Vertebral artery ending in PICA

My 17 yr old has been suffering with vision loss  and near fainting for the last 5 yrs.  During the last year, neurological symptoms have been added along with several autonomic symtoms (symptoms) (Orthostatic Hypotension, Gastro, BP fluctutations, Temp fluctuations, absence seizures, etc)  

She has been finally diagnosed with Dysautonomia.  Other incidental findings: trivial Mitral Vavle &  trivial triscupid valve regurgitation; trivial pulmonic valve insufficency; spina biffida occulta; left vertebral artery does not connect to basilar artery, it ends in PICA.

Question:  How common is it for the vertebral artery to NOT connect to the basilar artery, but instead end in PICA?  Does this in any way compromise the vascular system?  Would this be considered a congenital anomaly?  Is there any chance these things have any connection?

I have researched extensively and can find only incidental mentions of "Vertebral artery not connecting to basilar artery but instead ending in PICA" stating that it is quite rare.   But I cannot find any discussion on this that goes beyond that statement.  

Can anyone shed any more light on this anomaly?

[kkrylee]

I forgot to mention another incidental finding.  It seems that she very likely has Ehlers Danlos.