Fronto-orbito-nasal advancement a surgical approach based on skull development in treatment of craniofacial deformities

Abstract

The classical treatment of craniosynostosis is based on the fundamental work by Tessier. However, developmental aspects suggest modified osteotomy lines like fronto orbito nasal advancement combined with a modified midfacial distraction. This also makes it possible to take assess the different distances of the anterior displacement of the individual parts of the skull. Pioneering in therapy is less the syndrome itself than the accompanying symptoms such as respiration and intracranial pressure. For brain release we recommended (Joos 1998) the osteoclastic procedure according to Powiertowsky (1974) within the first 6 months of life. For further treatment frontoorbito–nasal advancement and modified midface distraction seem to achieve better results in enlarging the inner nose and a more harmonious profile.

1. Introduction

Since the fundamental work on the development of fronto-orbital malformations was described by¹ and their treatment,² the classical surgical therapy consists of a fronto-orbital advancement and Le Fort III osteotomy.³ The operative procedure was based on the classical fracture classification according to Ref. 4. This development was only made possible by improved possibilities of anesthesia and postoperative follow-up. In the past, the bony fragments were first fixed with wire sutures. Following the introduction of osteosynthesis techniques in the early seventies⁵ and their application in the midface⁶ and the cranio-facial region⁷ there was a significant improvement in management. As a result, different surgical procedures have been developed, such as monoblock osteotomy,⁸ or combined Le Fort III and Le Fort I osteotomies,⁹ leading to a marked improvement in outcomes. Parallel to these developments, the timing of the individual operative steps was varied¹⁰ and, for the first time, the early release of the brain¹¹ was discussed in order to improve the growth¹² and development of the children. With the introduction of the osteodistraction by¹³ and the application to the cranio-facial region,^{14, 15, 16} treatment options were significantly expanded (Fig. 1).

Fig. 1.

Different treatment options.

Despite the now standardized therapy,¹⁷ there are always significant problems that can manifest in early childhood in the restriction of vital functions such as respiration and food intake, as well as in increase in intracranial pressure with possible cerebral and ophthalmological damage and these all require early action. Later on, growth-related disturbances of the mid-face with consequent adverse effects on function and significant impairment of nasal breathing can arise. Despite the established therapeutic procedures, there are still ambiguities and problems that affect both the timing and the surgical procedures.

2. Aetiology

The syndromal malformations are usually gene mutations, which in particular represent a missense mutation of the FGFR2 gene.¹⁸ This follows an autosomal dominant inheritance, with almost exclusively new mutations. Apert syndrome is the only syndrome in this group with a direct genotype-phenotype correlation. Common to all these gene mutations is a similar phenotype. Damage to the mesenchymal primordial cranium and chondrocranium¹⁸ causes insufficient growth of the anterior chondrocranium resulting in an anterior-posterior shortening and wider transverse skull diameter (brachy-turricephalus). This results in a dysmorphism of the facial skull with hypertelorism, broad nasal root, flat orbitae and exophthalmos. Since the maxilla is severely shortened in the vertical and sagittal dimensions an extreme retropositon and retroinclination of the upper jaw arises and thus a pronounced pseudoprogenia with an open bite. Connected with the disorders of the skull are membranous or bony syndactyly of the hands and feet. Intraorally, 75% present with clefts of the palate and, due to the changed jaw geometry, a severely delayed and ectopic tooth eruption, as well as massive crowding (Fig. 2).

Fig. 2.

Skull deformation in Apert Syndrom: exopthalmus, hypertelorism, turricephalus, syndactyly, teeth eruption abnormalities.

The cephalometric signs of such malformations, which can only be verified with a¹⁹; are usually at least 10° retroinclination of the maxilla, reduction of the posterior skull base angle, enlargement of the anterior cranial base angle, and increased skull height and a significant shortening of the skull length (Fig. 3).^12.

Fig. 3.

Cephalometric signs of craniosynostosis in Delaire analysis.

