Velopharyngeal insufficiency (VPI) is known as a failure of the separation between nose and mouth, because of an anatomical dysfunction of the soft palate, the lateral or posterior wall of the pharynx.
The effect of such a dysfunction leads to functional problems with speech(hypernasality), eating and breathing. This gap can be treated surgically, although the operational technique which should be used is still controversial. The main object is to visualize the preoperative velopharyngeal dimensions and movements and adjust your postoperative goal upon these results. There are different diagnostic tools which can help visualize these movements and dimensions. This tools will be reviewed in this article.
The terms velopharyngeal "incompetence", "inadequacy" and "insufficiency" historically have been used interchangeably, although they do not necessarily mean the same thing. Velopharyngeal insufficiency includes any structural defect of the velum or pharyngeal walls at the level of the nasopharynx with insufficient tissue to accomplish closure, or there is some kind of mechanical interference with closure. It is important that the term insufficiency is used if it is an anatomical defect and not a neurological problem.
Velopharyngeal insufficiency (VPI) can be caused by a variety of disorders (structural, genetic, functional or acquired) and is very often associated with a cleft palate. Abnormal physiological separation of the oropharynx from the nasopharynx can lead to VPI and hypernasality.
The main objective of this article is to create an overview of the differential methods and (non-)surgical treatment of VPI.
- 1 Anatomy
- 2 Diagnosis of velopharyngeal insufficiency
- 3 Treatment of velopharyngeal insufficiency
- 4 Operation techniques
- 5 Non operation techniques
- 6 Conclusion
- 7 References
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Diagnosis of velopharyngeal insufficiency
An incorrect diagnosis can lead to insufficient differential management. Most surgeons have their own vision on diagnosis and differential management. If thought, for instance, that palatal length is the only variable necessary for achieving normal closure, differential management will be insufficient. Therefore the differential diagnosis is important, because otherwise treatment of the velopharynx may not be appropriate.
There is not one single operative approach to VPI because anatomical structures diverge a lot between individuals. With the diagnostic tools the surgeon is able to decide which technique should be used based on the anatomical situation of the individual. The goal of every operation is to achieve the best possible result with the assigned technique to each individual case.
A few methods to diagnose are described in the following paragraphs.
The first thing that is evaluated is the quality of speech of the patient also known as speech analysation. To come to the right diagnosis this is the gold standard in VPI evaluation. The speech scientist listens to the voice, articulation, motor speech and the velopharyngeal function of the patient. The main symptom is hypernasality of the voice. The patient is unable to create normal resonance because of nasal air emission.
These different emissions can be measured with nasometry. Nasometry is a test which calculates a ratio between the nasal and oral sound emissions. The ratios of the patient will be compared with a normal ratio and standard deviation. These ratios will help determine whether the operation was a success. Preoperative ratios will be compared with postoperative ratios.
The scientist also examines the patient for Obstructive Sleep Apnea Syndrome (OSAS), when this is positive the patient will be treated for OSAS first. When there is no sign of oral sleep apnea the patient will conduct a speech analyzation. If is proven that the patient has an indication for surgical treatment, the next step will be visualization of the mouth and pharyngeal cavity. Often the visualization is combined with audiometry or speech analyzation.
Nasoendoscopy is a non radiographic technique in which the physician uses a scope to enter the mouth of the patient. Usually the examiner uses a flexible scope, but in certain situations a rigid scope is used. Nasoendoscopy provides an overview of the anatomy of the velopharynx during phonation. With nasoendoscopy the vocal tract but especially the soft palate and the lateral wall of the pharynx can be visualized. Not only the location but also the movement can be visualized with nasoendoscopy.
There are some limitations of nasoendoscopy. Firstly it is hard to get an overview with nasoendoscopy with a rigid scope in small kids. Especially when there are abnormalities or obstructions in the nasal cavity, which are frequently found in children with a history of cleft palate. Secondly the nasoendoscope can cause irritations of the mucosa when the child does not cooperate.
