Surgery to decrease the diameter of the bony orbital entrance or to significantly build up the orbital floor to reduce volume requires an experienced craniofacial surgical team. Because of the high vascularity of NF tumors,

5the risks of extensive blood loss is always a major concern. Surgery to alter the bony orbit is difficult but can be effective in selected cases [20, 42]. A major problem with early osteotomies to reduce the orbital rim diameter or to shift the orbit up, however, is in determining how progressive and destructive any given orbital process will become. The problem with deferring orbital bone surgery to a later adult stage is that over time, with the gradual expansion of soft tissue tumor growth, the bony rims become thin and brittle. This adds to the surgical difficulties given the propensity for major loss of blood in the NF1 patient. Another factor is that while most adult patients and parents of affected children accept the concept of multiple soft tissue procedures, they are usually more reticent to undergo major orbital bony reconstruction when presented with the risk–benefit ratios and the prolonged postoperative course of major craniofacial reconstruction.

Elevation of the canthi rather than onlay grafts to the orbital floor or sectioning the orbital rims to achieve a smaller diameter is an alternative that can yield a reasonable result in many instances but may require wiring of the canthi into a higher position on the bony orbit. Even with this approach, there is a tendency for a downward drift over time. This is compounded by the gravitational pull of tumors in the cheek and lower face that can add to this downward drift. Care must be taken to protect the lacrimal drainage system during medial canthopexy, and bicanalicular silastic intubation may be of value for this purpose.

Further support of the lower lid and canthi with an autogenous fascia lata sling can be a useful adjunct. When there is still a noticeable vertical dystopia, use of a basedown prism in spectacles can also produce a more symmetric appearance if the patient does not wish to proceed with craniofacial bony reconstruction for this aspect of orbitofacial rehabilitation (Fig. 5.9g).

Summary for the Clinician

■It is not necessary to delay surgical intervention for disfiguring NF1 tumors.

■Patients and families often seek early intervention and are willing to tolerate the likelihood of multiple procedures.

■When approaching disfiguring proptosis, the surgeon must counsel the patient and family regarding the visual prognosis and weigh the overall benefit of removing an eye to rehabilitate a patient’s comfort, self-perception, and appearance.

■Orbital exenteration can be avoided except for cases of malignancy.

■Patients with NF1 require a lifetime of follow-up due to the tendency of tumor progression, recurrence, and involvement of other organ systems.

5.8The Natural History of NF1 Tumor Growth from Birth to Senescence

Growth or progression of NF1 tumors affecting the orbitofacial region is generally considered to begin in the first few years of life and then to advance more rapidly with natural growth spurts, slowing in the third decade of life. Unfortunately, there are no published studies documenting the long-term effects of NF1 in a large series of patients with multidecade follow-up. We have had a somewhat unusual opportunity, however, to observe the evolution and progression of NF1 tumors in such a patient over a period of more than 60 years (Fig. 5.10). What is evident from this case is that NF1 tumor growth does not always slow in progression after the second decade. Although we have photographic documentation of his appearance at 2 years of age, our direct experience with this patient began at age 37 when our surgical team first had the opportunity to evaluate him and then to perform

major orbitofacial tumor resection and reconstruction. Underscoring the problems with potential blood loss in the NF1 patient, his first procedure involved replacement of eight units of blood and then an additional four units

5postoperatively. At age 60, he presented with marked enopthalmos in his enucleated left socket, with his prosthesis lying flat in the socket, presumably due to orbital fat atrophy. Imaging, however, revealed this not to be due to atrophy of his dermis fat graft or orbital fat but to further atrophy of his temporal lobe, with the orbital contents herniating through the opening in his aplastic sphenoid bone. A large dermis fat graft from the inguinal region was placed to fill the upper lid sulcus and periorbit along with additional lid reconstruction to permit better positioning of his prosthesis. His appearance was further marred by the progression of cutaneous neurofibromas on both the right side of his face and his left as compared to his facial appearance 25 years earlier.

This case illustrates that NF1 tumors, although they may well be benign initially, can continue to manifest in the orbit and elsewhere for decades. It must be recognized

Summary for the Clinician

■Patients who suffer from NF1 present with a varied course that often involves tumor progression.

■New understanding of intracellular pathways and abnormal genes may allow future treatments to better target these tumors.

■While some authors recommend deferring definitive reconstructive surgery until after puberty, we believe that early intervention can better control expansion of soft tissues and possibly reduce bony orbital expansion.

■Of major importance, in addition to functional concerns, is the need to recognize the value of orbitofacial rehabilitation from an appearance perspective. Improving appearance is usually of critical importance to both the patient and family.

■It is critical to counsel older patients and the parents of young children regarding the likely necessity for multiple reconstructive procedures in the effort to approach normal orbitofacial function and appearance.

■It is also critical that NF1 patients be followed carefully from a systemic medical perspective during the entire lifetime as there are numerous secondary problems related to NF1 that may become manifest at any time.

that the risks for secondary malignancy, whether in sheath tumors, in secondary central nervous system tumors, or in other more distant locations, are of real significance, particularly in NF1 patients, thus mandating careful follow-up evaluations [44].

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