So things that can go wrong during cerebellar development include the chiari malformation.
Now, chiari malformation has a variety of subtypes but the main thing to remember
is that there´s too little space in the posterior cranial fossa.
So the cerebellum normally fits in that posterior cranial fossa very nicely
but with too little space, it has to go somewhere.
And in type I and type II chiari malformation,
the cerebellum partially herniates inferiorly through the foramen magnum.
In particular, the cerebellum tonsils tend to extend down the foramen magnum
and they put pressure on the medulla that´s located anterior to it.
Now, that pressure on the medulla can result in difficulty
with organizing your respiratory and heart activity
because your parasympathetic cardiorespiratory nucleus is located just in that area.
So this is tied to some problems with regulating breathing and heartbeat.
In addition, having that pressure can back up the flow of cerebral spinal fluid
causing hydrocephaly or even syringomyelia
which is going to be a cyst that develops in the central canal of the spinal cord
as fluid is unable to exit the central canal,
it builds up and creates a cyst in the upper cervical region.
And again, that is syringomyelia.
Now, another problem involving the cerebellum
is called Dandy-Walker Malformation.
And it´s a series of problems
that basically boil down to there being too little cerebellum.
Agenesis of the cerebellar vermis, the midline region of the cerebellum
can result in an expansion of the fourth ventricle.
If there´s no cerebellum there,
then, the space that it used to occupy will now be filled
with cerebrospinal fluid of the fourth ventricle.
And as that fluid builds up, it´s gonna cause a ballooning of the dura mater
that´s just superior to where the cerebellum´s going to be located.
So altogether, that´s known as Dandy-Walker Malformation
and this can result in post-natal hydrocephaly
and has a variety of other problems that need to be diagnosed radiologically
and this is a fairly good example
of what that´s going to look like in sagittal cross section.
Malformations of the Midbrain-Hindbrain are very rare,
but have been previously reported.
Patients present with abnormal eye movements -
due to the involvement of the oculomotor nuclei -, cranial nerve deficits -
such as dysphagia, trigeminal anesthesia or hearing loss.
Cognitive impairment and mental retardation are usual associated features.