- Abnormal shape of head: Patients with positional plagiocephaly typically present in infancy. Parents, primary care providers, or other caregivers note abnormal head shape. It is not thought to cause pain or neurological symptoms in typical situations.
Patterns of evolution
- Worsening flattening: Positional plagiocephaly can worsen when forces are continually applied to the same flat surface, leading to varying degrees of severity.
Time for evolution
- Weeks to months: Positional plagiocephaly typically worsens over weeks to months. With proper therapy, it can improve at the same rate. Evolution is more rapid in patients who are younger, secondary to increased skull pliability.
Evaluation at Presentation
Positional plagiocephaly usually can be diagnosed clinically by history and physical examination. Many tools are available for clinical diagnosis of positional plagiocephaly including anthropometric calipers, digital devices with software analysis, photography, imaging and three-dimensional scanning devices (20).
Standard examinations: Evaluation should include measurements of head circumference, a search for any signs of intracranial hypertension, and palpation for sutural ridging or deformity. The clinician should perform a complete neurological examination. During visual assessment, the head should be viewed from the front (facial view), back (posterior view), vertex (bird’s eye view), and side (lateral view) (4, 20, 33, 41).
Assessment of deformity: Many tools are available for clinical diagnosis of positional plagiocephaly including anthropometric calipers, digital devices with software analysis, photography, imaging, and three-dimensional scanning devices (4, 20, 33, 41, 46, 58). Anthropometric assessment can help provide accurate and consistent measurements to compare with age-appropriate norms and in individual patients over time. In addition to measures of head circumference, calipers can be used to measure the head length (from glabella to opisthocranion), biparietal diameter (head width), and occipital-frontal transcranial diameters. The difference between right and left transcranial diameters (the transdiagonal difference) can be used to help calculate severity in cases of unilateral positional plagiocephaly. The cranial index (the ratio of head width to head length multiplied by 100) can be used to help determine severity in cases of bilateral positional plagiocephaly. The cranial vault asymmetry index (CVAI) is the difference between the longer diagonal and the shorter diagonal in relation to the length of the longer diagonal multiplied by 100.
Measuring severity to quantitate: There has not been agreement as to the best method for assessing severity. The clinician’s rating of severity should be used as part of a holistic assessment (20). For unilateral positional plagiocephaly, mild cases are associated with flattening restricted to the back of the skull and a transdiagonal difference of 3–10 mm; moderate cases are associated with malposition of the ear or forehead deformity and a transdiagonal difference of 10-12 mm; and severe cases are associated with malar deformity or vertical or temporal skull growth and a transdiagonal difference of greater than 12 mm.
For evaluation using the CVAI, 3.5%-6.25% with minimal asymmetry in one posterior quadrant and no secondary changes is considered mild. A CVAI of 6.25%-8.75% with two quadrant involvement and minimal ear shift and/or anterior involvement is considered moderate. Severe cases are those which have a CVAI of 8.75%-11.0% with two or three quadrant involvement, moderate ear shift and noticeable orbit asymmetry. Lastly, very severe cases have a CVAI of >11.0% with three or four quadrant involvement, severe ear shift and anterior involvement including orbit and cheek asymmetry (17).
For bilateral posterior plagiocephaly (brachycephaly), mild cases are associated with central posterior deformity and a cranial index of 82–90%; moderate cases are associated with central posterior deformity and widening of the posterior skull and a cranial index of 90–100%; and severe cases are associated with vertical head growth or temporal bossing and a cranial index of greater than 100% (4, 18, 20, 27, 29, 41, 42, 43, 50).