Rare Craniofacial Clefts

Etiology

Two theories predominate in establishing a cause of these deformities: the classic theory and mesodermal penetration theory. Whereas a failure of fusion of the developing facial processes is proposed by the former, the role of neural crest cells in the development of the mesoderm and its failed penetration is the central tenet of the mesodermal penetration theory.

There is increasing evidence that genetic predisposition plays a role in the pathogenesis of these rare craniofacial clefts. ^, The genetic component is more clearly evident in true midline clefts, further emphasizing the role of neural crest cells during embryogenesis. ^, Hu and Helms have demonstrated the critical role played by SHH (Sonic Hedgehog) signaling in regulating the pattern of neural crest cell migrations as well as the development of the facial primordium. The transient loss of SHH signaling during the initial phases of neural plate patterning has been linked to abnormalities of craniofacial morphogenesis, leading to anomalies resembling cleft lip/palate defects, hypotelorism, and holoprosencephaly. Excessive SHH signaling has been linked to mediolateral increment in the frontal process as well as hypertelorism.

Classification

The complexity and heterogeneity of facial clefts pose a challenge to classification. Two main classifications are currently utilized: Van der Meulen’s embryonic classification and the more widely used anatomical classification proposed by Tessier. ^, The latter delineates 14 locations for clefts, with the palpebral fissure as a central landmark, much like a wheel with spokes. Facial clefts extending downwards from the palpebral fissure are assigned the numbers 1 to 7, starting at the midline with Tessier 0 and each subsequent number representing a facial cleft more laterally positioned. Cranial clefts extending cephalad from the palpebral fissures are numbered 8 to 14, where Tessier 8 is the most lateral and extends into the corner of the orbit and each sequential cranial cleft is more medial than the last. Facial and cranial clefts may exist separate from one another or combined, at which point they become true “craniofacial clefts.” In such cases, the representative cleft numbers usually sum to 14 (e.g., 0,14; 3,11; 4,10) (see Fig. 19.1 ). ^, A number 30 cleft of the midline mandible is also included in the Tessier classification ( Fig. 19.1 ).

When clinically classifying facial clefts, a number of important anatomical distinctions should be identified to assist in the proper diagnosis. For example, nasal structures are involved only in clefts nos. 0–3, while no. 4 is the first to avoid the nose. Radiologically, no. 4 is visualized medial to the infraorbital foramen, while no. 5 is localized lateral to this structure ( Table 19.1 ).

TABLE 19.1

Description of the Tessier Clefts: Course and Presentation ^a

Illustrations for clefts 0, 1, 2, 3, 4, 5, 6, 10, 12, and 14 from Bradley JP, Kawamoto HK. Craniofacial clefts. In: Rodriguez ED, Losee JE, Neligan PC, eds. Plastic Surgery . 4th edn. Volume 3: Craniofacial, Head and Neck Surgery and Pediatric Plastic Surgery . Elsevier; 2018.

