Comparative analysis of cranial vault remodeling versus endoscopic suturectomy in the treatment of unilateral lambdoid craniosynostosis

Abbas Rattani MD, MBe1,2, Coleman P. Riordan BS3, John G. Meara MD, DMD, MBA1,4, and Mark R. Proctor MD3
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  • 1 Program in Global Surgery and Social Change, Department of Global Health and Social Medicine, Harvard Medical School, Boston, Massachusetts;
  • | 2 Department of Surgery, Rush University Medical Center, Chicago, Illinois; and
  • | 3 Departments of Neurosurgery and
  • | 4 Plastic and Oral Surgery, Boston Children’s Hospital, Boston, Massachusetts
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OBJECTIVE

Unilateral lambdoid synostosis is the premature fusion of a lambdoid suture or sutures and represents the least common form of craniosynostosis, occurring in 1 in 40,000 births. Cranial vault remodeling (CVR) and endoscopic suturectomy with helmet therapy (ES) are surgical approaches that are used to allow for normal brain growth and improved craniofacial symmetry. The authors conducted a comparative outcomes analysis of patients with lambdoid synostosis undergoing either CVR or ES.

METHODS

The authors conducted a retrospective consecutive cohort study of patients with nonsyndromic lambdoid synostosis who underwent surgical correction identified from a single-institution database of patients with craniosynostosis seen between 2000 and 2018. Cranial growth was measured in head circumference percentile and z score.

RESULTS

Nineteen patients (8 female and 11 male) with isolated unilateral lambdoid synostosis were identified (8 right and 11 left). Six underwent CVR and 13 underwent ES. No statistically significant differences were noted between surgical groups with respect to suture laterality, the patient’s sex, and length of follow-up. Patients treated with ES presented and underwent surgery at a younger age than those treated with CVR (p = 0.0002 and p = 0.0001, respectively). Operating and anesthesia time, estimated blood loss, and ICU and total hospital days were significantly lower in ES (all p < 0.05). No significant differences were observed in pre- and postoperative head circumference percentiles or z scores between groups up to 36 months postoperatively. No patients required reoperation as of last follow-up.

CONCLUSIONS

Endoscopic management of lambdoid synostosis is safe, efficient, and efficacious in terms of intraoperative and long-term cranial growth outcomes when compared to CVR. The authors recommend this minimally invasive approach as an option for correction of lambdoid synostosis in patients presenting early in their course.

ABBREVIATIONS

CVR = cranial vault remodeling; EBL = estimated blood loss; ES = endoscopic suturectomy with helmet therapy; HCP = head circumference percentile.

OBJECTIVE

Unilateral lambdoid synostosis is the premature fusion of a lambdoid suture or sutures and represents the least common form of craniosynostosis, occurring in 1 in 40,000 births. Cranial vault remodeling (CVR) and endoscopic suturectomy with helmet therapy (ES) are surgical approaches that are used to allow for normal brain growth and improved craniofacial symmetry. The authors conducted a comparative outcomes analysis of patients with lambdoid synostosis undergoing either CVR or ES.

METHODS

The authors conducted a retrospective consecutive cohort study of patients with nonsyndromic lambdoid synostosis who underwent surgical correction identified from a single-institution database of patients with craniosynostosis seen between 2000 and 2018. Cranial growth was measured in head circumference percentile and z score.

RESULTS

Nineteen patients (8 female and 11 male) with isolated unilateral lambdoid synostosis were identified (8 right and 11 left). Six underwent CVR and 13 underwent ES. No statistically significant differences were noted between surgical groups with respect to suture laterality, the patient’s sex, and length of follow-up. Patients treated with ES presented and underwent surgery at a younger age than those treated with CVR (p = 0.0002 and p = 0.0001, respectively). Operating and anesthesia time, estimated blood loss, and ICU and total hospital days were significantly lower in ES (all p < 0.05). No significant differences were observed in pre- and postoperative head circumference percentiles or z scores between groups up to 36 months postoperatively. No patients required reoperation as of last follow-up.

CONCLUSIONS

Endoscopic management of lambdoid synostosis is safe, efficient, and efficacious in terms of intraoperative and long-term cranial growth outcomes when compared to CVR. The authors recommend this minimally invasive approach as an option for correction of lambdoid synostosis in patients presenting early in their course.

ABBREVIATIONS

CVR = cranial vault remodeling; EBL = estimated blood loss; ES = endoscopic suturectomy with helmet therapy; HCP = head circumference percentile.

In Brief

The authors compared outcomes of minimally invasive and open surgery in the correction of lambdoid craniosynostosis to address the paucity of available literature on this rare patient group. The authors found endoscopic suturectomy with helmet therapy to be more benign and efficient than open surgery, and equally safe and efficacious.

Craniosynostosis is a developmental anomaly typically defined by the premature and abnormal fusion of one or more of the 6 cranial sutures (sagittal, coronals, metopic, and lambdoids) resulting in abnormal cranial growth. Craniosynostosis has been estimated to occur in approximately 1 in 2300 births.1,2 Lambdoid synostosis is the premature fusion of one (unilateral) or both (bilateral) lambdoid suture or sutures. It is the least common form of craniosynostosis, with unilateral lambdoid synostosis occurring in approximately 1%–3% of single synostoses,3 or 1 in 40,000 births.4

Correctly distinguishing lambdoid synostosis from posterior plagiocephaly is essential given the marked differences in treatment. Corrective surgery is often recommended for lambdoid synostosis, whereas physical therapy, repositioning, and cranial orthosis are offered for plagiocephaly. Nonsynostotic plagiocephaly is deformational in etiology and is often caused by infant sleeping position.5,6 Lambdoid synostosis often presents with ipsilateral occipitoparietal flattening and contralateral frontal and parietal bossing, especially in the lateral portions of the skull; posterior displacement of the pinna; and tilted cranial base, giving a “windswept” trapezoidal deformity.7–9 These phenotypic characteristics and marked asymmetry render this pathology difficult to correct relative to other forms of craniosynostosis.9

The primary goal of surgical intervention for craniosynostosis is to allow for normal brain growth free of elevated intracranial pressure,1,10–12 with the secondary goal of achieving craniofacial symmetry.13 There are currently a few surgical strategies commonly used to correct craniosynostosis: open surgery (i.e., cranial vault remodeling [CVR]); open suture release with the placement of a distraction device; and minimally invasive or “closed” suture release (i.e., endoscopic suturectomy with helmet therapy [ES]).9,14–18 Relative to the more common types of craniosynostosis,19 very little has been published on the surgical outcomes of CVR and ES in the treatment of lambdoid synostosis. To this end, we conducted a comparative analysis of patients with lambdoid synostosis who underwent either an open or minimally invasive approach and their respective perioperative outcomes.

