Dolichocephaly is a term for a head shape that is longer and narrower than average, originating from the Greek words “dolichos” (long) and “kephalē” (head). The term is also used in veterinary science to classify certain animal breeds. It is purely descriptive of the skull’s dimensions and does not, on its own, imply a medical problem.
Identifying a Dolichocephalic Head Shape
The primary method for classifying head shape is the cephalic index (CI), a standardized measurement used in anthropology and medicine. This index is calculated by dividing the maximum width of the skull by its maximum length and then multiplying by 100. This ratio provides a quantitative way to describe the skull’s dimensions.
A head is categorized as dolichocephalic when the cephalic index is less than 76. This measurement places dolichocephaly at one end of a spectrum of head shapes. For comparison, an average shape is termed mesocephalic, while brachycephaly describes a head that is short and wide.
Observing a dolichocephalic shape involves noting a head that appears elongated from front to back, with a forehead that may seem more prominent. In some cases, the back of the head, or occiput, can also appear more pronounced. While visual assessment can suggest the shape, the cephalic index provides the definitive classification.
Common Causes in Human Infants
In infants, a dolichocephalic head shape is often a benign condition from positioning before or after birth. The infant skull is soft and malleable due to unfused bony plates, which allows it to be molded. This can occur in the womb from in-utero constraint, common in breech presentations or multiple-birth pregnancies.
After birth, the shape can be influenced by the infant’s sleeping position, known as positional molding. This can develop if a baby, particularly a premature infant, spends significant time lying on their side. This form of dolichocephaly often resolves on its own as the infant grows and becomes more mobile.
A less frequent but more serious cause is sagittal craniosynostosis. This involves the premature fusion of the sagittal suture, the fibrous joint on top of the skull. This early fusion prevents the skull from growing in width, forcing it to expand in length. Because the cause can range from harmless positioning to a condition requiring intervention, a healthcare provider should evaluate any concerns about an infant’s head shape.
Dolichocephalic Animal Breeds
In the animal kingdom, a dolichocephalic head shape is not a medical abnormality but a normal, genetic characteristic for certain breeds, particularly canines. This skull structure is common in sighthounds, breeds developed for hunting prey by sight. The long, narrow head shape is thought to contribute to their keen vision and aerodynamic profile.
Well-known examples of dolichocephalic dog breeds include the Greyhound, Whippet, Borzoi, and Collie. In these animals, the elongated skull is an inherited trait passed down through generations, not the result of external pressures as can occur in humans.