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 apnoea(OSA); abnormalities in the skull base and neurobehavioral impairment.

Common signs of Say–Meyer syndrome are trigonocephaly as well as head and neck symptoms. The head and neck symptoms come in the form of craniosynostosis affecting the metopic suture (the dense connective tissue structure that divides the two halves of the skull in children which usually fuse together by the age of six). Symptoms of Say–Meyer syndrome other than developmental delay and short stature include

- Intellectual disability.

- Low-set ears/posteriorly rotated ears

- Intellectual deficit as well as learning disability

- Intrauterine growth retardation (poor growth of a baby while it is in the mother's womb)

- Posterior fontanel

- Premature synostosis of the lambdoid suture (the fusion of the bones to the joint is premature)

- Narrow forehead

- Trigonocephaly (a frontal bone anomaly that is characterized by a premature fusion of the bones which gives the forehead a triangular shape)

- Hypotelorism or hypertelorism (reduced or increased width between the eyes)

- Craniosynostosis (when one or more seam-like junctions between two bones fuses by turning into bone. This changes the growth pattern of the skull)

- Low birth weight and height

The affected patients sometimes show a highly arched palate, clinodactyly (a defect in which toes or fingers are positioned abnormally) and ventricular septal defect (a heart defect that allows blood to pass directly from left to the right ventricle which is caused by an opening in the septum). Overall, Say–Meyer syndrome impairs growth, motor function, and mental state.

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 a Kleeblattschädel (cloverleaf skull), which presents with bulging of the different bones of the cranial vault. The condition is associated with thanatophoric dwarfism.

Trigonocephaly (Greek: 'trigonon' = triangle, 'kephale' = head) is a congenital condition of premature fusion of the metopic suture (Greek: 'metopon' = forehead) leading to a triangular shaped forehead. The merging of the two frontal bones leads to transverse growth restriction and parallel growth expansion. It may occur syndromic involving other abnormalities or isolated.

Diagnosis can be characterized by typical facial and cranial deformities.

Observatory signs of trigonocephaly are:

- a triangular shaped forehead seen from top view leading to a smaller anterior cranial fossa

- a visible and palpable midline ridge

- hypotelorism inducing ethmoidal hypoplasia

Imaging techniques (3D-CT, Röntgenography, MRI) show:

- epicanthal folds in limited cases

- teardrop shaped orbits angulated towards the midline of the forehead ('surprised coon' sign) in severe cases

- a contrast difference between a röntgenograph of a normal and a trigonocephalic skull

- anterior curving of the metopic suture seen from lateral view of the cranium on a röntgenograph

- a normal cephalic index (maximum cranium width / maximum cranium length) however, there is bitemporal shortening and biparietal broadening

The neuropsychological development is not always affected. These effects are only visible in a small percentage of children with trigonocephaly or other suture synostoses. Neuropsychological signs are:

- problems in behaviour, speech and language

- mental retardation

- neurodevelopmental delays such as ADHD (Attention Deficit Hyperactivity Disorder), ODD (Oppositional Defiant Disorder), ASD (Autism Spectrum Disorder) and CD (Conduct Disorder). Many of these delays become evident at school age.

Your baby's skull has seven bones. Normally, these bones don't fuse until around age 2, giving your baby's brain time to grow. Joints called cranial sutures, made of strong, fibrous tissue, hold these bones together. In the front of your baby's skull, the sutures intersect in the large soft spot (fontanel) on the top of your baby's head. Normally, the sutures remain flexible until the bones fuse. The signs of craniosynostosis may not be noticeable at birth, but they become apparent during the first few months of your baby's life. The symptoms differs from types of synostosis. First of all there is Sagittal synostosis (scaphocephaly). Premature fusion of the suture at the top of the head (sagittal suture) forces the head to grow long and narrow, rather than wide. Scaphocephaly is the most common type of craniosynostosis. The other one is called Coronal synostosis (anterior plagiocephaly). Premature fusion of a coronal suture — one of the structures that run from each ear to the sagittal suture on top of the head — may force your baby's forehead to flatten on the affected side. It may also raise the eye socket and cause a deviated nose and slanted skull. The Bicoronal synostosis (brachycephaly). When both of the coronal sutures fuse prematurely, your baby may have a flat, elevated forehead and brow.

