Fetal face and neck





Objectives


On completion of this chapter, you should be able to:




  • Discuss basic embryology of the face



  • Describe how to evaluate the fetal face and neck for normal features



  • Describe the sonographic findings of abnormalities of the fetal face and neck





Congenital anomalies of the face affect 1 in 600 births. Cleft lip, hypotelorism, hypertelorism, and micrognathia are examples of facial problems that may be found by ultrasound during pregnancy. Cleft lip and/or palate is the most common of these congenital anomalies and represents the fourth most common fetal face abnormality in the United States. Many anomalies of the face and neck can be caused by maternal drug use ( Table 59-1 ). As in other investigations, the detection of subtle facial malformations depends on the sonographer’s skill and ability to recognize facial pathology, the position of the fetus, maternal body habitus, uterine pathology, the amount of amniotic fluid near the face, and the availability of three-dimensional (3D)/four-dimensional (4D) volume ultrasound.



TABLE 59-1

Potential Fetal Malformations Associated with Maternal Drug Use and Infectious Disease



























































































































































































Drug Fetal Malformation(s)
Albuterol Tachycardia
Alcohol (ethanol) Microcephaly, micrognathia, cleft palate, short nose, hypoplastic philtrum, cardiac defects (VSD, ASD, double-outlet right ventricle, pulmonary atresia, dextrocardia, tetralogy of Fallot), IUGR, diaphragmatic hernia, pectus excavatum, radioulnar synostosis, scoliosis, bifid xiphoid, NTDs
Amantadine Cardiac defects (single ventricle with pulmonary atresia)
Aminopterin NTDs, hydrocephalus, incomplete skull ossification, brachycephaly, micrognathia, clubfoot, syndactyly, hypoplasia of thumb and fibula, IUGR
Angiotensin-converting enzyme (ACE) inhibitors Hypocalvaria, oligohydramnios, neonatal renal failure, hypotension, pulmonary hypoplasia, joint contractures, IUGR, stillbirth
Antithyroid drugs Goiter
Aspirin (Bayer, St. Joseph) Slight increased risk for gastroschisis; premature closure of the ductus arteriosus; intracranial hemorrhage in premature or LBW infants
Bromides Polydactyly, clubfoot, congenital hip dislocation
Busulfan Pyloric stenosis, cleft palate, microphthalmia, IUGR
Caffeine Musculoskeletal defects, hydronephrosis
Captopril Leg reduction
Carbamazepine NTDs, cardiac defects (atrial septal defect), nose hypoplasia, hypertelorism, cleft lip, congenital hip dislocation
Carbon monoxide Cerebral atrophy, hydrocephalus, fetal demise
Chlordiazepoxide Microcephaly, cardiac defects, duodenal atresia
Chloroquine Hemihypertrophy
Chlorpheniramine Hydrocephalus, polydactyly, congenital hip dislocation
Chlorpropamide Microcephaly, dysmorphic hands and fingers
Clomiphene NTDs, microcephaly, syndactyly, clubfoot, polydactyly, esophageal atresia
Cocaine Spontaneous abortion, placental abruption, prematurity, IUGR, possible cardiac defects, skull defects, genitourinary anomalies
Codeine Hydrocephalus, head defects, cleft palate, musculoskeletal defects, dislocated hip, pyloric stenosis, respiratory malformations
Cortisone Hydrocephalus, cardiac defects (VSD, coarctation of aorta), clubfoot, cleft lip
Coumadin NTDs, cardiac defects, scoliosis, skeletal deformities, nasal hypoplasia, stippled epiphyses, chondrodysplasia punctata, short phalanges, toe defects, incomplete rotation of gut, IUGR, bleeding
Cyclophosphamide Cardiac defects, cleft palate, flattened nasal bridge, four toes on each foot, syndactyly, hypoplastic midphalanx, craniosynostosis, microcephaly, hypotelorism, blepharophimosis, microphthalmos, shallow orbits with proptosis, malformed ears, flat nasal bridge with bulbous nasal tip
Cytarabine NTDs, cardiac defects, lobster claw hand, missing digits of feet, syndactyly
Cytomegalovirus Microcephaly, ventricular dilatation, cerebral calcification, ascites, hepatosplenomegaly, chorioretinitis, IUGR
Diazepam NTDs, cardiac defects, absence of arm, syndactyly, absence of thumbs, cleft lip and palate
Diethylstilbestrol Structural abnormalities of the cervix, vagina, uterine cavity; epididymal cysts, hypoplastic testes, cryptorchidism
Diuretics Respiratory malformations
Estrogens Cardiac defects, limb reduction
Fluconazole Brachycephaly, micrognathia, trigonocephaly, low ears, abnormal calvarial development, cleft palate, femoral bowing, thin ribs, humeral-radial fusion, arthrogryposis, heart defects
Fluorouracil Radial aplasia, absent thumbs, aplasia of esophagus and duodenum, hypoplasia of lungs
Heparin Bleeding
Imipramine NTDs, cleft palate, renal cysts, diaphragmatic hernia
Indomethacin Fetal demise, hemorrhage
Lithium NTDs, cardiac defects (VSD, Ebstein’s anomaly, mitral atresia, dextrocardia)
Lymphocytic choriomeningitis virus Hydrocephalus, intracranial calcifications, chorioretinitis
Methotrexate Oxycephaly, absence of frontal bones, large fontanels, micrognathia, long, webbed fingers, low-set ears, IUGR, dextrocardia
Methyl mercury Microcephaly, asymmetric head
Metronidazole Midline facial defects
Oral contraceptives NTDs, cardiac defects, vertebral defects, limb reduction, IUGR, tracheoesophageal malformation
Parovirus B19 Hydrocephalus, myocarditis, hydrops, stillbirth
Penicillamine (Cuprimine, Depen) Cutis laxa
Phenobarbital (Luminal) Hypoplastic fingernails, epicanthal folds, broad, depressed nasal bridge, short nose with long philtrum, increased risk for heart disease, oral clefts, urinary tract defects, hemorrhage
Phenylpropanolamine (Acutrim, Dexatrim, Phenyldrine) Slightly increased risk for gastroschisis; theoretic risk for bradycardia
Phenytoin (Dilantin, Phenytek) Coarctation of aorta, cardiac septal defects, microcephaly, wide anterior fontanelle, ocular hypertelorism, broad, depressed nasal bridge, short nose with bowed upper lip, short neck, cleft lip and palate, hypoplastic fingernails, growth deficiency
Primidone Cardiac defects (VSD), webbed neck, small mandible
Pseudoephedrine (Sudafed) Slightly increased risk for gastroschisis
Quinine Hydrocephalus, cardiac defects, facial defects, vertebral anomalies, dysmelias
Rubella Microcephaly, cataract, glaucoma, corneal opacity, chorioretinitis, microphthalmos, strabismus, patent ductus arteriosus, pulmonic stenosis, septal defects, growth deficiency; occasionally—hypospadias and cryptorchidism
Sulfasalazine (Azulfidine) Slightly increased risk for heart defects, oral clefts, and urinary tract defects
Tetracycline Limb hypoplasia, clubfoot
Thalidomide Cardiac defects, spine defects, limb reduction (amelia), phocomelia, hypoplasia, duodenal stenosis or atresia, pyloric stenosis
Thioguanine Missing digits
Tobacco IUGR
Toluene IUGR, neonatal hyperchloremia acidosis, possible mental dysfunction, cardiac defects, dysmorphic facies
Trifluoperazine Cardiac defects, phocomelia
Trimethadione Microcephaly, low-set ears, broad nasal bridge, cardiac defects (ASD, VSD), IUGR, cleft lip and palate, esophageal atresia, malformed hands, clubfoot
Valproic acid NTDs, microcephaly, wide fontanelle, cardiac defects, IUGR, cleft palate, hypoplastic nose, low-set ears, small mandible, depressed nasal bridge, polydactyly
Varicella Microcephaly, chorioretinitis, limb hypoplasia (with or without digits), clubfoot, cutaneous scars, growth deficiency
Warfarin (Coumadin) Nasal hypoplasia, depressed nasal bridge, stippling of uncalcified epiphyses, mild hypoplasia of nails, shortened fingers

ASD, Atrial septal defect; IUGR, intrauterine growth restriction; LBW, low birth weight; NTDs, neural tube defects; VSD, ventricular septal defect.

From Nyberg DA, Mahoney BS, Pretorius DH: Diagnostic ultrasound of fetal anomalies: text and atlas, St Louis, 1990, Mosby; and Nyberg DA, McGahan JP, Pretorius DH, Pilu G, editors: Diagnostic imaging of fetal anomalies, ed 2, Philadelphia, 2003, Lippincott Williams & Wilkins.




Embryology of the fetal face and neck


In its fourth week, the embryo has characteristic external features of the head and neck area in the form of a series of branchial arches, pouches, grooves, and membranes. These structures are referred to as the branchial apparatus and bear a resemblance to gills.


There are six branchial arches, but only the first four are visible externally ( Figure 59-1 , A ). The arches are separated by branchial grooves, and each is composed of a core of mesenchymal cells. The mesenchyme forms the cartilage, bone, muscle, and blood vessels.




FIGURE 59-1


A, Lateral view of the embryo at 28 days shows four of the six branchial arches, otic pit, and stomodeum. B, Frontal view of the embryo at 24 days demonstrates the nasal placode, maxillary prominence, and mandibular prominence.


The first branchial arch is also known as the mandibular arch; it forms the jaw, zygomatic bone, ear, and temporal bone ( Figure 59-1 , B ). The second branchial arch contributes to the hyoid bone.


The branchial arches consist of mesenchymal tissue derived from intraembryonic mesoderm covered by ectoderm and containing transderm. Neural crest cells migrate into the branchial arches and proliferate, resulting in swelling that demarcates each arch. The neural crest cells develop the skeletal parts of the face, and the mesoderm of each arch develops the musculature of the face and neck.


The maxillary prominences arise from the first branchial arch and grow cranially just under the eyes and the mandibular prominence, which grows inferiorly. The primitive mouth is an indentation on the surface of the ectoderm (referred to as the stomodeum ) ( Figure 59-2 ). By the fifth week of development, five prominences are identified: the frontal nasal prominence, forming the upper boundary of the stomodeum; the paired maxillary prominences of the first branchial arch, forming the lateral boundaries of the stomodeum; and the paired mandibular prominences, forming the caudal boundary.




FIGURE 59-2


Views of the embryo at 33 days show the stomodeum, lateral nasal prominence, and cervical sinus.


The nasal pits are formed as the surface ectoderm thickens into the nasal placodes on each side of the frontal nasal prominence; as these placodes invaginate, the nasal pits are formed ( Figure 59-3 ). Until 24 to 26 days of gestation, the stomodeum is separated from the pharynx by a membrane that ruptures by about the 26th day to place the primitive gut in communication with the amniotic cavity.




FIGURE 59-3


Frontal view of the embryo at 40 days shows the nasal pit and the medial nasal prominence.


The maxillary prominences grow medially between the fifth and eighth weeks. This growth compresses the medial nasal prominences together toward the midline. The two medial nasal prominences and the two maxillary prominences lateral to them fuse together to form the upper lip ( Figure 59-4 ). The medial nasal prominences form the medial aspect of the lip, which is the origin of the labial component of the lip, the upper incisor teeth, and the anterior aspect of the primary palate. The lateral nasal prominences form the alae of the nose. The maxillary prominences and lateral nasal prominences are separated by the nasolacrimal groove. The ectoderm in the floor of this groove forms the nasolacrimal duct and lacrimal sac.




FIGURE 59-4


First-trimester development of the roof of the mouth showing formation of the upper lip and palate.


The nose is formed in three parts. The bridge of the nose originates from the frontal prominence, the two medial nasal prominences form the crest and tip of the nose, and the lateral nasal prominences form the sides, or alae. The mandibular prominences merge at the end of the fourth to fifth week and form the lower lip, chin, and mandible.




Sonographic evaluation of the fetal face


Fetal facial evaluation is not routinely included in a basic fetal scan; however, when there is a family history of craniofacial malformation, or when another congenital anomaly is found, the face should be screened for a coexisting facial malformation. Many fetuses with a facial defect also have chromosomal abnormalities. Extensive facial screening may be hindered by bone shadowing, poor fetal position, oligohydramnios, uterine pathology, or maternal obesity. Certain facial anomalies often indicate a specific syndrome or condition (e.g., orbital fusion and a proboscis suggest alobar holoprosencephaly). The use of 3D and 4D ultrasound reconstruction has been shown in recent years to be a useful adjunct to conventional two-dimensional (2D) assessment of the fetal face ( Box 59-1 and Figures 59-5 to 59-8 ).



BOX 59-1

Sonographic Points to Remember





  • Features of the fetal face can be identified at the end of the first trimester.



  • The fetal profile is well imaged with transvaginal sonography beginning late first trimester to early second trimester (make sure adequate amniotic fluid surrounds the face) (see Figure 59-5 ).



  • The modified coronal view is best for imaging the cleft lip and palate (see Figure 59-6 ).



  • The maxilla and orbits are well imaged in a true coronal plane.



  • The lens of the eye is seen as a small echogenic circle within the orbit (see Figure 59-7 ).



  • The longitudinal view demonstrates the nasal bones, soft tissue, and mandible (useful to rule out micrognathia, anterior encephalocele, or nasal bridge defects; examine upper lip) (see Figure 59-8 ).



  • Transverse view shows orbital abnormalities and intraorbital distances (useful to evaluate the maxilla, mandible, and tongue).





FIGURE 59-5


The fetal profile is well seen with amniotic fluid surrounding the face. This is a useful plane to image the forehead, nose, lips, and chin.



FIGURE 59-6


A, Axial view through the upper (ul) and lower lip (ll) in a fetus with an open mouth. Note the nares (n) and nasal septum. This view is used to check for a cleft of the upper lip. B, In another fetus, the nasal septum is well seen and the vermilion tissue of the lips can be differentiated.



FIGURE 59-7


A, Coronal view showing facial features. Lens (l), zygomatic bone (z), maxilla (x), upper lip (ul), lower lip (ll), mandible (m), nasal bones (n). B, In the same fetus, in a more anterior coronal view, the upper and lower eyelids (arrows) and the nose (n) are shown.



FIGURE 59-8


A, Sagittal view in a 23-week fetus showing the contour of the face in profile. Note the smooth surface of the frontal bone (f) and the appearance of the nose, upper and lower lips, tongue (t), and chin (c). B, Coronal facial view in an 18-week fetus revealing a wide-open mouth. Note the nasal bones between the orbits (o).


Facial anomalies are heterogeneous and occur as isolated defects or as part of a syndrome. A family history of a facial anomaly (e.g., cleft lip) may prompt a targeted study, although recurrence risks are relatively low (less than 5%). Hemangiomas and teratomas may occur anywhere on the body, and the fetal head and neck are no exception. Any mass should be investigated with color Doppler to delineate any vascular characteristics ( Figure 59-9 ).




FIGURE 59-9


A, A soft tissue mass is seen overlying the fetal forehead (arrow). B, Color Doppler demonstrates the mass to have vascular flow within, suggesting a hemangioma.




Abnormalities of the face and neck


Abnormalities of the facial profile


Forehead.


The fetal forehead may be appreciated by evaluation of the profile. This is achieved by a series of midsagittal scans through the face. The fetal forehead (frontal bone) appears as a curvilinear surface with differentiation of the nose, lips, and chin seen inferiorly. This view allows diagnosis of anterior cephaloceles, which may arise from the frontal bone or midface. Sonographic findings of anterior cephaloceles will demonstrate abnormal profile and facial angle, changes in the sagittal position of the fetal face, and may cause widely spaced orbits (hypertelorism) ( Boxes 59-2 and 59-3 ).



BOX 59-2

Questions for the Sonographer Evaluating Facial Profile





  • Are the orbits normally spaced?



  • Are the nose and nasal bridge clearly imaged; is a proboscis or cebocephaly present?



  • Are any periorbital masses apparent?



  • Is the upper lip intact?



  • Is the tongue normal size?



  • Is the chin abnormally small?



  • Are the ears of normal size and in normal position?




BOX 59-3

Sonography of the Facial Profile





  • Use midsagittal scans through the face to assess the following:



  • Curvilinear surface with differentiation of forehead, nose, lips, and chin



  • Clover-leaf skull: appears as misshapened skull with clover-leaf appearance



  • Frontal bossing: may appear as lemon-shaped skull or absent, depressed nasal bridge



  • Strawberry-shaped cranium: bulging of frontal bones and wide occiput



  • Masses of nose and upper lip: distortion of facial profile (look for cleft lip)




Off-axis, or nonmidline, encephaloceles have also been reported with amniotic band syndrome. This occurs when the amnion disrupts early in the embryonic period, leaving strands of tissue within the uterus that may lead to malformation of the fetus.


Forehead hemangiomas are benign tumors composed of blood vessels and are less commonly found. The forehead is an unusual location for hemangiomas; if they are identified, the tumor will most likely be a large tumor and found during the third trimester. A high-resolution transducer in conjunction with 3D ultrasound should be used if one suspects this abnormality.


Skull.


Craniosynostosis (premature closure of any or all six of the cranial sutures) causes the fetal cranium to become abnormally shaped. Clover-leaf skull (Kleeblattschädel) appears as an unusually misshapen skull with a clover-leaf appearance in the anterior view. Clover-leaf skull has been associated with numerous skeletal dysplasias (most notably, thanatophoric dysplasia) and ventriculomegaly ( Figure 59-10 ). Trigonocephaly (premature closure of the metopic suture) may cause the forehead to have an elongated (tall) appearance in the sagittal plane and appear triangular shaped in the axial plane ( Figure 59-11 ). 3D imaging has been shown to be useful in evaluating fetal cranial sutures. Frontal bossing may be observed in a fetus with a lemon-shaped skull (from spina bifida) or with skeletal dysplasias. Any irregularities in the contour of the forehead should prompt the investigator to search for other malformations.


May 29, 2019 | Posted by in ULTRASONOGRAPHY | Comments Off on Fetal face and neck
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