The effect of natural growth on chin point deviation in patients with unilateral craniofacial microsomia: A retrospective study

Optimal age for mandibular distraction osteogenesis in craniofacial microsomia: A systematic review and meta-analysis

OBJECTIVE

This systematic review and meta-analysis aimed to determine the optimal timing for mandibular distraction osteogenesis in children with craniofacial microsomia based on long-term outcomes and relapse rates.

METHODS

A comprehensive search of PubMed, Embase, Cochrane Library, and Web of Science was conducted for studies published up to September 2024. Eligible studies included children aged ≤16 years with CFM who underwent MDO, with follow-up duration exceeding one year. The included population was divided into two groups based on age: children younger than 6 years and those aged 6-16 years. The primary outcome was the relapse rate measured by ramus height ratio, and secondary outcome was occlusal cant. Statistical analyses included heterogeneity assessment, random-effects modeling, and subgroup analysis based on follow-up duration.

RESULTS

Ten studies, comprising 175 patients, were included. The pooled relapse rate based on ramus height ratio was 67.8% (CI: 35.8-93.4%) for children under 6 years and 72.5% (CI: 10.5-94.4%) for those aged 6 years or older, with no statistically significant difference. Subgroup analysis showed that relapse rates increased significantly after five years of follow-up, suggesting progressive asymmetry due to slower growth on the affected side. When occlusal cant was used as a metric, higher relapse rates were observed in children over 6 years 95.6% (CI: 28.9-65.1%) compared to younger patients 46.8% (CI: 83.9-100%).

CONCLUSIONS

Despite early MDO providing psychosocial and developmental benefits, relapse rates remain high across all age groups, complicating the determination of an optimal timing. Long-term monitoring, individualized treatment plans, and refined severity grading systems are essential for improving outcomes in CFM patients. Future research should include standardized methodologies, larger groups, and advanced imaging techniques to optimize treatment strategies.

Hemifacial microsomia: a scoping review on progressive facial asymmetry due to mandibular deformity

PURPOSE

This scoping review explores various parameters of the mandible in progressive facial asymmetry (FA) in hemifacial microsomia (HFM) patients, highlighting its relationship with sex, population, and age group.

METHODS

The review was based on a comprehensive search of PubMed, EBSCOhost, and Web of Science. Eligible studies that met the inclusion criteria form part of the selection study. The included studies were appraised using screening and quantitative criteria of mixed-method appraisal tools. The authors utilised a pre-set data extraction form to obtain information from the included studies.

RESULTS

Eleven studies met the inclusion criteria. The mandible parameters used were angular measurements, chin point, ramal height, body length, and total length. There was no relationship between FA and sex in HFM patients in the included studies. Most of the studies were comprised of European participants (55%), followed by Americans (36%) and Chinese (9%). The age groups included in the selected studies were categorised as dentition age (18%), early-to-middle childhood (18%), and varied ages (64%). The data presented in this review only pertains to the anomalous characteristics recorded on the affected side in HFM patients. No concomitant control data was recorded in this review.

CONCLUSION

An assessment of the included studies revealed that FA does not increase with age in HFM. Hence, FA is non-progressive in HFM patients. This information is relevant to diagnosing and managing HFM patients. More reports are needed on the progression of FA in HFM patients.

Changes of functional units in type IIA craniofacial microsomia before puberty-a preliminary computed tomography study

BACKGROUND

The natural growth of the mandible in craniofacial microsomia (CFM) remains a topic of considerable debate. This study aims to characterize the mandibular architecture and its natural growth in children with type IIA CFM using functional unit analysis.

MATERIALS AND METHODS

16 sets CT data of 8 unoperated children with unilateral IIA CFM with an interval ranging from 2 to 6 years (3.4±1.5 years,AVR±SD)were collected. The baseline skeletal units' discrepancy in size, annual growth, and angular measurements were analyzed.

RESULTS

The condylar, coronoid, and body units were smaller (reaching 63%, 79%, and 90% of the unaffected side, respectively) while the angular unit was larger on the affected side. The condylar unit on the affected side grew slower than the unaffected side, at about 60% of its rate, and other units showed no statistically significant bilateral differences. The backward rotation angle of the affected body unit (BUA) increased from T1 to T2.

