Comparing Cephalic Index and Midsagittal Vector Analysis in Assessing Morphology in Sagittal Synostosis: A CT-Based Morphometric Analysis

Comparison of Morphometric Outcomes following Open Posterior Expansion versus Endoscopic Strip Craniectomy for Sagittal Synostosis

BACKGROUND

Open middle and posterior cranial vault expansion (OPVE) or endoscopic (ES) strip craniectomy are two surgical techniques for normalization of head shape in isolated sagittal synostosis. This study aims to compare 2-year cranial morphometrics after these two approaches.

METHODS

The authors performed morphometric analysis on preoperative [time (T) 0], immediately postoperative (T1), and 2-year (T2) postoperative computed tomographic scans of patients who underwent OPVE or ES before 4 months of age. Perioperative data and morphometrics were compared between the two groups and age-matched controls.

RESULTS

Nineteen patients were included in the ES cohort, 19 age-matched patients were included in the OPVE cohort, and 57 were included as controls. Median surgery time and blood transfusion volume were less for the ES approach (118 minutes and 0 cc, respectively) compared with OPVE (204 minutes and 250 cc, respectively). Anthropometric measurements after OPVE were closer in normal controls at T1 compared with ES, but the skull shapes were comparable at T2. In the midsagittal plane, anterior vault was higher after OPVE at T2 compared with both ES and controls, but the posterior length was shorter and closer to controls than in the ES cohort. Cranial volumes were like controls for both cohorts at T2. There was no difference in complication rate.

CONCLUSIONS

Both OPVE and ES techniques result in normalization of cranial shape in patients with isolated sagittal synostosis after 2 years with minimal morphometric differences. Family decision-making between the two approaches should be based on age at presentation, avoidance of blood transfusion, scar pattern, and availability of helmet molding and not on expected outcome.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Three-Dimensional Assessment of Frontal Bossing and Temporal Pinching in Patients with Sagittal Craniosynostosis Using Curvature Analysis

BACKGROUND

Sagittal craniosynostosis results in varying degrees of frontal bossing and bilateral temporal pinching. This study assessed the three-dimensional changes in these regions using curvature analysis and volumetric analysis before and 1 year after extended sagittal strip craniectomy (ESC) with postoperative helmet therapy.

METHODS

A retrospective review of three-dimensional photographs of 50 subjects treated with ESC with postoperative helmet therapy and 50 age-matched controls was performed. Images were collected preoperatively and 1 year postoperatively. Forehead convexity and temple concavity were quantified. Computed tomographic scans of subjects with and without sagittal synostosis were analyzed to assess the percentage of total intracranial volume (ICV) in the anterior cranial fossa before and after ESC with postoperative helmet therapy.

RESULTS

Forehead convexity in the ESC with postoperative helmet therapy group preoperatively (24.49 ± 3.16 m -1 ) was significantly greater than controls (22.48 ± 3.84 m -1 ; P = 0.005). Forehead convexity significantly decreased after ESC with postoperative helmet therapy (18.79 ± 2.43 m -1 ; P < 0.001) and did not differ from controls (19.67 ± 3.08 m -1 ; P = 0.115). The ESC group had more concave temples preoperatively (-10.27 ± 4.37 m -1 ) as compared with controls (-6.99 ± 3.55 m -1 ; P < 0.001). Temple concavity significantly decreased after ESC (-4.82 ± 3.17 m -1 ; P < 0.001) and did not differ from controls (-5.64 ± 3.27 m -1 ; P = 0.075). In the ESC group, the percentage ICV in the anterior cranial fossa decreased from 22.03% to 18.99% after surgery, whereas the anterior volume in controls was stable (17.74% to 16.81%).

CONCLUSIONS

The ESC group had significantly greater forehead convexity, temple concavity and anterior cranial fossa volume compared with controls. One year after ESC with postoperative helmet therapy, forehead convexity, temple concavity, and percentage ICV in the anterior fossa were comparable to controls.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Morphologic Differences in Sagittal Synostosis with Age before Surgery

BACKGROUND

It is important to determine whether sagittal synostosis-associated scaphocephaly is static in the presurgical period, or whether there are morphologic differences with time to include in surgical decision-making. The authors' purpose was to perform cross-sectional analysis of cranial morphology before any surgical intervention in children with sagittal synostosis younger than 9 months compared to matched controls.

