Infancy

Examine the sutures and fontanelles carefully (see the figure on the next page). The bones of the skull are separated from one another by membranous tissue spaces called sutures. The areas where the major sutures intersect in the anterior and posterior portions of the skull are known as fontanelles.

On palpation, the sutures feel like ridges and the fontanelles like soft concavities. The anterior fontanelle at birth measures 4 cm to 6 cm in diameter and usually closes between 4 and 26 months of age (90% between 7-19 mos). The posterior fontanelle measures 1 cm to 2 cm at birth and usually closes by 2 months.

An enlarged posterior fontanelle may be present in congenital hypothyroidism.

A bulging, tense fontanelle is observed in infants with increased intracranial pressure, which may be due to central nervous system infections, neoplastic disease, or hydrocephalus (obstruction of the circulation of cerebrospinal fluid within the ventricles of the brain).

Anterior fontanelle

Anterior fontanelle

Careful examination of the fontanelle is important because the fullness of the fontanelle reflects intracranial pressure. It is best to palpate the fontanelle while the baby is sitting quietly or being held upright. Experienced pediatric health care providers often have the habit of palpating the fontanelles at the beginning of the examination. In normal infants, the anterior fontanelle is soft and flat. Increased intracranial pressure produces a bulging, full anterior fontanelle and is seen when a baby cries, vomits, or has underlying pathology. Pulsations of the fontanelle reflect the peripheral pulse.

A depressed anterior fontanelle may be a sign of dehydration.

Overlap of the cranial bones at the sutures at birth, called molding, results from passage of the head through the birth canal; it disappears within 2 days.

Inspect the scalp veins carefully to assess for dilatation.

Assess the symmetry of the skull. A number of conditions can cause asymmetry of the skull in newborns and infants; some are normal or benign, while others reflect underlying pathology.

Dilated scalp veins are indicative of long-standing increased intracranial pressure.

A newborn's scalp is often swollen from localized subcutaneous edema over Another type of localized swelling the occipitoparietal region, called caput succedaneum, caused by distension of the scalp is a cephalohematoma, of capillaries and extravasation of blood and fluid resulting from the vacuum due to subperiosteal hemorrhage effect of rupture of the amniotic sac. This swelling often crosses over suture lines and resolves in 1 to 2 days.

The premature infant's head at birth is relatively long in the occipitofrontal diameter and narrow in the bitemporal diameter (dolichocephaly). Usually the skull shape normalizes within 1 to 2 years.

Asymmetry of the cranial vault (plagiocephaly) occurs when an infant lies mostly on one side, resulting in a flattening of the parieto-occipital region on the dependent side and a prominence of the frontal region on the opposite side. It disappears as the baby becomes more active and spends less time in one position, and symmetry is almost always restored. Interestingly, the current trend to have newborns sleep on their backs to reduce the risk for sudden infant death syndrome has resulted in more cases of plagiocephaly.

Measure the head circumference (p. 658) to detect abnormally large head size (macrocephaly) or small head (microcephaly), which may be due to an underlying disorder affecting the brain.

Examine the skull. You can perform the following maneuvers with care:

■ On palpation of the infant's skull, you may note that the cranial bones appear "soft" or pliable; they will become firmer with increasing gestational age. An exception occurs in a condition known as craniotabes, which is found in some normal infants but also in some with diseases. In this condition, the cranial bones feel pliable and springy, much as a ping-pong ball springs back upon pressure.

■ Percuss the parietal bone on each side of the skull using your index or middle finger. This will produce a "cracked pot" sound (Macewen's sign) in normal infants prior to closure of the cranial sutures.

Auscultation of the skull is not useful in young children because a systolic or continuous bruit may be heard over the temporal areas in many normal children. Older children with significant anemia may have a cranial bruit.

Transillumination of the skull may be helpful in the evaluation of an infant with possible central nervous system disease. In a completely darkened room, place a bright flashlight fitted with a soft rubber collar flush against the skull at various points. In normal infants, a 2-cm halo of light is present around the circumference of the flashlight placed over the frontoparietal area, and a 1-cm halo when placed over the occipital area.

Check the face of infants for symmetry. In utero positioning may result in transient facial asymmetries. If the head is flexed on the sternum, a shortened chin (micrognathia) may result. Pressure of the shoulder on the jaw may create a temporary lateral displacement of the mandible.

from the trauma of birth. This swelling does not cross over suture lines and resolves within 3 weeks. As the hemorrhage resolves and calcifies, there may be a palpable bony rim with a soft center.

While plagiocephaly may be due to positioning, it may also reflect pathology such as torticollis from injury to the sternocleidomastoid muscle at birth, or lack of stimulation of the infant. Premature closure of one or more cranial sutures causes craniosynos-tosis, with an abnormally shaped skull. Sagittal suture synostosis causes a narrow head due to lack of growth of the parietal bones. Palpation may reveal a raised bony ridge at the suture line. Craniotabes can be due to increased intracranial pressure as in hydrocephaly, metabolic disturbances such as rickets, and infection (e.g., congenital syphilis).

Macewen's sign is noted in older infants with high intracranial pressure that causes closed cranial sutures to separate (e.g., due to lead encephalopathy, brain tumor, or hydrocephalus).

An arteriovenous fistula in the brain can produce a loud bruit.

If the entire head "lights up," hydranencephaly or reduced size of the cerebral cortex is suspected. Localized bright spots may be seen with subdural effusions and poren-cephalic cysts.

Micrognathia may also be part of a syndrome, such as the Pierre Robin syndrome.

Examine the face for an overall impression of the facies; it is helpful to compare to the face of the parents. There are diagnostic facies in childhood (Table 17-12, pp. 768-769, shows several) that reflect chromosomal abnormalities, endocrine defects, chronic illness, and other disorders. While it is often difficult to distinguish abnormal facies from normal variants, here are some "pearls."

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