Neurocirugía.pósters

Biomechanical Assessment of Orbital Retraction in the Endoscopic Transorbital Approach : A Cadaveric Study

2026-02-27T00:00:00Z

Biomechanical Assessment of Orbital Retraction in the Endoscopic Transorbital Approach : A Cadaveric Study Odeibat, Yousef; Gago, Guilherme; Monsalve, Martin; Comeau, Marc-Olivier; Champagne, Pierre-Olivier Background: The endoscopic transorbital approach (ETOA) provides minimally invasive access to the skull base but requires orbital retraction across key zones to establish a surgical corridor. Retraction is essential for exposure but entails risks of orbital morbidity, such as optic neuropathy, muscle dysfunction, and venous congestion. While ophthalmologic studies describe intraorbital pressure thresholds for ischemia, their relevance to ETOA is uncertain. Quantitative data on retraction forces and pressures remain limited, and the biomechanical behavior of specific orbital zones during surgical maneuvers has not been systematically assessed. Objective: To quantify orbital retraction force and intraorbital pressure during key ETOA steps and identify location-specific biomechanical responses. Methods: Three human cadaveric specimens were studied. Retraction force (N) and intraorbital pressure (mmHg) were recorded at the optic canal (OC), superior orbital fissure (SOF), and inferior orbital fissure (IOF) under three conditions: baseline, after meningoorbital band (MOB) release, and after MOB release plus superior orbital rim (SOR) craniotomy. Stepwise comparisons, effect sizes, and correlation analyses were performed. Results: MOB release reduced force most at the OC (−0.78 N, −48.4%, p = 0.004), with smaller decreases at the SOF (−0.63 N, −32.9%) and IOF (−0.39 N, −21.8%). SOR craniotomy produced minimal additional change (≤0.03 N). For pressure, the SOF demonstrated the strongest response, with decreases of −26.1 mm Hg (−78.6%, p = 0.011) after MOB and −23.3 mm Hg (−69.3%, p = 0.015) following additional SOR craniotomy. OC (−7.1 mm Hg, −50.1%) and IOF (−7.4 mm Hg, −36.8%) showed smaller, nonsignificant changes. Force and pressure were modestly correlated overall (r = 0.39), strongest at the SOF (r = 0.67). Conclusion: Orbital retraction during ETOA shows location-specific biomechanical patterns: the OC is predominantly force-sensitive, while the SOF is pressure-sensitive. MOB release emerges as the key maneuver altering orbital mechanics, whereas SOR craniotomy contributes little additional effect. These findings provide a quantitative framework for orbital biomechanics in transorbital surgery.

Standardizing Surgical Freedom Measurement : A Tool for Objective Comparison of Skull Base Approaches

2026-02-27T00:00:00Z

Standardizing Surgical Freedom Measurement : A Tool for Objective Comparison of Skull Base Approaches Odeibat, Yousef; Gago, Guilherme; Monsalve, Martin; Agosti, Edoardo; Champagne, Pierre-Olivier Background: Surgical freedom quantifies proximal instrument maneuverability with fixed distal targets, critical for comparing neurosurgical approaches. Current methods lack standardization, using different geometries without universal scaling, preventing meaningful cross-study comparison. Objective: Develop and validate a standardized mathematical framework and software tool for surgical freedom measurement, enabling universal comparison across different surgical approaches. Methods: A standardized framework and dedicated calculator software were developed using 3D triangulation of proximal boundary points, normalized to maximum maneuverability (πL2, circle area with radius = probe length). Statistical evaluation of proximal and distal measurement errors was performed. The method was validated across seven cases: flat surface (control), skin incision (Kocher's point), parietal burr hole (dura), bifrontal (ICA-ACA junction), pterional (optic nerve), endoscopic endonasal (lateral opticocarotid recess), and far lateral (hypoglossal canal). Point reduction analysis (12 to 3 points) was performed to establish minimum sampling requirements. Results: The standardized method successfully differentiated surgical corridors: flat surface (95.8%), Kocher's point (87.5%), parietal burr hole (46.1%), pterional (17.6%), endonasal (8.0%), and far lateral (3.9%), demonstrating the framework's discriminatory capability. Point-reduction analysis showed a progressive drop from maximum surgical freedom as sampling points decreased: <1% with ≥10 points, 4% with 7 points, 7% with 6 points, 15% with 5 points, 26% with 4 points, and 50% with 3 points. Conclusion: This framework and software provide a standardized, mathematically rigorous method for surgical freedom quantification. The πL2 normalization enables universal comparison across different approaches and studies. Point-reduction analysis shows that ≥7 sampling points are necessary to maintain reliable measurement accuracy. Open-source implementation facilitates widespread adoption for surgical planning and research applications.

