A posterior transosseous S1 pedicle approach for accessing the superior hypogastric plexus

Chronic pelvic pain is often refractory to treatment. Superior hypogastric plexus (SHP) block is an established technique, but conventional approaches have limitations. We propose a novel posterior transosseous S1 pedicle approach to access the SHP, leveraging the reproducible osseous anatomy of the sacrum. This may offer improved spatial control and reduce procedural variability. The concept is based on anatomical reasoning and cadaveric fluoroscopic observations. Further cadaveric, imaging, and clinical studies are needed to validate its safety and feasibility.

Introduction

Chronic pelvic pain significantly impairs quality of life, and many patients do not respond to conservative treatments. SHP block is widely used for refractory pelvic pain, but traditional anterior and posterior approaches can be limited by anatomical variability and risks to adjacent structures. In spine surgery, transosseous pedicle approaches are routinely used for deep access with high reproducibility. The S1 pedicle is a well-defined osseous corridor. We hypothesise that a posterior transosseous approach through the S1 pedicle could provide a reliable route to the SHP.

Hypothesis

We hypothesise that a posterior transosseous S1 pedicle approach may allow controlled access to the retroperitoneal region near the SHP, reducing anatomical variability and procedural uncertainty.

The S1 pedicle has consistent morphology and is routinely accessed in spinal instrumentation. The anterior cortex of S1 lies close to the retroperitoneal space containing the SHP. Controlled advancement through the pedicle to the anterior cortex could theoretically reach this region. Fluoroscopic images from cadaveric orientation support the anatomical plausibility of this trajectory, showing a straight pathway toward the sacral promontory and contrast spread compatible with the SHP region. However, these images do not establish safety or clinical efficacy.

This approach may offer advantages over conventional soft‑tissue techniques: reliance on a fixed osseous corridor may reduce variability related to body habitus, and familiarity with pedicle techniques may aid reproducibility. These potential benefits remain hypothetical.

Evaluation of the Hypothesis

The proposed transosseous approach introduces a novel paradigm. Previous techniques include posteromedian transdiscal approaches, but these carry risks of disc injury. Ultrasound guidance has improved safety but remains operator‑dependent. The S1 pedicle pathway may offer greater consistency. However, this technique is conceptually derived from spine surgery and may be more familiar to spine surgeons than to pain specialists, requiring interdisciplinary training.

A stepwise research framework is proposed:

• Cadaveric study to define anatomical relationships and distances to critical structures.

• Imaging study using CT reconstructions to assess anatomical variability.

• Clinical feasibility study comparing the proposed approach with standard techniques, focusing on safety and technical success.

Limitations

This is a conceptual hypothesis based on anatomical reasoning and fluoroscopic observations, without cadaveric dissection or quantitative measurements. The relationship between the anterior sacral cortex and adjacent vessels (e.g., iliac vessels) has not been precisely defined. Contrast spread interpretation is indirect. Anatomical variability may affect reproducibility. Systematic validation is required before any clinical application.

Future Directions

Future work should prioritise cadaveric validation, imaging‑based studies, and clinical trials focusing on safety and efficacy. Interdisciplinary collaboration between spine surgeons and pain specialists will be essential for translation.

Conclusions

This article proposes that a posterior transosseous S1 pedicle approach may offer an anatomically plausible pathway to the SHP. Further anatomical, experimental, and clinical studies are needed to assess its safety, reproducibility, and clinical relevance.

 

Full text:

https://www.xiahepublishing.com/2472-0712/ERHM-2026-00006

 

The study was recently published in the Exploratory Research and Hypothesis in Medicine.

Exploratory Research and Hypothesis in Medicine (ERHM) publishes original exploratory research articles and state-of-the-art reviews that focus on novel findings and the most recent scientific advances that support new hypotheses in medicine. The journal accepts a wide range of topics, including innovative diagnostic and therapeutic modalities as well as insightful theories related to the practice of medicine. The exploratory research published in ERHM does not necessarily need to be comprehensive and conclusive, but the study design must be solid, the methodologies must be reliable, the results must be true, and the hypothesis must be rational and justifiable with evidence.

 

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