Craniosynostosis

The introduction of distraction osteogenesis to frontofacial monobloc advancement has increased the safety of the procedure. One hundred forty-seven patients with syndromic craniosynostosis underwent frontofacial monobloc advancement using 4 internal distractors. Twenty-five were aged 18 months or less. Ten patients presented with a tracheostomy, 5 (50%) were decannulated after surgery, and 3 others (30%) required an additional intervention before decannulation. Six patients required the addition of a transfacial pin and external traction. Very early frontofacial monobloc with 4 internal distractors is a safe and effective treatment to protect the ophthalmic, neurologic, and respiratory functions in infants with severe syndromic craniosynostosis.

Key points

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Frontofacial monobloc advancement with 4 internal distractors is safe and effective before age 18 months.
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Its main indications are vision-threatening exorbitism and sleep apnea with intolerance to noninvasive ventilation.
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Overcorrection is necessary.
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Facial stability and advancement can be optimized using a transfacial pin and external traction at bedside under extended sedation.

Syndromic craniosynostosis is a complex condition commonly associated to a mutation in one of the fibroblast growth factor receptor genes. ^, It results in severe functional and aesthetic impairments in the craniofacial skeleton. Surgical treatment aims to prevent further neurologic compromise and restore craniofacial dysmorphology. Early intracranial volume expansion prevents the risks of visual and cognitive impairment due to craniocerebral disproportion and intracranial hypertension.

The traditional strategy for syndromic craniosynostosis management is 2-stage and carries less risk for surgical morbidity than the more recent single-stage frontofacial monobloc advancement (FFMBA). The 2-stage strategy treats the craniosynostosis first by a frontoorbital advancement before 1 year of age. The treatment of the facial retrusion is delayed: the facial advancement (Le Fort III type) is performed at 5 to 6 years of age or even later, unless a severe breathing impairment requires an earlier surgical correction. ^, A secondary maxillary advancement (Le Fort I) might be necessary after 14 years of age to correct the maxillary hypoplasia caused by its congenital lack of growth, to obtain a class I occlusion. However, in this multiple-stage strategy, the facial retrusion treatment and its subsequent improvement of airways is delayed, and many teams prefer to use routine tracheostomy to address the sleep apnea syndrome. Tracheostomy is considered a useful procedure, but its morbidity certainly affects the child and family quality of life.

The simultaneous correction of the frontofacial retrusion prevents corneal desiccation resulting from exorbitism, chronic hypoxemia caused by impaired upper airway obstruction, and addresses the morphologic appearance. MBA can correct simultaneously the frontal and the facial retrusion and increase both orbits and airways. ^, However, as a result of the necessary osteotomy of the floor of the anterior skull base, the MBA produces 2 potentially detrimental consequences: the creation of a dead space within the anterior cranial fossa and the communication between the anterior cranial fossa and the nasal cavity. ^, ^, Consequently, infections can occur leading to reoperation and eventually to life-threatening complications such as meningitis and necrosis of the frontal bone. ^, ^, The authors previously demonstrated the reduction of those risks by the use of distraction osteogenesis. Thirty-years ago, the rate of infections associated with MBA was around 30% in our center, and there was an unacceptable mortality rate of 15% (Arnaud, unpublished data, 1999) in patients with a ventriculoperitoneal shunt undergoing MBA without distraction.

By using FFMBA early in age and with monobloc distraction osteogenesis (MBDO) (1) the rapid growth of the brain rapidly fills the dead space and reduces the risk of infection and (2) airway obstruction associated with severe midface retrusion can be concurrently treated. ^, MBDO’s main indications were initially restricted to vision-threatening exorbitism or severe breathing impairments in infants, in whom the benefits outweigh the risks. These indications were progressively extended in our institution to include younger and less severe patients. ^, Although this early implementation of MBDO may be considered controversial by some, we believe that this form of early intervention will benefit appropriately indicated patients. When required, posterior skull vault expansion is chronologically performed before MBDO. It decompresses the brain by increasing intracranial volume and can delay MBDO to a later time when the facial bones are larger and more robust. However, some patients still require a very early monobloc distraction osteogenesis (VEMDO) before 18 months of age, for severe exorbitism and/or severe respiratory obstruction.

Although we and other investigators have previously presented the safety and effectiveness of VEMDO, some craniofacial surgeons worldwide remain reluctant to this procedure, because of the associated morbidity risk. ^,

We present our experience with 147 monobloc distraction procedures in infants and children with syndromic craniosynostosis operated in our unit between September 2000 and November 2018. ^, In a subset of our patients, who will be separately analyzed, VEMDO was performed to avoid or remove a tracheostomy. The most severely affected patients treated with VEMDO underwent surgery before 1 year of age and required a transfacial pin and external traction. This surgical technique is detailed in the following section.