Multiview Videofluoroscopy is a radiographic technique, mostly to demonstrate the lateral and posterior wall of the pharynx. This is a questionable technique considering these children undergo radiographic examinations frequently. Also known is that children are more sensitive to radiographic examinations than adults. Most of the time barium is used in multiview videofluoroscopy. Besides the fact that videofluoroscopy provides an overview of the lateral and posterior walls of the pharynx, this technique also provides information about the length and movement of the soft palate, the posterior and the lateral walls.
The most frequently used diagnostic tools are videofluoroscopy and nasoendoscopy. Some studies conclude that the first step in the process of diagnosis is videofluoroscopy in combination with nasometry. Other studies show a favour for nasoendoscopy. But in general there is no preference of which tool should be used as a standard. Most studies conclude that it is necessary to individualise the decision on which diagnostic tool should be used.
Magnetic resonance imaging
A relatively new approach in the diagnosis is the magnetic resonance imaging (MRI), which is noninvasive. MRI uses the property of nuclear magnetic resonance to image nuclei of atoms inside the body. MRI is non radiographic and that's why you can repeat the MRI more often in short periods of time. In addition to, different studies show that the MRI is better as a diagnostic tool than videofluoroscopy for visualizing the anatomy of the velopharynx.
On the contrary there are still a few limitations of the MRI. Firstly artefacts can be shown on the images when the patient moves while imaging. Also artefacts will also be shown if the patient has orthodontic appliances. Secondly the MRI is limited in children who are claustrophobic.
Furthermore, in the MRI scanner movement of the sphincter leads to artefacts on the images. That is also the reason why nasoendoscopy is still needed for the information about the sphincter’s movement. Finally, the MRI is a more expensive diagnostic tool than the combination of nasoendoscopy and videofluoroscopy.
Because of these limits the MRI is not used at all. However, they use the MRI for a “bird view” of the child in the planning of the operation, but not in the progress of diagnosis. Maybe in a few years, when the technique of the MRI is better it will be the diagnostic tool for VPI.
Treatment of velopharyngeal insufficiency
The main objective of physical treatment is to achieve adequate velopharyngeal (VP) function and normal oral-nasal resonance.
The patient can learn to pronounce the words better with the help of a speech scientist. Also a speech scientist can help a patient to learn how to use the VP-port after surgery. Only if the VP mechanism is not working properly after surgery, speech therapy will be of little improvement.
Normally when the patient has VPI, first of all the palatum will be closed. If speech is not as aimed, palatoplasty will take place. This is an operation in which the velopharyngeal port is narrowed down and functionally improved.
Velopharyngeal insufficiency remains in 5-20% of the patients who underwent surgery for closing the palatal cleft. Therefore a secondary operation is necessary. Nowadays the procedure that is chosen the most from the palatoplasties is the pharyngeal flap or sphincter palatoplasty.
When the pharyngeal flap is used, a flap of the posterior wall is attached to the posterior border of the soft palate.The flap consists of mucosa and the superior pharyngeal constrictor muscle. The muscle stays attached to the pharyngeal wall at the upper side (superior flap) or at the lower side (inferior flap). The function of the muscle is to obstruct the pharyngeal port at the moment that the pharyngeal lateral walls move towards each other. It is important that the width and the level of insertion of the flap are properly constructed, because if the flap is too wide, the patient can have problems with breathing through the nose what can result in sleep apnea. Or a postoperative situation can be created with the same symptoms as before surgery. Although there are complications such as the flaps width can change because of contraction of the flap. This results in a situation with the same symptoms of hypernasality after a few weeks of surgery. Also a fistula can occur in 2.4% of the cases.
When the sphincter pharyngoplasty is used, both sides of the superior-based palatopharyngeal mucosa and muscle flaps are elevated. Because the distal parts (posterior tonsillar pillars, which the palatopharyngeal muscles are attached to) are sutured to the other side of the posterior wall the pharyngeal port will become smaller. As a result the tissue flaps cross each other, leading to a smaller port in the middle and a shorter distance between the palate and posterior pharyngeal wall.
