CranioFacial Abnormalities

Transcription

1 CranioFacial Abnormalities Variations of Shape of the Skull Normal Variations of Shape Dolichocephaly Brachycephaly Mesocephaly The normal human cranial shape demonstrates diversity related to both genetic and environmental influences and ranges from the extremes of the long, narrow dolicocephalic head with a cranial width-to-length index of less than 0.75, to the mesocephalic head with a cranial width-to-length index between 0.75 and 0.80, and to the wide, short, globular brachycephalic head with a cranial width-to-length index of greater than 0.80 Cranium s dysmorphology Cranium s dysmorphology has been divided into the three categories of malformations, deformations, and disruptions, depending on the earliest or primary defect in morphogenesis Malformations occur during the first 8 weeks of pregnancy during embryogenesis of a specific organ, result from genetic, environmental causes or a combination of the two, and are associated with higher recurrence rates than the environmentally related disruptions and deformations. Disruptions result from destructive processes that occur after organogenesis to arphogenetically normal tissue or organ (eg, amniotic banding resulting in a cleft lip). Disruptions are thought to be primarily environmental in origin and thus have low recurrence rates [5]. Deformations occur after embryogenesis and result from nondisruptive mechanical forces causing abnormal formations or distortions of morphogenetically normal body parts (eg, positional plagiocephaly). Deformations may be caused by direct local uterine or postnatal positional factors, may resolve with an altered environment, and are associated with low recurrence rates. Distinguishing true craniosynostosis or malformations from birth molding and from positional or deformational lambdoid plagiocephaly Differentiating between - birth molding, positional plagiocephaly without synostosis, and true synostosis is one of the first distinctions to be made and properly understood. In making this distinction, the history and physical examination provide the most valuable information. Normal birth molding results in findings that resolve within hours to weeks of birth without intervention and is clinically different in timing of

2 presentation and quality from positional or deformational lambdoid plagiocephaly. Characteristically, passage of the infant through the birth canal results in pressure in the anteroposterior dimensions and less in the sidetoside dimension. The calvarium thus grows longer in the vertical dimension as the parietal bones rise away from the skull base and the frontal and occipital bones slip under the anterior and posterior borders of the parietal bones, respectively. This overriding quality is often palpable and visible at birth but resolves, unlike synostosis cases, which are present at birth but progress, or deformational cases, which are generally not present at birth but develop during infancy Deformational plagiocephaly results from local pressure on a specific region of the skull, typically in one occipital region resulting in occipital/lambdoid plagiocephaly or the so-called lazy lambdoid. The clinical finding of lambdoid plagiocephaly is becoming more frequently seen by pediatric neurosurgeons and in m any practices is now the most common reason for referral to a pediatric neurosurgeon. Nonsynostotic plagiocephaly has been reported as occurring in up to 48% of healthy neonates [8]. This high incidence and the clinical similarities to actual lambdoid synostosis have fueled a renewed and widespread interest in the topic of lambdoid plagiocephaly and its treatment.. Craniosynostosis: Classification Terms Meaning Suture Involved Dolichocephaly Long head Sagittal suture Scaphocephaly Keel-shaped head Sagittal suture Acrocephaly Pointed head Coronal suture, Coronal/lambdoid, or all sutures Brachycephaly Short head Coronal suture Oxycephaly Tower-shaped head Coronal/lamboid or all sutures Trigonocephaly Triangular-shaped head Metopic suture Plagiocephaly Asymmetric head Unilateral lambdoid or positional Kleeblattschadel Cloverleaf skull Multiple but not all sutures Craniofacial dysostosis Midface deficiency Craniosynostosis with involvement of cranial base sutures." Emily B. Ridgway, MD*, Howard L. Weiner, MD; Skull deformities; Department of Neurological Surgery, New York University School of Medicine, 317 East 34th Street, New York, NY 10016, USA; Term Meaning Suture Involved

