craniosynostosis craniosynostosis craniosynostosis is a condition in which one or more of the fibrous sutures in a young infant's skull prematurely fuses by turning into bone (ossification), thereby changing the growth pattern of the skull. because the skull cannot expand perpendicular to the fused suture, it compensates by growing more in the direction parallel to the closed sutures. sometimes the resulting growth pattern provides the necessary space for the growing brain, but results in an abnormal head shape and abnormal facial features. in cases in which the compensation does not effectively provide enough space for the growing brain, craniosynostosis results in increased intracranial pressure leading possibly to visual impairment, sleeping impairment, eating difficulties, or an impairment of mental development combined with a significant reduction in iq. craniosynostosisother namescraniostenosischild with premature closure (craniosynostosis) of the lambdoid suture. notice the swelling on the right side of the headspecialtymedical geneticscomplicationsincreased intracranial pressureusual onsetduring young age craniosynostosis occurs in one in 2000 births. craniosynostosis is part of a syndrome in 15% to 40% of affected patients, but it usually occurs as an isolated condition. the term is from cranio, cranium; + syn, together; + ost, relating to bone; + osis, denoting a condition. signs and symptoms kinds of craniosynostosis children born with craniosynostosis have a distinct phenotype, i.e., appearance—observable traits caused by the expression of a condition's genes. the features of craniosynostosis' particular phenotype are determined by which suture is closed. the fusion of this suture causes a certain change in the shape of the skull; a deformity of the skull. virchow's law dictates that, when premature suture closure occurs, growth of the skull typically is restricted perpendicularly to the fused suture and enhanced in a plane parallel to it, thus trying to provide space for the fast-growing brain. using this law, the pattern of skull deformity in craniosynostosis often may be predicted. scaphocephaly an illustrative example of this phenomenon is scaphocephaly; the name providing a direct hint regarding the deformity of the skull. the literal meaning of the greek derived word 'scaphocephaly' is boat-head. a synonymous term is 'dolichocephaly' (the prefix dolicho- means elongated). premature sagittal suture closure restricts growth in a perpendicular plane, thus the head will not grow sideways and will remain narrow. this is best seen in a view standing above the child looking downward at the top of the head. compensatory growth occurs forward at the coronal suture and backward at the lambdoid suture giving respectively a prominent forehead, called frontal bossing, and a prominent back portion of the head, called coning. this is the most common form of craniosynostosis. trigonocephaly trigonocephaly is a result from the premature closure of the metopic suture. using virchow's law again to predict the resulting deformity, this fusion will result in a narrow forehead, which is even further emphasized by ridging of the suture. compensatory growth occurs at both the coronal sutures, thereby pushing the forehead forwards. the resulting shape can best be assessed from a top view again, which will reveal a somewhat triangular form of the head. trigonocephaly is also a greek-derived word, which can be translated as triangular-shaped head. a facial feature of metopic synostosis is hypotelorism; in the frontal view, it can be seen that the width between the eyes is smaller than usual. plagiocephaly head of plagiocephalic baby viewed from above the greek word πλάγιος plágios means "skew". plagiocephaly can be subclassified as anterior plagiocephaly or posterior plagiocephaly. anterior plagiocephaly anterior plagiocephaly is a clinical description of unilateral coronal synostosis. children born with unilateral coronal synostosis develop due to compensatory mechanisms a skew head; a plagiocephaly. the sagittal suture 'divides' the coronal suture in two halves; unilateral meaning that either the right side or the left side to the sagittal suture is fused. this fact immediately raises an important point. unlike closure of the sagittal or the metopic suture, right and left are not the same in unilateral coronal synostosis. this asymmetry shows in the skull deformity, as well as in the facial deformity and the complications. this time, the skull deformity can only partly be predicted using virchow's law. growth is arrested in the plane perpendicular to the fused suture and the forehead is flattened, but only at the ipsilateral side of the head. ipsilateral indicates the same side of the head as where the suture is closed. compensatory growth occurs in a parallel plane, as well as in a perpendicular plane. an increase in growth at the metopic and the sagittal suture accounts for the parallel plane and will result in bulging at the temporal fossa. compensatory growth in the perpendicular plane occurs on the side of the head with the patent coronal suture, the contralateral side. half of the forehead will bulge forwards. assessment of the skull from a top view shows asymmetry of the frontal bones, an increased width of the skull and a forward displacement of the ear at the ipsilateral side of the head. assessment of the skull from a frontal view will show asymmetrical features of the face, including a displacement of the chin point of the jaw and a deviation of the tip of the nose. the chin point is located more to the contralateral side of the head, due to the ipsilateral forward displacement of the temporomandibular joint together with the ear. the tip of the nose will also point towards the contralateral side. complications based on the skull deformation include malocclusion of the jaw, in as many as 90%; a subtle form of strabismus, caused by the asymmetrical placement of the orbits; and refractive error, particularly astigmatism, due to asymmetrical development of the orbits. posterior plagiocephaly unilateral lambdoid synostosis is also called posterior plagiocephaly, indicating that this gives, just like unilateral coronal synostosis, a 'skew head'. the difference is that this time, the deformity mostly shows at the occiput. by virchow's law, restriction of growth will occur at the ipsilateral side of the head; compensatory growth will occur at the contralateral side of the head. this growth pattern exerts an effect at the base of the skull, which is not even when the child is assessed from a point of view standing behind the child, as well as on the cervical spine, which shows a curvature. in addition, from a point of view standing behind the child, a bulging of the mastoid can