Methods

Study Design and Sample

This project was approved by the institutional review board of Boston Children’s Hospital. We designed a retrospective consecutive cohort study in accordance with STROBE guidelines. The study sample included patients with lambdoid synostosis from a large single-institution database of all surgical patients with craniosynostosis seen between 2000 and 2018. The first ES in a case of lambdoid synostosis at our institution was performed in October of 2005. Patients eligible for inclusion were all those with isolated unilateral lambdoid synostosis who underwent surgical correction at our institution. Diagnosis of lambdoid synostosis was confirmed preoperatively by CT and corroborated by the operating plastic and/or neurological surgeon. No limitations were placed on length of follow-up time. Patients were excluded if they were found to have multiple-suture fusion, prior surgeries, or syndromic diagnoses. At our institution, patients younger than 3 months of age are considered appropriate candidates for ES and either open or minimally invasive correction is offered, whereas older patients are offered open surgery.20 Of note, patients who are 3–6 months of age may still be eligible for ES at the discretion of the operating pediatric neurosurgeon in conjunction with parent preference, although the results are less reliable.

Data Collection

Data collection was performed by one reviewer (C.P.R.), with a second reviewer (A.R.) resolving discrepancies. Our primary independent variable was operative approach—CVR versus ES. Our primary dependent variables included perioperative (i.e., operating time, complications, estimated blood loss [EBL], blood transfusion volume, and ICU vs hospital floor stay) and postoperative (i.e., head circumference percentile [HCP] and z scores) outcomes. As most craniofacial surgeons are aware, standardized outcome measurements for lambdoid synostosis are generally lacking, whereas the head circumference profile serves as a surrogate to track adequate growth. Aesthetic outcomes are much more difficult to assess objectively for lambdoid synostosis, and the outcomes are significantly more subjective.

Complications were defined as all postoperative untoward events requiring treatment or management, ranging from surgical site infections to hematomas; postoperative fever and leukocytosis that self-resolved were not included. Head circumference was the only routinely charted pre- and postoperative variable for each patient. Head circumference measurements were standardized using age- and sex-matched z scores to allow comparison of the treatment groups with unaffected children, as previously described by Isaac et al.19 The z score accounts for the age at which the procedure was performed and thus allows comparison between the ES and the CVR group despite different ages at the time of surgery. A z score of 0 reflects the normal population mean, and deviation above or below from the mean is reflected by the magnitude and direction of the z score, according to the following formula: z = (x − μ)/σ, where x represents the patient head circumference, μ is the population mean head circumference (for a given age and sex), and σ is the population standard deviation.19

EBL values were collected first from the anesthesia report when available and then from the operative report. Secondary dependent variables included reoperation rate, helmet therapy duration, and revision (i.e., requiring a second operating room visit). Of note, helmet therapy duration was based on whichever period occurred first: normalization of the cranium or the child’s first birthday (which is often when cranial growth begins to slow). Other collected variables included demographic variables (i.e., sex, and age at presentation); preoperative presentation (i.e., age at operation, side of suture involvement, and HCP); and follow-up period. Once data collection was complete, patients were grouped by surgical approach for comparison.

Operative Technique

The open approach of CVR was performed with one of two techniques, based on surgeon preference. One open approach used by 2 of the plastic surgeons involved the use of wires. The patient was positioned prone and a coronal incision was made posterior to the area of the coronal suture in a zigzag pattern. Dissection in the subperiosteal plane was performed and extended below the region of the transverse sinus on the ipsilateral side of the synostosis and posteriorly to the level of the transverse sinus on the contralateral side. The parietal area was removed on each side of the midline, leaving intact a strip of cranium. The entire posterior parietal-occipital area was also removed approximately 2 cm below the transverse sinus. A 1.5-cm-wide strip of bone was used to buttress around the occiput for reconstruction. The bony sections were removed and remodeled. Partial-thickness circular cuts were made, followed by full-thickness radial cuts and insertion of 28-gauge wires around the circumference of the partial-thickness incisions. This allowed the cranial pieces to be molded in a radial fashion. A single strip of parietal cranium taken at the time of the craniectomy was then secured along the midline with interosseous wires and placed into the posterior-inferior edge of the craniectomy, and then it was secured bilaterally with absorbable plates and screws from the bar into the skull anteriorly. This was placed to give a rounded contour of the occiput. Barrel-stave cuts were made posterolaterally on the ipsilateral side of the synostosis to further expand the posterior cranium, followed by additional barrel staves in the contralateral parietal area to meet the contour. Beginning anteriorly, the bilateral parietal remodeled sections were secured to the midline peninsula over the sagittal sinus. The ipsilateral section was further secured to the inferior parietal temporal area with resorbable plates and screws. The 2 remodeled occipital sections were placed in position and secured with screws inferiorly to the newly placed bar. They were then secured to one another with interosseous wires and held to the parietal plates with resorbable plates and screws. Because the parietal sections were moved posteriorly to correspond to the expanded posterior cranium, coronal defects anteriorly were filled with cortical cancellous mush and held in place with fiber and glue. The galea was scored both anteriorly and posteriorly and the coronal incision was closed. No postoperative helmeting was required.

An alternative open approach did not use wires, and it had a different osteotomy pattern. The patient was placed prone, and a bicoronal incision was made and the scalp was taken down to the level just above the foramen magnum to facilitate the removal of the posterior calvarial bone. Multiple small burr holes were made to separate off the dura mater, and a craniectomy was performed with a high-speed drill to facilitate the removal of the parietal and occipital bones in one large piece. One cut was placed 2 cm inferior to the transverse sinus, a second cut was made 3 cm in front of the contralateral coronal suture, and a third cut was made paralleling the second cut on the side contralateral to the synostosis. The prominent bump caused by the windswept nature of the phenotype was excised. Next, multiple barrel-staving osteotomies were performed to correct the windswept appearance. Barrel-stave cuts were performed on the ipsilateral parietal segment to expand the ipsilateral parietal component. The contralateral parietal vertex was then removed. Particulate bone was harvested from the endocortical surface of this bone. Barrel-stave cuts were also made to decrease the external convexity of the bone. The occipital segment was also removed prior to barrel staving on the ipsilateral side to increase the convexity. These maneuvers aid in increasing the prominence of the ipsilateral parietal vertex area while subsequently decreasing the contralateral parietal region. It should also be noted that the occipital segment was posteriorly positioned approximately 7 mm from the parietal region, and this differential is such that the ipsilateral side is advanced posteriorly more than the contralateral, given the fact that the ipsilateral side is the one that is constricted. Following the reshaping, the bone was replaced in situ in a more anatomically correct fashion. Finally, a drain was placed prior to the closure of the coronal incision. No postoperative helmeting was required.

