Malformations in Cerebellar Development

00:01 So things that can go wrong during cerebellar development include the chiari malformation.

00:06 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.

00:14 So the cerebellum normally fits in that posterior cranial fossa very nicely but with too little space, it has to go somewhere.

00:21 And in type I and type II chiari malformation, the cerebellum partially herniates inferiorly through the foramen magnum.

00:30 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.

00:39 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.

00:54 So this is tied to some problems with regulating breathing and heartbeat.

00:59 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.

01:19 And again, that is syringomyelia.

01:21 Now, another problem involving the cerebellum is called Dandy-Walker Malformation.

01:26 And it´s a series of problems that basically boil down to there being too little cerebellum.

01:32 Agenesis of the cerebellar vermis, the midline region of the cerebellum can result in an expansion of the fourth ventricle.

01:40 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.

01:47 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.

01:57 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.

02:14 Malformations of the Midbrain-Hindbrain are very rare, but have been previously reported.

02:20 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.

02:33 Cognitive impairment and mental retardation are usual associated features.