Pediatric emergency medicine trisk 4011 4011

could be the result of severe papilledema or the because of the underlying
cause of hydrocephalus, for example, a large suprasellar tumor causing
obstructive hydrocephalus and compressing the optic chiasm. Double vision
might be described, usually from a unilateral or bilateral abducens nerve
palsy, a classic false-localizing sign in raised ICP. Focal neurologic deficits
attributable to the underlying cause of the hydrocephalus, such as ataxia
from a posterior fossa tumor or bitemporal hemianopia from a suprasellar
tumor, may also be present.
Clinical Pitfall. Benign macrocephaly is the most common diagnosis for
an increasing head circumference. The typical infant, more commonly
male, will be one whose head circumference has risen to or above the 98th
percentile; but without a bulging fontanelle nor overt clinical signs of
increased ICP. Brain imaging (by ultrasound, CT, or MRI) will show
enlarged subarachnoid spaces over both frontal lobes. This has sometimes
been termed “extraventricular obstructive hydrocephalus,” although it is not
truly hydrocephalus.
Diagnostic Imaging. Hydrocephalus is ultimately diagnosed with cranial
imaging. A CT scan provides very good detail to make the diagnosis, is
readily available, and can be done very quickly. It does, however, expose
the child to radiation. Axial CT imaging will show enlarged ventricles. The
pattern of enlarged ventricles, both lateral ventricles and third ventricle (or
“triventricular”) or all four ventricles, will vary depending on the etiology
of the hydrocephalus ( Fig. 122.4 ). MRI provides greater anatomical detail
of the brain and ventricles, but it can be less readily available and may
require use of a general anesthetic. Depending on the results of a CT, an
MRI may be necessary, particularly if a tumor is suspected or if CT is
unable to clearly elucidate the etiology. A fast-spin, limited sequence MRI
may also be considered to evaluate ventricular anatomy with radiation
exposure or need for sedation. Ultrasound may be the most appropriate
imaging modality for infants with suspected benign macrocephaly and a
patent anterior fontanelle. This may confirm diagnosis and no further

imaging may be necessary.
Management. When assessing a child with hydrocephalus, the acuity of
the situation needs to be thoroughly assessed. If the child is in extremis, for
example, an obtunded child or a lethargic infant with bradycardia, the
situation is emergent. After ensuring the basics of airway and