The minimally invasive approach of endoscopic suturectomy with helmeting was performed by a single surgeon. The patient was placed prone for better access to the posterior ridge. Two incisions were made perpendicular to the fused suture; one incision was near the junction of the contralateral lambdoid and sagittal suture, and the other incision was over the mastoid bulge. At each location a burr hole was placed and enlarged with a Kerrison rongeur to create a 1.5-cm strip. The superior portion of the craniectomy was taken up to the junction of the sagittal-lambdoid suture on the contralateral side, and the inferior portion was as low as the mastoid bone. Finally, the endoscope was used to connect the 2 gaps. Once clearance of the dura was accomplished, bone-cutting scissors were used to complete the craniectomy, leading to a 1.5-cm-wide gap from sagittal suture to the mastoid bulge, freeing the occipital bone completely from the parietal bone. Helmeting was initiated within the first postoperative week and continued until the cranial shape normalized—which often occurred before 1 year of age.

Statistical Analysis

Patient characteristics were summarized via descriptive statistics (mean, median, range, and SD) for each relevant continuous variable. In comparing CVR and ES, all continuous data (except HCP) were compared using the Mann-Whitney-Wilcoxon test for unpaired data and categorical variables were compared using Fisher’s exact test. The HCPs and z scores were calculated for each patient by plotting the head circumference (in centimeters) derived from the patient chart by the patient’s age in months against the WHO’s head circumference growth curves.21,22 The HCPs and corresponding z scores were compared between surgical groups by using an unpaired, heteroscedastic 2-tailed Student t-test for unequal data points, and a homoscedastic Student t-test was used for equal data points. Statistical significance was determined at p < 0.05.

Results

Study Population

During the 19-year study interval, 1275 infants with craniosynostosis were surgically treated at Boston Children’s Hospital. After the selection criteria were applied, a total of 19 patients with isolated lambdoid synostosis were identified (Table 1). There were 8 with right-sided and 11 with left-sided lambdoid synostosis. A total of 11 patients were male. No statistical difference was observed in the HCP and z scores between patient groups. Six patients underwent CVR, whereas 13 were treated with ES; details are provided as a CONSORT diagram (Fig. 1). No statistical significance was noted between the CVR and ES groups with respect to suture laterality, sex, and length of available follow-up data. The average length of available follow-up data was 42.1 months (range 6.4–103.7 months). The age at initial presentation and that at operation were significantly less for the ES group, averaging 3.3 and 3.9 months, respectively, whereas the CVR group tended to present later, at 11.1 months, undergoing treatment at 11.7 months of age. Helmet duration in the ES group averaged 6.0 months (median 5.9, range 3.7–9.3 months), and the average age at which patients discontinued helmet use was 10.1 months (median 10.0, range 7.6–12.4 months). All patients who underwent ES were helmeted until the patient was at least 7 months old.

TABLE 1.

Patient characteristics by surgical intervention for unilateral lambdoid synostosis

CharacteristicCVR (n = 6)ES (n = 13)p Value
Male, no.560.1770
Right lambdoid, no.351.0000
Age at presentation, mos11.12 ± 0.853.27 ± 1.210.0002
Age at op, mos11.68 ± 0.933.88 ± 1.360.0001
Duration of helmet therapy, mosNA6.02 ± 1.82NA
Age at helmet discontinuation, mosNA10.12 ± 1.78NA
Length of follow-up, mos54.63 ± 5.5938.29 ± 28.920.1630

NA = not applicable.

Unless otherwise indicated, data are presented as the mean ± SD.

FIG. 1.
FIG. 1.

CONSORT patient selection diagram. *A total of 6 patients received CVR and 13 received ES. Complete data were not consistently available in the chart for all patients. Thus, cohorts were compared and analyzed based on data availability.

Perioperative Outcomes

Operating and anesthesia time, EBL, and both ICU and total hospital days were significantly less in the ES group (Table 2). There were no intraoperative complications in either group (e.g., dural tear, CSF leak, parenchymal injury, etc.). However, 1 patient who received ES did experience a wound infection that required readmission for treatment. On average, ES took less than 1 hour to perform, whereas CVR took more than 3 hours. CVR required more than twice as much time under anesthesia as ES. The EBL was greatest in the CVR group, averaging 210 ml compared to 25 ml for ES. The median EBL for ES was 20 ml (IQR 15–30) and it was 225 ml (IQR 200–250) for CVR. Of 13 patients, only 1 of those who underwent ES reportedly experienced an EBL of 100 ml and subsequently required a blood transfusion of 120 ml, whereas 3 of the 5 patients who received CVR and in whom data were available required a blood transfusion (> 140 ml). None of the 19 patients in either the ES or CVR group required reoperation/revision.

TABLE 2.

Perioperative outcomes by surgical intervention for unilateral lambdoid synostosis

Periop OutcomeCVR (n = 4)ES (n = 13)p Value
Op time, mins191.25 ± 72.553.85 ± 8.380.0008
Total anesthesia time, mins300.50 ± 71.85142.85 ± 32.010.0008
Estimated blood loss, ml210.00 ± 67.5525.38 ± 23.580.0002
ICU length of stay, days*0.80 ± 0.450.15 ± 0.550.0350
Total hospital length of stay, days3.17 ± 0.751.23 ± 0.600.0005

Unless otherwise indicated, data are presented as the mean ± SD.

Based on 5 patients who underwent CVR.

Based on 6 patients who underwent CVR.

Clinical Outcomes

No statistically significant differences were observed in preoperative and postoperative HCPs or z scores between the CVR and ES groups up to 12 months postoperatively (Table 3). At each postoperative time interval (i.e., months 1, 6, 12, and 36), no consistent increase or decrease was observed over time. Although patients receiving CVR did have a lower average preoperative HCP compared to the ES group, no statistical difference was appreciated between preoperative groups. Available data with each time interval varied, and neither HCP nor z-score values for the same patient were pairable. Only postoperative follow-up at 36 months had equal data points (n = 3 in each group), and thus an unpaired, homoscedastic 2-tailed test revealed a statistical difference between the mean HCP values of the CVR (73.0 ± 6.1) and ES (93.4 ± 10.2) groups (p = 0.0412). However, z scores in this latter group were not significant, and thus values did not vary outside the normal distribution. No patients have required reoperation for correction as of the time of last follow-up.

TABLE 3.

