The appearance of a flat spot or asymmetry on an infant’s head is a common source of concern for parents. This phenomenon has two primary medical classifications: positional plagiocephaly and positional brachycephaly. Plagiocephaly involves an oblique or asymmetrical flattening on one side of the back of the skull, while brachycephaly presents as a symmetrical flattening across the entire back of the head. These conditions result from external pressure on the soft, rapidly growing skull bones during the first year of life. Management may range from simple repositioning to the use of a cranial orthosis, commonly called a helmet.
Identifying Visual Signs of Head Flattening
Parents can visually assess their baby’s head shape by examining it from several angles, particularly from above and behind. Positional plagiocephaly creates a distinct, uneven shape, often described as looking like a parallelogram when viewed from the top. The flattening occurs on one side of the back of the head, often resulting in a compensatory bulge in the forehead on the same side. The ear on the flattened side may also appear pushed forward relative to the opposite ear, indicating asymmetry beyond the back of the skull.
Brachycephaly involves symmetrical flattening across the back of the skull. This flattening causes the head to become wider than it is long, giving it a foreshortened appearance. The back of the head may look high and wide, and the forehead may bulge outward. In both conditions, the flattening is most noticeable around two to four months of age, when the skull is highly malleable and the baby spends significant time lying down.
Common Causes of Positional Head Abnormalities
Prolonged pressure exerted on the same area of the soft skull bones causes these head shape changes. This mechanical pressure results from the “Back to Sleep” campaign, which recommends placing infants on their backs to sleep to reduce the risk of Sudden Infant Death Syndrome (SIDS). The supine position increases the time spent resting on the back of the head.
A contributing factor is the infant’s positional preference, where the baby habitually turns their head to one side, leading to localized, consistent pressure on that favored area. Tightness in the neck muscles, called congenital muscular torticollis, frequently accompanies positional plagiocephaly. Torticollis restricts the baby’s ability to turn their head fully, forcing them to rest on the same spot and exacerbating the flattening. Prematurity is also a risk factor, as the skull bones of pre-term infants are softer at birth and they may have less developed neck muscle strength.
Early Interventions and Repositioning Strategies
Addressing positional head flattening begins with repositioning, which involves actively encouraging the baby to turn their head away from the flattened area. During awake, supervised periods, parents should maximize “tummy time,” aiming for several short sessions throughout the day that total at least an hour. Tummy time takes pressure off the back of the head and strengthens the neck, shoulder, and trunk muscles, improving head control.
Altering the baby’s environment can help encourage head rotation while they are in the crib. Caregivers should employ several strategies:
- Change the orientation of the crib or place mobiles and toys to encourage looking toward the non-flattened side.
- Limit the time the baby spends in “containers” like car seats, swings, and bouncers outside of necessary travel.
- These devices keep the head in a fixed position, increasing pressure on the skull.
- When holding or feeding, alternate sides and positions to vary contact and pressure points.
The Professional Assessment and Criteria for Helmet Use
If repositioning efforts do not lead to improvement, a professional assessment by a pediatrician, physical therapist, or craniofacial specialist is required. The specialist’s evaluation includes a physical examination to rule out craniosynostosis, where the skull plates fuse prematurely. The severity of the positional flattening is then quantified, often using specialized calipers or a cranial scanner to measure the head’s asymmetry and width-to-length ratio.
Cranial orthosis, or helmet therapy, is reserved for infants with moderate to severe deformities that have not responded to repositioning and physical therapy. For a helmet to be effective, it must be started during the period of rapid head growth, typically between four and six months of age, with the window closing after 10 months. The helmet is a custom-molded device designed to gently apply corrective pressure to prominent areas while allowing the flattened area space to round out as the brain grows. The helmet is worn for up to 23 hours a day for several months, requiring frequent adjustments to accommodate growth and ensure proper fit.