What is Craniosynostosis?
Craniosynostosis is a birth defect involving the development of the skull characterized by premature fusion of one or more suture or the connection between plates of the infant’s skull. Premature fusion of the plates resulted to a misshapen head of infant with this birth defect.
During birth, the cranium of a newborn child consists of several bones that are joined while being separated at the same time by a fibrous suture. The skull of newborn infant is fragile and malleable that the fibrous suture functions in allowing movement of the bone in relation to one another. It also absorbs the mechanical forces and deformation of the skull while allowing expansion necessary for the brain growth. The ongoing growth of the brain is what keeping the suture open and the normal growth of the skull is dependent of each suture.
Craniosynostosis equally affects both male and female genders. The occurrence is evident in cases of primary craniosynostosis when associated with other abnormalities of the craniofacial during the neonatal period while in infancy, both primary and secondary craniosynostosis becomes evident while the child is growing.
Craniofacial deformities are the evidence of craniosynostosis during birth or infancy period or may become evident when during the growing period a child displays delay in neurodevelopment. The symptoms may not be apparent at birth until the first few months of infant life.
General symptoms of craniosynostosis include:
- Misshapen skull
- Vanishing or a feeling of vanishing fontanels on the skull of the baby
- Delayed growth or no growth at all of the size of the baby’s head
- Hard ridge progression along suture that is affected
- Onset of intracranial pressure
The physical presentation varies depending on the category and type of craniosynostosis a child is suffering.
There are basically two categories of craniosynostosis classified according to the nature of onset and these are:
Primary craniosynostosis primarily involves one or more cranial suture that fused prematurely thereby restricting the brain from growing and increasing in size normally. Intracranial pressure if highly possible in this category as the brain is increasing in size.
Secondary craniosynostosis is the premature fusion of the cranial sutures that resulted from the brain’s failure to grow and increase in size due to an underlying condition. This however, is the more frequent craniosynostosis to occur. The process of brain growth impels separation of bone plates from sutures that the absence in the ability of the brain to grow allows for a premature fusion among cranial sutures.
The incidence of craniosynostosis may involve one or more sutures while manifestations or the clinical presentation depends on which suture is involved.
Types of craniosynostosis according to sutures involved:
Scaphocephaly or Sagittal synostosis is the premature fusion of cranial suture located on top of the head. It is the most common type of craniosynostosis with elongated and narrow skull deformity.
Anterior plagiocephaly of Coronal synostosis is the premature fusion of the suture that runs from each ear to the top of the head or the sagittal suture that gives the flatten characteristic of the forehead of the baby on the affected side. The eye socket may hoist up while the skull is inclined and the nose deviated.
Brachycephaly or Bicoronal synostosis involves both coronal sutures fusing prematurely giving the baby a prominent forehead and brow and a flattened head while biparietal diameter is increased.
Trigonocephaly of Metopic synostosis involves the suture running from the nose of the baby to the sagittal suture that gives a triangular appearance of the scalp. It is among the rare type of craniosynostosis.
Posterior plagiocephaly or Lambdoid synostosis is a rare type of craniosynostosis involving the lambdoid suture running transversely on the skull next to the back of the head. This type is characterized by a flattening on the affected side of the head of the baby.
It does not necessarily mean that a baby with a misshapen head is suffering from craniosynostosis. The deformity could however be accounted for the sleeping position of the baby. It should not worry parents of the baby as this positional molding is nothing serious or craniosynostosis.
No definite etiology has been identified for the implication of craniosynostosis. Genetic mutation has been implicated in the case of syndromic craniosynostosis while several factors have been considered in the case of nonsyndromic craniosynostosis while the definite etiology remains unidentified.
Factors considered leading to craniosynostosis:
Environmental factor contributes as a result of maternal exposure to such cigarette smoking and drugs containing amine. These environmental factors increase the risk for craniosynostosis through the effect in the fibroblast growth factor receptor gene.
Biomechanical factor includes constraint in the fetal head during pregnancy as a result of noggin and Indian Hedgehog protein decrease in expression which are the two most important influential factors in the development of bone.
Hormonal is considered a factor especially with the increase level of thyroid hormone. It is believed that hyperthyroid influences rapid bone maturity.
Medication taken by mothers at the time of pregnancy greatly affects the developing embryo. Valproic acid used for the treatment of epilepsy taken by pregnant women is considered a factor at risk for delivering a child with craniosynostosis.
Craniosynostosis involving fusion of a single suture and without any underlying condition usually does not require treatment as the skull deformity becomes less apparent with the development and growth of hair.
Surgery is commonly recommended and is the primary treatment for craniosynostosis involving multiple suture or single suture accompanied with underlying syndrome. The goal of surgery is in relief of intracranial pressure while providing enough space for the brain to grow and develop normally. Form of surgical procedures may include:
- Traditional surgery through incision of cranial bone and scalp while reshaping the affected area of the skull.
- Endoscopic surgery is less invasive that utilizes an endoscope to in opening the suture to allow normal growth and development of a baby’s brain.
Craniosynostosis associated with underlying syndrome requires for a regular follow-up post surgery to monitor head growth and intracranial pressure.
Picture collection of Craniosynostosis…