There are a few advantages with using this technique. First of all the procedure is relatively easy to execute. This makes the operation cheaper, also because of a reduced anesthesia time. Secondly the dynamic sphincter can be moved as result of a remaining neuromuscular innervation, what gives a better function of the velopharyngeal port. At last there is a lower complication rate, although obstructive sleep apnoea syndrome(OSAS) is associated.
Both the techniques are used often, but there is no standard operation. Pharyngeal flap surgery is not better than sphincter palatoplasty. It is more upon the surgeons experience, knowledge and preference which operation will be done. Also the patient’s age, and the size and nature of the velopharyngeal defect, contribute to which technique is used."
Posterior wall Augmentation
Another option for diminishing the velopharyngeal port is posterior wall augmentation. This technique is not often used. Additionally this technique can only be used for small gaps. When this operation is performed there are a several advantages. It is possible to narrow down the velopharyngeal port without modifying the function of the velum or lateral walls. Furthermore the chance of obstructing the airway is less, because the port can be closed more precisely. Many materials have been used for this closure: petroleum jelly, paraffin, cartilage, adjacent soft tissue, silastic, fat, Teflon and proplast. But results on the long term are very unpredictable. There are problems with tissue incompatibility and migration of the implant. Even migration to the brain is noticed.
Non operation techniques
Prosthesis are used for nonsurgical closure in a situation of velopharyngeal dysfunction. There are two types of prostheses. One called the speech bulb and the other one the palatal lift prosthesis. The speech bulb is an acrylic body that can be placed in the velopharyngeal port and can achieve obstruction. The palatal lift prosthesis is comparable with the speech bulb, but with a metal skeleton attached to the acrylic body. This will also obstruct the velopharyngeal port. It is a good option for patients that have enough tissue but a poor control of the coordination and timing of velopharyngeal movement. It is also used in patients with contraindications for surgery. It has also been used as a reversible test to confirm if a surgical intervention would help.
Pharyngeal flap and sphincter pharyngoplasty seem to be safe and reliable procedures for treating velopharyngeal dysfunction. Although not in all patients complete closure will be achieved after the surgical procedures, they do show a reduction of the size of the velopharyngeal defect. The planning of the surgical procedure seems to be the most important aspect of the surgery for correcting velopharyngeal dysfunction. To clarify the problems of each individual patient, diagnosis will be confirmed by hearing (speech analysis) and imaging (videofluoroscopy and nasoendoscopy) the defect. It is important to think about that these different diagnostic procedures can give a various result, because of the fact that what you hear does not necessarily correlate with what is seen.
The preoperative planning will give you important information about the movement of the soft palate, the lateral pharyngeal walls and posterior pharyngeal wall. The part of the soft palate with the maximal movement, gives you the precise level where tissue has to be attached. This information decides the length of the pharyngeal flap or lateral flaps. Likewise, the size and shape of the gap is considered for determining the width of the pharyngeal flap or lateral flaps. The dissymmetry will be corrected by placing an asymmetric flap or creating unilateral a wider flap in the sphincteroplasty procedure. This is why diagnostic tools contribute immensely in the approach of the problem, and consequently decide if the operation can be called a success. Moreover, it is concluded that the diagnostic tool that should be used has to be chosen on the aspect of the velopharyngeal defect of the individual.
A recent meta-analysis which used two RCT's (Randomised Controlled Trial), currently provides the highest quality data in comparing pharyngeal flap with sphincter pharyngoplasty. This study suggests a possible trend favouring the pharyngeal flap. However, in this meta-analysis only one out of two RCT’s shows a better outcome for the pharyngeal flap, the other RCT doesn’t show any difference. What’s needed next is more research to be done, so that the result of the meta-analysis can be supported.
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