Surgical Correction for Unilateral Lambdoid Synostosis: A Systematic Review

Three-dimensional Analysis of Facial Asymmetry in Unilateral Lambdoid Craniosynostosis

OBJECTIVE

Unilateral lambdoid synostosis (ULS) is characterized by occipital flattening, mastoid bulging, and contralateral parietal bossing. Anterior craniofacial features are less well-defined. This study utilizes volumetric, craniometric, and composite heat maps of three-dimensional (3D) rendered CT scans to analyze anterior craniofacial asymmetry in ULS and compared to controls.

DESIGN

A retrospective review of three-dimensional CT scans.

SETTING

Tertiary care pediatric institution.

PATIENTS, PARTICIPANTS

30 ULS and 30 control patients.

MAIN OUTCOME MEASURE(S)

Volumetric and craniometric analysis of the anterior fossa, orbits, zygomas, maxilla, and mandible was performed.

RESULTS

The anterior fossa volume was greater bilaterally (0.047, 0.038), and the fossa angle was more anterior contralaterally (<0.001) and more anterior bilaterally than controls (0.038, 0.033). The orbits had greater height and lesser depth bilaterally compared to controls (0.006, 0.009; < 0.001, < 0.001). Zygoma length was significantly greater on the contralateral side than controls (0.048; < 0.001). Nasal contralateral deviation of 3.57  ±  1.97°. The maxillary length was longer on the contralateral side (0.045). The mandibular angle was more anterior on the ipsilateral side and posterior on the contralateral side (<0.001) compared to controls (0.042, < 0.001). Chin had a contralateral deviation of 1.04  ±  3.74°.

CONCLUSIONS

ULS has significant asymmetry in the anterior craniofacial skeleton. There is a bilateral expansion of the anterior cranial fossa with greater frontal bossing on the contralateral side. Increased orbital height and decreased depth. Contralateral zygomatic and mandibular body lengthening with posterior mandibular deviation. These features may provide more effective diagnosis and potential clinical management strategies.

Cognitive Development in Lambdoid Craniosynostosis: A Systematic Review and Meta-Analysis

OBJECTIVE

Lambdoid craniosynostosis affects approximately 1 in 33 000 live births per year, and surgical correction is often sought in order to achieve normocephaly and allow for adequate brain growth. However, the effects of lambdoid synostosis and its treatment on cognitive development are unknown.

DESIGN

Systematic review and meta-analysis.

PATIENTS, PARTICIPANTS

A systematic review of Ovid Medline, Embase, Web of Science, Scopus, Cochrane Central Register of Controlled Trials, and Clinicaltrials.gov was conducted in January 2022. Included studies assessed cognitive development of patients with nonsyndromic unilateral lambdoid craniosynostosis.

MAIN OUTCOME MEASURES

Results of developmental tests were compared to normative data or controls to generate Hedges' g for meta-analysis.

RESULTS

Nine studies met the inclusion criteria. Meta-analysis of 3 studies describing general cognition showed that cases scored significantly lower than their peers, but within 1 standard deviation (g = 0.37, 95% CI [-0.64, -0.10], P = .01). Meta-analysis of verbal and psychomotor development showed no significant differences in children with lambdoid synostosis. Studies were of fair quality and had moderate-to-high heterogeneity.

CONCLUSIONS

Patients with lambdoid craniosynostosis may score slightly below average on tests of general cognition in comparison to normal controls, but results in other domains are variable. Analyses were limited by small sample sizes. Multidisciplinary care and involvement of a child psychologist may be helpful in identifying areas of concern and providing adequate scholastic support. Further research recruiting larger cohorts will be necessary to confirm these findings and extend them to other developmental domains such as attention and executive function.

