Colpocephaly refers to an abnormal appearance of the brain in which there is asymmetric dilatation of its lateral ventricle occipital horns, but with normal caliber frontal horns.[1] It is typically associated with microcephaly and developmental delay. Specific symptoms include decreased IQ, visual impairment, locomotor abnormalities, muscle spasms, and seizures.
Colpocephaly is a nonspecific finding and can be associated with multiple neurologic syndromes, including agenesis of the corpus callosum and Chiari malformation. It is thought to be related to an intrauterine disturbance that occurs between the second and sixth months of pregnancy. The finding may be indirectly suggested on ultrasound by the so called lemon sign, which occurs due to depression of the calvarium at the bilateral frontal suture lines, giving the calvarium the appearance of a lemon.[2][3]
Specific treatment depends on associated symptoms and the degree of dysfunction. Anticonvulsant medications can be given to prevent seizure complications, and physical therapy is used to prevent contractures (shrinkage or shortening of muscles) in patients that have limited mobility. The prognosis for individuals with colpocephaly depends on the severity of the associated conditions and the degree of abnormal brain development. Some children may benefit from special education.
The lemon sign refers to the shape of the fetal skull at ultrasonography (US) when the frontal bones lose their normal convex contour and appear flattened or inwardly scalloped. This gives the skull a shape similar to that of a lemon (Figs 1, 2). The sign is seen on transverse sonograms of the fetal cranium obtained at the level of the ventricles