Cleft No.	Soft Tissue	Skeletal
0	Starts in the midline, traverses the lip, alveolus and nasal components A: Hypoplasia Deficiencies of philtral columns Deficiencies of nasal structures (columella and septum) Arhinia may exist B: Hyperplasia Separated philtral columns Frenulum duplication Septal duplication Displaced alar cartilage Broad columella Clefted dorsum	Cleft travels between alveolus, maxilla and the nasal bones Central incisors laterally displaced V shape maxillary teeth Broad nasal bones and maxilla Broad body of the sphenoid The pterygoid plates are displaced laterally
1	Starts at Cupid’s bow and ascends through the soft triangle of the nose to the dome Cleft lip Notching of the soft triangle Deviation of the nasal tip Columella may be widened	Passes between the central and lateral incisors and through the alveolar process The central incisor may be missing The piriform aperture is violated lateral to the anterior nasal spine The nasal septum is spared Keel-shaped maxilla
2	Begins at Cupid’s bow (like no. 1 cleft), but courses through middle third of nostril (not dome) Travels medial to the palpebral fissure Cleft lip Disruption of the nostril The medial canthus displaced inferiorly The eyelid and lacrimal system are not disturbed	Crosses the alveolus between the lateral incisor and canine, into pyriform aperture The lateral incisor may be missing Nasal septum remains intact Enlarged ethmoid (hypertelorism)
3	Known as the oro-naso-ocular cleft Cleft lip through Cupid’s bow peak (similar to clefts no. 1 and 2), through alar base and medial canthus, separating nose from cheek Nasolacrimal disturbance (the cleft passes between the medial canthus and the inferior lacrimal punctum) Disruption of the nasal ala Blockage of the nasolacrimal duct and recurrent infections of the lacrimal sac are common Microphthalmia or anophthalmia in some cases The globe is displaced inferiorly and laterally	Starts at alveolus between lateral incisor and canine, involves lateral border of pyriform, into lacrimal groove Absence of the medial wall of the maxillary sinus Disruption of the frontal process of the maxilla Direct osseous communication of the oral, nasal, maxillary sinus and orbital cavities
4	Known as meloschisis (separation of cheek) Through lip lateral to Cupid’s bow, lateral to ala, through cheek, medial to infraorbital nerve, through the punctum Cleft lip The nasal ala is displaced superiorly The medial canthal tendon is displaced laterally and inferiorly The nasolacrimal system is affected	Through alveolus between the lateral incisor and canine, lateral to pyriform, into medial orbital rim and the floor May travel posteriorly to disrupt the palate and choanae Dystopia Extrophy of the maxillary sinus might be present
5	Cleft lip just medial to lateral commissure, through cheek, into the middle third of the lower eyelid Microphthalmia may be present	Posterior to cuspid, lateral to the infraorbital foramen, through the inferolateral orbital rim and orbital floor
6	Extends from oral commissure towards lateral lower lid May produce: antimongoloid slant palpebral slant, lower lid coloboma, lateral canthal tendon displacement laterally Ear malformations May present with nos. 7 and 8 clefts in Treacher Collins syndrome	Travels from posterior maxilla to the zygomaticomaxillary suture through the inferior orbital fissure Hypoplastic malar bone (but still present) There is no alveolar cleft, but a short posterior maxilla may result in an occlusal tilt Commonly associated with choanal atresia
7	The most common of the atypical craniofacial clefts Begins at the oral commissure and varies from a mild broadening to a complete cleft Extends laterally towards the ear and may involve masseter Macrostomia Hypoplasia of soft palate and tongue Parotid abnormalities, atrophic temporal muscle Ear malformations The lateral canthal tendon is inferiorly displaced Cranial nerves V and VII may be affected	Cleft passes through the pterygomaxillary junction Posterior maxilla and ramus are hypoplastic (causing orbital dystopia) The zygomatic arch is clefted Condyle and coronoid can be present Open bite or crossbite is seen Hypodontia of the upper maxillary can be present Associated with craniofacial microsomia (graded using the Pruzansky Kaban classification for mandibular component)
8	May present with a no.7 cleft Cleft through the lateral canthus and towards the temporal region Lateral canthal colobomas Epibulbar dermoid (associated with Goldenhar syndrome)	Centered at the frontozygomatic sutures Sesamoid bones may present in the temporalis–masseteric aponeurosis
9	The rarest of the craniofacial clefts Cleft through the superolateral third of the lid, brow, and into temporal hairline The lateral canthal tendon is not affected The hairline is disrupted Microphthalmia may be present	Through the superolateral angle of the orbit Cleft of the greater wing of the sphenoid The lateral orbital rim is rotated posterolaterally
10	Cleft through the middle third of upper eyelid, brow, and into hairline Upper eyelid coloboma (middle third) Ablepharia can be seen	Travels through the midportion of the superior orbital rim lateral to the supraorbital nerve, extends to the orbital roof, and into frontal bone A fronto-orbital encephalocele is commonly present The orbit is rotated laterally and inferiorly
11	Through the medial third of the upper eyelid and eyebrow, into the frontal hairline	Passes through the medial side of the supraorbital rim and orbital roof Can pass through the ethmoid labyrinth Hypertelorism can occur
12	Starts just medial to the medial canthus, through the root of the eyebrow The medial canthal tendon is displaced laterally The eyelid is not disrupted Hair loss of the medial portion of the eyebrow	Travels through the ethmoid labyrinth, towards the frontal bone Olfactory groove lies medial to the cleft Normal cribriform Hypertelorism The frontal process of the maxilla is broadened and flattened
13	Extends from the dome of nostril cephalad, medial to the eyelids and eyebrow Can extend to the hairline May involve the medial canthus	Extends from the piriform aperture through nasal bone or between nasal bone and frontal process of maxilla Hypertelorism
14	The cranial extension of no. 0 cleft A: Hypoplasia Holoprosencephaly (cyclopia, ethmocephaly, cebocephaly and primary palate agenesis) B: Dysraphia Encephalocele C: Hyperplasia Orbital hypertelorism	Travels through the frontal bone Broad crista galli and frontal sinus Hypotelorism or hypertelorism
30	Cleft through the midline tongue, lower lip, and chin A bifid tongue	Midline, through the mandibular symphysis, hyoid, and possibly sternum of varying degrees

a It is important to note that this table serves as a guide, and that the features described for each Tessier cleft classification may be present to a greater or lesser degree. Not all features noted need be present for each particular cleft.

