**3.2 Surgical techniques and its application**

Following comprehensive assessment from the craniofacial team, the choice of surgery basically depends on the aim, condition of the patient, skill of the surgeons and the facility. Hariri et al. [25] proposed for a protocol to indicate the type of intervention based on the aim of the functional rehabilitation. The protocol explained on the extend of surgical treatment depending on the patient's severity, age as well as whether it can be done in stages or in combination to address the issues.

In multiple aims for rehabilitation in very young patient for example, increased ICP with hydrocephalus would necessitate less extensive surgical intervention such as ventriculoperitoneal (VP) shunting, while severe orbital proptosis might indicate temporary tarsorraphy, and respiratory difficulty would necessitate a continuous airway pressure device, a nasal stent, or a tracheostomy depending on the severity and the specific anatomic obstruction. More extensive surgical procedures are usually deferred up to certain age to reduce possibility of complications.

#### *3.2.1 Posterior vault distraction/expansion*

Posterior cranial vault expansion is usually indicated in increased in ICP cases without other functional issues when the patient's age is more suitable [26, 27]. The aim is to increase the cranial volume to accommodate for the brain growth whilst reducing the intra cranial pressure.

#### *3.2.2 Fronto orbital advancement and Monobloc Le Fort III advancement*

Increased ICP with orbital proptosis might require fronto-orbital advancement with or without cranioplasty, and increased ICP in the presence of orbital proptosis and hypoplastic maxilla might require a monobloc as practiced in the authors' center. Surgery can be performed conventionally or combined with distraction osteogenesis (DO) technique, which is indicated for superior structural expansion and achieving simultaneous new histogenesis compared with conventional surgical procedures [28]. The application of DO in treating craniofacial deformity was first reported in 1992 [29]. Since then, the benefits of this technique in treating syndromic craniosynostosis as reported in the literature are similar to those in the present study, which

include marked improvements in functional parameters involving eye protection, preventing the increase of ICP, and treating airway deficiency [30–34].

### *3.2.3 Le Fort III osteotomy*

Le Fort III advancement is aimed on improving the proptotic condition as well as opening the space for the upper airway. Syndromic craniosynostosis patients may presented with restricted upper airway thus causing obstructive sleep apnoea and shallow orbital floor. This allows the floor of the orbit to be advanced while opening the upper airway region on the nasal and maxillary region. This technique can be performed via conventional advancement or via DO depending on the amount of advancement and the experience of the team.

### *3.2.4 Le Fort I osteotomy*

This is usually indicated in a later stage when the patient is more stable in growth to correct skeletal discrepancies such as retruded maxilla thus causing OSA. Therefore, the maxilla is advanced to gain space for airway. This procedure may be combined with other soft tissues surgery to gain optimum results in opening the airway such as tonsillectomy and adenoidectomy.
