Outcome analysis of molding helmet therapy using a classification for differentiation between plagiocephaly, brachycephaly and combination of both

PURPOSE

The incidence of positional head deformation has increased during the last decades. Helmet therapy has been proved to be a reliable method for the treatment of nonsynostotic skull deformities. Until today, a simple classification to differentiate between different head shapes has not been established.

MATERIALS AND METHODS

We suggest a classification system to group patients with plagiocephaly, brachycephaly, and a combination of both, using two simple values: cranial vault asymmetry (CVA), and cephalic index (CI). We further analyzed a study population of 1050 children treated with molding helmets to identify prognostic variables for better outcome within our proposed classification.

RESULTS

In all, 736 patients were male (70.10%) and 314 patients were female (29.90%). Mean improvement of cranial vault asymmetry index (CVAI) ranged from 2.94% to 7.08% (CVA 0.37 cm-0.86 cm) in subgroups of patients defined by classification and severity of deformation. In patients with brachycephaly, CI improved from 4.17% to 8.22%. Duration of therapy differed from 21 weeks to 24 weeks. Children aged 6 months or less showed greater improvement and shorter duration of therapy compared to older patients. In addition to early onset of therapy, classification and severity of deformation were significantly associated with a reduction of the deformation under therapy. There were distinct differences in outcomes between different head shapes.

CONCLUSION

Helmet therapy should be initiated early. Our analysis suggests that the proposed classification correctly identifies patients whose deformation is reduced under therapy.

LEVEL OF EVIDENCE

III.

Outcome analysis after helmet therapy using 3D photogrammetry in patients with deformational plagiocephaly: the role of root mean square

Deformational plagiocephaly (DP) is a multifactorial non-synostotic cranial deformity with a reported incidence as high as 1 in 7 infants in North America. Treatment options have focused on non-operative interventions including head repositioning and the use of an orthotic helmet device. Previous studies have used linear and two dimensional outcome measures to assess changes in cranial symmetry after helmet therapy. Our objective was to demonstrate improvement in head shape after treatment with a cranial molding helmet by using Root Mean Square (RMS), a measure unique to 3D photogrammetry, which takes into account both changes in volume and shape over time. Three dimensional photographs were obtained before and after molding helmet treatment in 40 infants (4-10 months old) with deformational plagiocephaly. Anatomical reference planes and measurements were recorded using the 3dMD Vultus(®) analysis software. RMS was used to quantify symmetry by superimposing left and right quadrants and calculating the mean value of aggregate distances between surfaces. Over 95% of the patients demonstrated an improvement in symmetry with helmet therapy. Furthermore, when the sample of infants was divided into two treatment subgroups, a statistically significant correlation was found between the age at the beginning of treatment and the change in the RMS value. When helmet therapy was started before 7 months of age a greater improvement in symmetry was seen. This work represents application of the technique of RMS analysis to demonstrate the efficacy of treatment of deformational plagiocephaly with a cranial molding helmet.

Three-dimensional analysis of positional plagiocephaly before and after molding helmet therapy in comparison to normal head growth

OBJECTIVE

Stereophotogrammetry enables a simple and radiation free longitudinal analysis of skull asymmetries: in a three-dimensional coordinate system various distances (length, breadth, cephalic index, oblique diameters, ear shift, head circumference) can be analyzed. We also defined separate volume sections in order to further quantify the degree of asymmetry in the posterior and anterior components of both sides of the head.

PATIENTS AND METHODS

In 51 infants (mean age, 6 months; SD 0.97) with positional plagiocephaly, we determined these parameters at the beginning as well as at the end of molding helmet therapy (mean therapy time 4.9 months). Thirty-seven infants without positional deformity (mean age, 6.4 months; SD 0.3) served as control group and provided data about what appears to be normal and how these parameters change during growth over a comparable period of time.

RESULTS

Compared with the control group, the plagiocephalic heads were more brachycephalic, but closely approximated the normal shape under molding therapy. The striking volume difference between the left and right posterior sections in the plagiocephalic children (the mean volume of the flattened side being 21% smaller than the one on the contralateral side) improved as well (to a residual difference of mean 8%) and ended up with a value close to the control group (mean 6%).

CONCLUSION

There is a broad clinical application area for stereophotogrammetry analyzing skull morphology: In plagiocephalic infants we demonstrate impressive changes of head shape under molding therapy; in normal-looking infants we describe the extent of unperceived asymmetry.