Incontinence can be caused by at least eight different urinary issues.  Sounds like a lot, huh?  I hadn't any idea about this until I investigated it myself.  With my multiple sclerosis I know that my brain sends messages that become faulty (due to damaged nerves) and my bladder sphincter sometimes doesn't open or more often it wants to open frequently, which causes issues of incontinence.

What follows is a basic rundown of the types of incontinence:

Urge Incontinence

This is the need to frequently urinate, with urgencies more than seven times a day or twice during the night.  This is most common in older adults.

Stress Incontinence

Weakened pelvic muscles, bladder walls, or urethral sphincter muscles, an enlarged prostate, and nerve damage can cause intolerable pressure on the bladder, causing urinary leakage. This condition is most common among women and it's often a result of pregnancy/childbirth.

Overflow Incontinence

This problem happens when a bladder cannot be completely emptied, thereby causing an overextended bladder that leads to frequent urination or leakage of urine.  This type of incontinence can be caused by urethral blockages (stones, tumors, an enlarged prostate) or weakened bladder muscles.

Functional Incontinence

Seniors (or sometimes younger people) experience this as a result of impairments in movement, thought, or communication.

Mixed Incontinence

This is a combination of two types of incontinence, usually urge and stress varieties.

Temporary Incontinence

Incontinence that comes and goes can be triggered by certain medical conditions or as a side-effect from medications or treatments.

Incontinence From Anatomical or Developmental Abnormalities

Physical abnormalities within the urinary system-- often congenital or developmental--- may cause incontinence.  Physical abnormalities may also rise during the lifecycle.  Damage to the nervous system through diseases (such as MS) or injury/trauma (spinal cord injuries) can result in loss of normal bladder functioning, or neurogenic bladder.

Bedwetting or Nocturnal Enuresis

Often a problem in children, bedwetting can be the result of an inherited delay in neurological control of the bladder.  After the age of five, it is considered an abnormality and it's usually treated with medication or a wakeup alarm device.

*For further reference: MayoClinic.org