The cranium consists of three main sections including the base of the cranium (occipital bone), the face (frontal bone), and the top (parietal bones) and sides (temporal bone) of the head. Most of the bones of the cranium are permanently set into place prior to birth. However, the temporal and parietal bones are separated by sutures, which remain open, allowing the head to slightly change in shape during childbirth. The cranial sutures eventually close within the first couple of years following birth, after the brain has finished growing.

In individuals with SCS, the coronal suture separating the frontal bones from the parietal bones, closes prematurely (craniosynostosis), occasionally even before birth. If the coronal suture closes asymmetrically or unilaterally, then the face and forehead will form unevenly, from side-to-side. People with SCS have pointy, tower-like heads because their brain is growing faster than their skull, resulting in increased intracranial pressure (ICP) and causing the top of the head and/or forehead to bulge out to allow for brain growth. The face appears uneven, particularly in the areas of the eyes and cheeks, and the forehead appears wide and tall.

Because of the abnormal forehead, there is less space for the normal facial features to develop. This results in shallow eye sockets and flat cheekbones. The shallow eye sockets make the eyes more prominent or bulging and cause the eyes to be more separated than normal (hypertelorism). The underdeveloped eye sockets, cheekbones, and lower jaw cause the face to appear flat. Furthermore, the minor downward slant of the eyes along with the drooping eyelids (ptosis) adds to the overall unevenness of the face.

Plagiocephaly, also known as flat head syndrome, is a condition characterized by an asymmetrical distortion (flattening of one side) of the skull. It is characterized by a flat spot on the back or one side of the head caused by remaining in a supine position for too long.

"Plagiocephaly" is the word that is used to describe a diagonal asymmetry across the head shape. This word particularly describes a flattening which is to one side at the back of the head and there is often some facial asymmetry. Plagiocephaly divides into two groups: synostotic plagiocephaly, with one or more fused cranial sutures, and nonsynostotic (deformational) plagiocephaly. Surgical treatment of these groups includes the deference method; however, the treatment of deformational plagiocephaly is controversial. Brachycephaly describes a very wide head shape with a flattening across the whole back of the head.

McGillivray syndrome is a very rare syndrome which is also known as a Craniosynostosis. It is characterized mainly by heart defects, skull and facial abnormalities and ambiguous genitalia. The symptoms of this syndrome are ventricular septal defect, patent ductus arteriosus, small jaw, undescended testes, and webbed fingers. Beside to these symptoms there are more symptoms which is related with bone structure and misshape.

McGillivray syndrome is a birth defect in which one or more of the joints between the bones of your baby's skull close prematurely, before your baby's brain is fully formed. When your baby has craniosynostosis, his or her brain cannot grow in its natural shape and the head is misshapen. It can affect one or more of the joints in your baby's skull. In some cases, craniosynostosis is associated with an underlying brain abnormality that prevents the brain from growing properly. Treating McGillivray usually involves surgery to separate the fused bones. If there is no underlying brain abnormality, the surgery allows baby’s brain to grow and develop in adequate space.

The cranial malformations are the most apparent effects of acrocephalosyndactyly. Craniosynostosis occurs, in which the cranial sutures close too soon, though the child's brain is still growing and expanding. Brachycephaly is the common pattern of growth, where the coronal sutures close prematurely, preventing the skull from expanding frontward or backward, and causing the brain to expand the skull to the sides and upwards. This results in another common characteristic, a high, prominent forehead with a flat back of the skull. Due to the premature closing of the coronal sutures, increased cranial pressure can develop, leading to mental deficiency. A flat or concave face may develop as a result of deficient growth in the mid-facial bones, leading to a conditir prognathism. Other features of acrocephalosyndactyly may include shallow bony orbits and broadly spaced eyes. Low-set ears are also a typical characteristic of branchial arch syndromes.

It is a disorder that is mostly characterized as developmental delay and short stature. Magnetic resonance imaging scans usually reveal that there is a decreased volume of white matter in the bilateral cerebral hemispheres, a brain stem that is smaller in size, and a thin corpus callosum (nerve fibers that connect the two hemispheres of the brain). The syndrome is one of the rare causes of short stature.

Individuals with SCS are all affected differently. Even within the same family, affected individuals have different features. The majority of individuals with SCS are moderately affected, with uneven facial features and a relatively flat face due to underdeveloped eye sockets, cheekbones, and lower jaw. In addition to the physical abnormalities, people with SCS also experience growth delays, which results in a relatively short stature. Although, most individuals with SCS are of normal intelligence, some individuals may have mild to moderate mental retardation (IQ from 50-70). More severe cases of SCS, with more serious facial deformities, occurs when multiple cranial sutures close prematurely.

