Multidisciplinary Collaboration in the Transorbital Approach (TOA) to Skull Base Surgery

The TOA is a relatively new minimally invasive surgical technique that uses the orbit of the eye as a corridor to access masses in deep-seated portions of the skull base, including the anterior and middle cranial fossae, cavernous sinus, Meckel’s cave, and selected posterior fossa regions. Unlike traditional craniotomy, the TOA provides direct lateral or anterolateral trajectories while avoiding brain retraction and reducing manipulation of critical neurovascular structures.

A variant of TOA, transorbital neuroendoscopic approaches (TONES) are performed through four different orbital quadrants (superior, lateral, medial, and inferior). These approaches provide lateral expansion to other minimally invasive techniques, such as the endoscopic endonasal approach, which are generally limited in their lateral extent due to the relationship to the internal carotid artery and cranial nerves.

Crossing these structures during surgery carries a heightened risk for irreparable injury. Access through the orbital quadrants can obviate some of these restrictions. TOA may be used alone or combined with the endoscopic endonasal approach to achieve multiportal access and expanded surgical freedom. Skills and instrumentation developed for endonasal skull base surgery translate well to TOA and facilitate safe dissection in narrow operative corridors.

The TOA: distinguishing features and patient benefits

The following features highlight the advantages of the TOA for patients:

• Direct access: The TOA offers a direct route to deep-seated skull base lesions, thereby minimizing brain retraction and manipulation of neurovascular structures.
• Multiple entry points: Although access is most often via the superior eyelid crease or eyebrow, the TOA may be performed through lateral, medial, or inferior orbital routes, depending on the target pathology, to ensure greater safety during surgery. Multiportal variants are enhanced by combining the transorbital approach with other techniques.
• Cosmetic outcomes: Incisions are typically concealed in the eyelid crease, resulting in excellent cosmetic results.
• Functional preservation: High rates of visual and cranial nerve function preservation have been reported, with most patients experiencing stable or improved visual outcomes and resolution of preoperative diplopia or proptosis.
• Low morbidity: Complication rates are low, with transient peri-orbital numbness, diplopia, or ptosis being the most common events, and these typically resolve over time. CSF leak and infection are rare.

Lesions, tumors, and masses best treated by the TOA

The indications for the TOA are expanding, and careful multidisciplinary evaluation and anatomical expertise are essential for optimal outcomes. The approach has been shown to be effective for certain types of skull base tumors, including spheno-orbital, anterior clinoid, and sphenoid wing meningiomas, as well as lesions that involve deeper areas such as the lateral cavernous sinus and Meckel’s cave. TOA can also be used to remove select orbital tumors—such as schwannomas, hemangiomas, and low-grade gliomas—as well as to reshape or decompress bone in disorders like fibrous dysplasia.

In addition, the TOA can be used for inflammatory, cystic, or vascular lesions of the anterior and middle skull base, and in combination with other surgical corridors for complex or recurrent skull base cancers. Because each case is highly individualized, careful patient selection and a coordinated plan involving neurosurgery, ENT surgeons, and oculoplastic surgery are essential for the best outcomes.

Case report 1: Spheno-orbital meningioma

Presentation

Mrs. M, a 44-year-old female, was referred to Penn Medicine with progressive right-sided eye pressure, proptosis, excessive tearing, diplopia, and blurry vision. She was evaluated by Drs. Christina Jackson and César Briceño of Penn Neurosurgery and Oculoplastic Surgery, respectively. Her MRI revealed a spheno-orbital meningioma with hyperostosis and dural involvement with compression against the right orbit, causing bowing of the lateral rectus muscle. Her ophthalmological exam demonstrated evidence of optic neuropathy.

Surgical planning

After joint evaluation by neurosurgery and oculoplastic surgery, it was recommended that Mrs. M have an endoscopic-assisted TOA with lateral orbitotomy for resection of the tumor to decompress the orbit and optic nerve while minimizing brain manipulation. The risks of surgery, including visual changes, double vision, CSF leak, and infection, were discussed, and the patient elected to proceed.

Procedure summary

After Mrs. M underwent registration to facilitate accurate intra-operative navigation of her preoperative images, a concealed superior eyelid incision extending to the lateral canthal fold was planned by Dr. Briceño. The skin was then incised, and the soft tissue was dissected down to the periosteum, which was then elevated laterally to expose the lateral orbital rim and medially to dissect the periorbita within the orbit. Laterally, the temporalis muscle was dissected off the sphenoid wing.

The dissection continued until the superior orbital fissure was visualized. To widen the corridor, the lateral orbital rim bone was then removed and set aside. The tumor, which involved bone along the sphenoid wing, was drilled and resected. The endoscope was then brought into the field to allow improved visualization at the depth of the corridor. Dr. Jackson then completed the exposure of the dura of the anterior and middle cranial fossa by drilling the rest of the bone along the skull base all the way back to the orbital apex. The tumor, which involved dural and intradural tissue, was excised circumferentially and removed en bloc until normal dural edges were reached. The site was then irrigated for hemostasis.

A fat graft was then harvested from the abdomen for reconstruction to minimize the risk of CSF leak and replace the volume of the resected lateral orbital wall. The orbital lateral rim was then reattached and secured with low-profile titanium plates and screws. The periosteum was then closed over the bone, followed by closure of the soft tissue and skin. Mrs. M was discharged on postoperative day 1 and on follow-up had improvement of her proptosis and diplopia.

Case Report 2: Fibrous Dysplasia of the Orbit

Presentation

Ms. N, a 33-year-old female with a history of fibrous dysplasia, presented for evaluation to Dr. Briceño with extensive bony overgrowth within the right orbit, causing downward displacement of the eye, resulting in misalignment, double vision, and compensatory head tilting.

Surgical strategy

A transorbital approach via the superior eyelid crease was planned to re-contour the right orbital walls using image-guided drilling of the dysplastic bone of the orbital wall, roof, and anterior cranial fossa. This would allow restoration of symmetry and decompression of the orbit to realign the right eye with the left.

Procedure

Ms. N underwent registration of the pre-operative high-resolution CAT scan of her orbit to allow for intra-operative navigation. A right superior eyelid crease incision was made, and dissection was carried out through the orbicularis muscle. The superolateral orbital rim was then exposed and its periosteum opened, raised, and dissected off the lateral orbital wall. The periosteum was raised and the periorbita dissected until the superior and inferior orbital fissure were visualized to completely expose the dysplastic bone.

With a combination of high-speed and bone-cutting ultrasonic image-guided aspiration, the excessive dysplastic bone within the right orbit and anterior cranial fossa was removed. Using image guidance and navigation, the right orbit was recontoured to match the contralateral side. Hemostasis was obtained, and the incision was closed without the need for implant reconstruction. Ms. N was discharged on postoperative day 1, and had improvement in ocular alignment and strain.

The TOA at Penn Medicine

Penn Medicine is one of the nation’s few centers offering multidisciplinary transorbital skull base surgery. The surgical team is led by Christina Jackson, MD; Jennifer E. Douglas, MD; and César Briceño, MD. TOA leverages advanced endoscopic techniques and a collaborative neurosurgical-otolaryngology-oculoplastic surgical team to advance the safety and scope of minimally invasive surgery for skull base tumors.

Clinical consult and patient referral

To speak with a provider or to refer a patient to Drs. Jackson, Douglas, or Briceño, please call 877-937-7366, or submit a referral through our secure online referral form.