Absence of the lateral philtral ridges: a clue to the structural basis of the philtrum

Muscle Flap Reconstruction Based on Muscle Tension Line Groups to Repair the Philtrum of Patients With Microform Cleft Lip or Secondary Cleft Lip

ABSTRACT

The muscle flap reconstruction technique was developed based on the concept of muscle tension line groups, which elucidates how nasolabial muscle tension helps maintain the shape of the philtrum. To investigate the operative effect, we reviewed 43 patients with microform cleft lip and 102 patients with secondary cleft lip treated with muscle flap reconstruction between January 2018 and June 2020. The patients were scanned using the digital three-dimensional stereophotogrammetry face system pre- and post-operatively, and comparative analysis of three-dimensional (3D) images was used to highlight variations of the philtrum. Visual analog scales were used to assess surgical outcomes. More than 6 months after the surgery, comparative 3D images of 37 patients (86.04%) with microform cleft lip and 86 patients (84.31%) with secondary cleft lip showed visible improvement in the prominence of the affected column. In addition, visual analog scale scores showed that 38 microform cleft lip patients (88.37%) and 89 secondary cleft lip patients (87.25%) had a good appearance. The postoperative prominence of the philtral column in both groups improved significantly compared to before surgery (P < 0.001 and P < 0.001, respectively). There was no significant difference in scores for philtrum prominence pre- and post-operatively between the 2 groups (P > 0.05). Muscle flap reconstruction is an effective means to create the 3D configuration of the philtrum. The biomechanical properties of muscles play a vital role in the morphological maintenance of the philtrum.

A review of the physical features of the fetal alcohol spectrum disorders

The fetal alcohol spectrum of disorders (FASD) includes four diagnostic categories for the clinical consequences of prenatal alcohol exposure (PAE) in the unborn child. Physical features are necessary for the diagnosis of the fetal alcohol syndrome (FAS) and partial pFAS. Moreover, these features are specific and a diagnosis of FAS can be made even in the absence of knowledge of PAE. Not only growth deficits, microcephaly and the 3 facial features (short palpebral fissures, smooth philtrum and narrow vermillion of the upper lip) are characteristic, since other dysmorphic features particularly in the hands are key to the recognition of FAS. Most features can be explained by the damage to the brain during pregnancy and can be replicated in animal models. Many different diagnostic guidelines are used for the diagnosis of FASD and the physical features are considered differently in each of them. There is a need for universal clinical criteria for the diagnosis of FASD if our goal is to favor universal recognition.

The philtrum in cleft lip: review of anatomy and techniques for construction

The philtrum is imperfectly formed in both unilateral and bilateral cleft lip. Surgical construction of this exquisite feature in the upper lip is challenging and often takes a back seat to construction of Cupid's bow and the nose. However, the philtrum is one of the defining features of a normal lip. The purpose of this review is to compile information on philtral anatomy and techniques for construction to guide the reader on his or her own quest to optimize cleft lip repair. In this article, we review the normal anatomy of the philtral dimple and ridges, with particular attention to pars peripheralis configuration. We also review methods for philtral construction during primary labial repair and secondary labial revision. For unilateral cleft lip, eversion of orbicularis oris muscle is necessary to build a philtral ridge. For bilateral cleft lip, emphasis is on proper design of the philtral flap and efforts to simulate a dimple and ridges. For secondary philtral correction, techniques include complete labial revision with various types of muscular re-repair and autologous philtral ridge augmentation. Objective methods are needed to document the efficacy of the many techniques for philtral construction and reconstruction.

Electrophysiological method to examine muscle fiber architecture in the upper lip in cleft-lip patients

OBJECTIVES

The upper lip's musculature comprises several muscle fiber groups with different spatial orientations for various lip movements. In the past, it has not been possible to describe these various groups and their motor units in detail with traditional methods of electromyography (EMG). The purpose of this investigation was to create a viable method for studying the architecture of upper-lip muscle fibers in patients with surgically closed cleft lip by refining the design of a flexible electrode array for multichannel EMG.

METHODS

Calibrated perioral photographs of 36 adult subjects were used to determine the basic geometry of an electrode array for use on different facial shapes. A total of 256 chloride silver electrodes, 1 mm in diameter, were distributed over this geometry to form a grid with interelectrode distances of 2.5 mm. Technical implementation of the electrode array was based on a modified technique used for flexible printed circuit boards. A double-sided adhesive tape with perforations was used to apply the array to the skin in the upper-lip area. Surface EMG signals were recorded while the subjects were performing various lip movements and exerting specific lip forces. The latter were recorded with a specially developed transducer.

