Experiences in the surgical treatment of cranio-orbital neurofibromatosis

Experiences in the surgical treatment of crania-orbital neurofibromatosis M. 0. POOLE Oxford Craniofacial

Unit, Radcliffe Infirmary,

Oxford

Summary-Experience with surgical management of crania-orbital neurofibromatosis in 11 patients is reported. The surgery has a relatively high complication rate compared with craniofacial procedures for other conditions. The presence of an eye which is to be preserved in the orbit introduces difficulties in producing improved appearance without compromising cornea1 cover. A two-stage approach is recommended when an eye is present. The cosmetic improvements have been disappointing to the surgical team but generally worthwhile to the patients and their families.

The skeletal abnormality of the orbit which occurs in a small proportion (less than 1%) of patients with neurofibromatosis was well described as long ago as 1931 (Moore). More recent study of this by a number of workers has delineated the problem more clearly (Hunt and Pugh 1961, Van der Meulen et al., 1982: Jackson et al., 1983; Marchac, 1984). In essence it is an absence of the membranous portions of the sphenoid and adjacent bones forming the boundary between the cranium and orbit. The natural history that the condition can follow is well shown by a series of photographs of a single patient (Fig. lA_F). The widening of the superior orbital fissure and loss of the adjacent bone in the greater and lesser wings of the sphenoid and orbital plate of the frontal bone results in a defect in the posterior part and roof of the orbit. Consequent on this the globe and orbital contents pulsate from transmitted intracranial pressure, and progressive proptosis occurs. Cystic collections of CSF may form in the arachnoid over the pole of the temporal lobe. Infiltration of the orbital soft tissues by neurofibromatous tissue usually occurs and often progresses, particularly in the upper lateral part of the orbit. The bony orbit becomes large but is still unable to accommodate the increased contents. Vision often becomes diminished or lost in the eye. Characteristic overlying soft tissue enlargement results in a variable amount of other facial tissues being involved as well. Upper eyelid hypertrophy and thickening with ptosis laterally is usual. Patients may also have various other manifestations of neurofibromatosis. It should be mentioned that not all patients with the bone defect progress right a1on.g the course outlined above (Fig. 2). 155

Typical radiological features are a large empty looking orbit (Fig. 3)-empty because the shadows of the sphenoid wings normally visible in the orbit are pale or absent. Computerised tomography shows the absence of bone, the herniation of intracranial contents into the orbit, the CSF collections over the temporal lobe, and the infiltration of the intraorbital contents with neurofibromatous soft tissue (Fig. 4). Until recently treatment was usually aimed at camouflaging measures. With the advent of craniofacial surgical techniques, repair of the bony defect in the posterior-superior part of the orbit using an intracranial approach is a more feasible proposition, together with expansion of the volume of the bony orbit. Such a procedure, which was described by Marchac in 1984, should stop pulsation of the globe and prevent further proptosis due to the intracranial communiction, and perhaps prevent further visual loss if it occurs from that cause. There are of course a number of other causes of visual loss in these patients (Martyn and Knox, 1972). Repair of the bony defect in the orbit is in fact nothing new and was performed by Dandy, a Baltimore neurosurgeon, with cranial bone graft, in 1927 with a good result (LeWald, 1933). The remainder of the problem, that is the intraorbital neurofibromatous infiltration, can be addressed at the same or at a procedure subsequent to the transcranial one. If the eye is blind it can be removed and a reasonable cosmetic result achieved with an external orbital prosthesis, as reported by Jackson et al. (1983). Van der Meulen ef al. (1982) reported socket reconstruction in this condition when the eye had been removed, and emphasised

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Fig. 1 Figure 1.-A chronological sequence of photographs of a patient with developing crania-orbital neurofibromatosis deformity. (A) at 17 months age; (B) at 21 months; CC) at 3 years; (D) at 12 years: (E) at 12 years after enucleation of the eye; (F) at 25 years with pulsatile mass in right orbital region.

the difficulty of this. Many patients, however, even if the eye is blind or almost so, do not want it removed. Measures to thin and reconstruct the involved eyelids over an existing eye result in some improvement in appearance but published results (Van der Meulen et al., 1982; Marchac, 1984) generally have not shown spectacular results. In this paper the experience with treating this

problem surgically is reported.

in the Oxford Craniofacial

Unit

Patients and methods Eleven patients with crania-orbital neurofibromatosis have been operated on, 10 of them with an intracranial approach to the back of the orbit to

