Hyperventilation Syndrome is not an uncommon disorder. The mechanisms that lead to the hyperventilation itself are not clear, though emotional distress/anxiety are amongst some of the provoking factors postulated. The hyperventilation leads to a decrease in carbon dioxide levels in the blood; with respect to neurological symptoms, a drop in blood carbon dioxide leads to a corresponding decrease in blood flow to the brain, which can in turn provoke events such as seizures.
I think it would be prudent for your wife to check with a primary physician with regards to her symptoms. It would be worthwhile identifying and addressing any stressors in her life at this time; furthermore there is technique of diaphragmatic breathing which the doctor (or someone he/she can refer you to) should be able to teach you - this can often be helpful. This combination of stress reduction and retraining from breathing have been found to be effective in addressing this condition.