Microform Cleft Lip


Microform Cleft Lip

John B. Mulliken


Lesser forms of incomplete cleft lip are categorized as minor-form, microform, and minimicroform.

Abridged rotation-advancement is recommended for repair of minor-form cleft lip.

Double unilimb Z-plasty (with muscular eversion and dermal graft augmentation) is described for repair of microform cleft lip.

Transmucosal muscular repair (with vertical lenticular excision at upper and lower vermilion junctions, if necessary) is used for mini-microform cleft lip.

Primary nasal correction is necessary for all three types of lesser form cleft lip.

First repair the major side for asymmetrical bilateral cleft lip with contralateral minimicroform or asymmetrical bilateral cleft lip with contralateral microform: decide between primary unilateral repair on major side and delayed correction on the lesser side or synchronous bilateral nasolabial repair.

Mother Nature’s minor mistakes provide clues to the origins of her major abnormalities. So it is with microform cleft lip. This uncommon anomaly is fascinating and causes a curious observer to ponder the pathogenesis of complete cleft lip. Veau1 called microform cleft lip the “first variety” on the “uninterrupted chain” of labial clefting; he illustrated these lesser variations with drawings traced from photographs.

Microform cleft lip has historically been called occult, minor, minimal, or congenital healed cleft lip.24 The old term forme fruste (French for “defaced” meaning atypical or aborted form) is a sciolism and should not be used.

I introduced the term mini-microform to designate a more subtle labial cleft involving discontinuity of the vermilion-cutaneous junction at the peak of the Cupid’s bow that remains level with the peak on the opposite side.5 Other features of a mini-microform cleft include slight notching of the mucosal free border, variable nostril deformity, and a philtral groove that forms on puckering, an indicator of orbicular hypoplasia. Usually no alveolar defect is present.


Fig. 42-1 A, Microform cleft lip. B, Mini-microform cleft lip. C, Minor-form cleft lip.

The term minor-form was coined to designate another type of lesser incomplete labial cleft.5 The features that differentiate a minor-form from a microform cleft lip include (1) a vermilion notch that extends more than 3 mm above the level of the Cupid’s bow peak point on the normal side, (2) muscular depression in the nostril sill, (3) nasal deformity (a short hemicolumella, dislocated genu, and laterally displaced alar base), and (4) a variable alveolar cleft. Distinction between minor-form and microform cleft lip is important (Fig. 42-1). An abridged rotation-advancement type repair, including primary nasal correction, is applicable for a minor-form, whereas a less extensive method is possible for repair of a microform.


The birth incidence of microform cleft lip is unknown. In my series, microform comprised 33 of 360 (9.2%) unilateral incomplete cleft lips.6 About one third of these (3% of unilateral incomplete cleft lips) were mini-microform clefts.

Too often these lesser anomalies are either overlooked or given insufficient attention by the neonatalogist or the pediatric attending in the nursery. Parents are commonly told not to worry because this minor birth defect is barely noticeable. Sometimes, they are counseled that the defect will improve with time, but if necessary, a minor procedure can be done when the child is older. Thus the first appointment with a plastic surgeon is often delayed. In my experience, the median age at presentation is 11 months (range, 2 weeks to 9 years).6 Clearly, neonatal specialists and pediatricians need to be educated that an infant with a microform cleft lip should be seen promptly. Referring physicians should know that a labial scar incurred in childhood or an older age is usually more obvious than a scar from an operation in infancy.

The surgeon who is fully focused on repair of a unilateral complete cleft lip and cleft palate may fail to notice a contralateral microform or mini-microform. In a retrospective review of my patients with unilateral clefts, a contralateral microform or mini-microform was present in 4% of unilateral incomplete and 2.5% of unilateral complete cleft lips. If these contralateral examples were included in demographic studies, the true incidence of bilateral labial clefting would be higher than reported in the literature.



