Table 3. A Grading System to Capture the Presence and Severity of the Orbit, Mandible, Ear, Nerve, and Soft Tissue Anomalies Commonly Associated with Craniofacial Microsomia*.
| Orbit | |
| O0 | Normal orbital size and position |
| O1 | Abnormal orbital size |
| O2 | Abnormal orbital position (arrow up or down) |
| O3 | Abnormal orbital size and position |
| Mandible | |
| M0 | Normal mandible |
| M1 | The mandible and glenoid fossa are small. |
| M2A | Short ramus, glenoid fossa is in anatomically acceptable position |
| M2B | Short ramus, TMJ is inferiorly, medially and anteriorly displaced with hypoplastic condyle |
| M3 | Complete absence of ramus, glenoid fossa and TMJ |
| Ear | |
| E0 | Normal ear |
| E1 | Mild hypoplasia & cupping, all structures present |
| E2 | Absence of external auditory canal with hypoplasia of concha |
| E3 | Malpositioned lobule with absent auricle, lobular remnant inferiorly and anteriorly displaced |
| Facial Nerve | |
| N0 | No facial nerve involvement |
| N1 | Upper facial nerve involvement (temporal zygomatic) |
| N2 | Lower facial nerve involvement (buccal, mandibular, cervical) |
| N3 | All branches of facial nerve affected |
| Soft Tissue | |
| S0 | No obvious soft tissue or muscle deficiency |
| S1 | Minimal subcutaneous/muscle deficiency |
| S2 | Moderate–between the two extremes S1 and S3 |
| S3 | Severe soft tissue deficiency due to subcutaneous and muscular hypoplasia |
TMJ, temporomandibular joint
*
The O.M.E.N.S. Classification System for quantifying the deformity of the orbit, mandible, ear, nerve, and soft tissue in hemifacial microsomia. (From Vento RA, LaBrie RA, Mulliken JB. The O.M.E.N.S. classification of hemifacial microsomia. Cleft Palate-Craniofacial Journal 1991; 28:68–76.)