2026 Proffered Presentations
S140: IPSILATERAL VERSUS CONTRALATERAL FLAP POSITIONING IN THE CONTRALATERAL TRANSMAXILLARY APPROACH: ANATOMICAL STUDY AND CLINICAL SERIES
Thibault Passeri1; Rakhmon Egamberdiev1; Longgang Yu2; Guoqiang Zhao2; Maria Karampouga1; Eric W. Wang2; Carl H. Snyderman2; Paul A. Gardner1; Garet Choby2; Georgios A. Zenonos1; 1Department of Neurological Surgery, University of Pittsburgh Medical Center (UPMC), Pittsburgh, USA; 2Department of Otolaryngology, University of Pittsburgh Medical Center (UPMC), Pittsburgh, USA
Introduction: The contralateral transmaxillary (CTM) approach provides an additional surgical corridor in skull base surgery, extending the endoscopic endonasal approach (EEA) to the petroclival region. By increasing the angle of attack, it allows improved retrocarotid access. Nonetheless, reconstruction requires careful selection of the vascularized flap side, which may limit applicability or compromise viability. This study compared ipsilateral versus contralateral pedicled flap harvest in the CTM approach and their impact on retrocarotid exposure through an anatomical cadaveric study and a clinical series.
Methods: A retrospective review of 62 CTM cases with pedicled flap reconstruction performed at our institution was conducted. In addition, 5 latex-injected, fixed adult cadaveric specimens were used to simulate combined EEA and CTM approaches, including drilling of the petrous apex, jugular tubercle, occipital condyle, and clivus (Figure 1). Vascularized flaps were harvested ipsilateral to the CTM corridor (n=3) or contralaterally (n=2). For ipsilateral flaps, a transpterygoid approach to the target side was performed. For contralateral flaps, the vidian nerve ipsilateral to the CTM corridor was sacrificed to transpose the pterygopalatine fossa and permit drilling of the pterygoid wedge. Flaps were oriented to minimize risk of injury while preserving working space. Pre- and post-dissection CT scans quantified drilling, and neuronavigation was used to measure the additional reach angles of CTM versus EEA at three critical levels while respecting the pedicle: (1) superior petrous bone, (2) intradural space below the abducens nerve (toward the facial nerve exit zone), and (3) jugular tubercle/occipital condyle (toward the lower cranial nerves). Maneuverability of the CTM corridor was defined as the angle between the most lateral trajectory reaching the contralateral side and the most medial trajectory toward the ipsilateral side at the petroclival suture. Internal carotid artery (ICA) displacement was also assessed.
Results: In our anatomical dissections, the mean angle advantage with CTM was comparable between ipsilateral and contralateral flaps at the petrous bone (26.37±0.59° vs 26.15±1.63°), intradurally superiorly (22.40±1.85° vs 23.50±2.83°), and intradurally inferiorly (21.20±1.48° vs 20.95±1.91°). Placing the flap contralateral to the CTM provided significantly greater maneuverability than placing it ipsilateral (39.6°±0.1 vs 30.6°±0.9, p=0.003). ICA displacement was greater with ipsilateral flaps (4.40 mm vs 0.75 mm). There was a non-statistically significant trend toward greater mean amount of petrous bone drilling with contralateral flaps (1.16±0.13 vs 0.87±0.17, p=0.12).
In the clinical series, the most frequent pathologies were chondrosarcomas (n=20, 32.3%), chordomas (n=19, 30.6%), cholesterol granulomas (n=7, 11.3%), and meningiomas (n=7, 11.3%). One flap necrosis occurred in the ipsilateral group (1.6%), while cerebrospinal fluid leakage was observed in 3 ipsilateral cases (4.8%) and two contralateral cases (3.2%).
Conclusions: The CTM approach is a feasible extension of the EEA to the petroclival region. Both ipsilateral and contralateral pedicled flap are safe and effective. Contralateral flaps provide greater maneuverability, whereas ipsilateral flaps, requiring transpterygoid extension, allows greater ICA displacement and vascular control. Flap side selection should be tailored to priorities: contralateral flaps when wider maneuverability is required, and ipsilateral flaps when ICA mobilization is necessary or when the contralateral flap is compromised.
