The impact of spheno-occipital synchondrosis exposure via extended endoscopic endonasal surgery on midface growth in pediatric patients
Authors: Beniwal Manish , Morisako Hiroki , Sasaki Tsuyoshi , Ikegami Masaki , Nagahama Atsufumi , Tanoue Yuta , Sakamoto Hiroaki , Goto Takeo 
Published: October 2024

OBJECTIVE
Pediatric extended endonasal procedures pose significant surgical challenges. Lesions from the suprasellar region to the lower clivus necessitate extensive exposure. This study examined whether drilling the spheno-occipital synchondrosis (SOS) to remove the posterior clinoid process and dorsum sellae (DS) for greater exposure affects pediatric midfacial growth.

METHODS
From 2014 to 2020, the authors performed endoscopic endonasal surgery (EES) in 14 patients aged 12 years or younger. The lesions consisted of 11 cases of craniopharyngioma, 1 pituitary neuroendocrine tumor, 1 Rathke’s cleft cyst, and 1 Langerhans cell histiocytosis. In 8 of the 14 cases, an extended EES procedure was used by exposing the SOS to remove the posterior clinoid process and DS. Measurement of the central face was based on head MRI before and after surgery. Measuring points were the sellae-nasion (SN) plane, the foremost points of the anterior maxilla (point A), and the maximum concavity point of the mandibular symphysis (point B). The authors measured and evaluated the SNA angle (angle created by the SN plane and the NA [a line connecting point A and the nasion] plane), SNB angle (angle created by the SN plane and the NB [a line connecting point B and the nasion] plane), and the ANB angle (angle created by the NA plane and the NB plane). In addition, a comparison was made with 6 pediatric cases in which transcranial surgery was performed for craniopharyngiomas.

RESULTS
In the extended EES group, the average preoperative age was 7 years, and the average postoperative age was 12 years. Mean preoperative angles in this group were 84° (SNA), 80.9° (SNB), and 3.1° (ANB); mean postoperative angles were 83.5° (SNA), 83.9° (SNB), and −0.4° (ANB). In the standard EES group, the average preoperative age was 9 years, and the average postoperative age was 14.5 years. Average preoperative angles in the standard EES group were 83° (SNA), 80.3° (SNB), and 2.7° (ANB); average postoperative angles were 82.7° (SNA), 81° (SNB), and 1.6° (ANB). In the transcranial surgery group, the average preoperative age was 4.5 years, and the average postoperative age was 9.8 years. Mean preoperative angles were 83.8° (SNA), 80.3° (SNB), and 3° (ANB); mean postoperative angles were 83.8° (SNA), 82.6° (SNB), and 1.2° (ANB). The only significant difference between groups was the postoperative ANB angle, which was negative in the extended EES group compared to the standard EES group, indicating the maxilla was positioned posteriorly compared to the mandible.

CONCLUSIONS
The measurement values of the EES groups and the transcranial surgery group exhibited minimal differences, except for a significant decrease in the postoperative ANB angle in the extended EES group compared with the standard EES group. These results show that extended EES may impact midface growth. Further research is required to understand the long-term impact of SOS exposure.