Comparative Anatomical Assessment of the Contralateral Precaruncular Approach to the Supraoptic Triangle : A Cadaveric Study

2026-02-27T00:00:00Z

Comparative Anatomical Assessment of the Contralateral Precaruncular Approach to the Supraoptic Triangle : A Cadaveric Study Gago, Guilherme; Odeibat, Yousef; Monsalve, Martin; Côté, Martin; Champagne, Pierre-Olivier Background: The supraoptic triangle (SOT) is a bony-dural region located along the superior surface of the optic canal, corresponding to the base of the anterior clinoid process. It is bounded inferiorly by the optic nerve, laterally by the upper projection of the lateral border of the lateral optico-carotid recess (LOCR), and superomedially by the planum sphenoidale. Although often targeted endonasally, this region is notoriously difficult to reach without significant manipulation of the optic nerve and internal carotid artery. Even after maximal bone removal via a transtuberculum–transplanum approach, exposure to the SOT remains limited due to its lateral and deep location. This study evaluates whether a transorbital contralateral precaruncular approach can enhance access to this region compared to standard endonasal routes. Methods: Four cadaveric heads (7 sides) were dissected. A transtuberculum–transplanum endonasal approach was performed in all specimens. Surgical access to the SOT was then assessed through three distinct routes: ipsilateral endonasal (IpsiEA), contralateral endonasal (ContraEA), and contralateral precaruncular (CPC). Quantitative metrics included working distance, fencing angle, vertical and horizontal angles of attack (AoA), surgical freedom (calculated as a percentage of the surface area of a reference sphere using a 12-point navigation model), and area of exposure (AOE). Statistical comparisons were made using paired t-tests (α = 0.05). Results: The CPC approach yielded the shortest working distance (51.3 ±8.3mm vs. 78.0 and 78.9 ± mm; p < 0.6). Conclusion: The contralateral precaruncular approach improves angular access and reduces working distance to the supraoptic triangle, supporting its use as a complementary route to reach the lateral optic canal and anterior clinoid region.

Gasserian Ganglion Stimulation in Refractory Trigeminal Neuralgia: A Single-Center Case Series

2025-11-18T00:00:00Z

Gasserian Ganglion Stimulation in Refractory Trigeminal Neuralgia: A Single-Center Case Series Villamil, Facundo; Solari, Matías; Nuñez, Maximiliano; Stella, Oscar Introduction:Trigeminal neuralgia (TN) is a severe neurological condition characterized by intense, paroxysmal, and disabling facial pain. Management can be especially challenging in patients refractory to pharmacological and surgical therapies. Gasserian ganglion stimulation (GGS) has emerged as a potential alternative in such cases; however, its use remains limited and underrepresented in current literature. Objective. To evaluate the clinical efficacy, pain evolution, and impact on quality of life in a cohort of patients with refractory TN treated with Gasserian ganglion stimulation at our institution. Method:We conducted a retrospective observational study of 10 adult patients with refractory TN who underwent GGS between January 2008 and May 2025. Demographic data, clinical history, TN subtype (according to Burchiel’s classification), affected territories, trigger points, and prior treatments were analyzed. Pain intensity was assessed using the Visual Analog Scale (VAS) and Barrow Neurological Institute (BNI) pain scale preoperatively, immediately postoperatively, at six months, and at final follow-up. Quality of life (QoL) and reduction in medication use were also evaluated. A female predominance (73%) was observed, with a mean age at diagnosis of 50 years. Based on Burchiel’s classification, 50% had type I TN, and 20% had deafferentation pain. Prior interventions were reported in 72% (n=8), predominantly radiofrequency thermocoagulation. Preoperatively, 60% (n=6) experienced severe pain (VAS 8–10), 30% (n=3) moderate pain (VAS 4–7), and 10% (n=1) mild pain (VAS 1–3). Immediately postoperatively, 50% (n=5) reported moderate pain, 30% (n=3) severe, and 20% (n=2) mild. A significant reduction in pain was observed (p=0.002). On the BNI scale, 60% (n=6) had a score of 4 preoperatively; at six months, 80% (n=8) achieved BNI ≤3b. At final follow-up, 50% (n=5) reached BNI 2, 30% (n=3) BNI 3b, and 20% (n=2) BNI 1 (p=0.0018). Following surgery, 90% reported fair to excellent QoL. At six months, 82% had reduced medication use, with only 27% continuing pharmacological treatment at final evaluation. Discussion: GGS appears to be a viable alternative for patients with refractory TN, especially those with multiple failed interventions. Our results align with international findings regarding procedural safety, sustained pain relief, and medication reduction. A trend was observed between the number of trigger points and pain severity, suggesting possible predictive factors, though statistical significance was not achieved in this limited sample. Conclusions:Gasserian ganglion stimulation is a safe and effective option for treating refractory TN, providing significant pain relief, high clinical response, and sustained improvements in quality of life. These findings support its inclusion as a therapeutic alternative in complex, recurrent, or treatment-resistant cases.