Fronto-ethmoidal meningoencephaloceles: morphology and treatment

British Journal of Plastic Surgery (1984) 37,271-284

0 1984 The Trustees of British Association of Plastic Surgeons

Fronto-ethmoidal meningoencephaloceles: morphology and treatment D. J. DAVID, L. SHEFFIELD, D. SIMPSON and J. WHITE South Australian Cranio-Facial Unit, Adelaide Children’s Hospital, Adelaide

Summary-Twenty-five cases of fronto-ethmoidal meningoencephaloceles have been studied. The relationship to other sincipital meningoencephaloceles is explored. In all cases the exit holes from the anterior cranial fossa are at the site of the foramen caecum. The facial component of the defect determines the sub-classification: naso-frontal, naso-ethmoidal and naso-orbital. The crania-facial deformity may consist of hypertelorism, orbital dystopia, elongation of the face and dental malocclusion. These reflect the distorting influence of the extruded intracranial contents on facial growth. Early removal of the meningoencephalocele by the crania-facial route is recommended to allow normal growth forces to be re-established. In older patients with established deformities translocation of the orbits may be necessary.

A congenital meningoencephalocele is a herniation of brain and meninges through a skull defect. The alternative name is cranium bifidum, giving the attractive but unproven assumption that these conditions are the cephalic equivalent of spina bifida. Spring (1854) wrote what was probably the first extensive monograph on the subject. He stated that LeDran (1740) introduced the term hernia cerebri; however, LeDran’s case was probably a cephalhaematoma. Spring himself attempted to distinguish between meningocele and cerebral hernia, the latter being divided into encephalocele and hydrencephalocele when hydrocephalus was present. The term meningoencephalocele seems appropriate because it describes the contents of the hernia. We wish to discuss the sincipital meningoencephaloceles which, by definition, present in the front of the skull and are seen externally. We consider classification, morphology and treatment with some comments on epidemiology. Modern methods and investigation offered by a multi-disciplinary Cranio-Facial Unit enable these lesions to be studied more thoroughly and treated more effectively.

and Suwanwela (1972), based on a paper by Meyer (1890), into: Fronto-ethmoidal-naso-frontal -naso-ethmoidal -naso-orbital Inter-frontal Cranio-facial clefts The bony defects associated with sincipital meningoencephaloceles have been included in many attempts to classify crania-facial clefts. Two of the most recent and significant endeavours are Tessier’s (1976) anatomical classification and Mazzola’s (1976) morphological classification based on embryological considerations. Tessier’s classification describes clefts arranged around the orbit and numbered 0 to 14; as he has written, this system “. . . does not prevent a more sophisticated or detailed explanation, but rather it provides an immediate reference to the exact location and character of what is being described”. Included in Tessier’s series and in subsequent article derived from his original paper (Kawamoto et al., 1977), are cases of sincipital meningoencephalocele of the naso-ethmoidal type, and cases of inter-frontal meningoencephalocele, which may both be classed as Tessier type 14 clefts. Mazzola uses the term fronto-nasal dysraphia, under which heading he makes a sharp distinction between the bifid nose and the midline fistulae. He

Classification

Meningoencephaloceles may be sub-divided into occipital, parietal, basal and sincipital. The latter group have been further classified by Suwanwela 271

272

BRITISH JOURNAL OF PLASTIC SURGERY

Fig. 1 Figure l-(A) Plain lateral radiograph showing a fronto-ethmoidal meningoencephalocele demonstrating the distortion at the root of the nose. (B) Sagittal tomogram giving a clearer definition of the relationship of the deformity to the face of skull and face. (C) Two-dimensional reconstruction from the computerised axial tomogram giving clearer definition of the deformity.

FRONTO-ETHMOIDAL

MENINGOENCEPHALOCELES:

MORPHOLOGY AND TREATMENT

has included in the sub-heading “bifid nose”, teratomas, dermoid cysts, and encephaloceles. He considers that these arise spontaneously, noting however that Cohen et al. (1971) have shown that some are inherited as dominant genes. We wish to describe the bony and soft tissue morphology of fronto-ethmoidal meningoencephaloceles and to make a clear distinction between these and other facial clefts included in both Tessier’s and Mazzola’s classifications.