Cardinal features of microform cleft lip include (1) a minor nasal deformity, (2) a philtral groove, (3) an indented free mucosal margin, and (4) a notched vermilion-cutaneous junction, with the disruption extending upward less than one fourth of labial height.7 Other labial abnormalities often include a slightly narrow medial vermilion and a strip of glabrous skin extending from the Cupid’s bow peak, partway up the lip. Although the white roll is disrupted, it is well formed in the medial and lateral segments.


The orbicularis oris muscular ring is incompletely formed in microform cleft lip; it has been variously described as being either malaligned or fibrotic.8,9 Stenström and Thilander10 noted that the pars alaris of the nasalis muscle is hypoplastic and suggested this accounts for the laterally displaced alar base. The philtral ridge is usually low; however, sometimes the medial side of the escarpment is overly prominent. A pathognomonic sign is the appearance of a furrow, just lateral to the line of the philtral ridge, as the child puckers the lips.9 In my dissections, I have observed that the pars marginalis of the orbicularis oris is often relatively well-formed, whereas the pars peripheralis is thin along the low-lying philtral ridge.

There is evidence for an “occult” cleft lip (that is, the appearance is normal, but the underlying muscle is abnormal). In a pilot study, Martin et al11 used labial ultrasonography and found a three-fold higher prevalence of minor hypoechoic defects of the orbicularis oris in first-degree relatives of subjects with cleft lip or palate in comparison with a control group. They suggested that this “subepithelial” orbicular discontinuity is a minor expression of the cleft phenotype. If such an occult cleft lip can be documented, this finding would be important for estimating recurrence risk and also would increase the power of genetic studies to identify putative genes that cause oral clefting.


In a microform, the nasal deformity is often more evident than the labial abnormality, although usually less obvious than the nasal distortion seen in incomplete cleft lip. The microform nasal tip is slightly flat, the nostril rim is a little drooped, hemicolumellar length is nearly normal, the sill is depressed, and the alar base is displaced laterally and somewhat underrotated. As a result, the nostril axis is more transverse than on the noncleft side.

Several investigators have suggested that, even in the absence of a microform labial cleft, such minor nostril asymmetry is at the far end of the spectrum of cleft lip. Fukuhara and Saito12,13 demonstrated unilateral nasopalatal bony abnormalities in a high proportion of apparently normal parents and siblings of children with cleft lip. Tolarová14 found a higher frequency of a depressed nostril in relatives of a child with a labial cleft and suggested this finding was an indicator of a genetic predisposition for this anomaly. Other investigators have shown no differences in the prevalence of nostril asymmetry in relatives of children with cleft lip or palate versus controls.15,16 Farkas and Cheung17 concluded that minor nostril distortions that resemble the cleft nasal deformity are rather common in the general population; they found these in 1.6% of otherwise healthy individuals.


Because a microform cleft is an expression of defective development of the primary palate, associated abnormalities of the teeth and alveolus are common. These include:

Bony deficiency around the lateral incisor12,13

Abnormal size, shape, and position of the lateral incisor18

Supernumerary tooth distal to the lateral incisor3

Impaction of the canine19

In one report, fathers of children with cleft lip had a higher prevalence of an impacted upper canine, as compared with a large noncleft control group.19 Earlier studies had shown no higher incidence of dental abnormalities in relatives of children with cleft lip or palate.20,21 Thus whether minor nasal asymmetries or dental anomalies represent a carrier state for cleft lip or palate remains unknown. Nevertheless, for genetic counseling and molecular studies, examining for a possibility of a microform in the parents and siblings of the child with overt cleft lip or palate is critical.22 Three cases have been reported of a microform cleft lip in association with an incomplete alveolar cleft and velar cleft or complete unilateral cleft of the secondary palate.6,23


In the literature on microform cleft lip, more attention has been paid to description and pathogenic speculation than to operative repair.6 Correction of a microform is commonly overlooked or only briefly addressed in surgical textbooks and atlases.

