Craniosynostosis, is a medical condition in which some or all of the
suture*Surgical suture, to describe stitches and other techniques for holding tissues together.* Geology, to describe a certain type of boundary between layers of rock....
s in the
skullThe skull is a bony structure found in the head of many animals. The skull supports the structures of the face and protects the head against injury....
of an
infantAn infant or baby is the term used to refer to the very young offspring of humans and other primates.-Infant:The term infant derives from the Latin word infans, meaning "unable to speak."...
or child close too early, causing problems with normal
brainThe human brain is the center of the human nervous system and is a highly complex organ. Enclosed in the cranium, it has the same general structure as the brains of other mammals, but is over three times as large as the brain of a typical mammal with an equivalent body size...
and skull growth. It can result in craniostenosis, which is the skull deformity caused by the premature closure of the cranial sutures. Also
intracranial pressureIntracranial pressure is the pressure in the cranium and thus in the brain tissue and cerebrospinal fluid ; this pressure is exerted on the brain's intracranial blood circulation vessels. ICP is maintained in a tight normal range dynamically, through the production and absorption of CSF and...
can be increased.
In humans, the adult skull is normally made up of 28 bones.
Craniosynostosis, is a medical condition in which some or all of the
suture*Surgical suture, to describe stitches and other techniques for holding tissues together.* Geology, to describe a certain type of boundary between layers of rock....
s in the
skullThe skull is a bony structure found in the head of many animals. The skull supports the structures of the face and protects the head against injury....
of an
infantAn infant or baby is the term used to refer to the very young offspring of humans and other primates.-Infant:The term infant derives from the Latin word infans, meaning "unable to speak."...
or child close too early, causing problems with normal
brainThe human brain is the center of the human nervous system and is a highly complex organ. Enclosed in the cranium, it has the same general structure as the brains of other mammals, but is over three times as large as the brain of a typical mammal with an equivalent body size...
and skull growth. It can result in craniostenosis, which is the skull deformity caused by the premature closure of the cranial sutures. Also
intracranial pressureIntracranial pressure is the pressure in the cranium and thus in the brain tissue and cerebrospinal fluid ; this pressure is exerted on the brain's intracranial blood circulation vessels. ICP is maintained in a tight normal range dynamically, through the production and absorption of CSF and...
can be increased.
Normal skull development
In humans, the adult skull is normally made up of 28 bones. The flat bones making up the cranial vault are joined together by sutures: rigid articulations permitting very little movement.
At birth, the human skull is made up of 45 separate bony elements. As growth occurs, many of these bony elements gradually fuse together into solid bone (for example, the
frontal boneThe frontal bone is a bone in the human skull that resembles a cockleshell in form, and consists of two portions:* a vertical portion, the squama frontalis, corresponding with the region of the forehead....
s).
The bones of the roof of the skull are initially separated by regions of dense
connective tissueConnective tissue is a form of fibrous tissue.. It is one of the four types of tissue in traditional classifications ....
.
At birth these regions are fibrous and moveable, necessary for birth and later growth. Larger regions of connective tissue, called
fontanelleA fontanelle is an anatomical feature on an infant's skull. Fontanelles are soft spots on a baby's head which, during birth, enable the bony plates of the skull to flex, allowing the child's head to pass through the birth canal. The ossification of the bones of the skull cause the fontanelles to...
s, occur where certain bony elements meet. As growth and ossification progress, the connective tissue of the fontanelles is invaded and replaced by bone. The posterior fontanelle usually closes by eight weeks, but the anterior fontanelle can remain up to eighteen months.
Pathophysiology
When one or more sutures fuse prematurely, skull growth can be restricted perpendicular to the suture. If multiple sutures fuse while the brain is still increasing in size, intracranial pressure can increase.
Primary craniosynostosis is believed to be a result of primary defect in the mesenchymal layer ossification in the cranial bones. Secondary craniosynostosis is a result of primary failure of brain growth.
Diagnosis
Physicians diagnose craniosynostosis through
physical examinationPhysical examination or clinical examination is the process by which a doctor investigates the body of a patient for signs of disease. It generally follows the taking of the medical history — an account of the symptoms as experienced by the patient...
, plain x-rays, and
CT scansComputed tomography is a medical imaging method employing tomography created by computer processing. Digital geometry processing is used to generate a three-dimensional image of the inside of an object from a large series of two-dimensional X-ray images taken around a single axis of rotation.CT...
