What is Frontal Bossing?
When a person has a forehead that is prominent and protruding, the medical term that can be used to describe it is frontal bossing. There is a clear connection between the development of the bones, the hormonal activity and the stature. Frontal bossing is most commonly identified in infants or small children. In general, the treatment is undertaken in accordance to the underlying condition that has led to such modifications in the first place. However, it is important to understand that such changes are permanent and cannot be corrected; the frontal bossing influences not only the bones of the skull but also the tissues at the level of the face and how they develop.
How is Frontal Bossing Recognized?
A child with frontal bossing can be easily recognized due to the enlarged or protruding forehead. Some children present an enlarged eyebrow ridge. Even though such changes are presented from an early age, they will become more obvious with the passing of time. As you will have the opportunity to read below, frontal bossing is often one of the signs that suggest a genetic disorder. Many congenital defects are also associated with such modifications. Apart from the frontal bossing, the child might present other physical deformities as well. The other facial bones might be enlarged, plus the ones of the mandible or the ones of the extremities.
Causes
These are the most common causes that can lead to the appearance of frontal bossing:
- Acromegaly – chronic condition in which abnormal quantities of the growth hormone are produced at the level of the pituitary gland; apart from the frontal bossing, those who are diagnosed with this condition present longer-than-average bones (extremities, jaws, skull)
- Taking certain medication during pregnancy – for example, anti-seizure drugs (trimethadione)
- Basal cell nevus syndrome – also known as the Gorlin syndrome or the nevoid basal cell carcinoma syndrome, it includes a group of defects that have a genetic basis; the syndrome affects not only the bones but also the skin, glands, nervous system and eyes
- Congenital syphilis – syphilis which is present in utero and at birth, due to the mother suffering from the sexually-transmitted disease
- Cleidocranial dysostosis – hereditary congenital disorder, which is primarily characterized by the delayed closure of the cranial sutures
- Russell-Silver syndrome – form of dwarfism, characterized by stunted growth, limb and/or facial asymmetry
- Rubinstein Taybi syndrome – also known as the broad thumb-hallux syndrome, this is a genetic disease that includes a series of symptoms, including the short stature and the intellectual disability
- Pfeiffer syndrome – genetic disorder, in which certain skull bones fusion prematurely (also known as craniosynostosis)
- Hurler syndrome – also known as mucopolysaccharidosis type I, this is a rare condition involving the metabolism (long chains of sugar cannot be broken down)
- Crouzon syndrome – autosomal dominant genetic disorder, in which certain bones of the skull fusion prematurely
- Abnormal growths – these are present either at the level of the forehead or in the entire skull
- Erythropoiesis – this happens when this process occurs away from long bones, such as in the patients suffering from chronic anemia (decrease in the volume of the bone marrow, which in turn leads to depressed intramedullary hematopoiesis)
- Thalassemia major
- Sickle cell anemia
In general, frontal bossing is due to underlying conditions that influence the level of the growth hormone. Certain genetic defects – PEX1, PEX13 and PEX26 genes – are also known to lead to physical deformities, frontal bossing included.
Diagnosis
These are the most common methods used for the diagnosis of frontal bossing:
- Physical examination of forehead and brow ridge
- Medical history of the patient
- When the frontal bossing was noticed for the first time
- Other symptoms that the child might present
- Unusual characteristics noticed by the parents
- Family history – genetic conditions, gene defects, inherited disorders
- Blood testing
- Growth hormone levels
- Genetic abnormalities
- Imaging studies – useful for confirming the cause of the frontal bossing; recommended tests include X-ray or MRI
X-rays reveal skull deformities that have led to the protrusion of the forehead or the brow ridge; the frontal bone of the skull appears protruding forwards (best appreciated on the sagittal image). MRI can identify deformities or abnormalities at the level of the skull bones or soft tissues.
Treatment
At the moment, there is no available treatment to cure frontal bossing. The treatment options concentrate on improving the symptoms of the underlying condition, especially if the patient experiences pain. The condition does not improve with the passing of time but, in majority of the patients, it does not become worse either. In the past few years, more and more patients have benefited from cosmetic surgery interventions – the results were positive, with many facial deformities being successfully treated. However, there is still a long way until frontal bossing can be treated through such interventions. There is no home care that can be considered or recommended for children diagnosed with frontal bossing.
In the future, it is believed that gene therapy might be able to correct the defects that lead to the appearance of genetic disorders. If that will be the case, this means that the frontal bossing will be prevented even before the embryo is formed. Scientists are constantly working on the possibility of manipulating genetic defects, trying to prevent abnormalities such as the frontal bossing. It is highly recommended that all parents get tested for genetic defects before actually deciding to conceive a baby.
Prevention
Unfortunately, it is not possible to prevent frontal bossing. Genetic counseling is useful during the conceiving and pre-natal period, as it can determine whether the child will suffer from a genetic disorder that may lead to such changes. In order to determine such risks, both parents will have to be tested (blood testing and urine analysis). If it is determined that one of the parents is a carrier of a defective gene, the doctor might recommend taking certain medication. Fertility treatments are also available for such cases. It is recommended that anti-seizure medication, such as trimethadione, is avoided during pregnancy. In this way, the risk of the child being born with frontal bossing is genuinely reduced.