Article Text

other Versions

Download PDFPDF
Novel fluoroscopic landmark to significantly facilitate the visualization of foramen ovale in treating idiopathic trigeminal neuralgia
  1. Liangliang He1,2,
  2. WenXing Zhao3,
  3. Po-Yi Paul Su2,
  4. Guili Guo4,
  5. Jianning Yue1,
  6. Jiaxiang Ni1,
  7. Liqiang Yang1 and
  8. Zhonghui Guan2
  1. 1Department of Pain Management, Xuanwu Hospital, Capital Medical University, Beijing, China
  2. 2Anesthesia and Perioperative Care, University of California San Francisco, San Francisco, California, USA
  3. 3Department of Anesthesiology, Pain Medicine and Critical Care Medicine,Aviation General Hospital of China Medical University and Beijing Institute of Translational Medicine, Chinese Academy of Sciences, Beijing, China
  4. 4Stroke Acute Care Center, Xuanwu Hospital, Capital Medical University, Beijing, China
  1. Correspondence to Dr Zhonghui Guan, Anesthesia and Perioperative Care, University of California San Francisco, San Francisco, California, USA; zhonghui.guan{at}; Dr Liqiang Yang, Department of Pain Management, Xuanwu Hospital, Capital Medical University, Beijing, China; yangliqiangxwpain{at}


Background and objectives Access through the foramen ovale (FO) is essential in performing trigeminal ganglion injection, glycerol rhizolysis, balloon compression, and radiofrequency thermocoagulation (RFT) to treat idiopathic trigeminal neuralgia (ITN). However, identification of the FO under fluoroscopy can be difficult and time-consuming, and thus exposes patients to increased radiation and procedure risks. Here we present the ‘H-figure’ as a novel fluoroscopic landmark to quickly visualize the FO.

Methods The H-figure landmark can be recognized as the medial border of the mandible and the lateral edge of the maxilla as the two vertical lines, and the superior line of petrous ridge of temporal bone (S-P-T line) as the horizontal line, and the FO fluoroscopic view is then optimized at the center of the H-figure immediately above the S-P-T line. We applied this landmark in a clinical cohort of 136 patients with ITN who underwent fluoroscopy-guided RFT of the trigeminal ganglion. We also compared the H-figure method with the traditional method. The primary outcome was the total number of fluoroscopic images required to visualize the FO (as a proxy of radiation exposure). Secondary measures included the procedure time required to finalize the FO view and the sensory testing voltage for paresthesia.

Results With the H-figure approach we were able to view the FO with an average of 4.2 fluoroscopic shots at an average time of 6.8 min. When compared with the non-H-figure traditional technique, the H-figure method required almost half the fluoroscopic shots in nearly half the procedure duration time, and paresthesia was evoked with half of the voltage.

Conclusion The H-figure is an easy fluoroscopic landmark that can help to view the FO with less radiation and procedure time, and the needles placed with this approach can be closer to the target for the RFT treatment of patients with ITN.

  • facial pain
  • methods
  • pain management
  • chronic pain

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.


  • LH, WZ and P-YPS contributed equally.

  • Contributors LH developed the method, managed the patients, conducted the analysis, and wrote the manuscript. W-XZ developed the method and managed the patients. P-YPS performed the power analysis and wrote the manuscript. GG contributed to assessment of the grade of FO images. JY contributed to the procedures. JN contributed to patient management. LY organized the study. ZG designed the study, supervised the analysis, and wrote the manuscript.

  • Funding LH is supported by a scholarship from the China Scholarship Council (CSC). ZG is supported by NIH (R01NS100801).

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.