.
Syndromes
Craniosynostosis often occurs alone, however about 20% of cases are associated with
syndromeIn medicine and psychology, the term syndrome refers to the association of several clinically recognizable features, signs , symptoms , phenomena or characteristics that often occur together, so that the presence of one feature alerts the physician to the presence of the others...
s. A syndrome is diagnosed by considering the presence of a variety of features,
signA medical sign is an objective indication of some medical fact or characteristic that may be detected by a physician during a physical examination of a patient....
s, and
symptomA symptom is a departure from normal function or feeling which is noticed by a patient, indicating the presence of disease or abnormality...
s throughout the body.
Genetic testingGenetic testing allows the genetic diagnosis of vulnerabilities to inherit diseases, and can also be used to determine a child's paternity or a person's ancestry. Normally, every person carries two copies of every gene, one inherited from their mother, one inherited from their father. The human...
may be available to confirm the diagnosis of a specific syndrome. A
family historyIn medicine, a family history consists of information about disorders that a patient's direct blood relatives have suffered from. Genealogy typically includes very little of the medical history of the family, but the medical history could be considered a specific subset of the total history of a...
of abnormal head shape can sometimes be found with genetic syndromes, though many syndromes are caused by new genetic
mutationIn biology, a mutation is a randomly derived change to the nucleotide sequence of the genetic material of an organism.Mutations can be caused by copying errors in the genetic material during cell division, or by exposure to mutagens , or can be induced by the organism itself, by cellular processes...
s, and there is no family history of the disorder.
The most common causes of syndromic craniosynostosis are
Crouzon syndromeCrouzon syndrome is a genetic disorder known as a branchial arch syndrome. Specifically, this syndrome affects the first branchial arch, which is the precursor of the maxillaand mandible...
and
Apert syndromeApert syndrome is a form of acrocephalosyndactyly, a congenital disorder characterized by malformations of the skull, face, hands and feet. It is classified as a branchial arch syndrome, affecting the first branchial arch, the precursor of the maxilla and mandible...
. However, there are over 150 syndromes associated with craniosynostosis. The following table lists some of the craniosynostosis syndromes, as well as prominent additional symptoms that are found in these syndromes — this is not a comprehensive list of all symptoms that could occur within each syndrome. There is considerable overlap of symptoms between many of these syndromes, and clinical evaluation by a
geneticistA geneticist is a scientist who studies genetics, the science of heredity and variation of organisms. A geneticist can be employed as a researcher or lecturer...
may be necessary to determine the most appropriate diagnosis.
The following syndromes are associated with
fibroblast growth factor receptorThe fibroblast growth factor receptors are, as their name implies, receptors which bind to members of the fibroblast growth factor family of proteins.-Structure:...
s:
| Name of syndrome |
Other signs and symptoms (along with craniosynostosis; may not all be present) |
OMIM reference |
Gene |
Crouzon syndromeCrouzon syndrome is a genetic disorder known as a branchial arch syndrome. Specifically, this syndrome affects the first branchial arch, which is the precursor of the maxillaand mandible...
|
wide-set, bulging eyes • beaked nose • flat face |
123500 |
FGFR2, FGFR3 Fibroblast growth factor receptor 3 is a protein that in humans is encoded by the FGFR3 gene. FGFR3 has also been designated as CD333 .-Structure and function:-Disease linkage:...
|
Apert syndromeApert syndrome is a form of acrocephalosyndactyly, a congenital disorder characterized by malformations of the skull, face, hands and feet. It is classified as a branchial arch syndrome, affecting the first branchial arch, the precursor of the maxilla and mandible...
|
fused fingers or toes • flat midface |
101200 |
FGFR2 |
| Crouzonodermoskeletal syndrome Crouzonodermoskeletal syndrome is a disorder characterized by the premature joining of certain bones of the skull during development and a skin condition called acanthosis nigricans....
|
wide-set, bulging eyes • beaked nose • flat face • dark, velvety skin fold Skin folds are areas of skin where it folds. Many skin folds are distinct, heritable anatomical features, and may be used for identification of animal species, while others are non-specific and may be produced either by individual development of an organism or by arbitrary application of force to...
s • spine abnormalities • benign growths in the jaw |
134934 |
FGFR3 Fibroblast growth factor receptor 3 is a protein that in humans is encoded by the FGFR3 gene. FGFR3 has also been designated as CD333 .-Structure and function:-Disease linkage:...