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4 Fig.1 Child with microcephaly1; Fig 2 Sagittal synostosis with scaphocephaly. (From Dufresne C, Carson B, Zinreich S. Complex craniofacial problems. New York: Churchill Livingstone; p. 189; with permission.); Fig 3 Unilateral cranial synostosis resulting in plagiocephaly. (From Dufresne C, Carson B,Zinreich S. Complex craniofacial problems. New York: Churchill Livingstone; p. 173; with permission.) ( DYSMORPHOLOGY (without the necessity of craniosynostosis) The study of asymmetrical or abnormal facial features is called dysmorphology (from the prefix "dys" meaning abnormal or impaired, and "morphology" meaning form or structure), and it is based on the establishment of certain average or "normal" physical traits something that is certainly hard to establish since there is no single "perfect" face in the world. Dysmorphology harkens back to Galton's eugenics studies in that regard, but there are simply some traits and combinations of traits that are very uncommon in any face, and so those variations are used by Hammond to isolate diseases and disorders. If a disease is characterized by a certain combination of variations, such as an upturned nose, eyes overly close together, and an excessive overbite, then physicians can use this information to run only those tests that would accurately diagnose whatever illness is characterized by those three traits appearing together on a face. This could be a key to early and less costly diagnoses of these diseases, of many which are obscure and are accompanied by other less visible but serious conditions, such as kidney or heart problems that require immediate treatment. In fact, dysmorphology* is a larger field than the study of craniosynostosis and of positional plagiocephaly and includes them. If the abnormal physical or developmental features spares the cranium that is the portion of the skull enclosing the brain, the braincase, it may still interest the lower part of the skull or the facial bones and the soft tissues of the head,

5 such as the vascular tissue. Many of the ugly faces, if not all, are due to some kind of dysmorphology of the head. That which interests the lower part of the body, such as as a stunted growth** - that might not at all be due to a genetic cause - or a true malformation of the body, like Marfan syndrome1, makes you also ugly and is part of dysmorphology. Dysmorphism has not only genetic causes, since overweight and mostly obesity, developed before adolescence creates some kind of dysmorphism, like Knock-knee or genu valgus; (by the contrary, genu varus may be due to some kind of genetic traits or hormonal imbalance creating this dysmorphic characteristic). Any affectation of the body that makes you ugly, but is not due to developmental biology, is not part of dysmorphology, like obesity and the Cushing's syndrome, but not the Cushing's disease 1, 2 that is part of it. ( ) ( ) ***. Hypothyroidism, while not been part of the field of dysmorphology, creates dysmorphic traits when it begin early in life, like in infancy or in childhood. A link to an interesting site in dysmorphology is the following: Dysmorphology: Carolyn Jones, M.D.,. PhD. Dysmorphism.? Morphologic developmental abnormalities. u1.0-b &isbn= (Nelson texbook of Pediatrics).

6 The adult human skull is divided into two regions, the cranial and the facial. The cranial region is the portion of the skull directly surrounding the brain; the facial region includes all the other bones of the skull. Exteriorly the cranial bones include 1. the two frontal bones, which constitute the forehead and which fuse together in adulthood; 2. the two parietal bones, which constitute the top of the head and which in early childhood are separated from the frontal bones by a space called the anterior fontanel; the single occipital bone, constituting the back of the skull, which is pierced by a large opening through which the spinal cord enters the cranial cavity; 3. and the two temporal bones, which constitute the temples and of the head and bear the zygomatic processes, or cheekbones. The human temporal bone represents the fusion of four bones found in lower mammals: the squamosal bone, which constitutes the side of the head and articulates with the jawbone; the petrosal bone, which contains the inner ear; the mastoid bone, which is behind the ear; and the tympanic bone, which surrounds the channel from the eardrum to the external ear. Internally, the cranial bones include 1. the ethmoid bone, which forms part of the septum of the nose and through which the olfactory nerves pass from the brain to the upper and middle turbinates; 2. the sphenoid bone, which constitutes most of the floor of the cranial cavity and which houses the pituitary gland; 3. and part of the occipital bone. The floor of the cranial cavity contains three terraced depressions, which contain the cerebellum and the frontal and temporal lobes of the cerebrum.