HCPs and z scores by surgical intervention for unilateral lambdoid synostosis at various time intervals

HCPz Score
Time IntervalAllCVRESp Value*AllCVRESp Value*
Preop: CVR, n = 5 vs ES, n = 1165.57 ± 35.19 (1.3–99.8)41.73 ± 35.54 (4.4–90.7)76.40 ± 30.65 (1.3–99.8)0.10230.59 ± 1.42 (−2.2 to 2.8)−0.32 ± 1.21 (−1.7 to 1.3)1.00 ± 1.36 (−2.2 to 2.8)0.0859
Postop
 1 mo: CVR, n = 2 vs ES, n = 1090.56 ± 11.63 (67.4–100)83.15 ± 22.32 (67.4–98.9)92.04 ± 9.76 (71.6–100)0.67301.79 ± 0.94 (0.5 to 3.3)1.38 ± 1.31 (0.5 to 2.3)1.88 ± 0.92 (0.6 to 3.3)0.6830
 6 mos: CVR, n = 2 vs ES, n = 985.53 ± 13.17 (54.4–100)73.15 ± 26.55 (54.4–91.9)88.28 ± 9.05 (75.8–100)0.56661.40 ± 0.97 (0.1 to 3.5)0.76 ± 0.91 (0.1 to 1.4)1.54 ± 0.97 (0.7 to 3.5)0.4179
 12 mos: CVR, n = 2 vs ES, n = 983.13 ± 28.60 (1.2–100)84.88 ± 6.96 (80.0–89.8)82.74 ± 31.86 (1.2–100)0.85981.51 ± 1.62 (−2.3 to 3.6)1.06 ± 0.30 (0.8 to 1.3)1.62 ± 1.79 (−2.3 to 3.6)0.4004
 36 mos: CVR, n = 3 vs ES, n = 383.16 ± 13.45 (68.8–100)72.98 ± 6.08 (68.8–80.0)93.35 ± 10.21 (81.6–100)0.04121.44 ± 1.26 (0.5 to 3.7)0.62 ± 0.19 (0.5 to 0.8)2.25 ± 1.40 (0.9 to 3.7)0.1159

Unless otherwise indicated, data are presented as the mean ± SD (range).

p value comparing CVR and ES at each time interval.

Unpaired homoscedastic 2-tailed Student t-test.

Aesthetic Outcomes

Because of the substantial cranial changes seen in unilateral lambdoid synostosis, it is difficult to accurately measure or compare aesthetic outcomes. Good correction of occipital asymmetry was achieved postoperatively with both CVR and ES. Although there is no metric for this, it was our empirical assessment that the characteristic contralateral parietal bossing, often referred to as the windswept appearance, was better treated in those children who underwent ES. It appears that the prolonged gentle pressure applied by the helmet can gradually shift the skull back toward the affected side (Fig. 2).

FIG. 2.
FIG. 2.

A: Preoperative anterior-posterior (upper image) and posterior-anterior (lower image) 3D CT images of 4-month-old patient who presented with left lambdoid synostosis. Frontal and contralateral parietal bossing with classic “windswept” trapezoidal deformity on the right is appreciated. B: Postoperative anterior-posterior photograph taken 5 years after correction with ES. Figure is available in color online only.

Discussion

Lambdoid synostosis is often difficult to correct with surgery secondary to the protean effects on skull growth and symmetry.9 Our comparative analysis of treatment approaches for nonsyndromic unilateral lambdoid synostosis yielded significantly better perioperative factors with ES and equal long-term outcomes regarding need for reoperation when compared to CVR. Additionally, this study represents, to our knowledge, the largest population of patients with lambdoid synostosis treated with ES in the published literature.9 Specifically, lower operating and anesthesia times, EBL, and total ICU and hospital days, and comparable cranial outcomes were noted in the ES compared to the CVR cohort.

From our initial operations in 2004, we have gradually evolved our experience with endoscopic synostosis surgery. We now firmly believe that a comprehensive craniofacial program truly should be able to offer both minimally invasive procedures and all versions of cranial vault reconstructive procedures. It is our general practice to offer either open or endoscopic surgery if we see the child before 3 months of age, or to generally proceed with the larger operations for patients older than 4 months of age. In addition, the cranial vault reconstructive procedures have all evolved over time. Earlier CVR approaches involved the use of wires (3 patients, 2000–2004), whereas later CVR approaches were wireless (3 patients, 2013). This is largely based on surgeon preference and the evolution of absorbable systems for the reconstruction of the skull in infants.

We believe there are several advantages to the endoscopic techniques based on our relatively extensive experience with nearly 700 cases and up to 16 years of follow-up.20 The endoscopic operations essentially try to restore normal physiology, and then use the helmet as an adjunct to redirect growth into the areas that had been deficient prior to the operation.9,23 We adopted this technique based on the initial work of Jimenez and Barone,24–26 and observed that the surgery was far more benign and outcomes were eminently comparable to those of open procedures.14,19,27,28 We have published these results for almost every single-suture synostosis as well as bilateral coronal synostosis.19,28–35 We have found this technique to be of particular value for asymmetrical conditions such as unilateral coronal synostosis as well as unilateral lambdoid synostosis, where it can be very hard to achieve symmetry.30,33 The early intervention along with the slow correction with a helmet seems to be particularly favorable to asymmetrical conditions.

The percentage of patients presenting with unilateral lambdoid synostosis (19 patients) out of all patients with craniosynostosis (1275 patients) in our institution was 1.5%. This is commensurate with the known incidence rate of lambdoid synostosis in humans. Earlier studies (e.g., in the 1990s) overreported lambdoid suture involvement among patients with craniosynostosis because of misdiagnosis and inclusion of deformational plagiocephaly.36–39 Thus, given the rare occurrence of this pathology, accurate diagnosis is imperative for appropriate treatment.13 We did not identify a single patient with bilateral involvement of the lambdoid sutures or other associated fusions, which is known to be very rare.39,40 However, our study did corroborate the finding of male predominance of lambdoid synostosis.40

Patients in the endoscopic group not only were surgically treated 8 months sooner, but also, on average, completed helmet therapy before the age at which patients in the CVR group underwent surgery. This age difference also explains the observed range in preoperative HCP and z scores between the ES and CVR groups. In agreement with previous studies on ES approaches to other types of craniosynostosis (including lambdoid), the operating and total anesthesia times, EBL, and both ICU and total hospital days were significantly less in the ES group compared to the CVR group, with no difference in intra- or postoperative complication rates.16–19,32,41–44

Of note, the one patient who underwent ES, who experienced an intraoperative EBL of 100 ml (> 2 SDs from the mean), requiring a blood transfusion, did experience a complication of a wound infection 22 days postoperatively, which required readmission and wound debridement, washout, and closure. The patient was readmitted 7 days later for a subsequent washout and placement of a Jackson-Pratt drain—despite this course, the patient was never systemically ill nor required reoperation for correction.

