One of the side effects from chronic catheter use may be neurogenic bladder leading to the symptoms you described.
You may want to ensure that there are no further stimuli to the bladder causing spasms. The Oxybutynin is a good medication to reduce this, also checking the urine to evaluate for infection would be another consideration.
Also, if the bladder is continuously distended, it may lose the function to spontaneously empty. This can be done with intermittent catheterization. Only time will tell if completely spontaneous urination would return. In the meantime, intermittent catheterization to prevent chronic distension should be discussed.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
Medical Weblog:
kevinmd_b