Carpenter syndrome presents several features:

- Tower-shaped skull (craniosynostosis)

- Additional or fused digits (fingers and toes)

- Obesity

- Reduced height

Intellectual disability is also common with the disorder, although some patients may have average intellectual capacity.

Common relevant features of acrocephalosyndactyly are a high-arched palate, pseudomandibular prognathism (appearing as mandibular prognathism), a narrow palate, and crowding of the teeth.

Carpenter Syndrome belongs to a group of rare genetic disorders known as acrocephalopolysyndactyly, abbreviated ACPS (RN, 2007). There were originally five types of ACPS, but this number has been decreased because they have been found to be closely related to one another or to other disorders (Paul A. Johnson, 2002).

The most common physical manifestation of Carpenter Syndrome is early fusing of the fibrous cranial sutures which results in an abnormally pointed head. The fusion of the skull bones is evident from birth (National Organization for Rare Disorders, Inc., 2008). Babies’ mobile cranial bones form a cone shape as the pass through the birth canal and soon thereafter return to a normal shape; however, a baby affected by carpenter syndrome maintains a cone shaped head.

A baby affected by Carpenter Syndrome will also display malformations of the face. An individual affected by the syndrome may have broad cheeks, a flat nasal bridge, and a wide upturned nose with abnormally large nasal openings. Their ears will most commonly be low, unevenly set, and malformed in structure. In addition to these facial abnormalities, individuals also have an underdeveloped maxilla and/ or mandible with a highly arched and narrow palate which makes speech a very difficult skill to master. Teeth are usually very late to come in and will be undersized and spaced far apart (Carpenter Syndrome-description).

Other physical abnormalities often associated with Carpenter Syndrome include extra digits. Extra toes are more commonly seen than fingers. Often both the toes and fingers are webbed, a process that occurs before the sixth week gestational period. Often their digits will be abnormally short, and the fingers are commonly missing an interphalangeal joint. Roughly half of the babies born with Carpenter Syndrome have some type of heart defect, and seventy five percent of individuals with this disease will experience some degree of development delay due to mild mental retardation (Carpenter Syndrome-description).

Many people with this disorder have a premature fusion of skull bones along the coronal suture. Not every case has had craniosynostosis however. Other parts of the skull may be malformed as well. This will usually cause an abnormally shaped head, wide-set eyes, low set ears and flattened cheekbones in these patients. About 5 percent of affected individuals have an enlarged head (macrocephaly). There may also be associated hearing loss in 10-33% of cases and it is important for affected individuals to have hearing tests to check on the possibility of a problem. They can lose about 33-100% of hearing.

Most people with this condition have normal intellect, but developmental delay and learning disabilities are possible. The signs and symptoms of Muenke syndrome vary among affected people, and some findings overlap with those seen in other craniosynostosis syndromes. Between 6 percent and 7 percent of people with the gene mutation associated with Muenke syndrome do not have any of the characteristic features of the disorder.

Slight plagiocephaly is routinely diagnosed at birth and may be the result of a restrictive intrauterine environment giving a "diamond" shaped head when seen from above. If there is premature union of skull bones, this is more properly called craniosynostosis.

The incidence of plagiocephaly has increased dramatically since the advent of anti-Sudden Infant Death Syndrome recommendations for parents to keep their babies on their backs.

Data also suggest that the rates of plagiocephaly is higher among twins and multiple births, premature babies, babies who were positioned in the breech position or back-to-back, as well as babies born after a prolonged labour.

Many of the characteristic facial features (among other) of Jackson–Weiss syndrome result from the premature fusion of the skull bones. The following are some of the more common, such as:

- Preaxial foot polydactyl

- Tarsal synostosis

- Frontal bossing

- Proptosis

Midfacial malformations can be subdivided into two different groups. One group with hypertelorism, this includes FND. The other with hypotelorism (a decreased distance between the eyes), this includes holoprosencephaly (failure of development of the forebrain). In addition, a facial cleft can be classified using the Tessier classification. Each of the clefts is numbered from 0 to 14. The 15 different types of clefts are then subdivided into 4 groups, based on their anatomical position in the face: midline clefts, paramedian clefts, orbital clefts and lateral clefts. FND is a midline cleft, classified as Tessier 0/14.

