in skull base reconstruction techniques (Fig. 1). The major advantages of an endoscopic approach include limited morbidity mainly due to avoidance of any brain retraction during the surgical intervention [2–4], avoidance of facial incisions and osteotomies, and reduced hospitalization time. Moreover, the magnification of surgical field visualization allows the surgeon to carefully identify tumor margins, the site of origin, and anatomical structures involved by the lesion.
Indications and Contraindications
In 2016, the indications and contraindications for endoscopic transnasal removal of sinonasal malignancies were summarized in detail (Table 1) [5]. Subsequently, we reported on a small series of patients with nasoethmoidal cancers of different histology and limited brain invasion, who had the lesion removed via a purely endoscopic approach. Local control at 3 years and complications were comparable to those in patients not receiving brain resection [6]. As mentioned earlier, a purely endoscopic approach is not always the ideal technique to achieve radical resection of a given tumor; accordingly, in borderline situations, the patient must be informed about the possibility of switching to a combined cranioendoscopic resection or CRF, depending on the extension of the disease, as assessed by the surgeon intraoperatively.
Fig. 1. Preoperative (a, b) and postoperative (c, d) contrast-enhanced MR scan of a 68-year-old patient, a woodworker, who presented with left unilateral epistaxis and nasal obstruction. Endoscopic endonasal biopsy of the lesion confirmed the suspicion of intestinal-type adenocarcinoma – G2. Neck ultrasound and CT scan of the chest and abdomen excluded other localizations of disease. The patient was submitted to ERTC that included the removal of both the ethmoidal complexes. Postoperatively, the patient underwent adjuvant irradiation of the surgical field (66 Gy on T and 54 Gy on N bilaterally, intensity modulated radiotherapy). Follow-up at 62 months showed no evidence of disease.
Cranioendoscopic resection, with frontal craniotomy, can be necessary in cases of massive involvement within the frontal sinus, infiltration of the dura far over the orbital roof, or extensive infiltration of the brain. On the other hand, CFR must be performed in cases of extensive lacrimal pathway infiltration, intraorbital invasion, hard-palate or anterolateral maxillary wall involvement, and/or erosion of the nasal bones; in these scenarios, more extensive resection with orbital exenteration or total maxillectomy is required [7–9].
Surgical Technique
Instrumentation
•HD camera and monitors with a recording system;
•0 and 45° endoscopes;
•long-handle endoscopic bipolar forceps;
•curved and double-curved cutting instruments;
•diode laser supports;
•microdebrider and powered instruments, long stem and curved drills;
•long dissection instruments and dural reconstruction instruments;
•intranasal vascular Doppler;
•Cavitron® ultrasonic surgical aspirator can be helpful in selected cases where the tumor is closely adjacent to vital structures;
•Magnetic navigation system.
Fig. 2. Step-by-step surgical technique of transnasal endoscopic surgery for malignancies of the sinus and anterior skull base. a Debulking of the lesion with tumor origin identification. b Exposure of the surgical field with nasal septum removal and frontal sinus approach according to a Draf type III procedure. c Centripetal removal of ethmoidal complexes. d Skull base removal. e Dural resection and intracranial work. f Multilayer skull base reconstruction. S, septum; T, tumor; IT, inferior turbinate; EC, ethmoidal complex.
Operative Setup
The patient is placed in a supine, 10–20° reverse-Trendelenburg position, with the head slightly hyperextended. The surgeon stands on the right side of the patient and the assistant stands on the left side. The nurse stands on the right of the operating surgeon. The anesthesiologist stands on the patient’s left side with the anesthesiology equipment, next to the assistant at the bottom of the surgical bed. Hypotensive general anesthesia is required [10]. A perioperative prophylactic antibiotic regimen including third-generation cephalosporin is used. Some minutes before surgery, the nasal cavities are packed with cottonoids soaked in 2% oxymetazoline, 1% oxybuprocaine, and adrenaline (1:100,000) solution to reduce bleeding and improve transnasal visualization.
Surgical Approach
According to the extension of the disease, the transnasal endoscopic resection can be performed unilaterally [11, 12] or bilaterally. In the first case the resection will be extended anteroposteriorly from the posterior wall of the frontal sinus back to the planum sphenoidale and laterolaterally from the nasal septum to the lamina papyracea; in the second case the resection will be extended from one lamina papyracea to the opposite one. The step-by-step technique of endoscopic endonasal resection (EER) is summarized in six main surgical phases (Fig. 2).
Identification of Tumor Origin
The lesion is gradually debulked allowing the surgeon to identify the precise site of origin of the tumor. In this phase, the surgeon must respect the surrounding anatomical landmarks, which will be important for the following surgical steps. En bloc resection can be achieved only for small tumors [10].
Exposure of the Surgical Field
This step involves the removal of two thirds of the nasal septum, allowing surgeons to gain enough space for a better maneuverability of endoscopic instruments, using the 2-nostrils 4-hands technique. Removal must be extended to identify the anterosuperior margin of the dissection, which is represented by the frontal sinusotomy (a Draf IIb in the case of monolateral EER or a Draf III in the case of bilateral EER), and the posteroinferior margin of dissection, which corresponds to a wide sphenoidotomy with removal of intersphenoidal septa and sphenoidal rostrum.
Centripetal Removal
Once the posteroinferior and anterosuperior margins of the resection are exposed, subperiosteal dissection
