Magnetic Resonance Imaging of the Velopharynx: Clinical Findings in Patients with Velopharyngeal Insufficiency

Abstract

Background: Magnetic resonance imaging (MRI) is the only imaging modality capable of directly visualizing the levator veli palatini (LVP) muscles: the primary muscles responsible for velopharyngeal closure during speech. MRI has been used to describe normal anatomy and physiology of the velopharynx in research studies, but there is limited experience with use of MRI in the clinical evaluation of patients with velopharyngeal insufficiency (VPI). Methods: MRI was used to evaluate the velopharyngeal mechanism in patients presenting for VPI management. The MRI followed a fully awake, nonsedated protocol with phonation sequences. Quantitative and qualitative measures of the velopharynx were obtained and compared with age- and sex-matched individuals with normal speech resonance. Results: MRI was completed successfully in 113 of 118 patients (96%). Compared with controls, patients with VPI after cleft palate repair had a shorter velum (P < 0.001), higher incidence of LVP discontinuity (P < 0.001), and shorter effective velar length (P < 0.001). Among patients with persistent VPI after pharyngeal flap placement, findings included a pharyngeal flap base located inferior to the palatal plane [11 of 15 (73%)], shorter velum (P < 0.001), and higher incidence of LVP discontinuity (P = 0.014). Patients presenting with noncleft VPI had a shorter (P = 0.004) and thinner velum (P < 0.001) and higher incidence of LVP discontinuity (P = 0.014). Conclusions: MRI provides direct evidence of LVP muscle anomalies and quantitative evaluation of both velar length and velopharyngeal gap. This information is unavailable with traditional VPI imaging tools, suggesting that MRI may be a useful tool for selecting surgical procedures to address patient-specific anatomic differences.

Measurement Matters: MRI Analysis of Differing Anatomic Measurement Techniques for Velar Length and the Velopharyngeal Needs Ratio

“…This is particularly relevant, given that recent studies have noted that small quantitative differences (<1 mm) have been reported to influence velopharyngeal function, and these differences may be correlated with the perception of hypernasality. 56,57 For example, in patients that demonstrate velopharyngeal insufficiency, use of the curvilinear measurement provides more accurate quantitative assessment of the velar morphology and likelihood for postoperative VP function, particularly as it relates to distraction osteogenesis 30 and obstructive sleep apnea. 58 Furthermore, functional differences may also be observed when assessing velar length during phonation due to patient-specific anatomy postpalatoplasty, again highlighting the need to precisely measure this structure using a curvilinear measurement.…”

The Pediatric Neuroradiologist's Practical Guide to Capture and Evaluate Pre- and Postoperative Velopharyngeal Insufficiency

“…19 As a result, most patients scheduled for velopharyngeal MR imaging will typically be between these ages; however, velopharyngeal MR imaging has been demonstrated in VPI surgical planning for patients ranging in age from 3 to 39 years (n ¼ 113 patients) at a single cleft craniofacial center in the United States. 10 Patients are required to be imaged both at rest and while producing and sustaining specific sounds. While typical MR imaging in young children is often performed with sedation or general anesthesia with use of a laryngeal mask airway to support the airway for breathing, successful velopharyngeal MR imaging requires that the patient be fully awake using a nonsedated protocol with no contrast or laryngeal mask airway.…”

“…7,8 MR imaging is a relatively newer clinical imaging diagnostic tool in cleft care that is being introduced into cleft craniofacial care units, particularly in the United States. [9][10][11] The interest in velopharyngeal MR imaging is primarily due to the advantage of MR imaging in visualizing the velopharyngeal musculature, which is not possible using nasopharyngoscopy and videofluoroscopy. [9][10][11] Similar to videofluoroscopy, MR imaging can be used to accurately quantify key velopharyngeal structures with the added benefits of section specificity (eg, the ability to select a precise midsagittal section without head rotation) and lack of ionizing radiation, which is present, though minimal, in videofluoroscopy.…”

“…[9][10][11] The interest in velopharyngeal MR imaging is primarily due to the advantage of MR imaging in visualizing the velopharyngeal musculature, which is not possible using nasopharyngoscopy and videofluoroscopy. [9][10][11] Similar to videofluoroscopy, MR imaging can be used to accurately quantify key velopharyngeal structures with the added benefits of section specificity (eg, the ability to select a precise midsagittal section without head rotation) and lack of ionizing radiation, which is present, though minimal, in videofluoroscopy. The use of MR imaging in the clinical assessment process may be particularly important when muscle reconstruction is being considered to treat VPI 12 or following a failed VPI surgery.…”