|Classification and external resources|
Velopharyngeal inadequacy (VPI) is a malfunction of a velopharyngeal mechanism.
The velopharyngeal mechanism is responsible for directing the transmission of sound energy and air pressure in both the oral cavity and the nasal cavity. When this mechanism is impaired in some way, the valve does not fully close, and a condition known as 'velopharyngeal inadequacy' can develop. VPI can either be congenital or acquired later in life.
Different terms can be used to describe this phenomenon in addition to “velopharyngeal inadequacy”. These terms and definitions are as follows:
- Velopharyngeal insufficiency: The inability of the velopharyngeal sphincter to sufficiently separate the nasal cavity from the oral cavity during speech.
- Velopharyngeal incompetency: When the soft palate and the lateral/posterior pharyngeal walls fail to separate the oral cavity from the nasal cavity during speech.
Although the definitions are similar, the etiologies correlated with each term differ slightly; however, in the field of medical professionals these terms are typically used interchangeably. Velopharyngeal inadequacy is the generic term most often used to describe the functionality of the velopharyngeal valve.
Relationship to cleft palate 
A cleft palate is one of the most common causes of VPI. Cleft palate is an anatomical abnormality that occurs in utero and is present at birth. This malformation can affect the lip, the lip and palate, or the palate only. A cleft palate can affect the mobility of the velopharyngeal valve, thereby resulting in VPI.
The most frequent types of cleft palates are overt, submucous, and occult submucous.
While cleft is the most common cause of VPI, other significant etiologies exist. These other causes are outlined in the chart below:
A common method to treat Velopharyngeal insufficiency is pharyngeal flap surgery, where tissue from the back of the mouth is used to close part of the gap. Other ways of treating velopharyngeal insufficiency is by placing a posterior nasopharyngeal wall implant (commonly cartilage or collagen) or type of soft palate lengthening procedure (i.e. VY palatoplasty).
- Conley SF, Gosain AK, Marks SM, Larson DL (1997). "Identification and assessment of velopharyngeal inadequacy". Am J Otolaryngol 18 (1): 38–46. doi:10.1016/S0196-0709(97)90047-8. PMID 9006676.
- Johns DF, Rohrich RJ, Awada M (2003). "Velopharyngeal incompetence: a guide for clinical evaluation". Plast. Reconstr. Surg. 112 (7): 1890–7; quiz 1898,1982. doi:10.1097/01.PRS.0000091245.32905.D5. PMID 14663236.
- McWilliams, Betty Jane; Peterson-Falzone, Sally J.; Hardin-Jones, Mary A.; Karnell, Michael P. (2001). Cleft palate speech. St. Louis: Mosby. ISBN 0-8151-3153-4.
- Hardin-Jones, Mary A.; Peterson-Falzone, Sally J.; Judith Trost-Cardamone; Karnell, Michael P. (2005). The Clinician's Guide to Treating Cleft Palate Speech. St. Louis: Mosby-Year Book. ISBN 0-323-02526-9.
- Willging JP (1999). "Velopharyngeal insufficiency". Int. J. Pediatr. Otorhinolaryngol. 49 Suppl 1: S307–9. doi:10.1016/S0165-5876(99)00182-2. PMID 10577827.