Utilizing Computer-Assisted Design and Virtual Surgical Planning for Correction of Unilateral Lambdoid Synostosis

Unilateral lambdoid synostosis is the rarest form of single-suture craniosynostosis. Although various surgical approaches have been described, cranial vault remodeling remains the predominant approach. To aid in surgical planning, preoperative virtual surgical modeling using a patient's presenting computed tomography scan can be used to increase reconstructive precision and to reduce operative time. Presented is a 7-month-old male with unilateral lambdoid synostosis who underwent medically modeled cranial vault reconstruction.

Rotation Advancement Distraction Osteogenesis Technique is Attributed to Unilateral Lambdoid Synostosis and is Used to Correct Posterior Plagiocephaly

Unilateral lambdoid synostosis is the rarest form of craniosynostosis. Surgical correction is technically challenging from a morphological standpoint and is used to decompress intracranial pressure. Herein, the authors present a "rotational advancement bone flap" technique for the repair of posterior plagiocephaly. A bicoronal skin incision was performed, to expose the occipital region. The rotational advancement bone flap was designed to hinge off the nonsynostotic side, and it was set up to include an occipital protrusion on the normal side. On the premature side, an advancement bone flap was set up to include the flattened and deformed occipital bone. A titanium cranial distractor, which was attached between the bone flap and the anterior bone. An absorbable plate, which would later become a hinge due to the movement of the bone flap, was attached to the area for reinforcement. The authors technique was able to decompress intracranial pressure with satisfactory esthetic outcomes.

Conventional posterior cranial vault expansion: indications and results-review of the literature

In the late 1980s, craniofacial surgery units reported suboptimal cosmetic results, cranial volume restriction, and intracranial hypertension after anterior cranial vault remodeling in bilateral coronal synostosis associated with severe brachyturricephaly. A possible explanation was a severe associated growth restriction of the posterior calvaria with radiological synostosis at the lambda sutures. "Conventional" or "fixed" posterior cranial vault expansion techniques were developed to address these limitations, sometimes as the first surgical step in a two-staged protocol of total calvarial reconstruction, combined with suboccipital decompression in cases of symptomatic cerebellar tonsillar herniation or, more easily, to resolve the characteristic occipital flattening of lambdoid synostosis. Various surgical approaches have been described; however, the indications for and timing of surgical treatment and postoperative evaluation of results still remain controversial. Although more invasive, conventional posterior cranial vault expansion has proven to be safe and offers a remodeled and protective bony vault immediately after surgery, but the underlying cranial base malformation remained untreated, with implications in the postoperative growth of the facial skeleton. Overcorrection, rigid stabilization, and grafting are also concerns to be addressed.

Clinical Features and the Use of Three-Dimensional Imaging for Unilateral Lambdoid Synostosis

INTRODUCTION

True isolated lambdoid craniosynostosis is rare. It requires corrective surgery to prevent intracranial pressure and aesthetic stigma by significant dyscrania. We summarize our case series for lambdoid craniosynostosis outlining the pathophysiology, clinical findings and surgical approaches and outcomes.

METHODOLOGY

A retrospective analysis of our data from 2010 to 2020 summarized our cases of true lambdoid synostosis. We have used the medical notes and the radiological findings from computed tomography scans to summarize a case series of isolated lambdoid synostosis.

RESULTS

Our case series demonstrated 7 patients with true isolated lambdoid craniosynostosis. In most cases surgical intervention in the form of posterior cranial vault remodeling utilizing a bandeau, based on occipital advancement techniques, has demonstrated the most consistently favorable aesthetic outcome.

CONCLUSIONS

Surgical referral to a craniofacial center should be sought early in difficult to diagnose cases. Although rare, surgical intervention is indicated to correct potentially increased intracranial pressure and to ameliorate cranial dyscrania.

Synostosis of the lambdoid suture: a spectrum

PURPOSE

Lambdoid synostosis (LS) is a rare condition, which is either isolated; associated with sagittal synostosis, the "Mercedes-Benz" syndrome (MBS); or with synostosis of the coronal sutures (oxycephalic form). In addition, LS is part of the phenotype of a growing number of genetic diseases. The nosology, pathophysiology, and management are controversial. We decided to review our experience with LS.