RESULTS

Despite an extremely dense grid of electrodes associated with downsized contacts, the electrode array could be precisely applied to the perforated adhesive tape. The electrode array remained firmly attached to the skin even during extensive lip movements. The recorded EMG signals offered high baseline stability and a strong signal-to-noise ratio, thus, allowing us to extract individual motor unit action potentials (MUAPs). Spatiotemporal tracking of MUAPs succeeded in demonstrating the course of muscle fibers belonging to individual motor units. Pilot measurements taken on subjects with surgically closed unilateral cleft lip revealed an asymmetric distribution of muscle activity surrounding the closed cleft-lip segments.

CONCLUSION

Our refined noninvasive electrophysiological method is capable of providing detailed information about muscle fiber architecture and the position, size, and organization of motor units in the lip area. It is thus feasible to conduct further studies to analyze differences in muscle morphology and motor control between surgically treated cleft-lip patients and noncleft individuals.

Mutations in Hedgehog acyltransferase (Hhat) perturb Hedgehog signaling, resulting in severe acrania-holoprosencephaly-agnathia craniofacial defects

Holoprosencephaly (HPE) is a failure of the forebrain to bifurcate and is the most common structural malformation of the embryonic brain. Mutations in SHH underlie most familial (17%) cases of HPE; and, consistent with this, Shh is expressed in midline embryonic cells and tissues and their derivatives that are affected in HPE. It has long been recognized that a graded series of facial anomalies occurs within the clinical spectrum of HPE, as HPE is often found in patients together with other malformations such as acrania, anencephaly, and agnathia. However, it is not known if these phenotypes arise through a common etiology and pathogenesis. Here we demonstrate for the first time using mouse models that Hedgehog acyltransferase (Hhat) loss-of-function leads to holoprosencephaly together with acrania and agnathia, which mimics the severe condition observed in humans. Hhat is required for post-translational palmitoylation of Hedgehog (Hh) proteins; and, in the absence of Hhat, Hh secretion from producing cells is diminished. We show through downregulation of the Hh receptor Ptch1 that loss of Hhat perturbs long-range Hh signaling, which in turn disrupts Fgf, Bmp and Erk signaling. Collectively, this leads to abnormal patterning and extensive apoptosis within the craniofacial primordial, together with defects in cartilage and bone differentiation. Therefore our work shows that Hhat loss-of-function underscrores HPE; but more importantly it provides a mechanism for the co-occurrence of acrania, holoprosencephaly, and agnathia. Future genetic studies should include HHAT as a potential candidate in the etiology and pathogenesis of HPE and its associated disorders.

Craniofacial anomalies account for approximately one third of all birth defects, and holoprosencephaly (HPE) is the most common structural malformation of the embryonic brain. HPE is a failure of the forebrain to bifurcate and is a heterogeneous disorder that is often found in patients together with other craniofacial malformations. Currently, it is not known if these phenotypes arise through a common etiology and pathogenesis, as the genetic lesions responsible for HPE have only been identified in about 20% of affected individuals. Here we demonstrate for the first time that Hedgehog acyltransferase (Hhat) loss-of-function leads to holoprosencephaly together with acrania and agnathia, which highlights the importance of Hh signaling in complex craniofacial disorders.

The morphological features and developmental changes of the philtral dimple: a guide to surgical intervention in cases of cleft lip

OBJECTIVE

This study was undertaken to analyse in detail the morphological features of the philtral dimple and the developmental changes of philtral morphology, including a comparison with patients with a cleft lip.

PATIENTS AND PARTICIPANTS

Fifty-five normal Japanese adults, seventy-five children and fifteen patients with complete unilateral cleft lip were referred for analysis.

DESIGN

3D facial data were acquired with a non-contacting laser scanner. We calculated the desired linear and angular components, defining the features of the philtrum with analysing software.

RESULTS

The philtral dimple was morphologically expressed by the two different deepest points in the horizontal and sagittal sectional view, respectively. These decreased with age and did not show any correlation. In contrast, philtral measurements on the X-Y coordinates increased during the course of development. Most of the linear and angular variables in the patients with the cleft lip had exhibited greater values than the normal subjects, reflecting the deformed philtral morphology.

CONCLUSIONS

To obtain an optimally natural philtral construction accompanied by a symmetrical lip in cleft surgery, it is critical to take into consideration both the geometric features of the philtral depth and age-appropriate morphological features of the philtrum as objective criteria.