CONCLUSION

This preliminary study suggests that the condyle unit is the center of mandible deformity in type IIA CFM and exhibits insufficient growth relative to the unaffected side . Meanwhile, the hemi-mandible on the affected side rotated posteriorly during growth, thus worsening spatial relation. Future studies with larger sample sizes that incorporate clinical assessments are needed to elucidate the progression of CFM.

An updated protocol for mandibular reconstruction in nongrowing patients with craniofacial microsomia with temporomandibular joint total prosthesis

The authors aim to present an updated protocol for mandibular reconstruction in nongrowing patients with Pruzansky/Kaban type IIb/III congenital craniofacial microsomia with customized temporomandibular joint (TMJ) prosthesis to reduce facial nerve (FN) damage and improve surgical accuracy. This is illustrated (using 3 cases) and is based on preoperative mapping of the FN using MRI for better virtual surgical planning of custom-made TMJ prosthesis. Intraoperative FN mapping and monitoring, as well as verification of the final result with intraoperative cone-beam computed tomography (CBCT) and 3D-reconstructed images is also achieved. All 3 patients presented mild transient postoperative facial palsy due to surgical soft tissue stretching which resolved within 2 months of surgery. All patients presented proper occlusion and mouth opening without pain, with an average incisal opening of 38.8 mm (range 35.5-42 mm) at two months of follow-up. Moreover, superposition of intraoperative and preoperative 3D reconstruction images ensured surgical accuracy and avoided the need for a potential reintervention. In conclusion, the proposed surgical protocol for mandibular reconstruction with customized alloplastic TMJ prosthesis in nongrowing patients with type IIb/III Pruzansky-Kaban congenital mandibular hypoplasia may reduce FN morbidity, improve surgical accuracy and final outcomes.

Facial asymmetry outcome of orthognathic surgery in mild craniofacial microsomia compared to non-syndromic class II asymmetry

OBJECTIVES

To compare the facial asymmetry after bimaxillary surgery between mild craniofacial microsomia (CFM) and non-syndromic class II asymmetry.

MATERIALS AND METHODS

Cone-beam computed tomography scans of adults with Pruzansky-Kaban types I and IIA CFM (CFM groups, n = 20), non-syndromic skeletal class II asymmetry (Class II group, n = 20), and normal controls (control group, n = 20) were compared. The area asymmetry of lower face and jaw bones was quantified. Landmark-based method was used to evaluate the lower facial asymmetry regarding midline, cants, and contour.

RESULTS

There were no significant postoperative differences in the hemi-facial and hemi-jaw area asymmetry between CFM and Class II groups, both of which were significantly larger than the control group. No significant difference was found in the midline deviation and lip and occlusal cants between CFM and Class II groups. The vertical contour asymmetry in CFM group became significantly larger than Class II group. Compared to the control group, the deviation of pronasale, subnasale, and soft-tissue menton, lip and occlusal cants, and sagittal and vertical contour asymmetry in CFM group were significantly larger, as were the deviation of subnasale and soft-tissue menton and vertical contour asymmetry in Class II group.

CONCLUSIONS

The vertical contour asymmetry of mild CFM was significantly larger than non-CFM class II after surgery, while the area asymmetry, midline deviation, cants, and sagittal contour asymmetry of lower face showed no significant difference.

CLINICAL RELEVANCE

Be aware that correcting vertical asymmetry of contour, lip, and dentition in CFM is still challenging.

Kaban-Pruzansky Grade Predicts Airway Severity in Hemifacial Microsomia

BACKGROUND

Children born with hemifacial microsomia (HFM) can experience airway compromise. There is a paucity of data correlating degree of HFM severity with airway difficulty. This study aims to determine the relationship between the degree of micrognathia and airway insufficiency in the HFM population.

METHODS

Patient demographics, airway function, Kaban-Pruzansky (KP) grade, and Cormack-Lehane (CL) grade were collected and compared with appropriate statistics for HFM patients treated between 2000 and 2022.

