A flat spot on the back of the head in an adult is a variation in skull shape that originates almost exclusively in infancy. This condition is described as either plagiocephaly or brachycephaly. Plagiocephaly refers to an asymmetrical distortion, resulting in flattening on one side of the back of the head, often making the head appear like a parallelogram from above. Brachycephaly describes a symmetrical flattening across the entire back of the skull, which can cause the head to look wider than typical. This adult head shape is a permanent result of the skull’s malleability during the first months of life.
How Skull Flatness Develops During Infancy
The shape of the adult skull is determined by what happened when the head was still soft and adaptable. An infant’s skull is not a single, solid bone but is composed of several bony plates connected by flexible, fibrous joints called sutures. These open sutures, along with the soft spots known as fontanelles, allow the skull to change shape during birth and accommodate the rapid growth of the brain.
The most common cause of a flat spot is positional head flattening. This occurs when continuous external pressure is applied to the same area of the soft skull over time. The “Back to Sleep” campaign, which recommends placing infants on their backs to reduce the risk of Sudden Infant Death Syndrome (SIDS), has inadvertently led to an increased incidence of this condition.
Spending extended periods in a supine position, whether for sleep or in carriers, car seats, or swings, places pressure on the occipital bone at the back of the head. If the pressure is consistently on one side, it leads to asymmetrical flattening. If the infant consistently rests on the center of the back of the head, it results in symmetrical flattening. This reshaping is a mechanical process, not a problem with the brain’s development, and the head shape becomes fixed as the infant grows.
Health and Neurological Concerns in Adults
For adults with a flattened head shape that resulted from positional forces in infancy, there is no associated cognitive impairment or neurological risk. The underlying brain structure develops normally, as the flattening is an external molding of the bone, not a restriction of brain growth. The cranial sutures typically begin to fuse and harden by the age of six months, with the process largely complete by two years of age, permanently setting the skull’s shape.
If the flatness was caused by common positional factors, the adult is not at any increased risk for headaches, neurological disorders, or cognitive issues. The adult skull is rigid and fully fused, protecting the mature brain. The primary distinction is with craniosynostosis, where one or more sutures prematurely fuse before or soon after birth. This premature fusion restricts the natural expansion of the skull, impacting brain growth and development, but this pathological condition is distinct from positional flatness and is usually treated in infancy.
Some adults with asymmetry from childhood plagiocephaly may experience secondary physical concerns. These can include subtle facial asymmetry, ear misalignment, or chronic neck pain due to muscle imbalances that developed to compensate for the head shape. However, these are related to musculoskeletal or aesthetic issues, not neurological function. An adult who has a flattened head associated with new symptoms, such as severe headaches, vision changes, or balance issues, should seek medical consultation.
The Permanence of Adult Skull Shape and Aesthetic Options
The adult skull is a rigid structure with fused sutures, meaning the shape achieved by the end of early childhood is permanent. This rigidity explains why treatments effective for infants, such as helmet therapy or repositioning techniques, are ineffective for an adult. The skull plates cannot be molded or reshaped by external pressure once the bones have matured.
Management in adulthood focuses primarily on aesthetic concerns. Hairstyle choices are often used, as longer hair can effectively conceal the flatness or asymmetry at the back of the head. This is relevant for men, since shorter hairstyles highlight the contour of the occipital bone.
For individuals seeking a physical alteration, options are limited to surgical procedures performed by craniofacial or plastic surgeons. These aesthetic skull reshaping procedures typically involve either augmentation or contouring. These surgeries carry risks associated with any major operation and are usually reserved for severe cases where the head shape causes significant psychological distress or functional impairment.
Augmentation
Augmentation involves the placement of custom-designed implants, made from materials such as polymethyl methacrylate (MMA) or PEEK, to build up the flattened area and create a more rounded contour.
Contouring
Contouring involves burring or reducing prominent areas of bone.