The prevalence of platybasia in patients with velopharyngeal incompetence.

Objectives : To estimate the prevalence of platybasia in patients with velopharyngeal incompetence (VPI) and its relation with palatal anomalies and syndromes. Design and Settings : Retrospective case analysis. Setting : A university-affiliated hospital. Patients : The VPI patients (n = 366) included five groups with either cleft lip and palate (CLP), cleft palate (CP) only, submucous cleft palate (SMCP), occult submucous cleft palate (OSMCP), or non-CP. The control group (n = 126) comprised healthy, normal-speech individuals. Outcome Measures : The cranial-base angle was measured by lateral cephalometric radiography. The prevalence of platybasia (defined as cranial base angle ≥ 137°) was estimated and the patient's syndromes were recorded. Results : The prevalence of platybasia was significantly higher in the VPI group (28.7%) than in the normal controls (2.4%) (P < .001). A significant difference (P < .01) was found in the prevalence of platybasia among the five VPI groups: 16.7%, 20.3%, 28.8%, 33.7%, and 40.3% for CLP, CP only, SMCP, OSMCP, and non-CP, respectively. No significant difference was found between the cranial-base angle of VPI patients and of controls and between the cranial-base angle of the five VPI groups. The VPI nonplatybasic patients had a significantly smaller cranial-base angle than normal controls (P < .01). Platybasia was the highest among patients with velocardiofacial syndrome (50%), followed by those with Pierre Robin syndrome (27.3%). Conclusions : Platybasia, which may cause enlargement of the nasopharyngeal space and difficulties in achieving velopharyngeal closure, can be found in high numbers of VPI patients with or without CP. This supports the belief that velopharyngeal anomaly may be part of a more complex craniofacial anomaly influenced by the cranial-base flexure.