Long-term outcomes, as measured by HCPs and corresponding z scores, were equal in both treatment groups and no statistical difference across follow-up intervals was appreciated. Marked improvement was appreciated between pre- and postoperative values in both groups as early as the first month of follow-up. Although data were unequal and varied in availability by patient across both groups, our findings remained in agreement with other surgical studies in the literature that also appreciate equal long-term outcomes.9,18,19,41–43 A homoscedastic 2-tailed Student t-test was favored over a heteroscedastic t-test in analyzing follow-up data at 36 months given equal numbers (Table 3), and no statistical difference was appreciated.

In a previous study comparing postoperative morphological and asymmetrical changes in the cranial base and posterior cranial vault of patients with lambdoid synostosis, Zubovic et al. found equal improvement in posterior cranial vault asymmetry following treatment with either CVR or ES.18 The authors briefly describe their perioperative findings; the operating times and EBLs in their 4 patients with ES were comparable to those of our 13 patients. The most notable differences between both studies were between the patients with CVR. Zubovic et al. reported longer operating times and larger EBL volumes, with 100% of their patients with CVR (n = 8) requiring blood transfusions, whereas only 60% of our patients with CVR required transfusions. Their results are in agreement with those in our cohort, allowing this report to substantially increase the published literature on this condition.

This single-institution retrospective cohort study is not without its limitations. In addition to the limitations of conducting a retrospective, nonrandomized study, the relatively small sample size should be considered in the interpretation and analysis of the data. The incidence of lambdoid synostosis is lower than metopic, coronal, and sagittal synostoses, and there is a clear paucity of surgical outcome studies for lambdoid synostosis in the medical literature.18,41 The variation in data completeness per patient and disproportionate sample sizes between the operative groups (as noted in Tables 2 and 3) may represent a selection bias and impact the generalizability of the statistical analysis. We attempted to address this by using conservative statistical analytical methods, which did not show significant differences between preoperative characteristics. Moreover, intra- and postoperative data for our small CVR cohort can further be corroborated by congruous data presented by Zubovic et al.18 Additional studies (i.e., prospective, randomized) would also be needed to further corroborate generalizability and expand the analysis to include developmental delay as part of the long-term outcomes, but with the low incidence of lambdoid synostosis these studies will be difficult to perform. Aesthetic outcomes could be better assessed via cranial base asymmetry or subjective evaluations such as the Whitaker classification, especially considering that the indication for operation in this population is generally aesthetic in the absence of increased intracranial pressure.45 Three-dimensional CT imaging would lend insights, but at the expense of exposing the child to significant radiation. Photographic or visual/subjective scoring assessments may also help in assessing both clinical and aesthetic outcomes.

Conclusions

ES is a more benign surgical treatment option than CVR in terms of operating time, time under anesthesia, EBL, transfusion frequency, and hospital course. Long-term outcomes appear to be favorable compared to open techniques as well. Thus, ES for the management of lambdoid synostosis is safe and efficient, and appears to be efficacious in terms of intraoperative and long-term cranial growth outcomes.

Acknowledgments

We acknowledge the R. Michael Scott Research Endowment Operating Fund and the Ingraham Fund for Neurosurgical Research for funding this project. We thank Steven Staffa for his comments on an earlier version of this manuscript, and Emily Day for her administrative assistance.

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: Rattani, Meara, Proctor. Acquisition of data: Riordan. Analysis and interpretation of data: Rattani. Drafting the article: Rattani, Riordan. Critically revising the article: all authors. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Rattani. Study supervision: Meara, Proctor.

Supplemental Information

Previous Presentations

Portions of this work were presented in poster form at the 18th Congress of the International Society of Craniofacial Surgery, Paris, France, September 16–19, 2019.

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    • Export Citation
  • 6

    Haas-Lude K, Wolff M, Will B, et al. Clinical and imaging findings in children with non-syndromic lambdoid synostosis. Eur J Pediatr. 2014;173(4):435440.

    • Search Google Scholar
    • Export Citation
  • 7

    Guillaume D. Evaluation of positional plagiocephaly in children. In: The ISPN Guide to Pediatric Neurosurgery. International Society for Pediatric Neurosurgery (ISPN); 2019.

    • Search Google Scholar
    • Export Citation
  • 8

    Hurmerinta K, Kiukkonen A, Hukki J, et al. Lambdoid synostosis versus positional posterior plagiocephaly, a comparison of skull base and shape of calvarium using computed tomography imaging. J Craniofac Surg. 2015;26(6):19171922.

    • Search Google Scholar
    • Export Citation
  • 9

    Proctor MR. Endoscopic craniosynostosis repair. Transl Pediatr. 2014;3(3):247258.

  • 10

    Becker DB, Petersen JD, Kane AA, et al. Speech, cognitive, and behavioral outcomes in nonsyndromic craniosynostosis. Plast Reconstr Surg. 2005;116(2):400407.

    • Search Google Scholar
    • Export Citation
  • 11

    Kapp-Simon KA, Speltz ML, Cunningham ML, et al. Neurodevelopment of children with single suture craniosynostosis: a review. Childs Nerv Syst. 2007;23(3):269281.

    • Search Google Scholar
    • Export Citation
  • 12

    Tamburrini G, Caldarelli M, Massimi L, et al. Intracranial pressure monitoring in children with single suture and complex craniosynostosis: a review. Childs Nerv Syst. 2005;21(10):913921.

    • Search Google Scholar
    • Export Citation
  • 13

    Smartt JM Jr, Reid RR, Singh DJ, Bartlett SP. True lambdoid craniosynostosis: long-term results of surgical and conservative therapy. Plast Reconstr Surg. 2007;120(4):9931003.

    • Search Google Scholar
    • Export Citation
  • 14

    Berry-Candelario J, Ridgway EB, Grondin RT, et al. Endoscope-assisted strip craniectomy and postoperative helmet therapy for treatment of craniosynostosis. Neurosurg Focus. 2011;31(2):E5.

    • Search Google Scholar
    • Export Citation
  • 15

    Fearon JA, Ruotolo RA, Kolar JC. Single sutural craniosynostoses: surgical outcomes and long-term growth. Plast Reconstr Surg. 2009;123(2):635642.

    • Search Google Scholar
    • Export Citation
  • 16

    Shah MN, Kane AA, Petersen JD, et al. Endoscopically assisted versus open repair of sagittal craniosynostosis: the St. Louis Children’s Hospital experience. J Neurosurg Pediatr. 2011;8(2):165170.