7 The facial bones include 1. the two nasal bones, which constitute the upper portion of the bridge of the nose; 2. the two lacrimal bones, which are located in each eye orbit next to the nose, close to the tear ducts; 3. the maxillary bone, which constitutes the upper jaw; 4. the mandible, which constitutes the lower jaw; 5. the two palatine bones of the hard palate; 6. the vomer, which, with a part of the ethmoid bone, constitutes the nasal septum; 7. and the two inferior turbinates of the nose. "Skull," Microsoft(R) Encarta(R) 98 Encyclopedia. (c) Microsoft Corporation. All rights reserved. Some FACIALLY-CHARACTERISTIC DISEASES Almost any layperson can recognize Down syndrome when they see it, but try to remember all of the combinations of facial characteristics for each of those 700 facially-characteristic diseases? It would be impossible. Here are just a very few examples of facial trait combinations found in some rare disease syndromes: Ablepharon Macrostomia: lack of or underdeveloped eyelids; absence of eyelashes and eyebrows, wide fish-like mouth, incompletely developed low-set ears Alagille: broad, prominent forehead, deep-set eyes, small, pointed chin1 Autism: autism itself is not a cranio-facial abnormality, even if some childrem with autism have them Fragile X: large head, long face1, prominent chin, ears1, and forehead ( rd _Edition.pdf )**** Williams: broad forehead, fullness around eyes, face narrower at temples. low nasal bridge, bulbous nose tip, philtrum longer, lips fuller and sometimes downturned at corners, lower jaw shorter Aperts Crouzon,, Rubenstein syndromes Langer-Giedion: pear-shaped nose, bulbous nose, small jaw, thin upper lip, large ears1, head smaller than normal Mowat-Wilson: square-shaped face, deep-set eyes, widely spaced eyes, broad nasal bridge, bulbous nasal tip, prominent and pointed chin1, large flaring eyebrows, uplifted and dimpled earlobes; with age the face elongates1, brows are bushier, and chin and jaw are more pronounced

8 ABOVE: Facial features of children with (top to bottom, left to right) Alagille, Fragile X, Williams, Aperts, Crouzon, Rubenstein syndromes and Trisomy 18 (mild and severe forms). ((0046) Hammond's database was not designed to find the perfect face or the perfect human being, or even to create the perfect human being, but it has so far shown to be an effective tool in diagnosing rare genetic diseases that present with specific facial characteristics. What does this have to do with facial features analysis in photographs? Simple, if you suspect that a rare genetic disease runs in your family, you may be able to see it in the photographs of your ancestors' faces. Or not... Sometimes, the abnormal craniofacial characteristics may be misleading. Only a genetic analysis can give the definitive diagnosis: * Dysmorphology is that field of biology which studies abnormal physical traits due developmental anomalies; clinical dysmorphology is that field of medicine which wants to prevent the propagation of those traits among humans and to treat and prevent any illness (physical or mental) or intellectual deficits that might be associated; (personally, besides having myself some dysmorphological traits, I know many people with them, some been public and important personage); although the dysmorphological traits often create problems that might not be evident to society; some small (if there are) dysmorphological traits - like strabismus1, a ( ), myopia1 ( ) ( ), malocclusion ( ) ectopic teethb ( ) ( ), some small facial asymmetry & hypochondroplasia (