213

Investigations All patients were admitted to the Unit at least one week prior to surgery and a routine crania-facial work-up was performed, as described by us elsewhere, David et al. (1982). This period is needed to complete the crania-facial mensuration, developmental assessment, neurological assessment, ophthalmological assessment and radiology which are essential in surgical planning. Since 1977 the latter mode of investigation-has undergone con-

Fig. 1 Figure l-(D)

Three dimensional reconstruction producing a vastly improved image.

Material Since 1977 the South Australian Cranio-Facial Unit has developed relationships with various South-East Asian countries, and in particular has treated patients referred from Malaysia. Twentytwo cases of meningoencephalocele have been referred to the South Australian Cranio-Facial Unit; twenty were referred from Malaysia, one from Indonesia, one from Papua New Guinea and one was an Australian. All patients had been previously assessed by local neuro-surgeons and/or plastic surgeons for referral to the central Unit. Factors involved in making this selection included whether the patient and family would benefit from complicated assessment and surgery. Patients with severe mental retardation and other associated problems rendering them unsuitable for surgery were thus eliminated. Three other patients were studied in Adelaide before the Cranio-Facial Unit was formed; two of these were Australian aboriginals and one an infant of European racial origin.

siderable development (Fig. 1). Plain radiographs and standard tomography have been supplanted by computerised axial tomography. Two dimensional reconstruction has been added and, latterly, three dimensional reconstruction as described by Hemmy et al. (1983). Three dimensional reconstruction gives a very accurate picture of the defect and displays particularly well the nature of the anterior fossa deformity in relation to the orbits and face. Accurate pre-operative classification of the lesion is possible and surgical planning is facilitated.

Age, sex and race

The patients referred from South-East Asia were relatively old, the age range referral being 1l/z to 19 years. The four cases born in Australia were seen much earlier, the age range being 2 weeks,to 15 months. In the combined series 13 were boys and 12 girls. The racial origins of the parents, in so far as these can be determined, are set out in Table 1.

274

BRITISH JOURNAL OF PLASTIC SURGERY

Genetic data Consanguinity was found in two families and in a third the parents of the affected child were distantly related. However, there was no history of encephaloceles or any other neural tube defect in any siblings, parents, or other relatives of the index cases. The striking finding from the genetic point of view, however, was that the paternal age seemed to be raised (Table 2). Statistical evidence of a raised paternal age is difficult to obtain: whilst Malaysian population figures are available for maternal age and birth order, there are no such statistics kept for paternal age. An estimate of the population distribution for paternal age has been made for this study by recording paternal age in 366 cases where births confined in the Penang hospitals are listed for the first 3 months of 1983. The mean paternal age obtained as well as the published population figures for 1979 in Malay births are shown in the Table. The mean paternal age of our cases is statistically significantly different from the mean paternal age in Penang (P < .05), whilst the population maternal age and birth order are not statistically different from that of our cases. A raised paternal age suggests that the course of this type of meningoencephalocele may be due to

an autosomal dominant mutation and, if this is confirmed, it would have important genetic counselling implications. The lack of familial cases and the geographic distribution of such meningoencephaloceles argue against dominant mutations as a cause. Further investigation is in progress and will be the subject of a separate report. Table 1

Sincipital meningoencephaloceles:

racial origins of

parents Racial origins

Number of cases

Malay (including Indonesia)

I8

Indian (born in Malaysia)

2

Australian Aboriginal

3

Papuan

1 1

European Total Table 2

25 Parental ages and birth order in 17 Malay cases

Mean parental age and birth order

Malay cases

Malay population Figures

Paternal age

31.3

32.1

Maternal age

29.4

28.0

3.8

3.4

Birth order

Fig. 2

Figure 2-Three dimensional reconstruction cribriform plate and crista galli.

of the anterior cranial fossa showing the exit hole and the relationship

of the

FRONTO-ETHMOIDAL

MENINGOENCEPHALOCELES:

MORPHOLOGY

Morphology of the bone defects The description fronto-ethmoidai is most appropriate because it describes the site of the cranial end of the defect which is always in the position of the foramen caecum at the junction of the frontal and

AND TREATMENT

ethmoid bones (Fig. 2). The posterior. margin of the defect is formed by the crista galli. This is often distorted and the cribriform plate is usually tilted downwards, as a deep central trough the anterior end of which is well below the planum sphenoidale;

Fig. 3 Figure 3-(A) reconstruction 2

275

A massive fronto-ethmoidal meningoencephalocele of the naso-frontal type. (B) The three-dimensional of the same patient shows the defect on the face with the frontal bone above and the nasal bones inferiorly.

