Extended Lateral Rhinotomy Incision

After bilateral temporary tarsorrhaphies and skin infiltration with epinephrine (1 in 200,000), an extended lateral rhinotomy incision is made. The soft tissues are dissected off the underlying facial bones with careful preservation of the periosteum (Fig. 19.26c). Full access to the anterior cranial fossa is effected via a “shield-shaped” window craniotomy that has miniplates placed initially to allow exact replacement following its removal and completion of the excisional part of the operative procedure. This small craniotomy bone flap is ~2.5 cm × 2.5 cm with the inferior point based over the frontal sinuses but not involving the supraorbital ridge (Fig. 19.26d). The bone flap is defined using a high-speed 2 mm rosehead drill. The bone, including the posterior wall of the frontal sinus, is drilled almost to dura and when sufficiently thin it can be fractured outward using a small curved elevator resulting in minimal trauma to the dura (Fig. 19.26e).

The dura is elevated over a wide front bilaterally and falls back posteriorly, obviating the need for any significant retraction on the frontal lobes even when progressing posteriorly onto the planum sphenoidale. Releasing the dura laterally from the frontal bone is key to this part of the procedure. The initial dissection toward the cribriform plate and ethmoidal roof proceeds extradurally to allow assessment of the degree of dural invasion by tumor (Fig. 19.26f), but an incision through the dura anterosuperiorly often becomes necessary to assess the extent of invasion through the dura and involvement of the olfactory bulbs, tracts, and adjacent frontal lobe (Fig. 19.26g). This allows assessment and decision making with regard to safe margins, excision of tumor, and placement of the osteotomies in the anterior cranial fossa floor (Fig. 19.26h).

The dissection is performed under the operating microscope, which gives excellent illumination and magnification of the entire orbital roofs, ethmoidal block, and cribriform plate area extending posteriorly to the posterior extent of the planum sphenoidale. Frontal lobe tissue is protected by 10 cm × 2 cm moistened neurosurgical patties and the anterior and posterior ethmoidal vessels are clearly defined and bipolar coagulated or clipped as appropriate (Fig. 19.26i).

Shrinkage of the brain is facilitated by deliberate hyperventilation to produce a pCO₂ of 2.7 to 3.3 kPa (20 to 25 mm Hg). A head up tilt of 15 to 20° and hypertension of 70 to 90 mm Hg systolic pressure is also used and, if insufficient, intravenous mannitol may be added (rarely required). The wide lateral freeing of the dura over the orbital plates facilitates the dura moving posteriorly and often placement of two or three 10 cm × 2 cm moistened neurosurgical patties is all that is required to allow excellent visualization of the floor of the anterior cranial fossa without any form of additional brain retraction.

En bloc removal of both ethmoidal complexes, cribriform plate, and the superior aspect of the nasal septum can now be performed via the osteotomies. The cranial osteotomy is outlined with a 2 mm rosehead burr to encompass both ethmoids and the anterior wall of the sphenoid sinus. Anteriorly, they are completed with a fissure burr through the frontonasal ducts into the orbit thus uniting intra- and extracranial cuts (Fig. 19.26j).

The specimen is freed by dividing the perpendicular plate of the ethmoid from the rest of the septum and delivered via the facial approach. Depending on the extent of disease, additional resection of overlying skin, nasal bones, frontal sinuses, orbital walls and contents, maxilla, pterygopalatine fossa, infratemporal fossa, dura, and brain may be undertaken, under frozen-section control where appropriate (Fig. 19.26k).

Accurate evaluation of orbital involvement is possible as the procedure gives excellent visualization of the posterior extent of the medial orbital wall (Fig. 19.26l). In cases in which the medial bony wall of the orbit has been breached but the periosteum is intact, the compromised area of the periosteum can be resected (Fig. 19.26m).

The dural defect is repaired with fascia lata in an underlay manner, placed between brain and remaining dura and carefully sutured or glued to give a cerebrospinal fluid–proof repair (Fig. 19.26n). A thin split-thickness skin graft is applied to this inferiorly and held in place with tissue glue (Fig. 19.26o). The resected area of periosteum is grafted with a fascia lata and split-thickness skin graft, preserving the globe and its musculature. Contraction of the graft results in remarkably little disturbance of ocular function (Fig. 19.26p).

A layer of absorbable gelatin sponge soaked in Sofradex (framycetin sulfate, gramicidin, and dexamethasone) ear drops is placed over any skin-grafted areas (Fig. 19.26q) and the whole cavity packed with 5-cm ribbon gauze soaked in Whitehead′s varnish (Fig. 19.26r). The shield of frontal bone is microplated back into position (Fig. 19.26s) and the periosteum and skin are closed in three layers (Fig. 19.26t).

Patients with very advanced disease may require additional modifications at closure, including median forehead and glabellar skin flaps to cover defects due to resection of involved skin over the nasal bones, or additional temporalis muscle flaps after removal of superolateral aspect of the orbit for extensive neoplasms. Occasional free flaps with microvascular anastomosis are necessary if there is an extensive area of the skull base necrosed by a tumor or previous radical radiotherapy. Iliac bone grafts may be used to replace significant quantities of bone resected frontonasally for extensive frontal sinus involvement. A moderate pressure scalp bandage is applied for 24 hours and the patients are kept lying at 30° for 3 to 4 days postoperatively. The Whitehead′s varnish packing is removed under general anesthesia 10 days after operation, at which time the cavity may be inspected. In older patients the cosmetic result of the procedure is satisfactory (Fig. 19.27).

The Orbit

All tissue removed in our craniofacial resection series was submitted for detailed histopathology and patients were stratified according to orbital and intracranial involvement as these were felt, early on, to be important factors affecting survival. No orbital involvement was found in 187 of the 308 patients (56%). Fifty-three patients (17%) underwent orbital clearance at the time of craniofacial resection and 50 (16%) underwent resection of orbital periosteum with preservation of the eye. Five of these individuals subsequently underwent secondary orbital clearance 5 months to 4 years later. Thus, the overall number of patients in our series requiring orbital clearance was 63 (20.5%).

Seventy-three patients (24%) had dural involvement and 17% had frontal lobe infiltration. A mean hospital stay was 14 days and the average operating time for the entire procedure was 3.3 hours.

Long-Term Follow-Up

The mean follow-up period of our 25-year study was 63 months and the actuarial disease-free survival for malignant tumors was 59% at 5 years, 40% at 10 years, and 33% at 15 years. For benign tumors, the actuarial disease-free survival was 92% at 5 years, falling to 82% at 10 years and 76% at 15 years. A disease-free survival for the larger cohorts of individual histologies is shown in Table 19.10. Multivariate analysis employing the Cox regression method identified brain involvement, type of malignancy, and orbital involvement as the three significant prognostic factors in our group as a whole. As in an earlier evaluation of this cohort, our strategy of resection of orbital periosteum with preservation of the eye in selected cases was supported by a statistically improved prognosis as compared with those undergoing orbital clearance. The 50 patients undergoing resection of orbital periosteum would initially have undergone an orbital clearance at the time of the craniofacial resection but only five of these patients subsequently lost the eye and without an apparent effect on prognosis (Fig. 19.28).