|
Jackson-Weiss syndromeJackson-Weiss syndrome is a genetic disorder characterized by foot abnormalities and the premature fusion of certain bones of the skull , which prevents further growth of the skull and affects the shape of the head and face...
|
enlarged, bent big toes • flat midface |
123150 |
FGFR1, FGFR2 |
Muenke syndromeMuenke Syndrome, also known as FGFR3-related craniosynostosis, is a human specific condition characterized by the premature closure of certain bones of the skull during development, which affects the shape of the head and face. Muenke syndrome occurs in about 1 in 30,000 newborns...
|
coronal synostosis • skeletal abnormalities of the hands or feet • hearing loss |
602849 |
FGFR3 Fibroblast growth factor receptor 3 is a protein that in humans is encoded by the FGFR3 gene. FGFR3 has also been designated as CD333 .-Structure and function:-Disease linkage:...
|
| Pfeiffer syndrome Pfeiffer syndrome is a genetic disorder characterized by the premature fusion of certain bones of the skull , which prevents further growth of the skull and affects the shape of the head and face. It is named for Rudolf Arthur Pfeiffer....
|
broad, short thumbs or big toes • webbed or fused fingers or toes |
101600 |
FGFR1, FGFR2 |
In addition, the following syndromes have been identified:
| Name of syndrome |
Other signs and symptoms (along with craniosynostosis; may not all be present) |
OMIM reference |
Gene |
| Loeys-Dietz syndrome Loeys-Dietz syndrome is a recently-discovered autosomal dominant genetic syndrome which has many features similar to Marfan syndrome, but which is caused by mutations in the genes encoding transforming growth factor beta receptor 1 or 2 .It was identified and characterized by American physician...
|
wide-set eyes • split uvula or cleft palate • arterial tortuosity • aneurysm An aneurysm or aneurism , is a localized, blood-filled dilation of a blood vessel caused by disease or weakening of the vessel wall....
s |
609192 |
TGFBR1 |
Saethre-Chotzen syndromeSaethre-Chotzen syndrome, also known as acrocephalosyndactyly type 3 and Chotzen syndrome is a very rare congenital syndrome characterised by craniosynostosis .It is an autosomal dominant disorder with the error being in the TWIST transcription factor.- Features :Classic...
|
facial asymmetry • low frontal hairline • drooping eyelids • webbed fingers or toes • broad big toes |
101400 |
TWIST1 |
| Shprintzen-Goldberg syndrome |
bulging eyes • flat face • herniaA hernia is protrusion of an organ or the muscular wall of an organ through the cavity that normally contains it. A hiatal hernia occurs when the stomach protrudes upwards into the mediastinum through the esophageal opening in the diaphragm.-Pathophysiology:...
s • long, thin fingers • developmental delay • mental retardationMental retardation is a generalized disorder, characterized by significantly impaired cognitive functioning and deficits in two or more adaptive behaviors with onset before the age of 18...
|
182212 |
FBN1 Fibrillin-1 is a protein that in humans is encoded by the FBN1 gene.This gene encodes a member of the fibrillin family. The encoded protein is a large, extracellular matrix glycoprotein that serve as a structural component of 10-12 nm calcium-binding microfibrils...
|
Differential diagnosis
A separate cause of abnormal head shape is
positional plagiocephalyPositional plagiocephaly, also known as deformational plagiocephaly or flathead syndrome, is a condition most commonly found in infants and is characterized by a flat spot on the back or one side of the head caused by remaining in one position for too long.-Causes:It can be caused by a condition...
— flattened or misshapen areas on the head that may develop due to sleeping position. While the appearance may look rather similar to craniosynostosis, the distinction is important. Positional plagiocephaly does not require surgery — treatment can be as simple as occasionally repositioning the child's head while sleeping or, in some cases, wearing a cranial band to mold the skull.
It has recently been discovered that using certain prescription drugs during pregnancy may lead to this disorder. (sertraline)
Treatment
SurgeryCraniofacial surgery is a surgical subspecialty of oral and maxillofacial surgery, plastic surgery, and ENT that deals with congenital and acquired deformities of the skull, face, and jaws. Although craniofacial treatment often involves manipulation of bone, craniofacial surgery is not...
is typically used to separate the fused sutures of the skull as well as to reshape the skull. To treat the cosmetic troubles, a combination of
orthodonticOrthodontics is a specialty of dentistry that is concerned with the study and treatment of malocclusions , which may be a result of tooth irregularity, disproportionate jaw relationships, or both...
and
orthognathic surgeryOrthognathic surgery is surgery to correct conditions of the jaw and face related to structure, growth, sleep apnea, TMJ disorders or to correct orthodontic problems that cannot be easily treated with braces. Originally coined by Dr. Harold Hargis, D.M.D., it is also used in treatment of...
can be used to relieve some of the midface deficiency.