be seen. minimal forehead asymmetries are typically seen. brachycephaly brachycephaly, or a 'short head', is the result of a closure of both the coronal sutures. following virchow's law, this will result in a child's head with a restriction of growth in the forward direction and in the backward direction: recessed frontal bones and a flattened occiput. compensatory growth will occur sideways, due to the sagittal suture, and upwards, due to the lambdoid sutures. turricephaly turricephaly, also known as oxycephaly, acrocephaly, and high-head syndrome, is a type of cephalic disorder. this is a term sometimes used to describe the premature closure of the coronal suture plus any other suture, like the lambdoid suture. pansynostosis the word pansynostosis is also greek-derived and can be translated as "all one bone", indicating that all of the sutures are closed. in general practice, the term is used to describe the children with three or more cranial sutures closed. pansynostosis can present in several ways. the appearance can be the same as that seen with primary microcephaly: a markedly small head, but with normal proportions. however, pansynostosis can also appear as kleeblattschädel (cloverleaf skull), which presents with bulging of the different bones of the cranial vault. the condition is associated with syndromes caused by mutations in fibroblast growth factor receptor genes (fgfr), including thanatophoric dwarfism type 2 (fgfr3) and pfeiffer syndrome type 2 (fgfr2). other forms apert syndrome: an abnormal skull shape, small upper jaw, and fusion of the fingers and toes. baller-gerold syndrome: craniosynostosis with radial aplasia. beare-stevenson syndrome: craniosynostosis with cutis gyrata, acanthosis nigricans, and digit anomalies. carpenter syndrome: acrocephaly with variable synostosis of the sagittal, lambdoid, and coronal sutures; peculiar facies, brachydactyly and syndactyly, foot polydactyly. crouzon syndrome: craniofacial abnormalities with bilateral coronal suture fusion; anterior and posterior of skull shortness, flat cheek bones and a flat nose. jackson-weiss syndrome: craniosynostosis with midfacial hypoplasia and foot anomalies. muenke syndrome: coronal craniosynostosis (plagiocephaly and brachycephaly), short feet and palms, hearing impairment, hypertelorism, and proptosis. pfeiffer syndrome: abnormalities of the skull, hands, and feet; wide-set, bulging eyes, an underdeveloped upper jaw, beaked nose. saethre–chotzen syndrome: short or broad head; the eyes may be spaced wide apart and have palpebral ptosis (droopy eyelids), and fingers maybe abnormally short and webbed. shprintzen-goldberg syndrome: craniosynostosis with marfanoid habitus and tissue anomalies. apert syndrome carpenter syndrome crouzon syndrome muenke syndrome pfeiffer syndrome saethre-chotzen syndrome complications not all cranial abnormalities seen in children with craniosynostosis are solely a consequence of the premature fusion of a cranial suture. this is especially true in the cases with syndromic craniosynostosis. findings include elevation of the intracranial pressure; obstructive sleep apnea (osa); abnormalities in the skull base and neurobehavioral impairment. elevated intracranial pressure when the icp is elevated the following symptomes may occur: vomiting, visual disturbance, bulging of the anterior fontanel, altered mental status, papilledema and headache. the main risks of prolonged elevated intracranial pressure may include cognitive impairment and impaired vision through prolonged papilledema and subsequent optic atrophy. these are the main reasons why fundoscopy should be performed during the physical examination of children with craniosynostosis. the causes of an elevation of the intracranial pressure are best understood using the monro-kellie doctrine. the monro-kellie doctrine reduces the cranial vault to a box with rigid walls. this box contains three elements: brain, intracranial blood and cerebrospinal fluid. the sum of volumes of these three elements is constant. an increase in one should cause a decrease in one or both of the remaining two, thereby preventing an elevation of the intracranial pressure. a compensatory mechanism involves the movement of cerebrospinal fluid from the cranial vault towards the spinal cord. the volume of blood in the cranial vault is auto-regulated by the brain, and will therefore not decrease that easily. intracranial pressure will rise as a result of continued brain growth within the rigid skull. it appears that in children with craniosynostosis, the expected decrease of intracranial blood is probably not occurring as it should according to the monro-kellie hypothesis. this is shown when the brain expands in the fixed skull, which gives a faster rise in intracranial pressure than would be expected. obstructive sleep apnea the short stops in breathing during the sleep are the mainstay of osa. other symptoms can be difficulty in breathing, snoring, day-time sleepiness and perspiration. the main causative agent of osa is the , which also poses a risk to the eyes that can be seen bulging out of the eye sockets. other factors, such as a micrognathism and adenoid hypertrophy, are likely to contribute in causing osa. the most common syndromic forms of craniosynostosis; i.e. apert, crouzon and pfeiffer, have an increased risk of developing osa. the children have nearly 50% chance of developing this condition. a theory regarding the involvement of osa as a causative agent for elevated intracranial pressure suggests an association with the auto-regulation of blood flow in the brain. certain cells in the brain respond specifically to an increase of co2 in the blood. the response involves vasodilatation of the cranial vault blood vessels, increasing the volume of one of the elements in the monro-kellie doctrine. the increase of co2 concentration in the blood is a consequence of impaired breathing, especially seen when the child with osa is sleeping. it is well documented that the highest spikes in intracranial pressure often occur during sleep. abnormalities in the skull base impaired venous outflow is often caused by a hypoplastic jugular foramen. this causes an increase in the intracranial blood volume, thereby causing an increase in intracranial pressure. this can be further complicated with a possible arnold–chiari malformation, which can partially obstruct the flow of cerebro-spinal fluid from the neurocranium to the spinal cord. the chiari malformation may be asymptomatic or present with ataxia, spasticity or abnormalities in breathing, swallowing or sleeping. due to the impaired venous outflow, which may be further complicated with an arnold–chiari malformation, there is often a clinical image of hydrocephalus present. hydrocephalus is seen in