METHODS

We reviewed retrospectively pediatric cases of LS proved on CT-scanner, isolated or associated with other conditions, followed in our craniofacial center during the last 15 years, regarding clinical presentation, anatomical lesions, syndromic associations, surgical management, and outcome.

RESULTS

We reviewed 48 cases: 6 isolated LS, 22 MBS, and 20 oxycephalic. A syndromic context was present in 72% (up to 80% of oxycephalic cases), and faciostenosis was present in 23%, mostly oxycephalic cases (40%). Transverse sinus agenesis was found in 61% of documented patients. A total of 31% of children had a dystocic birth, up to 45% of MBS. Decompressive craniectomy or cranioplasty was needed in a majority of patients, often young infants, while posterior fossa decompression was mostly performed in older children.

CONCLUSION

LS is rarely isolated and non syndromic; most cases are found in a wide spectrum of diseases, and LS is often associated with sagittal or coronal synostosis. Genetic evaluation is mandatory for LS; conversely, geneticists may require neurosurgical advice for LS in an increasing number of very rare diseases. The surgical management of LS should be tailored according to clinical presentation, age, and syndromic context.

A Posterior Rotational Flap Technique Using Distraction Osteogenesis for Unilateral Lambdoid Craniosynostosis

INTRODUCTION

The craniofacial asymmetry seen in unilateral lambdoid craniosynostosis may not be effectively treated by posterior cranial vault remodeling, endoscopic suturectomy, and helmet therapy, or suturectomy and distraction osteogenesis alone due to limitations in soft-tissue envelope expansion and relapse of the deformity. The authors report a series of unilateral lambdoid craniosynostosis patients treated with a posterior rotational cranial-flap technique using internal distraction osteogenesis.

METHODS

Posterior cranial vault reconstruction combined with internal distraction was used, aided by preoperative virtual surgical planning. An in situ posterior rotational flap osteotomy was utilized to maximize dural preservation. Primary outcome measures included age-adjusted volume change and age-adjusted percent volume change per mm distraction. Distraction characteristics and perioperative characteristics were also assessed.

RESULTS

A total of 5 patients were identified. Mean predistraction intracranial volume was 1087.5 cc (SD  = 202.3 cc) and mean postdistraction included intracranial volume was 1266.1cc (SD  = 131.8cc). Mean age-adjusted percent included intracranial volume change was 14.1% (SD  = 9.6%), and mean percent intracranial volume change per mm distraction was 0.43%/mm distraction (SD  = 0.37%/mm distraction). One patient developed a distractor site infection postoperatively that was treated successfully with oral antibiotics. All patients had a Whitaker score of 1 at one year follow up.

CONCLUSIONS

Posterior cranial vault remodeling using osteogenesis and a rotational cranial flap technique with dural preservation can be effectively used to maximize bone flap viability and limit postoperative relapse in patients with unilateral lambdoid craniosynostosis. Long term analysis as well as comparison to open techniques will need to be interrogated.

Computational modelling of patient specific spring assisted lambdoid craniosynostosis correction

Lambdoid craniosynostosis (LC) is a rare non-syndromic craniosynostosis characterised by fusion of the lambdoid sutures at the back of the head. Surgical correction including the spring assisted cranioplasty is the only option to correct the asymmetry at the skull in LC. However, the aesthetic outcome from spring assisted cranioplasty may remain suboptimal. The aim of this study is to develop a parametric finite element (FE) model of the LC skulls that could be used in the future to optimise spring surgery. The skull geometries from three different LC patients who underwent spring correction were reconstructed from the pre-operative computed tomography (CT) in Simpleware ScanIP. Initially, the skull growth between the pre-operative CT imaging and surgical intervention was simulated using MSC Marc. The osteotomies and spring implantation were performed to simulate the skull expansion due to the spring forces and skull growth between surgery and post-operative CT imaging in MSC Marc. Surface deviation between the FE models and post-operative skull models reconstructed from CT images changed between ± 5 mm over the skull geometries. Replicating spring assisted cranioplasty in LC patients allow to tune the parameters for surgical planning, which may help to improve outcomes in LC surgeries in the future.

