Fronto-orbito-zygomatic (FOZ) Approach
Surgical management of Skull –base pathologies remains one of the most challenging interventions for neurosurgeons. Advances in neuroimaging and surgical technologies coupled with promotion of tailored neurosurgical approaches promote precise clinical diagnosis, surgical planning and enhance neurosurgical outcome. The fronto-orbito-zygomatic (FOZ) approach with its variation welds multiple surgical avenues that facilitate better exposure and safe removal of the pathology. This approach is recommended for handling complex skull base tumors or vascular lesions located around the central skull base, cavernous sinus and upper clivus. The manuscript highlights detailed information about (FOZ) approach and how to master it.
Surgical management of skull base pathologies remains one of the most challenging tasks for neurosurgeons. Advances in neuroimaging and evolution of modern technologies have paved the way for a more precise diagnosis and better selection of the surgical approach.
The fronto-orbito-zygomatic (FOZ) approach welds several surgical avenues and satisfies the philosophy of skull base surgery by removing bone obstacles in favor of better exposure with minimal brain retraction. Historically, this approach evolved from the pioneering work of avant-garde neurosurgeons. Removal of the supraorbital ridge as part of the frontal craniotomy was first described by McArthur  in 1912 and Frazier  in 1913 to remove a pituitary tumor. Jane et al.  revived this approach to include the anterior orbital roof osteotomy in a single flap to approach vascular lesions and remove orbital tumors. The original description of pterional approach was credited to Heuer  in 1918, modified by Dandy  to clip an anterior communicating artery aneurysm in 1941, and later was refined and popularized by Yasargil  in 1969. Pellerin  and Hakuba  first described the orbito-zygomatic-malar approach to central skull base lesions in the early 1980s. FOZ approach was eventually adopted and modified by Al Mefty  and others [9, 12, 15] to include several variations that match the patient’s clinical condition, the pathology dealt with, and the neurosurgeon’s preference.
The FOZ approach provides an excellent neurosurgical avenue for safe removal of skull base tumors and management of complex vascular lesions around the central skull base, cavernous sinus, and upper clivus [1, 4, 7, 15]. Several publications quantified this approach and highlighted its advantages in the contemporary practice of skull base surgery .
3.2 Steps of the Approach
3.2.1 Position and Preparation
3.2.2 Skin Incision and Soft Tissue Dissection
Elevate a frontal skin flap, starting within 1 cm anterior to the tragus at the level of the zygomatic arch, extending behind the hairline, and just passing the midline in a slightly curved fashion. Pay special attention not to injure the frontal branch of the facial nerve or damage the superficial temporal artery for its potential use in EC-IC bypass.
Incise and dissect sharply a large vascularized frontal pericranial flap and reflect it over the skin flap to be in continuity with the periorbita at the level of the orbital roof. Mobilize the temporal muscle basely and laterally under the arch of the zygoma, but leave a muscle cuff attached to the superior temporal line on the frontal bone for reattachment.
3.2.3 Craniotomy and Orbito-zygomatic Osteotomy
3.2.4 Surgical Closure
Upon conclusion of the planned intradural intervention, the dura is closed in a watertight fashion using dura substitutes in order to guarantee brain relaxation and tent the dura to prevent postoperative epidural collection. The fronto-orbito-zygomatic bone flap is replaced and fixed in position with miniplates. The preservation of the roof and lateral wall of the orbit does not warrant additional bone reconstruction; however, if the osteotomy defect is large, then this can be reconstructed by using low-profile craniofacial miniplates that can be fixed to the FOZ flap and measured to the size and shape of the bone defect. The temporal muscle and fascia flap are sutured to the myofascial cuff left on the frontal bone. The skin incision is closed in a multilayer fashion leaving a small subgaleal closed drainage system.
3.3 Indications of the Approach
Fronto-orbito-zygomatic approach provides multiple short, wide, and direct corridors giving access for safe surgical management of complex skull base tumors and vascular pathologies located in the posterior orbit or at the central skull base, interpeduncular fossa, cavernous sinus, and upper clivus.
3.4 Limitation and Complication and How to Avoid
The FOZ approach may appear to be a complex intervention, but it is worth the effort whenever it is indicated. It provides excellent working channels and maneuverability to handle intraoperative complications. Risks of facial nerve injury and temporal muscle atrophy can be avoided by the subperiosteal elevation of the temporal muscle and minimal use of cautery. The approach as described above negates the need for major reconstruction; however, enophthalmos may occur in some cases as the result of greater bone loss due to excessive drilling or damage to the periorbital area during dissection. Therefore, proper placement of the osteotomy at the orbital roof and lateral wall under protection of the periorbita and repair of any ensuing defect in the periorbita by using a small pericranial patch are very important measures. It is recommended to reconstruct a larger bone defect in the orbita by using miniplates that can be fixed to the bone flap. Careful repair and obliteration of any opened air cells or air sinuses should handle the potential risk of CSF leakage resulting from drilling of the anterior clinoid process or the wall of the sinuses. The relatively common problem of transient periorbital swelling can be managed by early ambulation, head elevation, and application of cold compress.
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