores. These findings were more prominent in the conventional RF group; light microscopy reported 5.5% affected neurons in the pulsed RF group versus 14.26% in the conventional RF group, with additional central necrosis in the conventional RF group. The authors state the observed pulsed RF changes appeared reversible.

Outcomes measured

• Histopathological changes in rat brain tissue
• Electron-microscopic (ultrastructural) neuronal changes
• Proportion of affected neurons (light microscopy)
• Presence of central necrosis (conventional RF)

Limitations

• RF exposure parameters (e.g., frequency, power, temperature, pulse characteristics) not reported in the abstract
• No sham/control group described in the abstract
• Outcome assessment methods and blinding not described in the abstract
• Follow-up limited to 21 days
• Animal model; generalizability to humans unclear

Suggested hubs

• occupational-exposure (0.1)
  Involves radiofrequency energy application, but this is an interventional lesioning study rather than environmental/occupational exposure.

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    "exposure": {
        "band": null,
        "source": "stereotactic pulsed radiofrequency and conventional radiofrequency thermocoagulation (lesioning)",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "rats kept alive for 21 days after lesion application"
    },
    "population": "Male rats",
    "sample_size": 45,
    "outcomes": [
        "Histopathological changes in rat brain tissue",
        "Electron-microscopic (ultrastructural) neuronal changes",
        "Proportion of affected neurons (light microscopy)",
        "Presence of central necrosis (conventional RF)"
    ],
    "main_findings": "After stereotactic pulsed RF application, electron microscopy showed intracytoplasmic edema, clearer mitochondrial cristae, and openings in cell membrane pores. These findings were more prominent in the conventional RF group; light microscopy reported 5.5% affected neurons in the pulsed RF group versus 14.26% in the conventional RF group, with additional central necrosis in the conventional RF group. The authors state the observed pulsed RF changes appeared reversible.",
    "effect_direction": "harm",
    "limitations": [
        "RF exposure parameters (e.g., frequency, power, temperature, pulse characteristics) not reported in the abstract",
        "No sham/control group described in the abstract",
        "Outcome assessment methods and blinding not described in the abstract",
        "Follow-up limited to 21 days",
        "Animal model; generalizability to humans unclear"
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "pulsed radiofrequency",
        "conventional radiofrequency",
        "thermocoagulation",
        "rat brain",
        "stereotactic lesion",
        "histopathology",
        "electron microscopy",
        "neuronal ultrastructure",
        "necrosis"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
            "weight": 0.1000000000000000055511151231257827021181583404541015625,
            "reason": "Involves radiofrequency energy application, but this is an interventional lesioning study rather than environmental/occupational exposure."
        }
    ]
}

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