Endoscopic Spring-Mediated Distraction for Unilambdoid Craniosynostosis

BACKGROUND

Craniosynostosis treatment modalities have changed over time. These have included open calvarial remodeling, suturectomy with helmet molding, hand-powered distraction devices, and spring-mediated distraction. Implantable springs were first described for their use in treatment of craniosynostosis in 1998 (Lauritzen et al, Plast Reconstr Surg 121;2008:545-554). They have been used for the correction of craniosynostosis involving single and multiple sutures and have been placed through both endoscopic and open approaches. Their use for correction of lambdoid synostosis has been previously only described using an open approach (Arnaud et al, Child Nerv Syst 28;2012:1545-1549). The senior author has performed spring-mediated distraction for treating unilambdoid craniosynostosis using an endoscopic approach, which is described below and has not previously been reported by other authors.

METHODS

A retrospective analysis of our series of endoscopic unilambdoid synostosis repairs is included in this article. Patients were analyzed based on patient characteristics, operative details, and outcomes. The operation commences by approaching the lambdoid suture endoscopically through a 2- to 3-cm incision lateral to the lambdoid suture. Burr holes are placed on either side of the suture and a suturectomy is performed. Springs are bent preoperatively to a predetermined force. Two springs are placed across the suturectomy defect and the skin is closed. The patient is monitored for improvement in head shape and cranial X-rays are performed to measure the degree of distraction.

RESULTS

Seven patients underwent endoscopic spring-mediated distraction for unilambdoid craniosynostosis. The average age at the time of operation was 9.4 months. The median force of each spring placed was 7.0 N. The median length of hospital stay after spring placement was 2 days. Springs were removed at 5.6 months on average. Five patients had X-rays immediately after placement and prior to removal. Each spring expanded an average distance of 15.3 mm. There were no surgical complications. Three patients had both preoperative and postoperative computed tomography scans available. The angle of the cranial base, calculated by comparing foramen magnum to cribriform plate angles, improved 5.8° (12.3 preoperatively to 6.6 postoperatively).

CONCLUSION

Endoscopic spring-mediated distraction is a safe and effective method of treatment for unilambdoid craniosynostosis. The series represents the largest experience with this technique. The approach can be considered in all patients with unilambdoid synostosis given the efficacious improvement in vault remodeling, low patient morbidity, short operating time, and minimal inpatient stay.

A Novel Sand Dollar and Staves Technique for Unilateral Lambdoid Craniosynostosis

BACKGROUND

Unilateral lambdoid synostosis (ULS) is the rarest form of craniosynostosis. Due to the associated cranio-caudal shift seen in ULS, surgical correction is technically challenging from a morphological standpoint. Herein, the authors present a novel "Sand-Dollar and Staves" technique for the repair of ULS.

METHODS

A zigzag coronal incision is performed, and an anteriorly-based pericranial flaps are elevated. Prefabricated cutting guides are placed and the calvarium is marked. To treat the flattening on the ipsilateral side, a wedged suturectomy is performed with additional barrel staves. A large circle centered over the bulging on the contralateral side is cut out above the open lambdoid suture. This piece is barrel staved in a radial fashion, leaving the center intact and creating a Sand-Dollar appearance. This disk is then flattened and trimmed. The modified Sand-Dollar is fixed using an absorbable plating system. While gentle pressure is applied to the Sand-Dollar piece as it is being secured, the ipsilateral side demonstrates compensatory filling. Results are evaluated using the Whitaker Classification.

RESULTS

Four patients underwent surgical correction with this technique. The procedure was performed at mean age of 11.7 months. The mean operative time was 2.5 hours. Intraoperative blood loss was 50 to 100 ml. Total hospitalization time was 2 to 3 days. No post-operative complications were encountered. Whitaker scores ranged from 1 to 1.5. The mean follow-up was 10 months.

