Microendoscopic stereotactic-guided percutaneous radiofrequency trigeminal nucleotractotomy

Technical note

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Over the past few decades, various authors have performed open or stereotactic trigeminal nucleotractotomy for the treatment of neuropathic facial pain resistant to medical treatment. Stereotactic procedures can be performed percutaneously under local anesthesia, allowing intraoperative neurological examination as a method for target refinement. However, blind percutaneous procedures in the region of the atlantooccipital transition carry a considerably high risk of vascular injuries that may bring prohibitive neurological deficit or even death. To avoid such complications, the authors present the first clinical use of microendoscopy to assist percutaneous radiofrequency trigeminal nucleotractotomy. The aim of this article is to demonstrate intradural microendoscopic visualization of the medulla oblongata through an atlantooccipital percutaneous approach.


The authors present a case of severe postherpetic facial neuralgia in a patient who underwent the procedure and had satisfactory results. Stereotactic computational image planning for targeting the spinal trigeminal tract and nucleus in the posterolateral medulla was performed, allowing for an accurate percutaneous approach. Immediately before radiofrequency electrode insertion, a fine endoscope was introduced to visualize the structures in the cisterna magna.


Microendoscopic visualization offered clear identification of the pial surface of the medulla oblongata and its blood vessels, the arachnoid membrane, cranial nerve rootlets and their entry zone, and larger vessels such as the vertebral arteries and the branches of the posterior inferior cerebellar artery.


The initial application of this technique suggests that percutaneous microendoscopy may be useful for particular manipulation of the medulla oblongata, increasing the safety of the procedure and likely improving its effectiveness.

Abbreviations used in this paper: CN = cranial nerve; RF = radiofrequency; VAS = visual analog scale.

Article Information

Address correspondence to: Erich Talamoni Fonoff, M.D., Ph.D., Rua Dr. Ovídio Pires de Campos, 785, São Paulo SP, Brazil 01060-970. email: fonoffet@usp.br.

Please include this information when citing this paper: published online October 14, 2011; DOI: 10.3171/2011.8.JNS11618.

© AANS, except where prohibited by US copyright law.



  • View in gallery

    Left: Illustration of the sensory impairment in the left V1 and V2 segments caused by the neuropathic changes related to the postherpetic neuralgia before the procedure. The circles denote the areas of allodynia, the dark gray area designates the area of tactile and thermal hypesthesia, and the open triangles indicate the areas of hyperalgesia. The black triangle indicates the point of greatest pain and allodynia. Right: Illustration depicting the results of the sensory examination performed 18 months after the procedure, showing the area of residual pain (black triangle). Allodynia and hyperalgesia were eradicated by the procedure, and there was no change in the area of hypothesia.

  • View in gallery

    Preoperative sagittal (A), coronal (B), and axial (C) T1-weighted MR images showing the target planning for trigeminal nucleotractotomy in the medulla oblongata as well as the probe trajectory. These images were obtained from the intraoperative programming computer software and were enhanced for illustration of this report. The probe trajectory was programmed from the skin through the posterolateral atlantooccipital interspace into the cisterna magna.

  • View in gallery

    Endoscopic view of the brainstem surface at the level of the posterolateral medulla.

  • View in gallery

    Postoperative MR images showing the lesion spot in the posterolateral aspects of the medulla, represented by a hyperintense dot (arrows) surrounded by hypointense edema in sagittal (A), coronal (B), and axial (C) T1-weighted images and surrounding edema on the T2-weighted image (D).


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