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floor to elevate it if necessary. The orbital periosteum needed to be incised to allow the orbital contents to fill the larger space. The aim was to overcorrect the proptosis if possible. The medial canthal tendon was reattached in a higher, more posterior position by transnasal wiring. When a neurofibromatous mass was present in the upper outer part of the orbit, this was debulked to some extent at the same procedure, taking care not to remove the lacrimal gland or to stray into the deeper structures of the orbit, such as the lateral rectus. In five patients the intracranial operation and intraorbital debulking were carried out at the same procedure as attempts to improve the eyelids by thinning and correction of the lateral ptosis over an existing eyeball. In the others the eyelid surgery was delayed until a second stage. This consisted of a thinning of the outer end of the upper lid, reconstruction of the outer canthus after excision of excess tissue, and in some patients correction of the ptosis of the outer part of the upper lid (Fig. 6). Results

Fig. 2 Figure 2. A patient with pulsation of the orbital contents with some displacement. hut with little soft tissue involvement in the lids or facial tissues.

bone graft a substantial defect there. The other patient had extensive soft tissue infiltration with neurofibromatous tissue in the forehead and eyelids and orbit, but no bony defect or pulsation of the eye and so did not require craniotomy. None of our patients consented to the removal of a blind eye, although six were blind or had only minimal visual acuity in the eye and only one had previously had the eye removed. The intracranial surgery was performed through a fronto-temporal craniotomy with extradural dissection separating the dura from the orbital contents and exposing the boundaries of the bony defect. The dura was plicated where necessary over the temporal lobe and the bony defect repaired with cranial bone graft obtained by splitting the craniotorny bone flap. Also, the lateral wall of the orbit was moved further laterally after osteotomy (Marchat, 1984), and the roof of the orbit raised to increase the volume of the (already large) bony orbit (Fig. 5). Some bone was laid on the orbital

Complications have been common, and some serious (Table 1). We have observed that neurofibromatous tissue can bleed excessively and in addition wound healing is slow. As all neurofibromatous tissue cannot be removed, these observations may reflect important factors in the causation of postoperative complications. In general the complication rate is the highest we have encountered in any group having intracranial craniofacial surgery. The serious problems encountered were mainly neurosurgical, emphasising that these procedures should be done in a unit with full neurosurgical facilities. All were unexpected and it is difficult to make any suggestions as to how similar problems could be avoided in future cases. Five complications were related to extracranial eyelid surgery to thin the lids and correct ptosis, and in all five this was done at the same procedure as the intracranial and intraorbital surgery. While at the time of operation correction did not appear excessive in any of these, later problems of cornea1 exposure due to lid retraction developed and required secondary correction. Perhaps some dryness caused by interference with the lacrimal gland also contributed to this problem. Medial canthal drift, after an initially satisfactory canthal position, occurred in five of the ten patients-a high incidence. Progression of the

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Fig. 4

Figure 3.-Radiograph of a patient with the typical large empty-looking involved the orbits showing the defect in the posterior aspect of the orbit on the right.

orbit. Figure 4.-A

transverse

CT scan through

Fig. 6 Fig. 5 Figure S.-Diagrammatic representation of the skeletal procedure to enlarge the orbit and reconstruct the roof and posterior wall defects with bone grafts (after Marchac, 1984).

Figure 6.-Diagrams of the eyelid surgery. The wedge resection of hypertrophic lid tissues laterally (centre) should not include the orbicularis muscle, and the levator shortening should be conservative.

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Table 1

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Complications

TREATMENT

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Discussion

in 11 patients

Delayed extradural haematoma Cerebral oedema Pulmonary embolism Upper lid retraction/dry eye Recurrence of pulsating proptosis Progression of soft tissue disease

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I 5

I I

disease elsewhere in the face is a continuing problem in younger patients, for example in a child (Fig. 7A, B) whose maxilla is now extensively involved and enlarging. Quite gross oedema in the tissues involved by neurofibromatous infiltration is the rule postoperatively and can take months to resolve. The extent of the swelling, which may go well beyond the area of surgery, often reflects a far wider area of involvement by neurofibromatous tissue than has been expected from clinical examination. Some pre- and post-operative photographs to show the limited cosmetic improvement obtained are shown in Figures 7-10.