CONCLUSION

The Sand-Dollar and Staves procedure is a novel, single-stage approach for the management of ULS with decreased operative time, blood loss, and hospital stay with satisfactory aesthetic outcomes.

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

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.

Isolated Lambdoid Craniosynostosis

INTRODUCTION

Lambdoid craniosynostosis is an extremely rare anomaly in which there is premature fusion of one or both lambdoid sutures. The mainstay of treatment is surgical intervention, for which various procedures have been described, but there is a paucity of data on long-term outcomes. This study examines the long-term outcomes in the surgical management of this challenging condition, showing that accurate diagnosis and careful planning can lead to safe and consistent results.

MATERIALS AND METHODS

A retrospective chart review was performed looking at all cases of isolated lambdoid craniosynostosis treated with surgical intervention by the senior author from 1999 to 2016. Data collected included gender, age at diagnosis, age at surgery, length of follow up, method of diagnosis, side of affected suture, pre-operative and post-operative physical exam findings, surgical technique, complications, re-operation rate, and associated torticollis.

RESULTS

Twenty-five patients (N = 25) were included in the study. All patients underwent posterior calvarial remodeling with/without barrel stave osteotomies and full thickness calvarial bone grafts. Mean length of follow up after operative intervention was 43.8 months (+/- 23.2 months). All patients were judged to have significantly improved head contour which was near-normal at conversational distance during post-operative follow up by the senior author. Residual plagiocephaly was present in 24% of patients. There were no major complications in this series. Reoperation rate was 8%. Seventy-six percent of patients also presented with torticollis, of which 37% had refractory torticollis that required sternocleidomastoid (SCM) release by the senior author.

DISCUSSION

The authors present one of the largest series of operative cases of isolated lambdoid craniosynostosis to date. Our data show that with accurate diagnosis and careful planning, safe and consistent long-term results can be achieved with surgical intervention. A significant number of patients in our series also presented with concomitant torticollis. The authors recommend that all patients being evaluated for posterior plagiocephaly should also be evaluated for torticollis, because without recognition and intervention, patients may continue to have residual facial asymmetry and head shape abnormalities despite optimal surgical correction of the lambdoid synostosis.

Twenty-Year Review of a Single Surgeon's Experience Using a Unique Surgical Technique to Correct Lambdoidal Synostosis

BACKGROUND

Numerous techniques for the surgical management of lambdoidal synostosis have been previously described; however, no best practice technique currently exists. Surgical procedures range from complete posterior calvarial reconstruction to distraction osteogenesis techniques. Our primary purpose is to describe a novel approach to correct unilateral or bilateral lambdoidal synostosis.

METHODS

A retrospective review was performed on a single surgeon's experience with craniosynostosis (1994-2014). Specifically, craniosynostosis cases involving the lambdoidal suture, which were repaired using a novel 'tongue and groove' technique, were identified.

RESULTS

A total of 664 craniosynostosis cases were retrieved, with 21 primarily involving the lambdoidal suture (3.2%). Of these, 18 were unilateral and 3 were bilateral lambdoidal synostosis. Male-to-female ratio was 3:1. Average age of first encounter with a craniofacial physician was 33 weeks (8 months). Average age at time of surgery was 43 weeks (10.75 months). Complications of this technique included 1 patient who experienced refusion of his lambdoidal suture and fusion of his sagittal suture, and 4 who returned for bone graft coverage of full-thickness calvarial defects owing to a lack of complete reossification.

CONCLUSION

The "tongue and groove" technique represents a novel method for the management of lambdoidal synostosis with good esthetic outcomes, allowing immediate cranial stabilization with increased skull volume. This technique, used by the senior author for >20 years, provides a reproducible and reliable method of correcting lambdoidal synostosis.