The earliest documented history of facial clefts was first reported by Merkel and Trendelenburg, where they described facial clefts. However, Tessier illustrated a more detailed and systematic classification for craniofacial clefts that is widely accepted today. Tessier’s classification is unique given that it highlights the relationship between soft tissues and the underlying bone, stating that “a fissure of the soft tissue corresponds, as a general rule, with a cleft of the bony structure.” The converse is also possible. In addition, Tessier proposed the adoption of the term “cleft” for all craniofacial anomalies that fall along these lines, noting that there may be “excess” and/or “deficiency” clefts. Indeed, many surgeons consider both craniofacial microsomia and Treacher Collins syndrome as rare craniofacial clefts with variable amounts of soft tissue and bony involvement of the implicated Tessier cleft. For example, in craniofacial microsomia there may be a no. 7 cleft of the soft tissue associated with variable hypoplasia of the mandible whereas in Treacher Collins syndrome there may be a soft tissue cleft of nos. 6 or 7 and a hard tissue cleft of nos. 6, 7, and 8 or a combination thereof.

The main drawback of the Tessier classification is that it does not explain why clefts can occur at nonembryonic sites of fusion. While other authors have modified Tessier’s original classification, it continues to be the most widely utilized.

Van der Meulen’s embryological classification is considered by some to be more comprehensive as it attempts to explain why some clefts occur in areas unrelated to embryologic fusion. In this system the term “dysplasia” is used since not all malformations are true “clefts.” The dysplasias are classified according to time and location of developmental arrest (e.g., orbito-zygomatic dysplasia). Hypoplasia of the mandible is graded according to the Pruzansky classification and as adapted by Kaban et al. ^,

Management

The management of facial clefts necessitates a multidisciplinary approach due to the involvement of multiple facial structures. Priorities remain airway and globe protection, followed by functional concerns such as the separation of nasal, orbital, and oral spaces, lip competence and eating. Furthermore, the treatment of craniofacial clefts necessitates the reconstruction of soft tissue and skeletal hypoplasia to obtain optimal esthetic improvement. It is important to note that there is no known, standardized “one-size fits all” surgical approach that can be constantly followed. This is because the majority of patients present with unique facial deformities within characteristic patterns of facial clefts. Even in extremely rare facial anomalies, the goal of the craniofacial surgeon is to get the desired result with fewest numbers of corrective surgeries.

Skin

Facial cleft deformities usually involve shortening of the facial dimensions along the cleft, leading to a “short oculo-oral distance.” The goal of soft tissue closure is to normalize the face’s vertical height, as well as to achieve repositioning of critical structures such as canthi, lower eyelids, lips and nose using traditional soft-tissue transposition techniques such as Z-plasties, back-cuts and/or rotation-advancements. Such repositioning must also incorporate excision of scarred tissues associated with the cleft.

Another important concept is the placement of scars to avoid the violation of anatomical facial units. In cases where the facial cleft involves a single-facial unit such as Tessier nos. 1, 2 or 5, a Z-plasty can be employed to provide esthetically acceptable lengthening and correction ( Fig. 19.2 ).

In facial clefts involving more than one facial unit, such as Tessiers 3 or 4, a midface rotation-advancement flap may provide superior esthetics to traditional interdigitating flaps or Z-plasties by limiting scars along the lines dividing subunits, as espoused by Chen et al. The authors also describe the importance of the realignment and repair of facial muscles, noting that it provided more natural facial expression and animation, as well as progressive lengthening of the initially vertically-deficient midface ( Box 19.1 and Fig. 19.3 ).

Attention must also be given to the mucosa at the time of skin repair as a significant portion of facial clefts are full-thickness. As in the more common clefts of the lip and palate, the mucosa is similarly closed using interdigitating flaps, Z-plasties, back-cuts, etc. Due to tissue deficiency which may be present, one may repair these defects initially with local flaps (rotation/advancement, back-cuts, Z-plasties), and then later in life transpose the scars to the boundary of the esthetic subunits with additional soft tissue flaps and/or tissue expansion to recruit additional tissue.