Velopharyngeal dysfunction (VPD) is a general term. It is used to describe different disorders of the velopharyngeal valve. These include:
- Velopharyngeal insufficiency (VPI), which is due to abnormal structure
- Velopharyngeal incompetence (VPI), which is due to abnormal movement
- Velopharyngeal mislearning, which is due to abnormal speech sound production
Figure 4 shows velopharyngeal insufficiency (VPI), which is usually caused by an abnormality of soft palate. Velopharyngeal insufficiency is common in children with cleft palate or a submucous (under the skin) cleft. Signs of a submucous cleft are often hard to see when looking in the mouth. Sometimes a submucous cleft can only be seen by putting a scope in the nose to see the top of the soft palate.
Velopharyngeal insufficiency can also occur after adenoidectomy. This is because the adenoids are in the area where the velopharyngeal valve closes. For some children, adenoids help the valve close.
Figure 5 shows the position of the adenoid pad in the throat.
Figure 6 shows velopharyngeal incompetence (VPI), which is caused by poor movement of the velopharyngeal structures. This is due to a disorder or injury of the brain or cranial nerves. Cerebral palsy and traumatic brain injury are examples of disorders that cause velopharyngeal incompetence.
Velopharyngeal mislearning is when the child makes sounds in the pharynx, rather than in the mouth. Because of this placement, the velopharyngeal valve is open and the air and sound go through the nose, just like when there is VPI.