Not only is Chiari Malformation a complicated condition there are also different types of Chiari. At present doctors have found four types of chiari, they are ratied in terms of severity, with 1 being the least severe.  The types of Chiari are:-

 

Chiari I Malforamtion - this is when the base of the skull and upper spinal area are not formed properly.  It commonly goes undetected until the patient is is adolescent or adult years.

Chiari II Malformation - this is the most common type of chiari, it is when the brain shift downwards through the skull area.  This type of chiari can be linked to spina bifida and hydrocephalus.  The full term Arnold Chiari Malformation may be reserved for this type of chiari, although some doctors may use this full term for all four types of chiari.

Chiari III Malformation  - is when the back of the brain protrudes out of an opening in the skull area.

Chiari IV Malformation - this type of chiari is the most severe with lower chances of survival for the patient.  It is when the brain fails to develop properly.