276 the cribriform plate forms an angle of 45 to 50 degrees with the orbito-meatal plane. In our cases, the cranial exit holes varied in size and shape. All naso-frontal defects were round and central. All

BRITISH JOURNAL OF PLASTIC SURGERY

naso-orbital defects were bilobed (two patients from this group had been previously operated upon and one lobe of the exit hole had been obliterated by metal mesh). Two of the naso-

Fig. 4

Figure 4-(A) A fronto-ethmoidal meningoencephalocele of the naso-ethmoidal type. (B) Three dimensional reconstruction of the same child showing the distorted nasal bones above the crescentic deformities in the medial orbital walls and the depressed pyriform aperture inferiorly.

FRONTO-ETHMOIDAL

MENINGOENCEPHALOCELES:

MORPHOLOGY AND TREATMENT

277

Fig. 5 Figure 5-(A) A fronto-ethmoidal meningoencephalocele of the naso-orbital type. (B) The same patient showing the defect in the left medial orbital wall in the region of the frontal processes of the maxilla.

ethmoidal type were bilobed, while in one case the defect was lozenge-shaped and central; the remainder were round. The morphology of the facial bone defects showed more variation. In the naso-frontal type the holes were at the junction of the frontal and nasal bones (Fig. 3), the nasal bones being attached to the inferior margin of the defect which varied in shape. In the nuso-ethmoidal type, the facial defects lay between the nasal bones and the nasal cartilages (Fig. 4), the nasal bones being above and the nasal cartilages below. The nasal bones were deformed and often broadened, with crimped margins. The fronto-nasal angle was obliterated producing an over-hanging ledge. If the facial defect was confined to the nasal pyramid and was small and oval, the medial walls of the orbit were not involved. If, however, the meningoencephalocele was larger and the facial defect extended more laterally, then the anterior margins of the medial orbital walls were eroded and crescent-shaped.

meningoencephaloceles The naso-orbital present on the face through holes in the medial orbital wall (Fig. 5), in the frontal process of the maxilla and the lacrimal bones. In our cases the bony track was long and shaped like an inverted “Y”. The inverted “Y” may be asymmetrical as in the case shown in Fig. 5. These encephaloceles come through the frontal process of the maxilla onto the face leaving the nasal bones intact anteriorly and the lacrimal bones and lateral plate of the ethmoid intact posteriorly. However, during the passage of the cerebral hernia through the substance of the ethmoid the lateral plate of that bone is pushed laterally, forming a bony tunnel. General features of the face and facial skeleton In all cases the faces appear to be longer than normal (Fig. 6) although this is hard to measure with ordinary cephalometric techniques because some of the bony land-marks, particularly in the glabellar region, are obliterated. The pyriform

278

BRITISH

aperture and the nasal cartilages are misshapen; the aperture is shorter and broader than usual and displaced inferiorly. There was no evidence, however, in any case of a bifid nose or a midline nasal cleft. There was telecanthus in all cases with medial canthal dystopia in some and hypertelorism in most. As a rule the hypertelorism is not so severe as that associated with midline facial clefts; it is of the Tessier second degree variety with normal lateral canthal distance. Some patients had dental malocclusion which may be related to the deformity: the vertical plate of the ethmoid bone is attached to the tilted cribriform plate which is itself retro-displaced, presumably inducing secondary maxillary hypoplasia. The naso-ethmoidal type of encephalocele has a direct effect on the nasal septal cartilage pushing it downwards and backwards. It is as though the encephalocele has blown out onto the face through the weakened junction of the frontal and ethmoidal bones displacing the other-

