And so, this case in this
patient really brings up
an important discussion of the
differential for evaluation of
hypotonia in infancy or
evaluation of a floppy baby.
And we can see conditions
throughout the nervous system
that can present with hypotonia.
Central nervous system disorders
can cause neonatal hypotonia,
chromosomal disorders, metabolic
diseases, spinal cord injuries,
cerebral dysgenesis, abnormalities in the
formation of various cerebral structures
and even hypoxic-ischemic injuries in
the perinatal and postnatal period.
Typically, these also present
with other prominent findings
that would point us in the direction
of a central nervous system disorder.
we usually think of hyperreflexia
as reflecting central
nervous system disorders
and that is often not
present in the neonate.
And so central nervous system
conditions should be included
in the differential diagnosis
of hypotonia in infancy
or a floppy baby, a weak floppy,
reduced tone in a neonate.
Also, motor neuron disorders
and spinal muscle atrophy
is an important condition
as a motor neuron condition
that presents with
congenital floppy baby,
a hypotonic infant.
And there are a number of different
types of spinal muscle atrophies
that we'll be focused on
in a subsequent lecture.
Nerve conditions really
can present with hypotonia congenital
and infantile neuroaxonal degeneration,
which are very rare conditions.
Things you may just need to have
heard of but not understand precisely.
disorders can cause weakness.
Again, the neuromuscular junction is
critical for movement and motor function
and abnormalities in the
neuromuscular junction in the neonate
can present with
And that would be
congenital myasthenia gravis
from a channelopathy or
transient neonatal myasthenia.
From a mother that has myasthenia and those
antibodies are able to cross the placenta
and remain in the neonate during
that initial several days or weeks
and then gradually improve.
And then infant botulism, again,
very rare but important to consider.
And the last group of conditions
that should be considered
on the differential for a neonate,
or an infant with hypotonia
are muscle conditions,
problems with the muscle.
And there are two that
we're going to focus on
in this lecture that
are very important.
And that's congenital muscular
dystrophies and congenital myopathies.
And we're going to walk through
the differences between those two.
In both we have a muscle disorder,
so it's a muscular dystrophy,
a problem with a muscle or a
congenital myopathy, a muscle problem.
The muscular dystrophies are degenerative,
that's what's going on in the muscle.
And so we see degenerative findings,
and those conditions progress over time
that differs from
Myopathies are a problem
where the muscle doesn't die,
doesn't work right and patients are weak.
But there's not that progressive course
that we see with muscular dystrophies.
And so those are two very important
conditions that we need to consider
on the differential
for a floppy baby,
as well as metabolic
myopathies and then there are
some other congenital myopathies
that could be included.