Cephalic disorders is the given name for those congenital conditions that arise from problems occurring during the development of a child's central nervous system and brain in utero. Cephalic is the medical term for "head" and congenital describes any condition which is present at, having usually manifested itself previous to, the birth.
The abnormalities that cause cephalic disorders occur during the very early stages of fetal development. The unusual shape or size of the baby's head is the most notable sign. The prognosis for the child is dependent upon which areas of the brain are affected and to what degree. The various types of cephalic disorders cause a wide range of delays in development, physical handicaps and the most severe types cause premature death in the form of miscarriage or stillbirth. There are no cures for cephalic disorders as such. However, associated conditions such as epilepsy can be treated with medication.
Causes of Cephalic Disorders
There are many factors that can contribute to a fetus suffering from a cephalic disorder. Influences include genetic and hereditary conditions, environmental exposures, the mother taking certain medications during pregnancy and maternal infections. Some disorders occur due to the cranial sutures, fibrous joints that connect the skull bones, fusing prematurely. Most cephalic disorders, however, are known to have occurred due to some kind of disturbance in the very early stages of the fetal neurological development.
The Most Common Types of Cephalic Disorders
There are many different cephalic disorders, including;
Anencephaly - The result of the neural tube failing to close at the cephalic end. As this usually occurs between the 23rd-26th day of pregnancy the result is a large part of the brain, skull and scalp being absent. Infants who are born suffering from anencephaly are classed as being in a vegetative state. They are usually unconscious, deaf, blind and impervious to pain. While a few may have a rudimentary brainstem, the absence of a functioning cerebrum means they will never regain consciousness.
Colpocephaly - One of the signs of this disorder is the significant enlargement of the child's occipital horns; the rear portion of the chambers of the brain. The cause of this enlargement is the underdevelopment of the white matter present in the posterior cerebrum. Other characteristics of colpocephaly are an abnormally small head, microcephaly and a delay in development. Other features that may manifest include muscle spasms, seizure and motor abnormalities. The cause isn't known but researchers believe that colpocephaly is the result of an intrauterine disturbance, which occurs between months 2-6 of the pregnancy.
Holoprosencephaly - This disorder is characterised by the forefront of the embryo's brain failing to develop. Rather than dividing normally to form the separate halves of the brain it remains fused, resulting in development defects of the face, brain function and structure. A wide spectrum of brain and facial defects exist with Holoprosencephaly. At one end these are so severe that spontaneous death often occurs. At the other end the most common abnormalities affect the upper lip, nose and eyes but near normal development of the brain. Holoprosencephaly has three main classifications:
- Alobar holoprosencephaly is the most severe form and is associated with the most severe facial abnormalities.
- Semilobar holoprosencephaly, an intermediate form in which the hemispheres of the brain have a slight separation.
- Lobar holoprosencephaly is the least severe type as the brain has significant separation of the hemispheres. In the mildest cases of this disorder the brain can be almost normal.
Lissencephaly – For normal brain development the neurons, or nerve cells, must migrate to their correct location in the nervous system and then connect with each other. Lissencephaly and its associated disorders are the result of these neurons ending up in the wrong place. The result is an abnormal brain formation and the baby having a very small head. This disorder causes a spectrum of neurological disabilities.
Megalencephaly – Also known as macrencephaly, this disorder results in the head being much larger than normal. More boys suffer from this disorder than girls, and it's thought the abnormally large head could be caused by the brain growing too large. While an embryo’s brain is developing, the normal course of matters is that a pruning process takes place to remove the cells that aren't needed. Megalencephaly is the result of this neuronal pruning not taking place. Children can suffer from seizures, delays in development and severe motor difficulties.
Microcephaly – A much smaller head than normal is the chief characteristic of this disorder and many children with a smaller than average head can enjoy normal intelligence and development. However, this disorder is also commonly found as part of other disorders, including trisomy 21, or Down’s Syndrome. Along with their intellectual disabilities, many children with microcephaly suffer from sensory disorders, visual difficulties, cerebral palsy, underdeveloped motor skills, lack of coordination and balance and have difficulty learning and thinking in keeping with their age group. Microcephaly is also a symptom of other cephalic disorders including colpocephaly and lissencephaly.
Porencephaly – This disorder is caused by a pocket of cerebrospinal fluid forming in the baby's brain. It is through that this could be related to a stroke of infection either in utero or at some point in the neonatal period. While some children with porencephaly have a normal level intelligence and few developmental problems, other suffer from varying degrees of cognitive or motor difficulties.
Schizencephaly – This is one of the rarest cephalic disorders and is the result of cleft forming in either one or both of the brains hemispheres. The long term impairments are directly related to how many clefts exist and also their location. Some people with schizencephaly lead a relatively normal life whereas others can suffer from seizures or serious delays in their development.
The Rarest Types of Cephalic Disorders
Acephaly, Exencephaly, Macrocephaly, Micrencephaly, Octocephaly, Brachycephaly, Oxycephaly, Plagiocephaly, Scaphocephaly and Trigonocephaly are very rare and take on many forms. Acephaly, for example, only manifests in a twin pregnancy where the head and heart fails to form on one of the embryos. This effectively means it lives off the other fetus in a parasitic manner and has no chance of surviving independently.
Diagnosis of Cephalic Disorders
The signs and symptoms of the various cephalic disorders are dependent on the severity and nature of the disorder. Mild cases produce few, if any, symptoms, whereas the more significant ones could result in severe cognitive impairment and physical abnormalities. Many babies with significant cephalic disorder are miscarried, stillborn or do not live long after birth.
Which condition the child is suffering from also affects when it can be diagnosed. Parents who have a history of genetic problems may seek genetic counselling, whereas ultrasound scans during pregnancy can sometimes detect the most severe cephalic disorders. There are others that can't be confirmed until the child is born and the mildest cases may not be diagnosed until several years after birth.
Prevention of Cephalic Disorders
There is no pill or vaccine to prevent the manifestation of cephalic disorders. However, research has made several discoveries pertaining to certain strains and their possible causes. For example, the vitamin intake and diet of the mother has been found to be a contributory factor in ancencephly, thus all pregnant women are now advised to take folic acid from before they try to get pregnant through to the second trimester. As well as a genetic factor, micrencephaly is also thought to be related to the mother’s health. Rubella, diabetes and alcoholism could all be contributory factors.
Some cephalic disorders cannot be treated. Prognosis for patients with these disorders is usually poor. In other cases, complications associated with cephalic disorders may be treated with medications or other techniques. Physical therapy and special education can also help some patients with cephalic disorders.