Based on the experience of this unit a number of recommendations can be made. Decisions regarding whether or not surgical treatment is indicated should be made in the light of the complication rate and the somewhat limited cosmetic improvement which can be achieved. These factors need to be weighed against the deformity that is present and the distress it causes to the patient and family. There is no evidence as yet that early correction of pulsating proptosisavoids later visual deterioration. The surgery should be in an experienced craniofacial unit with full neurosurgical facilities. The best cosmetic results are in those patients whose eye can be removed and a satisfactory bed created for a well-made external orbital prosthesis (Fig. 11). Where the eye has vision or the patient wishes to retain a blind eye the improvement is far more limited and the likelihood of further surgery being required to revise the lids is high. Another group of patients who should get reasonable cosmetic improvement are those who have only pulsating proptosis without the soft tissue infiltra-

Fig. I

Fig1we 7.-~A child (A) before surgery and (B) after. Soft tissue and skeletal involvement mid 4acial

region.

by the condition

is continuing

in the rirght

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Fig. 8 Figure 8.-A proptosis.

patient

before and after surgery.

Note the tendency

to relapse of the medial canthal

position

and the degree of residual

Fig. 9 Figure 9.-Another patient before and after surgery. This is one of the patients who had problems with drying and exposure of the eye owing to retraction of the upper lid following simultaneous intracranial, intraorbital and eyelid surgery. The forehead scar was from previous surgery elsewhere.

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Fig. 10 Figure IO.-- Another

patient

before and after surgery

tion in the eyelids. Unfortunately none of our operated patients have been in this group and those we have seen have declined a major intracranial procedure because their deformity was not too severe. In view of the problems in patients with a retained eye in this series (of postoperative lid retraction and cornea1 exposure), a two-stage approach to the full-blown picture with pulsating proptosis is recommended. It is emphasised that debulking of an intraorbital soft tissue mass should be conservative. At the second stage to improve the eyelids great care must be taken to avoid tightening the lids too much over a proptosed globe, denervating the orbicularis oculi by extensive excisions in the muscle plane at the lateral ends of the lids. and overshortening the levator tendon. Any of these manoeuvres may improve the appearance at operation, only to lead to postoperative exposure of the cornea. Fig. 11 Figure Il.--The patient shown in Figure I after surgery to reconstruct the orbital walls and fashion a hollow orbital soft tissue cavity. and fitted with an external orbital prosthem.

162 The high incidence of stretching and redisplacement of the medial canthal tendon is not seen to the same extent after craniofacial procedures for other conditions such as congenital deformities or trauma. Whether the gross postoperative swelling which tends to occur in neurofibromatosis is responsible for this by stretching, or whether there are other reasons such as abnormalities in healing is not known. Overall, while there has been a significant incidence of problems in these patients, the cosmetic results have usually been worthwhile to the patients, although disappointing to the surgical team. All but one patient were glad they had the operation(s), and a few reported great improvement in their general self-image and outlook on life. References Hunt, J. C. and Pugh, D. G. (1961). Skeletal lesions in neurofibromatosis. Radiology. 76. 1. Jackson, I. T., Laws, E. R. and Martin, R. D. (1983). The surgical

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management of orbital neurofibromatosis. Plastic and Reconstructive Surgery, 71.75 1. LeWald, L. T. (1933). Congenital absence of the superior orbital wall associated with pulsating exophthalmos. American Journal of Roentgenology, 30,756. Marchac, D. (1984). Intracranial enlargement of the orbital cavity and palpebral remodeling for orbitopalpebral neurofibromatosis. Plastic and Reconstructive Surgery, 73, 534. Martyn, L. J. and Knox, D. L. (1972). Glial hamartoma of the retina in generalized neurofibromatosis: Von Recklinghausen’s disease. British Journalof Ophthalmology, 56,487. Moore, R. F. (1931). Diffuse neurofibromatosis with proptosis. British Journalof Ophthalmology, 15.272. Van der Meulen, J. C., Moscona, A. R., Vandrachen, M. and Hirschowitz, B. (1982). The management of orbitofacial neurofibromatosis. Annals of Plastic Surger?,, 8.213.

The Authors Michael D. Poole, FRCS, FRACS. Consultant Plastic and Reconstructive Sureeon. Oxford Craniofacial Unit. Radcliffe Infirmary, Oxford 0X2 kHE Requests

for reprints

to the author.

Paper received 27 May 1988. Accepted 11 July 1988.