Wnt signaling mediates regional specification in the vertebrate face

At early stages of development, the faces of vertebrate embryos look remarkably similar, yet within a very short timeframe they adopt species-specific facial characteristics. What are the mechanisms underlying this regional specification of the vertebrate face? Using transgenic Wnt reporter embryos we found a highly conserved pattern of Wnt responsiveness in the developing mouse face that later corresponded to derivatives of the frontonasal and maxillary prominences. We explored the consequences of disrupting Wnt signaling, first using a genetic approach. Mice carrying compound null mutations in the nuclear mediators Lef1 and Tcf4 exhibited radically altered facial features that culminated in a hyperteloric appearance and a foreshortened midface. We also used a biochemical approach to perturb Wnt signaling and found that in utero delivery of a Wnt antagonist, Dkk1,produced similar midfacial malformations. We tested the hypothesis that Wnt signaling is an evolutionarily conserved mechanism controlling facial morphogenesis by determining the pattern of Wnt responsiveness in avian faces,and then by evaluating the consequences of Wnt inhibition in the chick face. Collectively, these data elucidate a new role for Wnt signaling in regional specification of the vertebrate face, and suggest possible mechanisms whereby species-specific facial features are generated.

Holoprosencephaly: clinical, anatomic, and molecular dimensions

Holoprosencephaly is addressed under the following headings: alobar, semilobar, and lobar holoprosencephaly; arrhinencephaly; agenesis of the corpus callosum; pituitary abnormalities; hindbrain abnormalities; syntelencephaly; aprosencephaly/atelencephaly; neural tube defects; facial anomalies; median cleft lip; minor facial anomalies; single maxillary central incisor; holoprosencephaly-like phenotype; epidemiology; genetic causes of holoprosencephaly; teratogenic causes of holoprosencephaly; SHH mutations; ZIC2 mutations; SIX3 mutations; TGIF mutations; PTCH mutations; GLI2 mutations; FAST1 mutations; TDGF1 mutations; and DHCR7 mutations.

Malformations of the craniofacial region: evolutionary, embryonic, genetic, and clinical perspectives

Malformations of the craniofacial region are reviewed with respect to evolutionary, embryonic, genetic, and clinical perspectives under the following headings: How Old Is Our Head?, Head Organization Genes, Genetics of Craniofacial Anomalies, Craniofacial Derivatives, Anencephaly, Cephalocele, Holoprosencephaly, Craniosynostosis, Hypertelorism, Branchial Arch Anomalies, and Orofacial Clefting.

Genetic approaches to understanding brain development: holoprosencephaly as a model

Holoprosencephaly (HPE) is the most common major developmental defect of the forebrain in humans. Clinical expression is variable, ranging from a small brain with a single cerebral ventricle and cyclopia to clinically unaffected carriers in familial HPE. Significant etiologic heterogeneity exists in HPE and includes both genetic and environmental causes. Defects in the cell signaling pathway involving the Sonic Hedgehog (SHH) gene, as well as defects in the cholesterol biosynthesis have been shown to cause HPE in humans. More recently, HPE genes from additional signaling pathways have been identified. These discoveries and current genetic approaches serve as a paradigm for studying normal and abnormal brain morphogenesis. MRDD Research Reviews 6:15-21, 2000.

Fetal alcohol syndrome: changes in craniofacial form with age, cognition, and timing of ethanol exposure in the macaque

One component of the fetal alcohol syndrome (FAS) facial phenotype is a frontonasal anomaly characterized by a thin upper lip and a smooth philtrum. The expression of this anomaly can diminish with age and occurs infrequently in prenatal alcohol-exposed individuals. This study sought to explain these observations. Standardized craniofacial cephalograms of 18 nonhuman primates exposed weekly to ethanol or sucrose solution in utero were measured at ages 1, 6, 12, and 24 months to assess skeletal changes in craniofacial form with age, cognition, and timing of ethanol exposure. The data suggest that there may be a critical period for induction of alcohol-induced craniofacial alterations that occurs very early in gestation and is very short in duration (gestational days 19 or 20). The alterations were scarcely detectable at age 1 month, were most prominent at 6 months, and diminished progressively at 12 and 24 months in the macaque. The appearance and disappearance of the thin upper lip and smooth philtrum may be explained by underlying changes in skeletal structure with age. The infrequent occurrence of the FAS frontonasal anomaly may be explained, in part, by its short critical period of induction.

Absence of the superior labial frenulum in holoprosencephaly: a new diagnostic sign

The upper lip of 17 consecutive individuals with various forms of holoprosencephaly were examined either at autopsy or during clinical evaluation. A total of 88% of cases were missing the superior labial frenulum regardless of the severity of holoprosencephaly or other associated craniofacial defects. Because the frenulum was found to be missing across a complete clinical spectrum of holoprosencephaly including cases exhibiting only minimal craniofacial features, it should be inspected as part of the craniofacial examination, and its absence should be prompt imaging studies of the brain. Absence of the frenulum in holoprosencephaly also provides evidence that its embryonic origin is that of the medial nasal process.