Pediatric emergency medicine trisk 626

TABLE 96.2
EXAMPLES OF PRIMARY AND SECONDARY MICROCEPHALY
Primary microcephaly
Genetic

Environmental

Secondary microcephaly

Isolated
Autosomal recessive
Autosomal dominant
X-linked
Syndromic, e.g.,
Aicardi syndrome
Cornelia de Lange
Chromosomal
Trisomies
Microdeletions
Structural anomalies,
e.g.,
Holoprosencephaly
Anencephaly

Intrauterine
Infections
TORCH

Hemorrhage/Thrombosis

Teratogens

Drugs
Irradiation
Vascular accidents
Placental infarctions

Hypoxia–ischemia

Maternal disease
Malnutrition
Phenylketonuria

Inborn errors of
metabolism
Phenylketonuria
Galactosemia
Environmental
Irradiation
Heavy metal poisoning

Inborn errors of
metabolism

Infections

From Von der Hagen M, Pivarcsi M, Liebe J, et al. Diagnostic approach to microcephaly in childhood: a twocenter study and review of the literature. Dev Med Child Neurol 2014;56(8):732–741. Copyright © 2014
Mac Keith Press. Reprinted by permission of John Wiley & Sons, Inc.

Abnormalities of Head Shape
Craniosynostosis
Craniosynostosis occurs because of premature closure of one or more of the

cranial sutures, resulting in an abnormality in the shape of the head perpendicular
to the closed suture. It is occasionally accompanied by facial dysmorphism. In
cases where multiple sutures are involved, infants may develop increased
intracranial pressure and neurocognitive impairment. The incidence of
craniosynostosis is approximately 1 per 2,000 live births; sagittal synostosis being
the most common (40% to 55%). Primary craniosynostosis occurs when there is


primary closure of a suture and may be nonsyndromic (isolated) or syndromic
(with associated anomalies as in Apert, Crouzon, and Pfeiffer syndromes).
Secondary craniosynostosis is caused by a systemic disorder (e.g., thalassemia).
Pathogenesis is thought to be multifactorial but fundamentally related to
premature signaling of the dura to the sutures to close prematurely before
completion of brain growth. Fibroblastic growth factor receptor (FGFR1 and 2)
mutations have been implicated in both the nonsyndromic and syndromic types.
Diagnosis of craniosynostosis is made on clinical appearance of the shape ( Fig.
96.22 ). Palpation reveals a ridge along the closed suture and compensatory
bossing, or deformity on the contralateral side. In brachycephaly syndromes, the
orbit is shallow with proptosis of the eyes, and there is a characteristic “parrot
beak” nose (short, stubby, and upturned). Physical examination may reveal
polysyndactyly (Apert syndrome) or broad toes and thumbs (Pfeiffer syndrome).
Skull radiographs and CT scan are needed to delineate single versus multiple
suture involvement. Corrective surgery should ideally occur before 6 months of
age. Surgery allows remodeling of the skull, relieves cranial pressure, and
improves cosmetic outcome. Prognosis depends on the type of craniosynostosis,
the timing of the surgery, and the number of sutures or facial bones involved. All
syndromic craniosynostosis usually involve the coronal sutures. Corrective
surgeries are directed at expansion of the anterior and posterior cranial vaults and
are more complex, requiring a dedicated multidisciplinary craniofacial team.
Deformational Plagiocephaly

Deformational plagiocephaly applies to asymmetry of the cranium caused by
flattening of one side of the occiput. Incidence has increased since 1992, after
institution of the “back to sleep” campaign. Constant mechanical pressure applied
to one side of the head (preferential turning or sleeping on the same side) results
in flattening of that side so that the head assumes a parallelogram shape
(flattening of the occiput with bossing of the ipsilateral frontal pole). Contributing
mechanical forces include in utero forces (bicornuate uterus or twin pregnancy),
or postnatal conditions, such as preferential head turning torticollis or vertebral
anomalies. At birth, infants have round heads but will develop this shape after a
few months. The ipsilateral ear is displaced anteriorly but both ears are in the
same horizontal plane. Deformational plagiocephaly should be differentiated
from lambdoid suture synostosis, which occurs at birth, with frontal bossing on
the contralateral side and posterior and downward displacement of the ears. Skull
radiography is usually not necessary if the baby has a typical history and physical
examination. Treatment is nonsurgical. Parents are encouraged to alternate head


position of the infant and allow infants 30 minutes of tummy time while awake to
prevent the occurrence of deformational plagiocephaly. Neck exercises to
encourage range of motion have also been found to be helpful in combination
with positioning. Alternately, infants with severe deformational plagiocephaly
may benefit from helmets, or head bands worn during the day. Corrective surgery
is rarely needed for those who do not respond to nonsurgical measures. Prognosis
is good and the shape improves after infants gain head control and begin to sit.


FIGURE 96.22 Morphologic types of craniosynostosis. Diagrammatic views of different
morphologic types of craniosynostosis are shown in the center of the figure. The premature
closed suture is marked as a bold line . The sutures involved determine the shape of the skull.
The diagrammatic view of each synostosis type is matched with the corresponding radiologic

findings. The fused suture is seen as a hypertrophic keel or ridge on the x-rays. (Reprinted with
permission from Paul Mongan P, Soriano III SG, Sloan TB, et al. Practical Approach to
Neuroanesthesia . Philadelphia, PA: Lippincott Williams & Wilkins; 2013.)