JOURNAL

OF PLASTIC

SURGERY

wise normal orbits and nasal capsule, widening the orbits and lengthening the face. In contrast with the clefts, which appear to have a deficiency of tissue at their margins, the defects of the frontoethmoidal meningoencephaloceles are like tunnels or blow-outs. Neuropathology of the meningoencephalocele The pathological constituents of the herniations varied. No patient had extension of the ventricular system into the defect. Some patients had viable brain at the neck of the encephalocele but distal to the defect in the dura mater, biopsies mostly consisted of glial tissue, often infiltrated with fibrous trabeculae. Nine patients had undergone previous surgery; seven had had intra-cranial operations only and two had intra-cranial operations plus attempts to excise the facial lesions. In those cases where the neck of the encephalocele had been divided at previous surgery, there was no significant spontaneous atrophy of the facial extension. Histologically the glial masses did not look markedly atrophic, certainly they remained in sufficient bulk to produce a significant distortion of the face. The soft tissue mass of the meningoencephalocele may extend into the orbits and fuse with the periorbitum making excision of the orbital component of the mass extremely difficult. The tumour may flow over the infra-orbital rim medially which then becomes indented and depressed. The overlying skin is usually of full thickness, but may be discoloured or scarred from previous ulceration and healing. The skin is often thickened and crusty. In only one case was the skin cover of the extruded cerebral tissue defective: in this neonate the cerebral hernia was covered only by a thin layer of epidermis. Ocular problems At presentation 4 patients had decreased visual acuity and 3 patients suffered from squint. In 11 patients lacrimal drainage dysfunction was demonstrated and there was orbital dystopia in 3 patients. Neurological problems

Fig. 6 Figure 6-The typical long ethmoidal meningoencephalocele.

face

associated

with

fronto-

Four patients showed developmental retardation. Six patients had hydrocephalus and in two there was previous history of epilepsy. In all patients capable of being assessed, there was no evidence of anosmia before or after surgery.

FRONTO-ETHMOIDAL

MENINGOENCEPHALOCELES:

MORPHOLOGY AND TREATMENT

219

Fig. I Figure 7-Pre-operative photograph of a child where both orbits have been translocated meningoencephalocele. (B) Post-operative photograph.

Treatment In all 22 patients treated by the Cranio-Facial Unit, a combined approach was used. Access was gained by a bi-coronal scalp flap. Where there was a large soft tissue mass on the face requiring removal or where there was previous facial scarring, an additional nasal incision was made. The first step was wide sub-periosteal exposure of the craniofacial skeleton to outline the facial exit holes of the encephalocele. The planned osteotomies were then marked out on the skeleton with marking pencil and in many cases the sub-cranial bone cuts were made at this stage. The neurosurgeon then performed a frontal craniotomy removing the frontal bone as a free graft. If this was thick enough it was split according to the techniques described by Tessier (1982) and the inner table was used for grafting; otherwise two or even three ribs were harvested, one with a small cap of costal cartilage to use as a bone-graft for the nose. Where there was hypertelorism affecting both orbits, the orbits were translocated medially to move the globes of the eyes. Thirteen patients required translocation

after transcranial

removal of the

of both orbits, four patients required movement of one orbit only and five patients had osteotomy of the medial orbital walls, canthopexy and bonegrafting of the nasal defect. Before these orbital translocations were attempted, the neurosurgical dissection of the anterior cranial fossa was undertaken. The roofs of the orbits and the dural neck of the meningoencephalocele were exposed extra-durally as far as the cranial bony defect; additional exposure was often obtained by excising a rectangle of bone from the glabellar region which could be replaced if there was no hypertelorism to correct. The dura was then. opened on each side. The cerebral herniation was then inspected and as much as possible conserved; the neck of the encephalocele was then transsected and the dural defect repaired, usually with a piece of temporalis fascia. The remaining orbital cuts were then made. In the naso-ethmoidal type of deformity, the medial orbital walls were often found to be defective and the angle of the cribriform plate so steep that the translocated orbits came to overlie

280

Figure 8-(A)

BRITISH

Pre-operative

photograph

of a patient

Fig. 8 where one orbit has been moved.

JOURNAL

OF PLASTIC

(B) Post-operative

Fig. 9 Figure 9-(A) Pre-operative photograph where medial orbital wall osteotomies, trans-nasal were performed after removal of the meningoencephalocele. (B) Post-operative photograph.

canthopexies

SURGERY

photograph.

and nasal bone-grafts

FRONTO-ETHMOIDAL

MENINGOENCEPHALOCELES:

MORPHOLOGY

281

AND TREATMENT

Fig. 10 Figure ! lo- -(A) apaltient with facial clefting and severe hypertelorism this ps Itien It’s skxlll. Compare with Fig. 4 (A) and (B).