In the late nineteenth century, Nélaton described an inverted V-shaped incision, extending just above the cleft, converting the wound to a diamond shape that was closed vertically. The results using his method were considered unsatisfactory by early twentieth century standards. Veau also used a type of straight-line repair, similar to that described earlier by Rose24 and Thompson.25 He pared the edges of the microform, apposed the muscular elements, and completed the closure with careful attention to vermilion-mucosal height.1 LeMesurier26 adapted his rectangular flap method for “minor notches,” placing the medial join at the center of the lip. Based on panel assessment of photographs, Thomson and Delpero27 found no differences between the Tennison (low triangular flap) method and the Millard (rotation-advancement) technique for correction of microform cleft lip. The Rose-Thompson repair of a microform continued to have its advocates. Harding28 added a small releasing incision at the medial vermilion-cutaneous junction into which he inserted a small, laterally based, triangular flap. Musgrave29 illustrated an excellent result using straight-line closure but applied the rotation-advancement principle in his correction of another microform.

Millard30 wrote that between 1954 and 1976 he had repaired only two cleft lips without a cutaneous excision or rotation-advancement incisions: One patient needed only closure of a vermilion notch and the other presented as a vertical cutaneous groove that was elevated with a dermal graft. Millard also recalled an adult microform cleft lip that he corrected by direct excision of the philtral furrow, “reverse” rotation-advancement of the muscular layers, V-Y rolldown to build up the deficient mucosal border, and advancement of the alar base.

Onizuka7 devised several methods to address the particular distortions of a microform cleft lip rather than use the conventional methods for repair of complete forms. Many of these techniques for primary repair of microforms were derived from methods used for secondary cleft labial deformities. Onizuka exposes the hypoplastic orbicularis oris through Z-plasty incisions in the sill and at the vermilion-cutaneous junction. A superiorly based medial (“central”) muscular flap is transposed over the lateral muscular layer; this is “fixed” by through-and-through percutaneous sutures tied over bolsters on each side. In an editorial comment on Onizuka’s paper, Millard was adamant that bolster sutures do not give a permanent philtral elevation. Onizuka uses a Z-plasty to correct the vermilion-cutaneous notch and connects it to a second Z-plasty at the free mucosal margin. He also places a Z-plasty in the nostril sill so that the lateral limb elevates the depressed columellar base. A W-plasty is used to correct the minimally slumped alar rim; otherwise, Onizuka undermines, elevates, and secures the lower lateral cartilage to the ipsilateral upper lateral cartilage.

For microform cleft lip, Cho31,32 described a transmucosal repair of the thin orbicularis oris along the philtral line. Through a sagittal mucosal incision on the posterior side of the lip, he dissects the muscular layers, leaving the most anterior lamella, splits the muscles into two leaves in the coronal plane, and vertically interdigitates the flaps to build a thick muscular ridge. The anterior leaflet of the lateral muscular flap is sutured to the dermis to emphasize the philtral dimple. He uses a Z-plasty at the notched vermilioncutaneous junction and a reverse-U incision and V-Y-plasty for the nasal deformity.31



Closure of a minor-form cleft lip follows the rotation-advancement principle and employs much the same, but less extensive, technical maneuvers as for a complete form.33 The rotation incision extends just to the columellar base. The C-flap is elevated in the medial sill and needs only slight retrogression to lengthen the hemicolumella. A short perialar incision is needed to disjoin the alar base from the lateral labial element. The alar base is advanced into symmetrical position and secured to the C-flap and to underlying muscle. Because the rotational incision does not cross the philtral line, the lip will need a little further elongation. The medial Cupid’s bow peak is lowered by a short vermilion-cutaneous incision and advancement and inset of a tiny (2 mm or less), laterally based, triangular flap of white roll and cutaneous lip. The slumped and often splayed lower lateral cartilage is exposed through a rim incision and secured to the opposite genu and ipsilateral upper lateral cartilage (Fig. 42-2).


May 11, 2019 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Microform Cleft Lip
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