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Craniofacial syndromes and distraction osteogenesis
Most craniofacial syndromes stem from a disturbance of neural crest cells and the first and second pharyngeal arches; Treacher Collins is bilateral and symmetric with a lower eyelid coloboma, and hemifacial microsomia is unilateral and asymmetric — and treatment combines bone reconstruction, distraction osteogenesis and ear reconstruction.
Why it matters in the exam
Treacher Collins syndrome (TCOF1, dominant inheritance) includes downslanting palpebral fissures, a coloboma of the lateral third of the lower eyelid, hypoplasia of the cheek bones and zygoma, microtia and a small mandible with a risk of airway obstruction. The zygoma and orbit are reconstructed with skull (calvarial) bone grafts, the preferred donor site in craniofacial surgery. Hemifacial microsomia (craniofacial microsomia) is a disorder of the first and second arches on one side: small mandible, microtia, facial nerve weakness and deficient soft tissue; the mandible is graded by Pruzansky-Kaban (I, IIa, IIb, III), and the whole condition by OMENS. CHARGE (CHD7) includes coloboma, heart defect, choanal atresia, retarded growth, genital anomalies and ear anomalies. The mandible develops from the first pharyngeal arch.
Distraction osteogenesis rests on Ilizarov's principles: osteotomy, a latency phase of 5 to 7 days, a distraction phase at about 1 mm per day, and a consolidation phase lasting about 2 times the distraction time; the soft tissues lengthen together with the bone. It is used for a small mandible with airway obstruction (Pierre Robin, Treacher Collins) and in microsomia. Parry-Romberg is progressive hemifacial atrophy of fat, skin and sometimes bone, which advances for years and then stops; reconstruction with fat grafting or a free flap is done after the disease stabilises. Craniofacial clefts are classified by Tessier with numbers 0 to 14 around the orbit. Median craniofacial hypoplasia is linked to the holoprosencephaly spectrum and close-set eyes, whereas median (frontonasal) dysplasia includes widely spaced eyes (hypertelorism) and a usually normal brain.
Key points
- Treacher Collins — TCOF1, bilateral, lower eyelid coloboma.
- Microsomia — arches 1 and 2, unilateral.
- Distraction: latency 5 to 7 days, 1 mm per day, consolidation 2 times.
- Preferred donor site for facial bone — the skull.
- Parry-Romberg — reconstruct after stabilisation.
Summary table
| Syndrome | Gene or mechanism | Signs | Main reconstruction |
|---|---|---|---|
| Treacher Collins | TCOF1, dominant | Bilateral, lower eyelid coloboma, small zygoma | Calvarial bone grafts to the zygoma, mandibular distraction |
| Hemifacial microsomia | Arches 1 and 2, unilateral | Small mandible, microtia, nerve 7 | Mandibular distraction, ear reconstruction |
| CHARGE | CHD7 | Coloboma, heart, choanae, ears | By the systems involved |
| Parry-Romberg | Progressive atrophy | Sunken half-face | Fat grafting or flap after stabilisation |
| Distraction osteogenesis | Ilizarov principles | Latency 5 to 7 days, 1 mm per day | Consolidation 2 times the distraction time |
A free exam question
יילוד חדש הסובל מדה-סטורציה ספונטנית. בבדיקתו ממצאים של glossoptosis ,retrognathia ללא שסע בחיך. במסגרת הבירור בוצעה אנדוסקופיה )pharyngoscopy and naso-endoscopy( אך ללא ממצא סטורציות תכופות-חסימתי כלשהו. היילוד סובל מדה. מה השלב הבא בטיפול? (the question as examined, in Hebrew)
- א. חיפוש אחר אתיולוגיה הקשורה ל- CNS או לריאות, שבגינה ישנה דה-סטורציה. בינתיים לתת תמיכה נשימתית
- ב. הכנסת טראכיאוסטומיה באופן מיידי
- ג. מיידי tongue lip adhesion ביצוע
- ד. mandibular distraction osteogenesis התחלת תהליך של
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Sources
- Plastic Surgery (Neligan), 5th edition (2023) — Craniofacial microsomia; Treacher Collins syndrome; Craniofacial clefts
- ACPA Parameters for evaluation and treatment of craniofacial differences, 2018 revision — Team care
- Ilizarov principles of distraction osteogenesis as applied to the craniofacial skeleton, current reviews — Latency, distraction and consolidation phases
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.