with a short face. (B) The three dimension

al ret :onstruction

of

282 the cribriform plate. The soft tissue mass was often very vascular and required careful dissection from the overlying skin and from the orbit where it was often closely adherent to the periorbitum. Care was taken not to remove too much skin from the midline over the nose as the soft tissue in this area has the capacity to “take up” in the first few months post-operatively. The presence of hydrocephalus need not contraindicate definitive crania-facial surgery. If possible, we prefer to avoid a pre-operative shunt. In three cases, preliminary external ventricular drainage was needed and was continued for 48 hours after operation; in two of these, the child’s state worsened post-operatively when the drain was removed and a subsequent vetriculo-peritoneal shunt was necessary. Operative results

All patients undergoing tram-cranial correction for fronto-ethmoidal meningoencephalocele survived the surgery. Surgery was usually accomplished between 4 and 8 hours and complications, apart from the acute post-operative hydrocephalus in two patients mentioned above, were minimal. Three patients had CSF rhinorrhoea which ceased spontaneously. Several patients had squints postoperatively, in all but two of these the problem resolved spontaneously, however in two patients the squints were of sufficient severity to warrant further surgical correction. Fig. 7 shows pre- and post-operative results of a patient requiring translocation of both orbits. Fig. 8 shows the results of a patient requiring one orbit to be translocated medially and Fig. 9 shows a case of a younger child requiring removal of the meningoencephalocele, osteotomies of the medial orbital walls and nasal bone-grafting. Discussion

We suggest that fronto-ethmoidal meningoencephaloceles are fundamentally different in origin from the midline clefts. The meningoencephalocele is a “blow-out” of the intra-cranial contents, through a midline tunnel from the anterior cranial fossa into the facial skeleton. The skeletal deformities relate to the space occupying effect of the hernia of extruded brain and are not intrinsic to the tissues themselves. If this view is correct, early complete surgery should allow the developing brain and eyes to mould the orbital skeleton and

BRITISH

JOURNAL

OF PLASTIC

SURGERY

the forces generated by the nasal airway, speech and mastication will remodel the facial deformity (Naim-Ur-Rahman 1979). The midline clefts of the nose on the other hand have a deficiency of tissue; the abnormality being intrinsic to the tissues themselves and early surgery of these cases would not be expected to help. It has been suggested that meningoencephaloceles are one of the neural tube defects, to be considered with anencephaly and myelomeningocele as a varying expression of a single developmental aberration. Sincipital encephaloceles pose difficulties however in that they do not have the circumstantial supporting evidence of sibling affection. Suwanwela et al. (1971) of Bangkok have studied a large number of sincipital encephaloceles and found no record of siblings with other congenital neurological malformation. This has been the case in our 25 patients. There are also extraordinary geographic peculiarities in the distribution of fronto-ethmoidal meningoencephaloceles: these malformations are common in Malaysia, Thailand and Burma, but rare in Europe, North America, Australia as well as in Japan and China. There is also some evidence that sincipital lesions are common in some parts of Russia (Barrow and Simpson 1966). The high incidence in Thailand and apparently also in Malaysia seems definite, and in both countries it is the Thais and Malays, not the Chinese who are affected, despite the presence in these countries of large Chinese ethnic minorities. Thus in their epidemiology the sincipital fronto-ethmoidal meningoencephaloceles show remarkable peculiarities and in the present state of knowledge it seems unwise to include them with other neural tube defects. They may indeed result from some unknown environmental agent, perhaps dietetic. Our findings of an apparent increase in paternal age of the patients suggests that an autosomal dominant gene mutation may account for the occurrence of the lesion but this requires further investigation of cases and population norms. Until recently, fronto-ethmoidal meningoencephaloceles were initially treated by neurosurgeons, plastic surgeons being as a rule consulted secondarily to deal with established deformities. The advent of crania-facial surgery allows definitive correction of the deformity at a single stage. Division of the neck of the encephalocele is not enough to wither the distal component of the extruded tissue, or to prevent distortion of the developing facial skeleton. Cranio-facial surgery is

FRONTO-ETHMOIDAL

MENINGOENCEPHALOCELES:

MORPHOLOGY AND TREATMENT

283

Fig. 11

Figure 1l-(A) Pre-surgical photograph of an Australian Aboriginal child with a naso-frontal type of meningoencephalocele the operation was performed at 4 months of age. (B) Post-operative photograph at one year of age.