Besides this, the additional anomalies seen in FND can be subdivided by region. None of these anomalies are specific for the syndrome of FND, but they do occur more often in patients with FND than in the population. The anomalies that may be present are:

- Nasal: mild anomalies to nostrils that are far apart and a broad nasal root, a notch or cleft of the nose and accessory nasal tags.

- Ocular: narrowed eye slits, almond shaped eyes, epicanthal folds (extra eyelid tissue), epibulbar dermoids (benign tumors of the eye), upper eyelid colombas (full thickness upper eyelid defects), microphtalmos (one or two small eyes), congenital cataract and degeneration of the eye with retinal detachment.

- Facial: telecanthus (an increased distance between the corners of the eye), a median cleft of the upper lip and/or palatum, and a V-shaped hairline.

- Others: polydactyly (an excess of fingers or toes), syndactyly (fused fingers or toes), brachydactyly (short fingers and/or toes), clinodactyly (bending of the fifth fingers towards the fourth fingers), preauricular skin tags, an absent tragus, low set ears, deafness, small frontal sinuses, mental retardation, encephalocele (protrusion of the brain), spina bifida (split spine), meningoencephalocele (protrusion of both meninges), umbilical hernia, cryptorchidism (absence of one or two testes) and possibly cardiac anomalies.

The clefts of the face that are present in FND are vertical clefts. These can differ in severity. When they are less severe, they often present with hypertelorism and normal brain development.

Mental retardation is more likely when the hypertelorism is more severe or when extracephalic anomalies occur.

The Pai Syndrome is a rare subtype of frontonasal dysplasia. It is a triad of developmental defects of the face, comprising midline cleft of the upper lip, nasal and facial skin polyps and central nervous system lipomas. When all the cases are compared, a difference in severity of the midline cleft of the upper lip can be seen. The mild form presents with just a gap between the upper teeth. The severe group presents with a complete cleft of the upper lip and alveolar ridge.

Nervous system lipomas are rare congenital benign tumors of the central nervous system, mostly located in the medial line and especially in the corpus callosum. Generally, patients with these lipomas present with strokes. However, patients with the Pai syndrome don’t. That is why it is suggested that isolated nervous system lipomas have a different embryological origin than the lipomas present in the Pai syndrome. The treatment of CNS lipomas mainly consists of observation and follow up.

Skin lipomas occur relatively often in the normal population. However, facial and nasal lipomas are rare, especially in childhood. However, the Pai syndrome often present with facial and nasal polyps. These skin lipomas are benign, and are therefore more a cosmetic problem than a functional problem.

The skin lipomas can develop on different parts of the face. The most common place is the nose. Other common places are the forehead, the conjunctivae and the frenulum linguae. The amount of skin lipomas is not related to the severity of the midline clefting.

Patients with the Pai syndrome have a normal neuropsychological development.

Until today there is no known cause for the Pai syndrome.

The large variety in phenotypes make the Pai syndrome difficult to diagnose. Thus the incidence of Pai syndrome seems to be underestimated.

Scaphocephaly is a type of cephalic disorder which occurs when there is a premature fusion of the sagittal suture. The sagittal suture joins together the two parietal bones of skull. Scaphocephaly is the most common of the craniosynostosis conditions and is characterized by a long, narrow head.

The term is from Greek "skaphe" meaning 'light boat or skiff' and "kephale" meaning 'head') describes a specific shape of a long narrow head that resembles an inverted boat.

Metopism is the condition of having a persistent metopic suture, or persistence of the frontal metopic suture in the adult human skull. The premature fusion of cranial sutures named craniosynostosis, it is “simple” when only one cranial suture is involved and “compound” when two or more cranial sutures are involved. Metopism is the opposite of craniosynostosis. The main factor of the metopic suture is to increase the volume of the anterior cranial fossa. The frontal bone includes the forehead, and the roofs of the orbits (bony sockets) of the eyes.

The frontal bone has vertical portion (squama) and horizontal portion (orbital part). Some adults have a metopic or frontal suture in the vertical portion. In uterine period in right and left half of frontal region of the fetus there is a membrane tissue. On each half a primary ossification center appears about the end of the second month of the fetus. Primary ossification center extends to form the corresponding half of the vertical part (squama) and horizontal part (orbital part) of the frontal bone.

