Velopharyngeal incompetence (VPI)
Velopharyngeal incompetence, or VPI, is the inability of the velum (soft palate) and related musculature to close the nasopharynx, separating the oral and nasal cavities for the production of oral consonants. A VPI can be caused by a deficiency of the velum or an increased size of the pharynx. The latter is difficult to diagnose without imaging.
A VPI usually has a physiological origin and requires physical management, such as surgery or prosthesis. A VPI might also be a sound substitution. It is now more correctly referred to as a "nasal snort.” The hallmarks are nasal air escape only on specific sounds, usually the sibilant sounds (s, z); normal resonance; and no nasal air escape on other consonant (plosive) sounds. Oral air flow for "s" can usually be taught easily. Since this is a sound substitution, it requires speech therapy. Surgery is unwarranted.
A VPI might also be considered when the nasopharynx is obstructed and cannot open adequately for breathing and producing the three nasal consonants (resulting in hyponasality). The cause may be hypertrophied adenoids, aggressive pharyngoplasty or narrowed nasopharynx from other causes. This is difficult to diagnose without imaging.
Possible symptoms of VPI
Symptoms can vary and include:
- Nasal air escape
- Reduced oral pressure for consonants
- Compensatory articulation including glottal stops, pharyngeal fricatives and nasal snorts (more correctly labeled posterior nasal fricatives)
Velopharyngeal function is the functional relationship between the velopharyngeal musculature and the pharyngeal space. Both should be evaluated.
Possible causes of VPI
The primary causes of hypernasality are structural deficits, neurological disorders and faulty learning.
Structural deficits include:
Neurological causes, or dysarthrias, include: