The face is unique, both because of variability in size and shape and because of personal expression and emotion. Movements around the eyes and mouth contribute to the overall gestalt. Evaluation of the craniofacies is complex.
The development of the shape of the human head and face depends on a variety of interactive genetic and environmental factors. Intrinsic or extrinsic pressure and neuromuscular function contribute to the overall shape. Both nature and nurture should be considered when evaluating the individual with unusual craniofacial structures.
To define properly what is different in the individual with dysmorphic craniofacial features is a challenge. Comprehensive anthropometric descriptions have become available for many conditions for which data were previously lacking, and standards have been developed for several disorders so that affected children can be compared with their similarly affected peers and normal family members.
For practical purposes, in this text, we have limited the craniofacial measurements to those we find useful. The reader will find further details in references at the end of this chapter.
Development of the face from five facial primordia appearing around the stomodeum or primitive mouth occurs mainly between the fifth and eighth weeks of gestation. The five facial primordia consist of the frontonasal prominence, the paired maxillary prominences of the first branchial arch, and the paired mandibular prominences of the first branchial arch. The frontonasal prominence forms the forehead and the dorsum and apex of the nose. The alae nasi are derived from the lateral nasal prominences. The fleshy nasal septum and the philtrum are formed by the medial nasal prominences. The maxillary prominences form the upper cheek regions and most of the upper lip. The mandibular prominences give rise to the lower lip, the chin, and the lower cheek regions.
The primitive lips and cheeks are invaded by second branchial arch mesenchyme giving rise to the facial muscles. These muscles of facial expression are supplied by the facial nerve. The mesenchyme of the first pair of branchial arches gives rise to the muscles of mastication, which are innervated by the trigeminal nerve.
Maldevelopment of the components of the first branchial arch results in various congenital malformations of the eyes, ears, mandible, and palate. Maldevelopment is generally believed to be caused by insufficient migration or proliferation of cranial neural crest cells into the first branchial arch.
Development of the tongue, face, lips, jaws, palate pharynx, and neck largely involves transformation of the branchial apparatus into adult structures. Most congenital malformations of the head and neck originate during that transformation (e.g., branchial cysts, sinuses, fistulae). Because of the complicated development of the face and palate, congenital malformations resulting from an arrest of development and/or a failure of fusion of the prominences and processes are not uncommon.
There is also rapid growth of the face and jaws coinciding with the eruption of the deciduous teeth. These changes are even more marked after the permanent teeth erupt. There is concurrent enlargement of the frontal and facial regions associated with the increase in size of the perinasal air sinuses, which are generally rudimentary or absent at birth. Growth of the sinuses is important in altering the shape of the face.
Measurement of the craniofacies requires only a few standard instruments: sliding and spreading calipers and a tape-measure. In addition, a modified protractor and an instrument to determine ear location and rotation are useful but not essential. A general rule when measuring between two soft tissue landmarks is that the hard tips of the calipers touch but do not press on the skin surface. In contrast, when measuring between bony landmarks, the blunt pointers of the calipers are presented against the bony surface. When measuring the circumference, the length, or the width of the head, the examiner must be certain that the metric tape or the tips of the calipers are sufficiently pressed against the skull to eliminate the effect of thick hair cover. Accurate measurement requires correct use of the instrument and knowledge of the peculiarities of the landmark. For this reason, we have provided detailed explanations of measurement techniques and pitfalls for each particular parameter.
For measurement of the craniofacies, it is often easiest to have the head resting on a head support from a chair. However, this is not always possible in the field. If necessary, an assistant may gently hold the subject's head. Full exposure of the soft nose (alar shape, columella, nasal floor, nostrils) in the frontal plane is facilitated if the head is in the reclining position. Orbital measurements are most easily obtained when the patient's body is in a recumbent position with the eyes gazing straight up to the ceiling and the plane of the facial profile in the vertical.
The standard orientation of the head for craniofacial measurement is the Frankfort horizontal (FH). In this position, the line connecting the lowest point on the lower margin of each bony orbit (orbitale) and the highest point on the upper margin of the cutaneous external auditory meatus (porion) is horizontal. When the subject is recumbent, the FH becomes vertical.
An alternative head position (the rest position) is determined by the subject's own feeling of the natural head balance. In healthy persons, in the rest position, the inclination of the line connecting the orbitale and the porion (ear opening) is about 5 degrees higher than it is in the FH. Since the subject's head tends to return to the rest position during examination, head position must be rechecked before each measurement. Correct positioning techniques and use of standard landmarks are important, not only for the evaluation of the normal face, but particularly in the assessment of subjects with a cranial or facial anomaly. The most common palpable landmarks of the craniofacies are shown in Fig. 7.1, and a full definition of each of these landmarks is present in the Glossary.
An alternative approach to craniofacial measurement involves a photoanthropometric method using frontal and profile photographs. Photographs are standardized (one-fifth, one-fourth, one-third, one-half, or life-size) for quantification of surface features, to allow scientific, accurate documentations. Some centers prefer to have the patient free-standing, while other researchers have developed complex machinery to keep the patient in a fixed position at a defined distance from the camera. Details and sources of error are available in articles listed in the bibliography.
Another approach to craniofacial measurement involves craniofacial pattern profile analysis, which provides a simple and readily understandable method of classifying, illustrating, and comparing pattern deviations from the normal state. Measurements, from radiographs of the head and face are converted into normalized z scores (standard deviation units). After conversion into z scores, the pattern profile can be presented in simple graphic form. The reader is directed to the bibliography at the end of this chapter for further details.
A fourth approach to craniofacial measurement, cephalometry, employs radiography. For most analyses, only lateral cephalograms are taken. Most radiographic head films are still taken according to the standards of Holly Broadbent, who established them more than 50 years ago. His format for taking head films was quickly adopted by the scientific community because of the consensus that his instrumentaion, radiographs, and data were impeccable. Probably his major contribution was designing a cephalostat or orthodontic head-holder. Although the clinical
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