3. Problem

The main problem in all syndromic craniosynostoses (for example, Apert, Crouzon, Pfeiffer) is the premature closure of all sutures both in the area of the neuro- and the viscerocranium. This causes severe cranial malformations that affect the development of the brain, the orbit,²⁰ the nose, the midface and the ears and are associated with atypical facies. The previous approaches were often limited to the question of plastic correction, either suturectomy, which was usually performed at the end of the first year of life and carried the risk of intracranial pressure, or a fronto-orbital advancement at about 2 years. The necessary midface advancement is commonly performed at different times around age of 15 years.¹⁰ recommended an early surgical procedure with fronto-orbital advancement and simultaneous midface mobilization in the first months of life.¹² recommended relief of intracranial pressure within the first 6 months of life to relieve the brain by the osteoclastic procedure according to Ref. 21. With this method a significant improvement in cranial growth could be achieved in contrast to suturectomy.¹¹ Based on our experience to date, it is necessary to aim for a more differentiated view of syndromal malformations, as there is a considerable range of variations within the individual syndromes, which require a step-by-step therapy (Fig. 4, Fig. 5).

Fig. 4.

Variations of Apert syndrome.

Fig. 5.

Variations of morbus crouzon.

Primary therapy has to be based less on the syndrome itself, more on the postnatal symptoms. Of particular importance are two symptoms:

4. Respiration and development of intracranial pressure

Both symptoms may require immediate action with respiratory protection and relief of the brain. The common therapy is:

• 1.Elimination of severe respiratory problems mostly through tracheostomy
• 2.Early release of pressure on the brain, mostly through suturectomy by neurosurgeons, possibly followed by fronto-orbital advancement
• 3.The correction of the midface mostly by Le Fort III osteotomy/distraction at about 15 years.

Efforts to perform both fronto-orbital advancement and midface mobilization as early as the first weeks of life, as suggested by¹⁰; were unsuccessful. Therefore, usually after the first year of life, the correction of the neurocranium is performed by fronto-orbital advancement. However, this approach ignores the fact that the greatest growth potential of the neurocranium is directly after birth and gradually decreases until the fourth year of life. In our opinion, therefore, a very early relief of the brain in the form of an osteoclastic procedure based on²¹ should be performed in order to normalize the pathological growth processes as early as possible. (Joos1998).

5. Operation technique

The classic surgical procedure described by² is the separation of neuro- and viscerocranium at the Le Fort III level in two stages:

• 1.Fronto-orbital advancement in infancy and
• 2.Le Fort III osteotomy or Le Fort III distraction in adolescent age.

This procedure is based on the classification of Le Fort⁴ in traumatology (Fig. 6).

Fig. 6.

Classic procedure.

Developmental evolution shows, however, that the corresponding facial parts develop from different embryological regions that do not correspond to the Le Fort III level. The forehead and the nose develop from the frontal process with the laterally standing orbitae, while the upper jaw arises from the lateral maxillary processes, which unite below the nose in the midline (Fig. 7). This also explains the varying degrees of developmental disorders at the various levels of the facial skeleton. Thus, the growth deficit in the frontal plane is about 1–1.5 cm, in the fronto-nasal plane also about 1–1.5 cm, but on the occlusal plane 2–2.5 cm (Fig. 8).

Fig. 7.

Development of the midface from the frontal process and the two maxillary processes. Red line marks the border between nose and maxilla (Courtesy Prof. Erik Schulte Mainz).

Fig. 8.

Growth deficit in different levels.

This suggests performing appropriate osteotomies to correct cranio-facial malformations not at the Le Fort III level, but according to the embryological growth lines and to separate the orbito-nasal area from the midface (Fig. 9).

Fig. 9.

Instead of Le Fort III Ostetomy (red line) fronto-orbito-nasal advancement (dark blue line) and midface distraction (bright blue line).

This also makes it possible to take assess the different distances of the anterior displacement of the individual parts of the skull. The distances that need to be balanced vary considerably across levels. Thus, in the frontal area, the extent of the forward displacement is about 1–1.5 cm, as well as in the orbital and nasal areas, while in the mid-facial area, in particular at the level of the occlusal plane, it is usually 2–2.5 cm .(Fig. 9)⁹ attempted to address this fact by simultaneously performing a Le Fort III osteotomy combined with an osteotomy at the Le Fort I level.

