Fig. 15.1 Ossifying fibroma. (a) The degree of orbital displacement is significant enough to create proptosis and a cosmetic deformity. (b) The orbital apex is compressed but springs the optical canal. (c) Previous partial resection performed elsewhere resulted in improvement to nasal airway only and persistent sinus dysfunction. (d) The surgeon needs to be prepared to use reliable fixed landmarks rather than “sinus” anatomy to complete the resection.
Orbital invasion is defined as a tumor that has breached/involved the periorbita. These tumors are largely determined by the site of origin and by the histology of the tumor. The orbit may be involved by direct extension from tumors in surrounding areas such as the nasal cavity, paranasal sinuses, mandible, cranial cavity or skull base, or by metastases. Adenocarcinomas and squamous cell carcinomas (SCC) are the most common tumor types involved. 2 Perineural spread is another mode for tumor extension. In particular, SCC and adenoid cystic carcinomas have a propensity for perineural spread. 3, 4 SCC has a high propensity for local recurrence 5 and SCC and undifferentiated carcinomas favor the worst prognosis. 6
Orbital involvement by tumor portends a less favorable prognosis and orbital soft-tissue tumor involvement is an independent risk factor for survival. 7, 8, 9, 10 Indications for orbital exenteration are controversial and no universal criteria exist for the degree of orbital involvement that necessitates exenteration or safe preservation. Ianetti et al devised a grading system for orbital invasion 11—grade 1: erosion/destruction of the medial orbital wall; grade 2: extraconal invasion of periorbital fat; and grade 3: invasion of the medial rectus muscle, ocular bulb, optic nerve, and/or overlying skin. 5 Currently, grade 3 orbital invasion is the most accepted criteria for exenteration. 12, 13 However, other authors also use involvement of intraconal fat or the orbital apex as indications for exenteration. 5, 12 Positive orbital margins are another risk factor for local recurrence and may warrant consideration of exenteration. 5 Essentially, the two considerations are the functional and oncologic outcomes of the preserved orbit.
For tumors medial and inferior to the optic nerve, endoscopic approaches are often appropriate as these provide direct access to the medial orbital wall. These approaches include endoscopic transnasal approaches and endoscopic-assisted approaches such as transcaruncular, transconjunctival, 14, 15 transblepharoplasty, 16 transorbital, 17 and trans-supraorbital approaches. When tumor creeps superior and lateral to the orbit, anterior and anterolateral open approaches are more appropriate. This chapter will focus on endoscopic transnasal approaches.
15.2 Common Pathology
15.2.1 Benign
Fibro-osseous:
fibrous dysplasia.
osteoma.
ossifying fibroma.
Invasive fungal disease.
Inverting papilloma.
Vascular lesions:
hemangioma.
hemangiopericytoma.
Meningioma.
Foreign body.
15.2.2 Malignant
SCC.
Neuroectodermal and neuroendocrine tumors:
olfactory neuroblastoma.
mucosal melanoma.
sinonasal undifferentiated carcinoma.
Rhabdomyosarcoma.
Lymphoma.
Salivary gland–type carcinoma:
adenoid cystic carcinoma.
asdenocarcinoma.
mucoepidermoid carcinoma.
15.3 Patient Selection and Indications
15.3.1 Patient Presentation
Skull base neoplasms with orbital involvement commonly present with insidious symptoms such as nasal obstruction, rhinorrhea, epistaxis, headache, facial pain, hyposmia/anosmia, and epiphora. As tumors progress, patients may experience/demonstrate exophthalmos, globe dystopia, chemosis, facial swelling, cheek mass, facial paresthesia, visual field defects, diplopia, reduced visual acuity, or loss of vision. Loss of corneal sensation indicates nasociliary nerve involvement and may present as dry eye and corneal opacification resulting in loss of vision. Involvement of the cavernous sinus may produce diplopia, restricted ocular movement, or pupillary changes such as mydriasis or miosis, due to involvement of the third, fourth, or sixth cranial nerves or the sympathetic nerves within the cavernous sinus. The optic nerve is less often involved 18 and, therefore, pupillary afferent defects are uncommon at presentation without orbital apex compression or involvement. Diplopia or the fixed eye is more common ( ▶ Fig. 15.2).
Fig. 15.2 Squamous cell carcinoma: the posterior extent of orbital involvement is critical. (a) These magnetic resonance images demonstrate the right sphenoid and roof involvement. (b) The tumor abuts the internal carotid artery, but the lateral opticocarotid recess appears free of disease. (c) The optic nerve and the origin of the ophthalmic artery immediately below it appear clear. Tumor was removed and postoperative radiotherapy was given to this area. There was no margin here but to drill bone from the lateral sphenoid wall. Dura was resected over the planum to a free margin. The patient died 4 years postresection from a perineural spread along the third cranial nerve with pontine mass. The local area was otherwise free of gross disease.
15.3.2 Indications
Endoscopic orbital surgery is suitable for any pathology medial and/or inferior to the optic nerve (the neural axis).
15.3.3 Contraindications
Endoscopic orbital surgery is contraindicated in the following circumstances:
Significant tumor lateral or superior to the optic nerve.
Malignant tumor involving the globe, extraocular musculature, eyelids.
Tumor involving the optic nerve.
15.3.4 Diagnostic Workup
Multidisciplinary tumor board presentation.
Ophthalmology assessment. There are four constructs to consider:
Afferent visual function: visual acuity, color vision, papillary reaction/afferent defect, automated visual field testing.
Ocular motility: ductions, prismatic measurement of strabismus.
Lacrimal outflow functional: clinical epiphora, lacrimal irrigation.
Cosmesis: exophthalmometry, ptosis/eyelid position measurements
Consideration of pre-op radiotherapy and/or chemotherapy to reduce tumor size to avoid/minimize injury to vital structures. 19
15.3.5 Imaging
CT:
Predicts lamina papyracea involvement with 91% sensitivity and 55% specificity. 20
Predicts involvement of lacrimal system with 100% sensitivity and 45% specificity 20 ( ▶ Fig. 15.3).
MRI:
Determines periorbital involvement with 93% sensitivity and 81% specificity. 20
Periorbital thickening less than 2 to 3 mm is usually not a sign of true invasion ( ▶ Fig. 15.2 and ▶ Fig. 15.3). 21
Consideration for image guidance/stereotactic/neuronavigational imaging and preoperative corticosteroids ± antibiotics ( ▶ Fig. 15.4).
Fig. 15.3 Squamous cell carcinoma: computed tomography scans are critical for assessing the bone erosion associated with malignancy. The bone surrounding the lacrimal duct and sac is eroded (a) as well as the bone of the medial orbital wall, ethmoid roof and crista galli (b). Magnetic resonance imaging confirms anterior extension (c) and pushing margin (d) that histologically involved the dura but not the periorbita. Both were resected with no gross disease beyond.
Fig. 15.4 Osteoma: a classic frontoethmoidal osteoma rarely produces cosmetic abnormalities and is more likely to present with sinus dysfunction (a). Managing the approach to frontal sinus and superior access is important (b). The inflammation around tumors seen in the right nose (c) and middle meatus (d) can be managed with preoperative corticosteroid to improve the surgical field and hemostasis upon removal.
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