Nonsyndromic Craniosynostosis and Deformational Head Shape Disorders

This article provides an overview of etiology, epidemiology, pathology, diagnosis, and treatment of nonsyndromic craniosynostosis, including sagittal, metopic, coronal, lambdoid, and complex synostosis. Detailed discussion is presented regarding indications for surgical intervention and management options, including frontoorbital advancement, cranial vault reconstruction, endoscopic strip craniectomy, spring-assisted strip craniectomy, and cranial vault distraction osteogenesis. Deformational plagiocephaly is also presented with treatment options including repositioning, physical therapy, and helmet therapy.

Sutures Possess Strong Regenerative Capacity for Calvarial Bone Injury

Repair of calvarial bony defects remains challenging for craniofacial surgeons. Injury experiments on animal calvarial bones are widely used to study healing mechanisms and test tissue engineering approaches. Previously, we identified Gli1+ cells within the calvarial sutures as stem cells supporting calvarial bone turnover and injury repair. In this study, we tested the regenerative capacity of the suture region compared with other areas of calvarial bone. Injuries were made to mouse sagittal sutures or other areas of the calvarial bone at varying distances from the suture. Samples were collected at different time points after injury for evaluation. MicroCT and histological analyses were conducted. EdU incorporation analysis was performed to assay cell proliferation. Gli1-Cre^ERT2;Tdtomato^flox mice were used to trace the fate of Gli1+ stem cells after injury. Calvarial sutures possess much stronger regeneration capability than the nonsuture bony areas of the calvaria. The healing rate of the calvarial bone is inversely proportional to the distance between the suture and injury site: injuries closer to the suture heal faster. After complete removal of the sagittal suture, regeneration and restoration of normal organization occur within 6 weeks. Gli1+ cells within the suture mesenchyme are the cellular source for injury repair and bone regeneration. These results demonstrate that calvarial bone healing is not an evenly distributed event on the calvarial surface. Sutures contain stem cells and are the origin of calvarial bone tissue regeneration. Therefore, current practice in calvarial surgery needs to be reevaluated and modified. These findings also necessitate the design of new approaches for repairing calvarial bony defects.

Lambdoid Craniosynostosis: The Relationship with Chiari Deformations and an Analysis of Surgical Outcomes

BACKGROUND

A relationship between lambdoid craniosynostosis and Chiari deformations has been suggested, but the true extent of this association remains uncertain. The authors reviewed a single center's experience treating lambdoid synostosis to further elucidate this relationship, examine surgical outcomes, and identify associations that might impact future treatments.

METHODS

A retrospective chart review was performed of all patients treated for lambdoid craniosynostosis, excluding the syndromic craniosynostoses. Operative data, scans, hospitalization, and subsequent surgical procedures were tracked. All patients were treated with remodeling procedures, but those with Chiari deformations underwent additional simultaneous suboccipital decompressions.

RESULTS

Over 22 years, 1006 nonsyndromic craniosynostosis patients were treated, 45 of whom (4.5 percent) presented with lambdoid involvement: 25 single-suture and 20 multiple-suture (complex craniosynostosis). Magnetic resonance imaging revealed that 60 percent of children with unilateral synostosis and 71 percent with a complex synostosis had associated Chiari deformations. The mean surgical age was 12 months, and the average follow-up was 5.7 years: two patients developed syringomyelia requiring transcervical decompressions and two underwent secondary posterior remodeling procedures (one unilateral and one complex synostosis) while undergoing later Chiari decompressions. No patients treated with initial suboccipital decompressions have subsequently developed symptoms requiring treatment.

CONCLUSIONS

The majority of children with lambdoid synostosis develop Chiari deformations; therefore, routine preoperative and postoperative magnetic resonance imaging should be considered. The treatment of lambdoid craniosynostosis with cranial remodeling procedures, including incontinuity suboccipital decompressions when Chiari deformations were present, was associated with few complications. Ninety-six percent of those with isolated fusions were managed with a single procedure.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.