Anemia of Prematurity - Portal Neonatal

cases, the spinal cord is attached to the superior aspect of the sac. The myelomeningocele has many
other associated CNS anomalies that require attention.
Table 2. Anomalies of the CNS Associated with Myelomeningocele
Anomalies Associated with
Myelomeningocele
Approximate Percent of Patients
Chiari II malformation 90%+
Hydrocephalus 90%+
Syringomyelia 88%
Brainstem malformations (cranial nerve) 75%
Cerebral ventricle abnormalities 90%+
Cerebellar heterotopias 40%
Cerebral heterotopias 40%
Agenesis of the corpus callosum 12%
Polymicrogyria 15-30%
Chiari II malformation
Symptomatic Chiari II malformation can occur anytime after birth. The symptomatic Chiari II
presentation can be as subtle as new hoarseness and pneumonia or as obvious as a progressive
quadriparesis. A brain and cervical cord MRI in patients with myelomeningocele invariably
demonstrates a Chiari II malformation with a herniated vermis and syringomyelia. Very few patients
require decompression after their first year of life for a symptomatic Chiari II malformation. The
surgeon must first and foremost check to see if the shunt apparatus is functioning. Most of the time, a
partial or complete obstruction of a VP shunt (based on a shunt tap or surgical exploration) is the
etiology of the new brainstem findings. A shunt malfunction causes the hindbrain to herniate and
compress the cord, thus causing many of the new findings. Timely repair of the shunt leads to a good
outcome with reversal of most deficits.
Hindbrain anomalies
Pathophysiology of Chiari malformations (CMs) has fascinated neurosurgeons and provided a
constant stream of literature on the presentation and presumed etiology for the past century. Although
originally thought to be a rare neuroembryological disorder associated with NTD, CMs have been
recognized with increased frequency in the past 5 decades. The number of patients seen for this
disorder has increased since the widespread application of MRI. Another increase in patient referrals
has occurred more recently as with improved understanding of the rather wide spectrum of clinical
presentation.
In 1883, John Cleland published “Contribution to the study of spina bifida, encephalocele and
anencephalus” in the Journal of Anatomy and Physiology. Cleland made several novel observations
regarding hindbrain malformations on infant autopsy specimens. He described an elongated
brainstem and cerebellar vermis, which protruded into the cervical canal in a full-term infant with
spinal bifida and craniolacunae. Eight years later, Hans Chiari, professor of morbid anatomy at
Charles University in Prague, published similar observations on congenital anomalies in the
cerebellum and brain stem and commented on the a priori contributions of Cleland. Chiari further