RESULTS

Seventy patients underwent 365 operations with KP grading as follows: 34% KP grade I, 23% KP grade IIA, 11% KP grade IIB, and 33% KP grade III. Goldenhar syndrome was present in 40% of patients and 16% had bilateral disease. KP grade ( P < 0.001) predicted mean number of airway-affecting procedures undergone and difficult airway status ( P < 0.001), with 75% of difficult airways in KP grade III patients. There was no association of airway compromise with Goldenhar syndrome, laterality, or age ( P > 0.05). Most CL grades were I (61%) or IIA (13%), with fewer grade IIB, grade III, and grade IV (4% to 7%). KP grade predicted CL grade ( P < 0.001), with 71% of grade IV views and 64% of grade III views seen in KP grade III patients.

CONCLUSIONS

KP grade correlated with airway severity in HFM. Patients do not appear to outgrow their CL grade, as previously hypothesized, suggesting that KP grade III patients remain at increased risk for airway insufficiency into the teen years. Given the potential significant morbidity associated with airway compromise, proper identification and preparation for a challenging airway is a critical part of caring for patients with HFM.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, III.

3D-CT measurements of facial symmetry in severe CFM patients: A comparative study between mandibular ascending ramus distraction osteogenesis and bone grafting

This study aims to compare the effects of mandibular distraction osteogenesis (MDO) and bone grafting on the facial symmetry of children with Pruzansky-Kaban type IIB and III craniofacial microsomia (CFM). Medical records and three-dimensional computed tomography (3D-CT) data of CFM patients who had primarily undergone MDO and bone grafting were collected. A retrospective analysis of pre-and post-operative 3D imaging data was conducted to compare the improvement rate in facial symmetry between the two groups based on occlusal cant, affected/unaffected ramus height ratio and chin point deviation. The data were tested for normality using the Shapiro-Wilk test. When the data followed a normal distribution, a paired sample t-test was employed for the comparison between preoperative and postoperative data. When the data did not follow a normal distribution, the Wilcoxon signed-rank test for paired samples was used for preoperative and postoperative comparison. The study included 18 children with type IIB and III CFM, 11 in the MDO group and 7 in the bone grafting group. In the MDO group, postoperative Gn-FH and Gn-Cor distances increased significantly, whereas the postoperative Gn-Mid distance decreased significantly. Occlusal cant decreased significantly and ramus height affected/unaffected ratio increased significantly after MDO. In the bone graft group, there was no statistically significant difference in the postoperative ratios of chin deviation, occlusal cant, and ramus height affected/unaffected compared to the preoperative values. Compared to bone grafting, MDO can significantly enhance ramus height ratio, level occlusal plane, and centralize the chin point among patients with CFM. Furthermore, MDO achieves superior enhancements in facial symmetry.

Vascular variation of temporoparietal fascia in microtia associated with hemifacial microsomia

The study analyzed vascular variations in microtia associated with hemifacial microsomia (HFM). A retrospective analysis was conducted on 47 patients with microtia and HFM, who underwent computed tomography angiography between November 2011 and May 2022. The vascular course and branching supplying the TPF were analyzed. Craniometric measurements were conducted to determine the horizontal distance from the porion and fronto-zygomatic suture (F-Z suture) to the vessels. On the affected side, the TPF was primarily supplied by either the superficial temporal artery (STA) or the postauricular artery-originated STA (Po-STA). The Po-STA (n = 29) was more prevalent than the STA (n = 18), and mostly exhibited a single frontal branch (n = 20). Craniometric analysis revealed that the Po-STA was closer to the porion, ear vestige, and F-Z suture than the STA on the non-affected side. Furthermore, a significant correlation was observed between the severity of mandibular hypoplasia and presence of Po-STA variation (Cramer's V = 0.498, p = 0.005). Microtia associated with HFM exhibits vascular variations in the TPF - in particular, a unique Po-STA variation. The Po-STA is prone to injury during ear reconstruction because of its proximity to the external auditory canal and ear vestige. Surgeons should be cautious of these anatomical variations for safer ear reconstruction procedures, and utilize preoperative imaging for meticulous planning.