    • Search Google Scholar
    • Export Citation
  • 17

    Thompson DR, Zurakowski D, Haberkern CM, et al. Endoscopic versus open repair for craniosynostosis in infants using propensity score matching to compare outcomes: a multicenter study from the Pediatric Craniofacial Collaborative Group. Anesth Analg. 2018;126(3):968975.

    • Search Google Scholar
    • Export Citation
  • 18

    Zubovic E, Woo AS, Skolnick GB, et al. Cranial base and posterior cranial vault asymmetry after open and endoscopic repair of isolated lambdoid craniosynostosis. J Craniofac Surg. 2015;26(5):15681573.

    • Search Google Scholar
    • Export Citation
  • 19

    Isaac KV, Meara JG, Proctor MR. Analysis of clinical outcomes for treatment of sagittal craniosynostosis: a comparison of endoscopic suturectomy and cranial vault remodeling. J Neurosurg Pediatr. 2018;22(5):467474.

    • Search Google Scholar
    • Export Citation
  • 20

    Riordan CP, Zurakowski D, Meier PM, et al. Minimally invasive endoscopic surgery for infantile craniosynostosis: a longitudinal cohort study. J Pediatr. 2020;216:142149.e2.

    • Search Google Scholar
    • Export Citation
  • 21

    de Onis M, Garza C, Victora CG, et al. The WHO Multicentre Growth Reference Study: planning, study design, and methodology. Food Nutr Bull. 2004;25(1)(suppl):S15–S26.

    • Search Google Scholar
    • Export Citation
  • 22

    WHO Multicentre Growth Reference Study Group. Reliability of anthropometric measurements in the WHO Multicentre Growth Reference Study. Acta Paediatr Suppl. 2006;450:3846.

    • Search Google Scholar
    • Export Citation
  • 23

    Proctor MR. Endoscopic cranial suture release for the treatment of craniosynostosis—is it the future? J Craniofac Surg. 2012;23(1):225228.

    • Search Google Scholar
    • Export Citation
  • 24

    Barone CM, Jimenez DF. Endoscopic craniectomy for early correction of craniosynostosis. Plast Reconstr Surg. 1999;104(7):19651975.

  • 25

    Jimenez DF, Barone CM. Endoscopic craniectomy for early surgical correction of sagittal craniosynostosis. J Neurosurg. 1998;88(1):7781.

    • Search Google Scholar
    • Export Citation
  • 26

    Jimenez DF, Barone CM, Cartwright CC, Baker L. Early management of craniosynostosis using endoscopic-assisted strip craniectomies and cranial orthotic molding therapy. Pediatrics. 2002;110(1 Pt 1):97104.

    • Search Google Scholar
    • Export Citation
  • 27

    Riordan CP, Zurakowski D, Meier PM, et al. Minimally invasive endoscopic surgery for infantile craniosynostosis: a longitudinal cohort study. J Pediatr. 2020;216:142149.e2.

    • Search Google Scholar
    • Export Citation
  • 28

    Rottgers SA, Syed HR, Jodeh DS, et al. Craniometric analysis of endoscopic suturectomy for bilateral coronal craniosynostosis. Plast Reconstr Surg. 2019;143(1):183196.

    • Search Google Scholar
    • Export Citation
  • 29

    Brown L, Proctor MR. Endoscopically assisted correction of sagittal craniosynostosis. AORN J. 2011;93(5):566581.

  • 30

    Masserano B, Woo AS, Skolnick GB, et al. The temporal region in unilateral coronal craniosynostosis: fronto-orbital advancement versus endoscopy-assisted strip craniectomy. Cleft Palate Craniofac J. 2018;55(3):423429.

    • Search Google Scholar
    • Export Citation
  • 31

    Ridgway EB, Berry-Candelario J, Grondin RT, et al. The management of sagittal synostosis using endoscopic suturectomy and postoperative helmet therapy. J Neurosurg Pediatr. 2011;7(6):620626.

    • Search Google Scholar
    • Export Citation
  • 32

    Rottgers SA, Lohani S, Proctor MR. Outcomes of endoscopic suturectomy with postoperative helmet therapy in bilateral coronal craniosynostosis. J Neurosurg Pediatr. 2016;18(3):281286.

    • Search Google Scholar
    • Export Citation
  • 33

    Tan SP, Proctor MR, Mulliken JB, Rogers GF. Early frontofacial symmetry after correction of unilateral coronal synostosis: frontoorbital advancement vs endoscopic strip craniectomy and helmet therapy. J Craniofac Surg. 2013;24(4):11901194.

    • Search Google Scholar
    • Export Citation
  • 34

    Williams CT, Segar DJ, Naidoo SD, et al. Evaluation of endoscopic strip craniectomy and orthotic therapy for bilateral coronal craniosynostosis. J Craniofac Surg. 2019;30(2):453457.

    • Search Google Scholar
    • Export Citation
  • 35

    Wood BC, Proctor MR, Rogers GF. The effects of whole-vault cranioplasty versus strip craniectomy on long-term neuropsychological outcomes in sagittal craniosynostosis. Plast Reconstr Surg. 2015;135(5):925e926e.

    • Search Google Scholar
    • Export Citation
  • 36

    Chumas PD, Cinalli G, Arnaud E, et al. Classification of previously unclassified cases of craniosynostosis. J Neurosurg. 1997;86(2):177181.

  • 37

    Cohen MM Jr. Lambdoid synostosis is an overdiagnosed condition. Am J Med Genet. 1996;61(1):9899.

  • 38

    Greene AK, Mulliken JB, Proctor MR, et al. Phenotypically unusual combined craniosynostoses: presentation and management. Plast Reconstr Surg. 2008;122(3):853862.

    • Search Google Scholar
    • Export Citation
  • 39

    Sloan GM, Wells KC, Raffel C, McComb JG. Surgical treatment of craniosynostosis: outcome analysis of 250 consecutive patients. Pediatrics. 1997;100(1):E2.

    • Search Google Scholar
    • Export Citation
  • 40

    Rodriguez-Feo C, Winocour J, Ramirez R, et al. Twenty-year review of a single surgeon’s experience using a unique surgical technique to correct lambdoidal synostosis. J Craniofac Surg. 2017;28(7):17611765.

    • Search Google Scholar
    • Export Citation
  • 41

    Al-Jabri T, Eccles S. Surgical correction for unilateral lambdoid synostosis: a systematic review. J Craniofac Surg. 2014;25(4):12661272.

    • Search Google Scholar
    • Export Citation
  • 42

    Bennett KG, Hespe GE, Vercler CJ, Buchman SR. Short- and long-term outcomes by procedure type for nonsagittal single-suture craniosynostosis. J Craniofac Surg. 2019;30(2):458464.

