Endonasal Endoscopic Transethmoidal Transcribriform Approach: Technical Update and Practical Points

A recent technical note offers a stepwise update of the endonasal endoscopic transethmoidal transcribriform approach (EETTA) for midline anterior cranial fossa (ACF) lesions, describing it as a minimally invasive endonasal corridor to the ventral skull base. The authors outline anticipated procedural advantages in this setting, including avoidance of brain retraction, early control of ethmoidal arterial supply, and improved endoscopic visualization of midline anatomy and tumor margins, along with cosmetic considerations and the potential for shorter hospital stays and faster recovery. They present the update as a practical walkthrough that links indications and anatomic boundaries to an operative sequence and reconstruction steps described as critical to preventing cerebrospinal fluid (CSF) leak.

Case selection is framed around explicit anatomic and disease limits, summarized as favoring small-to-moderate tumors (cited as <30–40 mm) that remain medial to key neurovascular structures and are limited laterally by the lamina papyracea, with anterior and posterior boundaries discussed relative to the frontal sinus and ethmoidal arteries. They add that extensive lateral extension, lesions positioned high along the posterior table of the frontal sinus, or scenarios requiring margins not achievable through the nasal corridor may prompt consideration of alternative or combined routes, as described. To illustrate feasibility across pathologies, they present four examples—two olfactory groove meningiomas, one esthesioneuroblastoma, and one recurrent inverted papilloma—and report near-total or gross-total resection across the set; the inverted papilloma case required combined transcranial and endoscopic resection because lateral intracranial extension limited access from below. These boundaries are used to connect endonasal exposure with what can be accessed within the described corridor.

After setup steps (including neuronavigation calibration and preparation for graft harvest), the authors describe an endonasal sequence that begins with harvesting a large vascularized nasoseptal flap and storing it in the nasopharynx. A superior septectomy is then used to create binarial access to the ventral skull base, followed by uncinectomy and ethmoidectomy with attention to the lamina papyracea while progressing through the bulla to expose the fovea ethmoidalis. A Draf II frontal sinusotomy is described in most cases, and the anterior ethmoidal artery is coagulated and divided before skull base work proceeds. They then outline cauterization and removal of mucosa and olfactory epithelium over the cribriform plate, bilateral cribriform plate resection, dural excision and opening to expose the rectus gyri, intracranial tumor debulking using standard microneurosurgical technique, and hemostasis with adjuncts including FLOSEAL®. Overall, the sequence is presented as anatomy-driven and landmark-guided.

Reconstruction is positioned as central to the technique, with the authors detailing multilayer reconstruction using an inlay acellular dermal allograft, an autologous fascia lata graft, and coverage with a vascularized pedicled nasoseptal flap. For larger cribriform defects and associated dead space, they report using autologous fat packing, while noting that Gelfoam® may be preferred when facilitating postoperative imaging is a priority. The postoperative pathway described includes neurointensive care unit monitoring and a lumbar drain incorporated to support closure, with drain removal on postoperative day 3 in their institutional protocol. These closure steps are described as integral technical components of the corridor, rather than a brief add-on to resection.

In the discussion, the authors identify CSF leak as the primary complication concern for endoscopic endonasal work at the anterior skull base, citing contemporary leak ranges of approximately 4–10% in experienced settings in their institutional and literature context. They describe a staged, institution-specific approach to postoperative CSF leakage: continuation of lumbar drainage, followed by prompt revision surgery if leakage persists, with identification of the source and either a new vascularized flap or repeat multilayer repair, as reported. They also note learning-curve and training considerations, describing specialized instrumentation, multidisciplinary expertise, and protocol familiarity as elements they associate with execution of both resection and reconstruction. Taken together, the paper frames EETTA as applicable to selected midline ACF lesions when the stated anatomic boundaries and closure strategy remain central to planning and execution.

Key Takeaways:

• Selection limits for EETTA were described around small-to-moderate midline ACF lesions, with lateral reach constrained by the lamina papyracea and extensive lateral or high frontal-sinus involvement noted as potential reasons for alternative or combined access.
• A stepwise operative sequence was reported, including nasoseptal flap harvest and binarial access, ethmoid/frontal sinus work with ethmoidal artery management, cribriform/dural opening, tumor debulking, and hemostasis adjunct use, followed by layered closure.
• CSF leak was a primary complication focus, and the authors reported an institution-specific escalation protocol (continued lumbar drainage, with revision multilayer repair if leakage persisted).