Continuous Positive Airway Pressure (CPAP) Therapy for Velopharyngeal Incompetency

Continuous positive airway pressure therapy was proposed by David P. Kuehn as a way to reduce hypernasality. It is a behavioral technique that assumes the patient can learn how to use their velopharyngeal mechanism in a more appropriate manner to improve speech functionality. The patient wears a nasal mask on their face and increased compressed air pressure is sent through a hose into the nasal cavity. The soft palate is forced to work against and overcome this load of air pressure as it enters the VP port and creates resistance against the velopharyngeal closure muscles as the patient carries out specially designed speech tasks. In order to do this, the patient must elevate their velum and draw the pharyngeal walls inward. This exercise can be compared to a weightlifting program for the soft palate. The muscles of VP closure (i.e., levator palatine) are strengthened through this resistance exercise program, and this ultimately results in the person's ability to properly close the VP port during speech, leading to reduced hypernasality (Russel, 2006). According to Henne and Kuehn (2003), CPAP may be beneficial for those who demonstrate velopharyngeal weakness but still have the ability to move their velum fairly well. It also aids those who have a small velopharyngeal gap (less than 2 mm), mild to moderate hypernasality, patients with a cleft palate that has caused hypernasality, those who have undergone pharyngeal flap surgery, and patients who demonstrate persistent hypernasality after a phryngoplasty procedure.

There are three main physiological principles surrounding CPAP therapy. These include overloading, progressive resistance, and specially designed speech tasks. Overloading refers to an increase of the load or amount of air pressure exerted on the velopharyngeal mechanism. The VP closure muscles are then forced to adapt and strengthen in direct correlation to the weight being exerted on them. Progressive resistance refers to a gradual increase in exercise intensity over time. In CPAP therapy, the VP muscles will have to adapt to the gradual overloading of air pressure. Lastly, the patient is instructed to exercise the muscles of VP closure using specially designed speech tasks to activate their corresponding motor nerve pathways and ultimately strengthen these muscles. These principles are integrated into treatment, resulting in an overall reduction of hypernasality (Russel, 2006).

According to Kuehn (1997), CPAP treatment is carried out at home six days per week for eight weeks, and each week, the amount and duration of exerted intranasal air pressure is increased. The first week, the air pressure is set at 4 cm H₂0 and the session lasts 10 minutes. The second week, the session lasts 12 minutes, and this (+2 minutes) pattern continues until 24 minutes during the eighth and final week of treatment. While wearing the nasal mask, the patient repeats a series of utterances while working against the exerted air pressure. The utterances follow a (VNCV) vowel-nasal consonant-pressure consonant-vowel pattern (i.e., /insi/). This speech pattern forces the patient to lower the velum during the production of the nasal consonant (i.e., /n/) and rapidly follow it with elevation of the velum to produce the pressure consonant (i.e., /s/). The second syllable of each word is also emphasized to enhance the power of the stroke. During each session from beginning to end, the patient continuously produces 50 VNCV words, then 6 short sentences (to simulate conversational speech) alternately with and without nasal consonants.

CPAP therapy still needs further research to determine its true effectiveness. Results of Kuehn's (2002) studies indicated that listeners perceived a decrease of hypernasality, but average decreases were small. Future research should include instrument-based measures of hypersnaslity prior to and following CPAP therapy, because these would most likely present a greater change in hypernasality than changes simply perceived by a listener (Russel, 2006).

References:
Henne, L. J., & Kuehn, D. P. (2003). Speech evaluation and treatment for patients with cleft palate. American Journal of Speech-Language Pathology, 12, 103-109.

Kuehn, D. P. (1997). The development of a new technique for treating hypernasality: CPAP. American Journal of Speech-Language Pathology, 6, 5-8.

Russel, B.A. (2006, May). Treatment of hypernasality in children with Down Syndrome. Retrieved June 2, 2008, from http://www.speechpathology.com/Articles/pf_article_detail.asp?article_id=293