Overriding Metopic Suture

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Examination of the head involves a thorough assessment of its shape, symmetry, and fontanelles. The skull may be molded, especially if the labor was prolonged and the head was engaged for a long period. The skull of a child born by cesarean section has a characteristic roundness.

Figure 24-17 Sacral hypertrichosis.

Overriding Sutures

In the newborn, the sutures are frequently felt as ridges as a result of the overriding of the cranial bones by molding as the skull passes through the vaginal canal. Palpate the fontanelles, or ''soft spots.'' The anterior fontanelle is located at the junction of the sagittal and coronal sutures, is usually 1.5 to 2.5 inches (4 to 6 cm) in diameter, and appears diamond-shaped. The triangular posterior fontanelle is located at the junction of the sagittal and lambdoid sutures and measures 0.4 to 0.8 inch (1 to 2 cm) in diameter. Normally, the fontanelles are flat. A bulging fontanelle may be indicative of increased intracranial pressure;a depressed fontanelle may be seen in dehydration. Normally during crying, the fontanelles bulge. Pulsations of the fontanelles reflect the pulse. The anterior fontanelle normally closes by 18 months of age, but there is a wide range of normality; the posterior fontanelle should be closed by 2 months of age and may already be closed in the neonatal period. The locations of the fontanelles are shown in Figure 24-18.

Caput succedaneum is edema of the soft tissues over the vertex of the skull that is related to the birth process during a vertex delivery. The normal movement of the fetal head through the birth canal produces a marked molding of the very soft fetal skull and scalp edema. This swelling, which is present at delivery, crosses the sutures and resolves in the first few days. In a face presentation, there can be diffuse swelling, discoloration, and swelling of the new-born's face.

Caput succedaneum should be differentiated from a cephalohematoma, which is a subperi-osteal hemorrhage limited to one cranial bone, often the parietal. There is no discoloration of the overlying scalp, and the swelling does not cross the suture line. The swelling is usually not visible until several hours or days after birth, inasmuch as subperiosteal bleeding is generally a slow process. About 15% of cephalohematomas are bilateral, and each is palpably distinct from the other side. No treatment is required for cephalohematomas, which are generally resorbed by 2 to 12 weeks, depending on the size. Figure 24-19 shows a newborn with a caput

Cephalohematoma And Craniosynostosis

— Coronal suture

Sagittal suture

Lambdoid suture

Anterior fontanelle

— Coronal suture

Figure 24-18 Location of the fontanelles.

Sagittal suture

Figure 24-18 Location of the fontanelles.

Posterior fontanelle

Lambdoid suture

Skull Anatomy Overriding Sutures

succedaneum; Figure 24-20 shows a child with a cephalohematoma. Note in Figure 24-20 that the swelling stops in the midline at the sagittal suture; this is characteristic of a cephalohema-toma, and the extravasated blood may contribute to jaundice.

A few days after delivery, the head shape should return to normal. An unusual head shape may be due to craniosynostosis, premature closure of the sutures of the skull, or may represent a deformational process, caused by unusual forces acting on the otherwise normal skull. The latter condition, termed plagiocephaly, may become worse during the first few months of life because the infant will prefer to rest his or her head on one side. This position of comfort dictates which side of the occiput is more prominent. After 6 months, when the infant is able to sit unassisted, the plagiocephaly caused by intrauterine deformation gradually resolves.

Craniosynostosis is a malformation caused by sutural closure at an unusually early age. Closure of the coronal sutures leads to brachycephaly, in which the head is short in the antero-posterior diameter and wider laterally. This is the opposite of the head shape that results from premature closure of the sagittal suture, a head that is long in the anteroposterior diameter and narrow laterally (a skull shape known as dolichocephalic). Premature closure of one lambdoid suture leads to posterior plagiocephaly that does not resolve on its own.

Newborn Overriding SuturesOverriding Sagittal Suture

Inspect the skull for symmetry.

Inspect the scalp for lesions from fetal scalp electrodes, used for monitoring fetal well-being during difficult labors, and for areas of alopecia. A 0.4- to 0.8-inch (1- to 2-cm) well-demarcated area of smooth shiny skin with no hair may represent aplasia cutis congenita, an abnormality of fetal development of unknown cause. Usually an isolated finding in an otherwise well newborn, aplasia cutis also occurs commonly in trisomy 13.

Inspect the face for symmetry. The eye creases should be equal. Observe the infant as he or she sucks or cries. The mouth should remain on a level plane. If it is asymmetric, suspect a facial paralysis or a congenital anomaly of one or more facial muscles, a condition known as asymmetric crying facies syndrome. Figure 24-21 shows a 2-day-old neonate born by forceps extraction with a traumatic peripheral facial nerve palsy.* Notice the involvement of the entire left side of the face with failure of the left eye to close and the drooping of the corner of the left side of the mouth. Failure of eye closure on the affected side is usually the first noticeable sign of a peripheral facial palsy. During labor and delivery, the peripheral portion of the facial nerve may be compressed over the stylomastoid foramen through which the nerve emerges, or where the nerve traverses the ramus of the mandible.

The face may reveal abnormal features such as epicanthal folds, widely spaced eyes, or low-set ears, each of which may be associated with congenital defects.

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  • primrose
    How to mold and reconstruct a born baby's head?
    2 years ago
  • Guendalina
    When should overriding sutures resolve by?
    4 months ago

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