The consideration of developmental growth processes inevitably leads to the adaptation of the osteotomy lines and the entire operative procedure to the embryological dividing lines. Since 2007, instead of fronto-orbital advancement followed by Le Fort III distraction, we have performed fronto-orbito-nasal advancement, followed by a modified midfacial distraction. The consequence of fronto-orbito-nasal advancement is that it leads to a significant enlargement of the inner nose and thus improves nasal breathing. In addition, the fronto-nasal transition is much more harmoneous than after fronto-orbital advancement .(Fig. 10)

Fig. 10.

Cerebro – orbital release by fronto-orbito-nasal advancement.

At the age of about 16 years, we perform a modified midface distraction of the order of 2–2.5 cm. The advantage of the modified midfacial distraction is that it not only reduces or even compensates for the sagittal discrepancy between the upper and lower jaw, but also enlarges and lengthens the nose and thus improves nasal breathing again (Fig. 11). If in early childhood exists severe breathing problems, we perform this procedure much earlier, but you have to take in account that it has to be done later again. After early removal of the intraoral distractors (3–4 weeks postoperative) a postoperative treatment with Delaire mask^12,22 is performed for half a year.

Fig. 11.

Modified midface distraction.

To prepare the midfacial distraction,²³ an orthodontic pre-treatment for the formation of the dental arches is required.²⁴ Since this often takes a long time - due to ankylosis of the teeth - it is recommended to perform a corticotomy of the individual teeth as described by^{25, 26, 27} (Fig. 12). The ankylosis of the teeth is due to the fact that the periodontium is comparable to a cranio-facial suture and is also affected in generalized cranio-facio-synostosis. Therefore, care must be taken during orthodontic treatment to avoid pronounced root resorption. With the help of a corresponding corticotomy of the individual teeth (Fig. 13) and well directed teeth extractions this fact can be taken into account.²⁸

Fig. 12.

Corticotomy (Düker1975).

Fig. 13.

Corticotomy.

6. Discussion

² classic procedure for treating cranio-facial malformations is fronto-orbital advancement, followed by Le Fort III osteotomy. The separation of neurocranium and viscerocranium was based on the usual traumatological classification according to Ref. 4. However, it turned out that this procedure has problems that are due to the different degrees of movement of the individual parts of the skull in the different planes. While the range of motion in the fronto-orbital-nasal plane is about 1.5 cm, it is about 2–2.5 cm on the occlusal plane. In addition, this does not improve nasal breathing and the fronto-nasal transition is often aesthetically unpleasant. To compensate for this,⁸ has proposed the monoblock osteotomy and⁹ a simultaneous Le Fort III and Le Fort I osteotomy. However, these procedures have not prevailed and could not improve the problem.²⁹ Mostly multiple reconstruction procedures together with surgical orthognathic corrections were necessary to achieve facial symmetry.³¹ The manifest midfacial hypoplasia is often treated by midfacial advancement with different distractor systems and the benefits of midfacial advancement by distraction osteogenesis have been well studied.³⁰

With the fronto-orbito-nasal advancement on the one hand the profile and on the other hand the nasal breathing could be significantly improved. The modified mid-face distraction has the same effect. The procedure has been proven on 20 patients since 2007. To conclude, further cases need to be dealt with and evaluated.

7. Summery

The classical treatment of craniosynostosis is based on the fundamental work by Tessier. However, developmental aspects suggest modified osteotomy lines like fronto orbito nasal advancement combined with a modified midfacial distraction. This also makes it possible to take assess the different distances of the anterior displacement of the individual parts of the skull. Pioneering in therapy is less the syndrome itself than the accompanying symptoms such as respiration and intracranial pressure. For brain release we recommended¹² the osteoclastic procedure according to Ref. 21 within the first 6 months of life. For further treatment fronto- orbito–nasal advancement and modified midface distraction seem to achieve better results in enlarging the inner nose and a more harmonious profile.