title: Relationship in hypoplasia between the masticatory muscles and the craniofacial skeleton in hemifacial microsomia, as determined by 3-D CT imaging.
abstract: The purpose of this study, based on three-dimensional (3-D) computed tomographic (CT) reconstructions, was to evaluate the relation between underdevelopment of masticatory muscles and hypoplasia of the craniofacial skeleton in hemifacial microsomia (HFM). In 25 patients with HFM and 19 control patients the volumes of the masseter, the temporal, and the medial-pterygoid and lateral-pterygoid muscles were measured on the basis of CT scans, using three-dimensional segmentation and voxel addition. The size and shape of the craniofacial structures were classified, using three-dimensional imaging based on CT scans. Contiguous 1.5-mm computed tomography scans were made with a Philips Tomoscan 350 and processed by a Cemax 1500X 3-D workstation. Using the Pearson product moment correlation coefficient, the Pruzansky/Kaban classification system, the new Craniofacial Deformity Scoring System, Cranial Deformity Scoring System, and Mandibular Deformity Scoring System (MDS) demonstrated correlation coefficients with the "masseter muscle percentage" varying from 0.71 to 0.81 (P < 0.05), with the medial pterygoid muscle percentage correlation coefficient varying from 0.43 to 0.56 (P < 0.05), with the lateral pterygoid muscle percentage correlation coefficient varying from 0.55 to 0.61 (P < 0.05), and with the temporal muscle percentage correlation coefficient varying from 0.67 to 0.84 (P < 0.05). The normal right/left difference in volume of the masticatory muscles of the control patients, calculated as a percentage of the total, demonstrated small differences of 3.4% to 4.8%. Bony malformations are associated with underdevelopment of the masseter and the temporal muscles, and demonstrate a tendency toward a clear relationship. The degree of muscular underdevelopment of the different muscles of mastication in one patient could vary widely. The normal right/left difference of the masticatory muscles of the control patients is minimal. The volume of the masticatory muscles of the non-affected side does not demonstrate a compensatory effect in patients with HFM.
authors: Department of Orthodontics, Craniofacial Centre of the University Hospital Rotterdam, Dr Molewaterplein 60, 3015 GJ Rotterdam, The Netherlands. c.fischer@acta.nl
authors: C E
authors: CE
authors: Huisinga-Fischer
authors: F W
authors: FW
authors: Zonneveld
authors: J M
authors: JM
authors: Vaandrager
authors: B
authors: B
authors: Prahl-Andersen
mesh_terms: D000704:Analysis of Variance; D016022:Case-Control Studies; D002508:Cephalometry / Q000379:methods; D002648:Child; D005146:Facial Asymmetry / Q000000981:diagnostic imaging* / Q000473:pathology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008410:Masticatory Muscles / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000473:pathology*; D008865:Microstomia / Q000000981:diagnostic imaging / Q000473:pathology; D009334:Neck Muscles / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000473:pathology; D012044:Regression Analysis; D012886:Skull / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000473:pathology*; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed