Lambdoid synostosis and occipital plagiocephaly: clinical decision rules for surgical intervention

Distinguishing Between Lambdoid Craniosynostosis and Deformational Plagiocephaly: A Review of This Paradigm Shift in Clinical Decision-Making and Lesson for the Future

The cause of occipital asymmtery can be either extrinsic or intrinsic. Intrinsic causes include lambdoid craniosynsotosis. This condition is generally treated with cranial vault expansion surgery. Extrinsic causes include deformational plagiocephaly, which became commonplace after the "Back to Sleep Campaign" instituted in the 1980s by the American Academy of Pediatrics. The treatment of this condition is non surgical. Dr. Joseph Gruss was instumental in differentiating between these conditions and reducing the number of unnecessary surgeries that were previously being performed.

Craniosynostosis of the lambdoid suture

Craniosynostosis affecting the lambdoid suture is uncommon. The definition of lambdoid craniosynostosis solely applies to those cases demonstrating true suture obliteration, similar to other forms of craniosynostosis. In patients presenting with posterior plagiocephaly, true lambdoid craniosynostosis must be differentiated from the much more common positional molding. It can occur in a unilateral form, a bilateral form, or as part of a complex craniosynostosis. In children with craniofacial syndromes, synostosis of the lambdoid suture most often is seen within the context of a pansynostotic picture. Chiari malformations are commonly seen in multisutural and syndromic types of craniosynostosis that affect the lambdoid sutures. Posterior cranial vault remodeling is recommended to provide adequate intracranial volume to allow for brain growth and to normalize the skull shape. Although many techniques have been described for the correction of lambdoid synostosis, optimal outcomes may result from those techniques based on the concept of occipital advancement.

Predictors of severity in deformational plagiocephaly

Multiple risk factors for deformational plagiocephaly (DP) have been reported. The purpose of this study was to establish the impact of these variables on the severity of this deformity. A prospective cohort study was performed. Parents completed a standardized questionnaire assessing potential risk factors for DP before assessment. Examination included measurement of transcranial difference (TCD; ie, difference in oblique cranial lengths), evaluation of head tilt, and rotational asymmetry. Pearson correlation coefficient, 1-way analysis of variance, and 2-sample t-test were used to quantify the relationship between identified risk factors and TCD. A total of 434 patients with DP were evaluated. Male-to-female ratio was 2:1; mean gestational age was 36.5 weeks. Deformational plagiocephaly was first appreciated at a mean infant age of 6 weeks. A preexisting diagnosis of torticollis was noted in fewer than 50%. Mean TCD was 11.2 mm. Head tilt was documented in 80% of infants, and mean head rotational asymmetry was 16.4 degrees. Deformational plagiocephaly was more severe in multiple birth pregnancies (P < 0.05), males (P < 0.05), infants with a favorite head position (P < 0.01), preexamination diagnosis of torticollis (P < 0.05), and infants with a head tilt (P < 0.05). Lower gestational age (P < 0.05) and greater head rotational asymmetry (P < 0.0001) were found to correlate with DP severity. This study suggests that the relationship between the severity of DP and certain risk factors can be quantified. The presence and degree of cervical imbalance correlate strongly with deformational cranial asymmetry.

True Lambdoid Craniosynostosis: Long-Term Results of Surgical and Conservative Therapy

BACKGROUND

True lambdoid synostosis is a rare malformation. Few clinical reports have examined the efficacy of conservative or surgical management in the care of these patients.

METHODS

All patients with a diagnosis of true lambdoid synostosis treated by the senior author (S.P.B.) at The Children's Hospital of Philadelphia between 1990 and 2005 were included in the study. Both qualitative and quantitative assessments of craniofacial growth were performed following either conservative or surgical management. Qualitative assessments were made based on preoperative and postoperative photographs, computed tomographic scans, and a review of patient charts. A quantitative assessment of ear position was performed using craniometric analysis and the appropriate statistical tests.

RESULTS

The study included nine patients--six who underwent surgical intervention and three who did not undergo transcranial surgery to date. The authors' analysis of patient data revealed a predictable craniofacial dysmorphism manifest as occipital flattening, an ipsilateral occipitomastoid bulge, and a pronounced hemifacial deficiency. Generally, these malformations improved following operative management. A quantitative analysis of preoperative and postoperative ear position displayed no statistically significant vertical or anteroposterior displacement. In one untreated patient, true lambdoid synostosis resulted in persistent severe asymmetry of the cranial vault and facial skeleton.

CONCLUSIONS

True lambdoid synostosis, if left untreated, results in pronounced craniofacial asymmetry. Although a diversity of clinical presentations exists, diagnostic features include occipital flattening, an ipsilateral occipitomastoid bulge, and a contralateral hemifacial deficiency. Posterior vault switch cranioplasty is an effective treatment for true lambdoid synostosis when performed in the first year of life.