Möbius syndrome: classification and grading system

Möbius syndrome is characterized by facial abnormalities, but the limbs, chest wall, spine, and soft tissues also can be involved. There is no system for categorizing the various anomalies, grading phenotypic severity, designing treatment protocols, or assessing therapeutic results. This is a retrospective analysis of 27 patients with Möbius syndrome seen in our craniofacial unit from 1980 to 1994. We categorized and graded the cranial nerve deficits and diverse musculoskeletal abnormalities of the face, upper and lower limbs, and trunk. The first letter for each of five potentially involved structures, i.e., cranial nerve, lower limb, upper limb, face, and thorax, formed the acronym CLUFT. The structural and/or functional deficits for each component were graded on a scale of 0 to 3. Complete facial nerve paralysis was documented in 11 patients and paresis in 16. Facial nerve paralysis was bilaterally symmetric in 17 of 26 patients. Sixth nerve paralysis was present in 23 of 27 patients; other cranial nerves were affected in 8 of 27 patients. Lower limbs were involved in 10 of 27 patients and upper limbs in 7 of 27 patients. Facial structures were affected in 17 of 27 patients (e.g., microtia, micrognathia, and microphthalmia), and chest wall deformities were found in 8 of 27 patients (e.g., scoliosis, hypoplasia of the breast, pectoral muscles, and scapula). We noted that microtia primarily involved second pharyngeal arch-derived structures. The CLUFT system permits categorization and comparison of Möbius patients for phenotypic and management outcome studies. Documentation of the widespread structural anomalies suggests that pathogenesis involves vascular disruption; a detailed prenatal history is indicated.