Typical surgery begins with a
zigzagA zigzag is a pattern made up of small corners at variable angles, though constant within the zigzag, tracing a path between two parallel lines; it can be described as both jagged and fairly regular....
incision from
earThe ear is the organ that detects sound. The vertebrate ear shows a common biology from fish to humans, with variations in structure according to order and species. It not only acts as a receiver for sound, but plays a major role in the sense of balance and body position...
to ear across the top of the
headIn anatomy, the head of an animal is the rostral part that usually comprises the brain, eyes, ears, nose, and mouth...
. The
scarScars are areas of fibrous tissue that replace normal skin after injury. A scar results from the biologic process of wound repair in the skin and other tissues of the body. Thus, scarring is a natural part of the healing process. With the exception of very minor lesions, every wound Scars (also...
left by this type of incision makes the
hairHair is a protein filament that grows through the epidermis from follicles deep within the dermis. The fine, soft hair found on many nonhuman mammals is typically called fur; wool is the characteristically curly hair found on sheep and goats. Found exclusively in mammals, hair is one of the...
look more natural than that left by a straight incision would. Leroy clips are typically used to curtail bleeding, as
cauterizationThe medical practice or technique of cauterization is a medical term describing the burning of part of a body to remove or close off a part of it in a process called cautery, which destroys some tissue
would not result in an aesthetically pleasing result upon healing. Once the scalpThe scalp is the anatomical area bordered by the face anteriorly and the neck to the sides and posteriorly.-Layers:It is usually described as having five layers, which can be remembered with the mnemonic "SCALP":....
is peeled back, pilot holes are drilled through the skull. These pilot holes are then connected, separating the skull into several pieces. Once reshaped, these pieces are placed back on the head (typically in an altered configuration) and held together by a combination of dissolving sutures, plates, and screwA screw, or bolt, is a type of fastener characterized by a helical ridge, known as an external thread or just thread, wrapped around a cylinder. Some screw threads are designed to mate with a complementary thread, known as an internal thread, often in the form of a nut or a object that has the...
s. These plates and screws are typically made of a copolymer composed of polyglycolicPolyglycolide or Polyglycolic acid is a biodegradable, thermoplastic polymer and the simplest linear, aliphatic polyester. It can be prepared starting from glycolic acid by means of polycondensation or ring-opening polymerization. PGA has been known since 1954 as a tough fiber-forming polymer...
and polylactic acidPolylactic acid or polylactide is a biodegradable, thermoplastic, aliphatic polyester derived from renewable resources, such as corn starch or sugarcanes...
and will break down into waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
and carbon dioxideCarbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state...
within a year. Demineralized bone matrix or bone morphogenetic proteinBone Morphogenetic Proteins are a group of growth factors and cytokines known for their ability to induce the formation of bone and cartilage.-Types:Originally, seven such proteins were discovered...
s are often used to fill gaps left by the expanded skull, encouraging the body to grow new bone in a process called intramembranous ossificationIntramembranous ossification is one of the two essential processes during fetal development of the mammalian skeletal system resulting in the creation of bone tissue. Unlike endochondral ossification, which is the other process, cartilage is not present during intramembranous ossification...
. Once the hemostatic scalp clips are removed, sutures are again used to close the incision.
Newer approaches include minimally invasive endoscopic assisted removal of the closed suture followed by treatment with custom made molding helmets. These surgeries are associated with significantly less blood loss, swelling, hospital length of stay and pain. The results have been excellent in the majority of patients treated this way. Endoscopic surgery, however, is indicated only for very young infants(< 6 months of age). Older children require the more extensive surgery described above.
Epidemiology
The incidenceIncidence is a measure of the risk of developing some new condition within a specified period of time. Although sometimes loosely expressed simply as the number of new cases during some time period, it is better expressed as a proportion or a rate with a denominator.Incidence proportion is the...
of craniosynostosis has been described as 1 in 2500 live births. The earliest known case is a child dated to 530,000 BP found in Atapuerca Spain.
External links