Cranial

cranial nerves nerves that are attached to the brain and pass through the openings of the skull; see anatomic Table of Nerves in the Appendices. There are 12 pairs of cranial nerves, symmetrically arranged so that they are distributed mainly to the structures of the head and neck. The one exception is the vagus nerve, which extends down to serve structures in the chest and abdomen. Some of the cranial nerves are both sensory and motor (controlling motion as well as conducting sensory impulses), while others are either only sensory or only motor.

A. your question troubled me... from what i know of bone development - what you say can very much happen but i never heard of a case like that.and i looked a bit about maybe some information about it, but i'm pretty sure that the name you gave is not the disease that she has, it's just a description. Cranial means skull, Trans means cross over and Annular means ring. but if you'll find the right name, or if it is really the real name, here is a bit of places you might find information-

http://www.merck.com/mmhe/sec05.html

http://www.nlm.nih.gov/medlineplus/bonediseases.html

A. An arachnoid cyst that leads to symptoms usually needs treatment. Mild symptoms as you suggested are ok to left untreated however gradual onset of new symptoms may arise such as seizures, paralysis and other complications, therefore once symptoms occur one should consider treatment.