    • Search Google Scholar
    • Export Citation
  • 43

    Braun TL, Eisemann BS, Olorunnipa O, et al. Safety outcomes in endoscopic versus open repair of metopic craniosynostosis. J Craniofac Surg. 2018;29(4):856860.

    • Search Google Scholar
    • Export Citation
  • 44

    Han RH, Nguyen DC, Bruck BS, et al. Characterization of complications associated with open and endoscopic craniosynostosis surgery at a single institution. J Neurosurg Pediatr. 2016;17(3):361370.

    • Search Google Scholar
    • Export Citation
  • 45

    Wes AM, Naran S, Sun J, et al. The Whitaker classification of craniosynostosis outcomes: an assessment of interrater reliability. Plast Reconstr Surg. 2017;140(4):579e586e.

    • Search Google Scholar
    • Export Citation

Diagram from Prolo et al. (pp 179–188).

Contributor Notes

Correspondence Abbas Rattani: Rush University Medical Center, Chicago, IL. abbas_rattani@rush.edu.

INCLUDE WHEN CITING Published online April 17, 2020; DOI: 10.3171/2020.2.PEDS19522.

Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

  • View in gallery

    CONSORT patient selection diagram. *A total of 6 patients received CVR and 13 received ES. Complete data were not consistently available in the chart for all patients. Thus, cohorts were compared and analyzed based on data availability.

  • View in gallery

    A: Preoperative anterior-posterior (upper image) and posterior-anterior (lower image) 3D CT images of 4-month-old patient who presented with left lambdoid synostosis. Frontal and contralateral parietal bossing with classic “windswept” trapezoidal deformity on the right is appreciated. B: Postoperative anterior-posterior photograph taken 5 years after correction with ES. Figure is available in color online only.

  • 1

    Rhodes JL, Tye GW, Fearon JA. Craniosynostosis of the lambdoid suture. Semin Plast Surg. 2014;28(3):138143.

  • 2

    Slater BJ, Lenton KA, Kwan MD, et al. Cranial sutures: a brief review. Plast Reconstr Surg. 2008;121(4):170e178e.

  • 3

    Mulliken JB, Vander Woude DL, Hansen M, et al. Analysis of posterior plagiocephaly: deformational versus synostotic. Plast Reconstr Surg. 1999;103(2):371380.

    • Search Google Scholar
    • Export Citation
  • 4

    Kadlub N, Persing JA, da Silva Freitas R, Shin JH. Familial lambdoid craniosynostosis between father and son. J Craniofac Surg. 2008;19(3):850854.

    • Search Google Scholar
    • Export Citation
  • 5

    Ellenbogen RG, Gruss JS, Cunningham ML. Update on craniofacial surgery: the differential diagnosis of lambdoid synostosis/posterior plagiocephaly. Clin Neurosurg. 2000;47:303318.

    • Search Google Scholar
    • Export Citation
  • 6

    Haas-Lude K, Wolff M, Will B, et al. Clinical and imaging findings in children with non-syndromic lambdoid synostosis. Eur J Pediatr. 2014;173(4):435440.

    • Search Google Scholar
    • Export Citation
  • 7

    Guillaume D. Evaluation of positional plagiocephaly in children. In: The ISPN Guide to Pediatric Neurosurgery. International Society for Pediatric Neurosurgery (ISPN); 2019.

    • Search Google Scholar
    • Export Citation
  • 8

    Hurmerinta K, Kiukkonen A, Hukki J, et al. Lambdoid synostosis versus positional posterior plagiocephaly, a comparison of skull base and shape of calvarium using computed tomography imaging. J Craniofac Surg. 2015;26(6):19171922.

    • Search Google Scholar
    • Export Citation
  • 9

    Proctor MR. Endoscopic craniosynostosis repair. Transl Pediatr. 2014;3(3):247258.

  • 10

    Becker DB, Petersen JD, Kane AA, et al. Speech, cognitive, and behavioral outcomes in nonsyndromic craniosynostosis. Plast Reconstr Surg. 2005;116(2):400407.

    • Search Google Scholar
    • Export Citation
  • 11

    Kapp-Simon KA, Speltz ML, Cunningham ML, et al. Neurodevelopment of children with single suture craniosynostosis: a review. Childs Nerv Syst. 2007;23(3):269281.

    • Search Google Scholar
    • Export Citation
  • 12

    Tamburrini G, Caldarelli M, Massimi L, et al. Intracranial pressure monitoring in children with single suture and complex craniosynostosis: a review. Childs Nerv Syst. 2005;21(10):913921.

    • Search Google Scholar
    • Export Citation
  • 13

    Smartt JM Jr, Reid RR, Singh DJ, Bartlett SP. True lambdoid craniosynostosis: long-term results of surgical and conservative therapy. Plast Reconstr Surg. 2007;120(4):9931003.

    • Search Google Scholar
    • Export Citation
  • 14

    Berry-Candelario J, Ridgway EB, Grondin RT, et al. Endoscope-assisted strip craniectomy and postoperative helmet therapy for treatment of craniosynostosis. Neurosurg Focus. 2011;31(2):E5.

    • Search Google Scholar
    • Export Citation
  • 15

    Fearon JA, Ruotolo RA, Kolar JC. Single sutural craniosynostoses: surgical outcomes and long-term growth. Plast Reconstr Surg. 2009;123(2):635642.

    • Search Google Scholar
    • Export Citation
  • 16

    Shah MN, Kane AA, Petersen JD, et al. Endoscopically assisted versus open repair of sagittal craniosynostosis: the St. Louis Children’s Hospital experience. J Neurosurg Pediatr. 2011;8(2):165170.

    • Search Google Scholar
    • Export Citation
  • 17

    Thompson DR, Zurakowski D, Haberkern CM, et al. Endoscopic versus open repair for craniosynostosis in infants using propensity score matching to compare outcomes: a multicenter study from the Pediatric Craniofacial Collaborative Group. Anesth Analg. 2018;126(3):968975.

    • Search Google Scholar
    • Export Citation
  • 18

    Zubovic E, Woo AS, Skolnick GB, et al. Cranial base and posterior cranial vault asymmetry after open and endoscopic repair of isolated lambdoid craniosynostosis. J Craniofac Surg. 2015;26(5):15681573.

    • Search Google Scholar
    • Export Citation
  • 19

    Isaac KV, Meara JG, Proctor MR. Analysis of clinical outcomes for treatment of sagittal craniosynostosis: a comparison of endoscopic suturectomy and cranial vault remodeling. J Neurosurg Pediatr. 2018;22(5):467474.

