Commonly referred to as hypernasality, velopharyngeal insufficiency or VPI is a resonance disorder (how the cavities of the mouth and nose affect the way speech sounds) that results from too much air moving through the nose during speech. This is caused by insufficient structure or function of the soft palate.
When we speak, air normally passes through the mouth and nose. The back part of the roof of the mouth is made of soft tissue that moves. This is called the velum or soft palate (as opposed to the hard palate or bony part of the roof of your mouth). You can see it move up (elevate) if you look in someone's mouth while the person says "ahh." If too little air passes through the nose, the person's speech will sound hyponasal (as if they have a cold). If too much air passes through the nose, the person's speech will sound hypernasal (as if someone if talking out of their nose). If the soft palate is too short, abnormal or moves too little, sufficient closure of the pathway between the back of the mouth up to the nose does not occur. Air then escapes into the nasal cavity, creating greater nasal resonance.
Resonance is how the air sounds within the "chamber" it is vibrating. When we speak, we inhale air into the lungs before we begin. The air moves out of the lungs and passes through the vocal folds and continues up into the mouth and nose. The size and shape of the neck, mouth and nose affect the vibration of the air and the resonance, thereby making everyone's voice unique. In short, the size and shape (structure) as well as the movement (function) of the velum affect resonance.
In English, only three sounds (/m/, /n/, /ng/ as in "sing") are made with the velum "open," allowing air to pass through the nose. The velum should be closed for clear production of all other sounds. When the velum (or soft palate) and pharynx (back walls of the mouth/oral cavity) meet, we call it velopharyngeal closure.
What causes VPI?
- Cleft palate when a child was born with an opening in the soft or hard palate
- Congenitally short palate when a child was born with a palate that simply was not large/long enough to close off the back of the mouth from the nose
- Skeletal abnormalities of the head/neck, such as a condition where the jaw or neck are in irregular positions
- Neurological impairment affecting the muscles of the soft palate such as stroke, amyotrophic lateral sclerosis (ALS), cerebral palsy, etc. This means that the structures of the palate, pharynx, mouth and nose are considered to be normal, but the muscle movement required to completely close off the back of the mouth to the nose is impaired because the brain is unable to communicate with those muscles due to brain damage
- Enlarged tonsils, which may prevent closure of the valve between the mouth and nose (causing hypernasality) or hold it closed (causing hyponasality)
- After adenoidectomy, because the adenoids may have been playing a role in velopharyngeal closure before they were removed
- After surgery for midface advancement, because a new neck/jaw/mouth alignment may affect velopharyngeal closure
- Genetic syndromes which impact craniofacial development (eg, Velocardiofacial syndrome).
What are the symptoms?
There are several ways in which speech can be affected. Speech may sound hypernasal (more air resonating in the nose than there should be). Because air is escaping into the nasal cavity, there may be insufficient air pressure in the mouth while talking. This results in weak speech sounds and unclear/distorted articulation (speech sound production). Sometimes we may notice compensatory articulations. These are non-speech sounds that are created when desired sounds cannot be produced. Nasal air emissions (irregular snorts/bursts of air from the nose) during speech, loss of liquids through the nose while drinking and nasal grimace (a tightening of the facial muscles during speech which may look effortful) are other signs/symptoms of VPI.
How is it corrected?
VPI may be treated with a combination of speech therapy, surgical procedures (such as a pharyngeal flap, sphincteroplasty or posterior pharyngeal wall implant) and/or prosthetic devices. Even with surgical intervention, speech therapy is usually recommended to help patients change their speech habits and normalize resonance.
Evaluation and Speech Therapy
Cleveland Hearing & Speech Center (CHSC) offers speech therapy services for individuals who suspect or have been diagnosed with VPI. We can conduct a perceptual evaluation. This involves listening to and analyzing speech sound production, resonance and other aspects of speaking. If the evaluation confirms suspicions, affected individuals are referred to a craniofacial team. This is a team of medical experts that usually consists of a plastic surgeon, dentist, ENT, audiologist, nurse, speech-language pathologist (SLP) and social worker. These professionals will conduct additional testing if needed. Some of the common procedures include nasendoscopy (an tiny video camera moved through to nose to view the soft palate in action) and/or videofloroscopic evaluation (a fluorescent X-ray study). Team recommendations may be carried out by our therapists. SLPs at CHSC work in conjunction with the craniofacial team and school therapists to coordinate speech therapy goals.