High-frequency ultrasound confirmation of positional plagiocephaly.

OBJECT: Positional plagiocephaly has become an increasing problem for pediatricians and craniofacial specialists. Diagnosis is commonly based on history and clinical features, but may be difficult in some cases when characteristic features are missing and radiographic studies seem to be necessary. Near-field high-frequency ultrasound has been used to evaluate the sonographic findings of suture anatomy and confirm the diagnosis of positional plagiocephaly as well as provide information of prognostic value.
METHODS: The authors report on 100 pediatric patients between the ages of 2 and 13 months, who were admitted to their department since 2004 with an abnormal head shape suggesting nonsynostotic plagiocephaly (NSP). Suture anatomy was examined using a 7.5-MHz linear transducer and a Siemens Elegra ultrasound scanner by two independent investigators. Measurements of suture width and bone thickness were obtained, and the findings were correlated with clinical data as well as sonographic and histopathological findings in both normal and fused cranial sutures. Interobserver variability was assessed by means of paired t-tests. Linear regression analyses were used for correlating patient age with suture width and bone thickness. Patency of lambdoid sutures was confirmed in 99 cases in which the clinical findings suggested NSP. Morphological characteristics of the sutures--interosseous hypoechoic areas between hyperechoic bone plates--were comparable to those of normal cranial sutures. In one patient, partial synostosis was diagnosed. Overlapping hyperechoic bone plates were found in 51 patients on the affected side of the skull and in 36 patients on the unaffected side. Suture width decreased over time from 6.5 to 2 mm, and thickness of bone in the affected area increased from 0.6 to 1.2 mm until the age of 13 months. The method was found to be limited by age (upper limit 13 months) and anatomical variations but did not show any interobserver variability (p < 0.05).
CONCLUSIONS: High-frequency ultrasound is a relatively inexpensive, safe, and easy-to-use tool for confirming the diagnosis of positional plagiocephaly and excluding true synostosis. Overlapping bone plates may be seen on the affected side of the skull in a majority of plagiocephalic patients, but this finding seems to have no prognostic value regarding early fusion of sutures and therefore should not affect treatment decisions. With its lack of interobserver variability and the advantage of not involving ionizing radiation, sonography has the potential to be a standard modality for investigating plagiocephaly in infants and should be offered in craniofacial outpatient clinics.