    • Search Google Scholar
    • Export Citation
  • 20

    Riordan CP, Zurakowski D, Meier PM, et al. Minimally invasive endoscopic surgery for infantile craniosynostosis: a longitudinal cohort study. J Pediatr. 2020;216:142149.e2.

    • Search Google Scholar
    • Export Citation
  • 21

    de Onis M, Garza C, Victora CG, et al. The WHO Multicentre Growth Reference Study: planning, study design, and methodology. Food Nutr Bull. 2004;25(1)(suppl):S15–S26.

    • Search Google Scholar
    • Export Citation
  • 22

    WHO Multicentre Growth Reference Study Group. Reliability of anthropometric measurements in the WHO Multicentre Growth Reference Study. Acta Paediatr Suppl. 2006;450:3846.

    • Search Google Scholar
    • Export Citation
  • 23

    Proctor MR. Endoscopic cranial suture release for the treatment of craniosynostosis—is it the future? J Craniofac Surg. 2012;23(1):225228.

    • Search Google Scholar
    • Export Citation
  • 24

    Barone CM, Jimenez DF. Endoscopic craniectomy for early correction of craniosynostosis. Plast Reconstr Surg. 1999;104(7):19651975.

  • 25

    Jimenez DF, Barone CM. Endoscopic craniectomy for early surgical correction of sagittal craniosynostosis. J Neurosurg. 1998;88(1):7781.

    • Search Google Scholar
    • Export Citation
  • 26

    Jimenez DF, Barone CM, Cartwright CC, Baker L. Early management of craniosynostosis using endoscopic-assisted strip craniectomies and cranial orthotic molding therapy. Pediatrics. 2002;110(1 Pt 1):97104.

    • Search Google Scholar
    • Export Citation
  • 27

    Riordan CP, Zurakowski D, Meier PM, et al. Minimally invasive endoscopic surgery for infantile craniosynostosis: a longitudinal cohort study. J Pediatr. 2020;216:142149.e2.

    • Search Google Scholar
    • Export Citation
  • 28

    Rottgers SA, Syed HR, Jodeh DS, et al. Craniometric analysis of endoscopic suturectomy for bilateral coronal craniosynostosis. Plast Reconstr Surg. 2019;143(1):183196.

    • Search Google Scholar
    • Export Citation
  • 29

    Brown L, Proctor MR. Endoscopically assisted correction of sagittal craniosynostosis. AORN J. 2011;93(5):566581.

  • 30

    Masserano B, Woo AS, Skolnick GB, et al. The temporal region in unilateral coronal craniosynostosis: fronto-orbital advancement versus endoscopy-assisted strip craniectomy. Cleft Palate Craniofac J. 2018;55(3):423429.

    • Search Google Scholar
    • Export Citation
  • 31

    Ridgway EB, Berry-Candelario J, Grondin RT, et al. The management of sagittal synostosis using endoscopic suturectomy and postoperative helmet therapy. J Neurosurg Pediatr. 2011;7(6):620626.

    • Search Google Scholar
    • Export Citation
  • 32

    Rottgers SA, Lohani S, Proctor MR. Outcomes of endoscopic suturectomy with postoperative helmet therapy in bilateral coronal craniosynostosis. J Neurosurg Pediatr. 2016;18(3):281286.

    • Search Google Scholar
    • Export Citation
  • 33

    Tan SP, Proctor MR, Mulliken JB, Rogers GF. Early frontofacial symmetry after correction of unilateral coronal synostosis: frontoorbital advancement vs endoscopic strip craniectomy and helmet therapy. J Craniofac Surg. 2013;24(4):11901194.

    • Search Google Scholar
    • Export Citation
  • 34

    Williams CT, Segar DJ, Naidoo SD, et al. Evaluation of endoscopic strip craniectomy and orthotic therapy for bilateral coronal craniosynostosis. J Craniofac Surg. 2019;30(2):453457.

    • Search Google Scholar
    • Export Citation
  • 35

    Wood BC, Proctor MR, Rogers GF. The effects of whole-vault cranioplasty versus strip craniectomy on long-term neuropsychological outcomes in sagittal craniosynostosis. Plast Reconstr Surg. 2015;135(5):925e926e.

    • Search Google Scholar
    • Export Citation
  • 36

    Chumas PD, Cinalli G, Arnaud E, et al. Classification of previously unclassified cases of craniosynostosis. J Neurosurg. 1997;86(2):177181.

  • 37

    Cohen MM Jr. Lambdoid synostosis is an overdiagnosed condition. Am J Med Genet. 1996;61(1):9899.

  • 38

    Greene AK, Mulliken JB, Proctor MR, et al. Phenotypically unusual combined craniosynostoses: presentation and management. Plast Reconstr Surg. 2008;122(3):853862.

    • Search Google Scholar
    • Export Citation
  • 39

    Sloan GM, Wells KC, Raffel C, McComb JG. Surgical treatment of craniosynostosis: outcome analysis of 250 consecutive patients. Pediatrics. 1997;100(1):E2.

    • Search Google Scholar
    • Export Citation
  • 40

    Rodriguez-Feo C, Winocour J, Ramirez R, et al. Twenty-year review of a single surgeon’s experience using a unique surgical technique to correct lambdoidal synostosis. J Craniofac Surg. 2017;28(7):17611765.

    • Search Google Scholar
    • Export Citation
  • 41

    Al-Jabri T, Eccles S. Surgical correction for unilateral lambdoid synostosis: a systematic review. J Craniofac Surg. 2014;25(4):12661272.

    • Search Google Scholar
    • Export Citation
  • 42

    Bennett KG, Hespe GE, Vercler CJ, Buchman SR. Short- and long-term outcomes by procedure type for nonsagittal single-suture craniosynostosis. J Craniofac Surg. 2019;30(2):458464.

    • Search Google Scholar
    • Export Citation
  • 43

    Braun TL, Eisemann BS, Olorunnipa O, et al. Safety outcomes in endoscopic versus open repair of metopic craniosynostosis. J Craniofac Surg. 2018;29(4):856860.

    • Search Google Scholar
    • Export Citation
  • 44

    Han RH, Nguyen DC, Bruck BS, et al. Characterization of complications associated with open and endoscopic craniosynostosis surgery at a single institution. J Neurosurg Pediatr. 2016;17(3):361370.

    • Search Google Scholar
    • Export Citation
  • 45

    Wes AM, Naran S, Sun J, et al. The Whitaker classification of craniosynostosis outcomes: an assessment of interrater reliability. Plast Reconstr Surg. 2017;140(4):579e586e.

    • Search Google Scholar
    • Export Citation

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