A new entity: Chiari Zero malformation and its surgical method.

Recently, Iskandar et al described "Chiari Zero malformation" to characterize some kind of syringomyelia that exhibits classic Chiari-type symptoms with little to no herniation, but there is some dilemma about whether it is actually present. We presented a 38-year-old-man with a diagnosis of cervical syringomyelia. In his neurological examination, there was monoparesia at the left leg together with hypoesthesia below thoracal 7. He had initially been treated with syringopleural shunting successfully. Nine months after surgery, his syringomyelia had regrown and he clinically deteriorated. It was accepted as "a Chiari zero malformation". We performed craniovertebral decompression only. Although there was no tonsillar herniation, his syringomyelia was completely resolved and his neurological status was improved six months after the craniovertebral decompression, This case suggested that "Chiari zero malformation" description is remarkable and craniovertebral decompression is a suitable surgical approach for this entity.