Velopharyngeal insufficiency is a disorder of structure that causes a failure of the velum (soft palate) to close against the posterior pharyngeal wall (back wall of the throat) during speech in order to close off the nose (nasal cavity) during oral speech production. This is important because speech requires sound (from the vocal folds) and airflow (from the lungs) to be directed into the oral cavity (mouth) for the production of all speech sound with the exception of nasal sounds (m, n, and ng). If complete closure does not occur during speech, this can cause hypernasality (a resonance disorder) and/or audible nasal emission during speech (a speech sound disorder). In addition, there may be inadequate airflow to produce most consonants, making them sound weak or omitted.
The terms "velopharyngeal insufficiency" "velopharyngeal incompetence, "velopharyngeal inadequacy" and "velopharyngeal dysfunction" have often been used interchangeably, although they do not mean the same thing. "Velopharyngeal dysfunction" now refers to abnormality of the velopharyngeal valve, regardless of cause. Velopharyngeal insufficiency includes any structural defect of the velum or mechanical interference with closure. Causes include a history of cleft palate, adenoidectomy, irregular adenoids, cervical spine anomalies, or oral/pharyngeal tumor removal. In contrast, "velopharyngeal incompetence" refers to a neurogenic cause of inadequate velopharyngeal closure. Causes may include stroke, traumatic brain injury, cerebral palsy, or neuromuscular disorders. It is important that the term "velopharyngeal insufficiency" is used if it is an anatomical defect and not a neurological problem.
Anatomy
Diagnosis
Speech analysis
Velopharyngeal insufficiency can be diagnosed by a speech pathologist through a perceptual speech assessment. Speech characteristics of VPI include hypernasality (too much sound in the nasal cavity during speech) and/or audible nasal emission of air during speech. Nasal emission can also cause the consonants to be very weak in intensity and pressure. The patient may develop compensatory productions for consonants, where the sounds are produced in the pharynx (throat area) where there is adequate airflow.
Nasometry
Nasometry is a method of measuring the acoustic correlates of resonance and velopharyngeal function through a computer-based instrument. Nasometry testing gives the speech pathologist a nasalance score, which is the percentage of nasal sound of the total (nasal plus oral) sound during speech. This score can be compared to normative values for the speech passage. Nasometry is useful in the evaluation of hypernasality because it provides objective measurements of the function of the velopharyngeal valve. As such, it is often used for pre-and post-surgical comparisons and to determine speech outcomes as a result of certain surgical interventions.
Nasopharyngoscopy
Nasopharyngoscopy is endoscopic technique in which the physician or speech pathologist passes a small scope through the patient's nose to the nasopharynx. The nasal cavity is typically numbed before the procedure, so there is minimal discomfort. Nasopharyngoscopy provides a view of the velum (soft palate) and pharyngeal walls (walls of the throat) during nasal breathing and during speech. The advantage of this technique over videofluoroscopy is that the examiner can see the size, location, and cause of the velopharyngeal opening very clearly and without harm (e.g., radiation) to the patient. Even very small openings can be visualized. This information is helpful in determining appropriate surgical or prosthetic management for the patient. The disadvantage of this technique is that the vertical level velar elevation is less obvious than with videofluoroscopy, although this is not a big concern.