recommended with removal of the extruded brain and repair of the dura and anterior cranial fossa and the appropriate osteotomy and bone-grafts, preferably in the first 3 months of life in the hope that the airway will establish normal growth forces of the crania-facial skeleton and allow the face to assume more normal proportions. The simplest operation, namely the moving of the medial orbital walls with bone-grafting and canthopexies is the operation of choice in the first years of life (Fig. 11). In the older patient, however, the displaced orbits can be reconstructed in three dimensions if necessary. Acknowledgements The authors wish to express their thanks to Mr La1 Kumar and Dr Chandran Arianayagam, Department of Plastic Surgery at the General Hospital, Kuala Lumpur and Dato Arumugasamy of the Department of Neurosurgery, Kuala Lumpur for their part in referring cases to the South Australian Cranio-Facial Unit and in the continuing management of these patients. Professor Harvey Carey of the Universiti Sains Malaysia kindly arranged to study the parental ages of babies delivered at the Penang Hospital. We wish also to thank Miss Gael Philips of Department of Histopathology of the Adelaide Children’s Hospital for her contribution to the histopathology of frontoethmoidal meningoencephaloceles.

where

References Barrow N. and Simpson, D. A. (1966). Cranium bifidum: investigation, prognosis and management. Australian Paediatric Joutpal, 2, 20.

Cohen, M. M. Jr., Sedano, H. O., Gorlan, R. J. and Jirasek, J. E. (1971). Fronto-nasal dysplasia (median cleft face syndrome): comments on etiology and pathogenesis. Birth Defects 7(7), 117. David, D. J., Poswillo, D. and Simpson, D. A. (1982). The Craniosynostoses: Causes, Natural History and Management. Berlin: Springer Verlag.

Hemmy, D. C., Herman, G. T. and David, D. J. (1983). Three-dimensional reconstruction of the skull and facial bones utilising computed tomography in crania-facial surgery. Transactions of the VIII International Congress of Plastic Surgery, Montreal.

Kawamoto, H. K., Wang, M. K. H. and Macomber, W. B. (1977). Rare crania-facial clefts in J. M. Converse, Ed. Reconstructive Plastic Surgery, 2nd Edition, Philadelphia: W. B. Saunders. LeDran, H. F. (1740). Observations in Surgery, London: James Hodges. Mazzola, R. F. (1976). Congenital malformations in the fronto-nasal areas; their pathogenesis and classification. Clinics in Plastic Surgery, 3, 573.

Meyer von, E. (1890). Uber Eine Basale Hirnhernie In der Gegend der Lamina Cribrosa. Virchows Archiv (Pathologische Anatomie) 120, 309.

284

BRITISH JOURNAL OF PLASTIC SURGERY

Naim-Ur-Rahman (1979). Naso-encephalocele: treatment by transcranial operation. Journal of the Neurological Sciences, 42,73.

Spring, A. (1854). Monographie de la hernie du cerveau et de quelques lesions voisines. Memoires de L’Academie Royale de Medecine de Belgique. Suwanwela, C., Sukabote, C. and Suwanwela, N. (1971). Fronto-ethmoidal encephalomeningoceles. Surgery, 69, 617. Suwanwela, C. and Suwanwela, N. (1972). A morphological classification of sincipital encephalomeningoceles. Journal of Neurosurgery,

36,201.

The Authors David J. David, MB, FRCS(Ed), FRCS, FRACS, Head of the South Australian Cranio-Facial Unit, Adelaide Children’s Hospital. Leslie Sheffield, FRACP, MSc, DCH, BMedSc, Medical Geneticist, Adelaide Children’s Hospital. Donald Simpson, MS, FRCS, FRACS, Director of Neurosurgery, Adelaide Children’s Hospital. Julian White, MB, BS, Registrar, South Australian CranioFacial Unit, Adelaide Children’s Hospital.

Tessier, P. (1976). Anatomical classification of facial, craniofacial and latero-facial clefts. Journal of Maxilla-facial Surgery, 4, 69.

Tessier, P. (1982). Autogenous bone grafts taken from the calvarium for facial and cranial applications. Clinics in Plastic Surgery, 9, 531.

Requests for reprints to: David J. David, MB, FRCS(Ed), FRCS. FRACS. South Australian Cranio-Facial Unit. Adelaide Children’s Hospital, King William Road, North ‘Adelaide, South Australia 5006.