METHODS

The authors performed morphometric analysis on computed tomographic scans from 111 untreated isolated sagittal synostosis patients younger than 9 months and 37 age-matched normal controls. The authors divided the patients into three age groups and performed statistical comparison between sagittal synostosis and controls for each group.

RESULTS

Sagittal synostosis cephalic indices were stable and lower in patients than in controls across groups. Total cranial volume was equivalent, but sagittal synostosis patients had a greater posterior volume than controls at all ages and a smaller middle fossa volume at older ages. Pterional width was greater in sagittal synostosis patients than in controls for each age group. Frontal bossing vectors were most severe in the youngest age groups and least in the older group. Occipital protuberance was consistent across the age groups.

CONCLUSIONS

Upper parietal narrowing and occipital protuberance were the consistent deformities across age groups, with the most parietal constriction seen in older patients. Frontal bossing was not consistent and was more severe in the younger patients. The authors did not detect significant pterional constriction, and the appearance of constriction is relative to adjacent morphology and not absolute.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, II.

Long-term Follow-up of Preoperative Infant Event-related Potentials in School-age Children with Craniosynostosis

Supplemental Digital Content is available in the text.

Background:

Previous studies demonstrated impaired auditory processing in children with sagittal and metopic craniosynostosis before surgical correction. This study investigated whether worse presurgical neural response as assessed by event-related potentials (ERP) was predictive of poorer school-age neurocognition.

Methods:

Preoperative infant ERP was recorded in 15 sagittal and 18 metopic patients. Mismatch negativity and P150 paradigms were derived from ERP recordings, as previously published. Of those, 13 sagittal and 13 metopic patients returned for neurocognitive evaluation 6 or more years later. ERP was correlated to neurocognitive outcomes using Spearman's correlations controlling for age. Two-tailed t-tests were used to evaluate the influence of age at the time of surgery (6 months) and morphologic severity on neurocognitive outcomes

Results:

In the sagittal group, no significant correlations were found between preoperative mismatch negativity or P150 amplitudes and neurocognitive outcomes. Although no correlation was found between mismatch negativity and neurocognitive outcome in the metopic group, those with lower P150 amplitudes had higher scores in performance IQ (r = −0.877, P < 0.001) and full-scale IQ (r = −0.893, P < 0.001). Morphologic severity and neurocognitive outcomes showed no relationship in the sagittal or metopic groups. Patients who received surgery at less than 6 months had higher full-scale IQ (109.69 versus 95.92, P = 0.025), visuomotor integration (103.15 versus 90.46, P = 0.041), and visual perception scores (105.69 versus 96.08, P = 0.033).

Conclusions:

Preoperative infant ERP does not correlate with school-age neurocognitive outcomes. Earlier age at the time of surgery was associated with improved neurocognitive outcomes.

Craniometric and Volumetric Analyses of Cranial Base and Cranial Vault Differences in Patients With Nonsyndromic Single-Suture Sagittal Craniosynostosis

PURPOSE

How different from "normal" are the cranial base and vault of infants with nonsyndromic, single-suture sagittal synostosis (NSSS)? This study quantitatively addresses this question utilizing computed tomography (CT) analytic technology.

METHOD

Head CT scans of infants with NSSS and normocephalic controls were analyzed using Mimics to calculate craniometric angles, distances, and segmented volumes. Craniometric measurements and asymmetry indices were compared between NSSS and control groups using linear regressions controlling for age. Ratios of anterior-, middle-, and posterior-to-total cranial vault volume were compared between groups using beta regressions controlling for age.

RESULTS

Seventeen patients with NSSS and 19 controls were identified. Cranial index and interoccipital angle were significantly smaller in NSSS compared with controls (P = 0.003 and <0.001, respectively). Right-but not left-external acoustic meatus angle and internal acoustic meatus-to-midline distance were significantly greater in NSSS than in controls (P = 0.021 and 0.016, respectively). NSSS patients and controls did not significantly differ in any asymmetry indices, except for the articular fossa angle asymmetry index (P = 0.016). Anterior vault volume proportion was greater in NSSS relative to controls (proportion ratio = 1.63, P < 0.001). NSSS trended toward a smaller posterior vault volume proportion (P = 0.068) yet did not differ in middle vault volume proportion compared with controls.

CONCLUSION

In this small study, patients with nonsyndromic, single-suture sagittal craniosynostosis had relatively similar cranial base measurements, and larger anterior vault volumes, when compared with controls. Further work is needed to confirm the possibility of rightward asymmetry of the anterior cranial base.