At birth the frontal bone contains two portions, separated by the metopic (frontal) suture. Metopism is the condition of having a persistent metopic suture. Metopic suture is regularly obliterated, except at its lower part, by the eighth year, but infrequently persists throughout life. There is no single proven cause of metopism. The occurrence is from mild to serious situations. Visional, learning, and behavioral problems may happen in serious metopism. Some don't need any medical treatment. Surgery is a successful approach for those who need it. Treatment teams include: neurosurgeons, plastic surgeons, neurologists, oral and maxillofacial surgeons, audiologists, neuroscience nursing professionals, speech therapists, physical therapists, dentist, otolaryngologists, ophthalmologists, psychiatrists, psychologists and social workers.

As a result of the changes to the developing embryo, the symptoms are very pronounced features, especially in the face. Low-set ears are a typical characteristic, as in all of the disorders which are called branchial arch syndromes. The reason for this abnormality is that ears on a foetus are much lower than those on an adult. During normal development, the ears "travel" upward on the head; however, in Crouzon patients, this pattern of development is disrupted. Ear canal malformations are extremely common, generally resulting in some hearing loss. In particularly severe cases, Ménière's disease may occur.

The most notable characteristic of Crouzon syndrome is craniosynostosis, as described above; however it usually presents as brachycephaly resulting in the appearance of a short and broad head. Exophthalmos (bulging eyes due to shallow eye sockets after early fusion of surrounding bones), hypertelorism (greater than normal distance between the eyes), and psittichorhina (beak-like nose) are also symptoms. Additionally, external strabismus is a common occurrence, which can be thought of as opposite from the eye position found in Down syndrome. Lastly, hypoplastic maxilla (insufficient growth of the midface) results in relative mandibular prognathism (chin appears to protrude despite normal growth of mandible) and gives the effect of the patient having a concave face. Crouzon syndrome is also associated with patent ductus arteriosus (PDA) and aortic coarctation.

For reasons that are not entirely clear, most Crouzon patients also have noticeably shorter humerus and femur bones relative to the rest of their bodies than members of the general population. A small percentage of Crouzon patients also have what is called "Type II" Crouzon syndrome, distinguished by partial syndactyly.

Jackson–Weiss syndrome (JWS) is a genetic disorder characterized by foot abnormalities and the premature fusion of certain bones of the skull (craniosynostosis), which prevents further growth of the skull and affects the shape of the head and face. This genetic disorder can also sometimes cause intellectual disability and crossed eyes as well, it was characterized in 1976.

Cleidocranial dysostosis is a general skeletal condition so named from the collarbone (cleido-) and cranium deformities which people with it often have.

People with the condition usually present with a painless swelling in the area of the clavicles at 2–3 years of age. Common features are:

- Clavicles (collarbones) can be partly missing leaving only the medial part of the bone. In 10% cases, they are completely missing. If the collarbones are completely missing or reduced to small vestiges, this allows hypermobility of the shoulders including ability to touch the shoulders together in front of the chest. The defect is bilateral 80% of the time. Partial collarbones may cause nerve damage symptoms and therefore have to be removed by surgery.

- The mandible is prognathic due to hypoplasia of maxilla (micrognathism) and other facial bones.

- A soft spot or larger soft area in the top of the head where the fontanelle failed to close, or the fontanelle closes late.

- Bones and joints are underdeveloped. People are shorter and their frames are smaller than their siblings who do not have the condition.

- The permanent teeth include supernumerary teeth. Unless these supernumeraries are removed they will crowd the adult teeth in what already may be an underdeveloped jaw. If so, the supernumeraries will probably need to be removed to make space for the adult teeth. Up to 13 supernumarary teeth have been observed. Teeth may also be displaced. Cementum formation may be deficient.

- Failure of eruption of permanent teeth.

- Bossing (bulging) of the forehead.

- Open skull sutures, large fontanelles.

- Hypertelorism.

- Delayed ossification of bones forming symphysis pubis, producing a widened symphysis.

- Coxa vara can occur, limiting abduction and causing Trendelenburg gait.

- Short middle fifth phalanges, sometimes causing short and wide fingers.

- Vertebral abnormalities.

- On rare occasions, brachial plexus irritation can occur.

- Scoliosis, spina bifida and syringomyelia have also been described.

Other features are: parietal bossing, basilar invagination (atlantoaxial impaction), persistent metopic suture, abnormal ear structures with hearing loss, supernumerary ribs, hemivertebrae with spondylosis, small and high scapulae, hypoplasia of illiac bones, absence of the pubic bone, short / absent fibular bones, short / absent radial bones, hypoplastic terminal phalanges.