9 ) ( ) - if they are not associated to bigger developmental problems, may not be a problem to the social environment of the individual, but might still be one to the total achievement of the later. Finally, another field of medicine that deals with dysmorphology is esthetic or plastic surgery ( ). ** They describe as stunted any man who is shorter than 160 cm and any woman shorter than 145 cm (Mayan Indian men averaged only m (5 ft 2 in) in height and the women averaged m (4 ft 8 in)) ( ) *** Morphology is the branch of biology that deals with the developmental form and structure of organisms without consideration of function. (American Heritage Dictionary)). **** They describe girls with Fagile X Syndrome as shy. However, they present behavioral problems and that may not be the case if they present some kind of hyperandrogenism due to the fragile X; they can be hypersexual and have a Messalinic trait a In the Medline linked page on strabismus, ten conditions have been named when the strabismus appears in childhood, but, when it it occurs in the family or is hereditary, only four condtions can be named and they are in bold. Furthermore, if the stabismus accompanies Developmental Verbal Dyspraxia (DVD)', also known as Childhood Apraxia of Speech (CAS) also known commonly as blurred speech, other conditions can be considered such as Autism, some forms of Epilepsy, Fragile X syndrome, Galactosemia, and chromosome translocations involving duplications, like in Trisomy 18, or deletions ( ) 1. Apert syndrome 2. Cerebral palsy 3. Congenital rubella 4. Hemangioma near the eye during infancy 5. Incontinentia pigmenti syndrome 6. Noonan syndrome 7. Prader-Willi syndrome 8. Retinopathy of prematurity 9. Retinoblastoma 10. Traumatic brain injury 11. Trisomy 18 There are mild, intermediate and severe forms of trisomy 18. Eliot ( ) seen in a picture above has a mild form. b I know some people with malocclusion due to protusion of the maxillary dental arch and many of them appear to me as people with low IQ. Ectopic teeth has been linked to a gene and cases have been linked to a craniosynostosis but there are often other severe phenotypical traits associated ( ); Maxillary hypoplasia is commonly associated with synostosis of the calvarial bones, particularly in severe forms of craniosynostosis such as Crouzon and Apert syndromes (MIM and , respectively),10 as a result of precocious ossification of maxillary sutures. In the affected children in this study, the severity of maxillary hypoplasia varied from moderate to mild and was less pronounced compared to severe cases of Crouzon syndrome, suggesting a later onset of fusion of sutures of the maxillary complex associated with IL11RA mutations. ( ) ( ) (Nieminen P. & al.; Inactivation of IL11 Signaling Causes Craniosynostosis, Delayed Tooth Eruption, and Supernumerary Teeth ; American Journal of Human Genetics, v.89(1); Jul 15, 2011PMC ) Personnally, I know some people with those anomalies, but I do not know what kind of diseases they have; a genetic analysis would be necessary and I would have to investigate more on them; in fact, I met more people with dysmorphism, and I saw or paid attention to maybe more than a hundred, in my life: in my primary school, I have a picture of the first class with some classmates looking as dysmorphic; inmy high-school, besides of me,

10 six classmates would have suffered of dysmorphism; in my college at Montreal, almost the same number of class comrads; when I went to a diplomate s school or faculty, at Strasbourg I would have as acquaintances seven people with dysmorphic traits and, in Port-au-Prince, maybe five or six. At Strasbourg, where I began my medical study I saw, for the first time, two cases of mongolism and, in Port-au-Prince, my first cases of Marfan syndrome in a family. In the building where I live presently, since the year 2000, I think that in every floor, (11 at all) from the basement to the eleventh, there might be cases of dysmorphism. However, I would have met even more cases than the ones suggested above in my life, like chess-mates, etc.. 2 Cushing's syndrome n. 1. A syndrome caused by an increased production of ACTH from a tumor of the adrenal cortex or of the anterior lobe of the pituitary gland, or by excessive intake of glucocorticoids. It is characterized by obesity and weakening of the muscles. Cush ing's disease ( k sh ¹ngz) n. 1. The form of Cushing's syndrome involving the pituitary gland and beginning early in life (American Heritage Dictionary [AHD4]) Steele, J. ; DYSMORPHOLOGY; Diagnosing Genetic Disease Based On Asymmetric and Abnormal Facial Features; Joelle Steele Enterprises; Olympia, Washington; United States of America; (0046)