It is a fetal abnormality of the brain in which the brain of the fetus remains underdeveloped and does not divide into two hemispheres, which is the real norm.
Definition: Holoprosencephaly may result in the way the baby’s face and head develop at the time of birth. It has been divided into four types according to the severity of the condition.
These types are:
- Soft knit.
- Interhemispheric medium.
The more severe the condition, the more severe the deformity of the face and head of the child due to holoprosencephaly. Children with the most severe type of holoprosencephaly tend to have only one eye and the nasal structure of the nose is tubular located above the eye.
In the less severe forms of holoprosencephaly, both eyes are present, but they are very close to each other. These children will have intellectual disabilities and learning disabilities and will always require special education.
The reason for holoprosencephaly is still unknown, but there are certain genetic factors that, according to studies, may play a role in the development of the disease.
The prognosis for children with this condition is extremely poor and in severe forms of this condition, the child is usually a dead baby or can survive up to six months of age as a result of holoprosencephaly.
What are the causes of holoprosencephaly?
As indicated above, the exact cause is still unknown, but some studies suggest that the abnormality occurs within the first weeks of pregnancy.
The onset of diabetes when the woman is pregnant puts the fetus at risk of having holoprosencephaly, although in most cases an intrauterine cause is not known.
Some studies suggest a genetic role in the development of the disease.
It has been seen that about 40% of children born with this condition have a chromosomal abnormality whose most common abnormality is a condition called trisomy 13 in which there are three copies of chromosome 13 instead of the usual 2, one of each parent .
In some cases, there is a change in a specific gene that causes the gene to act abnormally, resulting in the development of holoprosencephaly.
Symptoms, according to types
The symptoms of holoprosencephaly vary according to the severity of the condition and the category to which the condition belongs. It can occur within a wide variety of clinical severity.
As indicated above, holoprosencephaly is divided into four subtypes according to the extent of separation of the hemispheres and, as such, the symptoms are different for each subtype.
Symptoms of Alobar holoprosencephaly : in this form of holoprosencephaly, there is absolutely no division of the brain and, as such, the child tends to have only one eye, a tubular nasal structure, cleft lip that can be unilateral or bilateral, and flattened nose
Symptoms of holoprosencephaly Semi-Lobar : in this form of holoprosencephaly, the division of the hemispheres occurs but the left hemisphere fuses in the right hemisphere in the frontal and parietal lobes.
Children who fall into the category of holoprosencephaly will have very close eyes to each other and the eyeballs may be abnormally small or, in some cases, even absent.
In addition, the bridge and the tip of the nose will flatten and there will be a cleft lip, a nostril and a cleft palate.
Symptoms of holoprosencephaly Lobar : in this form of holoprosencephaly, the brain is divided into two hemispheres but the cerebral hemisphere is fused. Symptoms may include bilateral cleft lip, eyes that are very close to each other and flattened nose.
Symptoms of middle interhemispheric holoprosencephaly : in this form of holoprosencephaly, the brain fuses from the middle and the symptoms include eyes that are very close to each other and the nose flattened and narrowed.
In addition, children with holoprosencephaly also tend to have a variety of other symptoms that include:
- Defects of the neural tube.
- Pituitary dysfunction.
- Extremely low stature.
- Feeding problems.
- Development delays
- Intellectual disability
How is holoprosencephaly diagnosed?
Since it is a defect that can be easily seen at the birth of the child, there is no definitive evidence to confirm the diagnosis; however, by means of imaging studies such as an MRI or a computerized tomography of the brain, the extent of the disease and its subtype can be diagnosed.
In addition, holoprosencephaly can also be diagnosed prenatally by abdominal ultrasound of the mother that will clearly show the abnormality in the facial features that confirm the diagnosis.
The treatment for holoprosencephaly is usually supportive and specific for the deformity that the child has and, therefore, depends on each case.
To identify any pituitary anomaly, an evaluation by an endocrinologist can be made. For the treatment of seizures, medications can be administered to control them and, therefore, a neurologist should be consulted.
Plastic surgery should be consulted to correct the cleft lip and cleft palate as well as to reconstruct other facial deformities that are part of the holoprosencephaly.
For developmental delays, a specialist in this field of medical science can be a great help to help parents and the child.
In general, the treatment of holoprosencephaly requires a multidisciplinary approach that includes neurologists, plastic surgeons, special education teachers, and psychologists who can formulate a plan on how to best treat the child and keep him comfortable during the treatment of holoprosencephaly.
It is very difficult for the parents of the affected child to cope with the disease process and, therefore, counseling sessions are also quite useful for parents.
What is the prognosis or life expectancy in holoprosencephaly?
The prognosis is variable and depends on the subtype of the disease. The alobar form of holoprosencephaly, which is the most severe form, has the worst prognosis and most children do not survive beyond six months.
Children affected in a much milder way can survive up to a year or more. Children with a semi-lobar or lobar subtype can survive for approximately two years after the diagnosis of holoprosencephaly.