Posterior Cranial Vault Distraction Osteogenesis In Mercedes Benz Pattern Craniosynostosis Utilizing A Posterior-Superior Distraction Vector
Fady P. Marji, MD1,2, Lucas Dvoracek, MD1,3, Lisa Block, MD1,3, Erin Anstadt, MD1,4, Jesse Goldstein, MD1,2, Joseph E. Losee1,4.
1University of Pittsburgh Medical Center, Pittsburgh, PA, USA, 2Childrens Hospital of Pittsburgh, Pittsburgh, PA, USA, 3Childrens Hospital of Pittsburgh, Pittsburgh, Pittsburgh, PA, USA, 4Childrens Hospital of Pittsburgh, Pittsburgh, PA, United States, Pittsburgh, PA, USA.
Purpose: In complex craniosynostosis, the trisutural fusion pattern involving the sagittal and bilateral lambdoid sutures is known as Mercedes Benz Syndrome (MBS). The purpose of this study was to review a series of patients with this rare form of synostosis treated with posterior cranial vault distraction osteogenesis (PVDO) using a posterior-superior distraction vector and assess management outcomes.
Methods: A retrospective clinical outcomes assessment of patients identified with Mercedes Benz pattern craniosynostosis treated with PVDO using a posterior-superior distraction vector was performed. Patient demographics, perioperative data, and 3D-computed tomography (3D-CT) anthropologic measurements were reviewed. Significance was ascertained by t test.
Results: From 2014-2018, 4 non-syndromic patients underwent bilateral PVDO in the setting of bilateral lambdoid and sagittal synostosis. All patients were treated with parietotemporal and occipital craniotomy with frontoparietal barrel stave osteotomies. Bilateral internal distractors were placed posterolaterally with a posterior-superior vector. One patient had asymptomatic Chiari I malformation. Evidence of raised intracranial pressure (ICP) was present in 1 patient. Mean age at diagnosis was 5.42 months (range, 0.69 to 5.69 months). Mean age at surgery was 10.08 months (range, 7.50 to 13.31 months). Average estimated blood loss was 100.00 cc (± 90.14 cc). Average length of hospital stay was 3 days (range, 2 to 4 days). Distraction was initiated on postoperative day 2 at a rate of 1 mm per day for an average of 31.67 days (range, 25 to 40 days). Total distraction length averaged 30.33 mm (±1.10 mm). Distraction hardware was removed after a mean consolidation period of 3.87 months (range, 2.96 to 4.73 months). There were no perioperative complications. Mean time interval of pre-operative and post-operative 3D-CT imaging was 8.78 months (range, 5.98 to 14.17 months). Clinical and radiological improvement was observed in all cases. Craniometric comparison of 3D-CT imaging demonstrated an increase in cranial vault volume of 40.9 percent (range, 28.50 to 57.12 percent; p= 0.02). Mean posterior cranial height increased by 15.11 percent (±8.20 percent; p=0.04). Mean basofrontal angle decreased by 4.46 percent (±1.56 percent; p=0.02), indicating an improvement in frontal bossing.
Conclusions: PVDO using a posterior-superior distraction vector is a safe and effective operative modality for management of MBS, improving both anterior and posterior cranial morphology. Further studies are needed to elucidate whether this vector has superior outcomes when compared to a conventional posterior-inferior vector.
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