are rare in neonates. A bilateral lesion involving either cranial nerve
V or XII may produce obstructive apnea. Bilateral phrenic nerve injuries
produce central apnea. Bilateral phrenic nerve injury may occur with bilateral
brachial plexus injuries.
Myoneural junction disorders
are common in the neonatal period. Botulism and transient myasthenia gravis
are the most common neuromuscular disorders that affect the myoneural
junction in neonates. Botulism affects the presynaptic area preventing
the normal release of acetylcholine. Botulism produces signs of smooth
and striated muscle dysfunction. Smooth muscle dysfunction leads to constipation
and pupillary abnormalities. Striated muscle dysfunction leads to weakness
and hypotonia. Myasthenia gravis is a postsynaptic disease. It affects
the nicotinic receptors of the striated muscle. Myasthenia gravis presents
with weakness and hypotonia but no evidence of autonomic dysfunction.
Muscle disease may produce apnea.
Neonates with myotonic dystrophy often need prolonged respiratory support
in the neonatal period because of frequent apnea. Myotonic dystrophy is
diagnosed by shaking hands with the mother. A mother with myotonic dystrophy
has difficulty performing maneuvers that require muscle relaxation after
a muscle contraction such as releasing one’s hand after a handshake.
CAUSES OF APNEA
episodes of nonneurological cause are more frequent than apnea of neurologic
origin. Nonneurologic causes of apnea are gastroesophageal reflux, upper
airway abnormality, systemic illness, and pulmonary disease.