Patients and methods

Patients with syndromic craniosynostosis who underwent FFMBDO between September 2000 and November 2018 were included. Two subgroups were created based on the age at surgery: patients operated after age 18 months (group 1) and VEMDO patients who were operated before age 18 months (group 2). Charts were reviewed for demographic characteristics, tracheostomy status, polysomnographic data, fundoscopic examinations, and surgical history.

All study patients were operated by the senior author (EA) according to a standardized procedure that will be detailed later. ^, ^, There was a slight variation in some patients of group 2 in whom 16 underwent the standard procedure and 9 had a transfacial pin inserted at the zygomatic level.

Group 1 included children older than 18 months (122 patients).

Surgical Technique

Under general anesthesia, the scalp is opened or reopened through a coronal approach. After subgaleal undermining, 2 anteriorly based paramedial frontal periosteal flaps are dissected and prepared to isolate the skull from the nasal cavities. Temporal muscle flaps are also elevated to expose the lateral aspects of the orbits. The osteotomy lines are marked and a long tenon (bandeau extension) designed bilaterally behind the supraorbital bar within the flattest part of the temporal fossa. This modification will facilitate consolidation at the upper level of the orbit if limited osteogenesis occurs at other bony sites. A frontal bone craniotomy is performed for intracranial access. Subsequently, the monobloc osteotomies are completed as previously described. A complete bilateral pterygomaxillary disjunction is confirmed visual through complete movement of the monobloc segment using pediatric Rowe forceps. This complete liberation of the skull base from the face is critical to avoid insufficient advancement and/or bending of the hemifaces during activation. Two internal distractors (Arnaud cranial distractors, KLS Martin, Tuttlingen, Germany) are inserted at the extremity of each bony tongue, as parallel to each other as possible. The distractors are fixed with Champy 2 mm in diameter, 3- to 5-mm long metallic screws or SonicWeld™ rivets (KLS Martin, Tuttlingen, Germany). Sealing of the anterior cranial fossa from the nasal cavities is performed by crossing the 2 pericranial flaps at the midline after transposing them across the orbital roof and suturing their anterior border to the supraorbital bar using resorbable sutures through the bone. This biological seal is reinforced by applying 1 mL of fibrin glue. The bony forehead flap is trimmed at its inferior edge by resecting 2 laterally based small triangles and fixed to the upper edge of the supraorbital bar by 4 to 6 stainless steel 3/10 mm wires; this allows for the posterior tilting of the forehead and contributed to the reduction of the future retrofrontal dead space. Two other distractors (Marchac maxillary distractors) are used at the lower aspect of the temporal fossa, with the anterior part located behind the zygomatic bone. Fixation is done with metallic Champy neuro screws (smooth tip). The distraction is started at day 3 unless a significant cerebrospinal fluid (CSF) leak is noted ( Fig. 1 ).

Group 2 of 25 children aged 18 months or less underwent VEMDO ( Table 1 ).

Table 1

Demographic characteristics of patients undergoing very early monobloc distraction osteogenesis (age 18 months or less)

	Frequency (%) (n = 25)	Mean ± SD
Sex
Male	13 (52%)
Female	12 (48%)
Age (mo)		13.5 ± 3.9
Syndrome
Crouzon	7 (28%)
Pfeiffer	8 (33%)
Apert	8 (33%)
Crouzon with acanthosis nigricans	1 (5%)
Tracheostomy at presentation	9 (36%)
Tonsillectomy, turbinectomy, and/or adenoidectomy before VEMDO ^a	7 (28%)
Foramen magnum decompression (Chiari) before VEMDO ^a	5 (20%)
Posterior vault decompression before VEMDO ^a	14 (56%)
Ventriculoperitoneal shunt or endoscopic third ventriculostomy before VEMDO ^a	6 (24%)

a VEMDO, very early monobloc distraction osteogenesis.

In 9 patients an additional surgical step was carried out with the insertion of a 20- to 22-mm Kirschner wire (K-wire) transfacially (zygoma to zygoma). In 6 of these patients, the transfacial pin was attached to an external pulley system providing external traction anteriorly (1–3 kg weight). The target traction weight was achieved with the head slightly lifted from the surface of the bed ( Fig. 2 ). This last subgroup is detailed later in Table 2 .

Table 2

Demographic characteristics of patients undergoing very early monobloc distraction osteogenesis with transfacial pin and external traction

	Frequency (%) (n = 6)	Mean ± SD
Sex
Male	3 (50%)
Female	3 (50%)
Age (mo)		11.2 ± 4.9
Syndrome
Crouzon	2 (33%)
Pfeiffer	3 (50%)
Crouzon with Acanthosis nigricans	1 (17%)
Tracheostomy at presentation	5 (83.3%)
Turbinectomy before VEMDO ^a	1 (17%)
Posterior vault decompression before VEMDO ^a	4 (67%)
Foramen magnum decompression (Chiari) before VEMDO ^a	2 (33%)
Shunt or endoscopic third ventriculostomy before VEMDO ^a	4 (67%)