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As blueh20 mentions carbon dioxide maintenance issues are very likely to play a major part in central sleep apnea.

I deal with these issues by:

Reducing stress (50%)
Monitoring and responding to changes in my CPAP treatment (30%)
Moving well (10%) Note: Expensive Pedometer and Personal Trainer used.
Eating well (10%) Note: Dietitian and cooking classes used.

If the carbon dioxide issues are not contained by the above I have been known to use EERS[1] under the watchful eye of my doctor.

[1] :
Gilmartin G, McGeehan B, Vigneault K, Daly RW, Manento M, Weiss JW, Thomas RJ.
Treatment of positive airway pressure treatment-associated respiratory instability with enhanced expiratory rebreathing space (EERS).
Source: J Clin Sleep Med. 2010 Dec 15;6(6):529-38. Division of Pulmonary, Critical Care and Sleep Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA.
Link: http://www.ncbi.nlm.nih.gov/pubmed/21206741

Central apnea, periodic breathing and complex apnea are all part of the spectrum of chemoreflex-mediated sleep apnea.
There are some centers (in the Boston area for exmple) who have far better expertise than others. Check it out, you can be helped.
Those with central apnea in any form and normal MRI likely are just born with enhanced chemosensitivity.
The most extreme form is called "idiopathic central sleep apnea" - the hypercapnic response is specifically elevated.