Cephalic disorders are conditions affecting the brain and central nervous system of a developing fetus. The severity of the disorder can range from mild to profound. Many of the most severe forms of cephalic disorder are fatal.

Types of cephalic disorders include anencephaly, colpocephaly, holoprosencephaly, hydranencephaly, lissencephaly, megalencephaly, microcephaly, porencephaly and schizencephaly.

In most cases, cephalic disorders are caused by disturbances that occur early in fetal neurological development. A combination of factors can cause cephalic disorders, including hereditary or genetic conditions, and exposures to certain environmental factors, such as medications and environmental toxins (e.g., maternal infections and exposure to radiation).

Signs and symptoms of cephalic disorders vary depending on the nature and severity of the disorders. Mild cases of cephalic disorder produce few if any symptoms. More significant cases of cephalic disorder may result in severe physical abnormalities and profound cognitive impairment. Many children with significant cephalic disorders do not live long, are miscarried or arrive stillborn.

The time at which a specific cephalic disorder can be diagnosed depends on the condition. Some can be diagnosed before a child is born, such as through an ultrasound test. In some cases, parents may choose genetic counseling if they have a family history of certain genetic problems. Others cannot be confirmed until after birth. In some cases, a cephalic disorder may not be identified until symptoms appear a few years after the child is born.

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.

Cephalic disorders are congenital diseases that occur when the developing brain and nervous system of a fetus is abnormal or damaged. A number of factors can cause these conditions to develop, and the severity of the disorder can range from mild to profound. Many of the most severe forms of cephalic disorder are fatal.

“Cephalic” means head or related to the head. During development, the cells that will make up the human brain and spine roll into a cylindrical mass known as the neural tube. This narrow sheath closes sometime during the third or fourth weeks of pregnancy and become the brain and spinal cord.

The development of the nervous system proceeds through four major processes:

• Cell proliferation. Nerve cells divide to form new generations of cells.
  
  
• Cell migration. Nerve cells move to their proper place in the body.
  
  
• Cell differentiation. Cells acquire individual characteristics.
  
  
• Cell death. The natural process by which cells dissolve.

Cephalic disorders occur when something goes wrong during this process of development. Chronic and disabling disorders may develop as a result of such abnormalities. The severity of disability depends on the abnormality and can vary tremendously from patient to patient.

There are several different types of cephalic disorders. The most common types include:

• Anencephaly. This is a type of neural tube defect (NTD) resulting from failure of the cephalic (head) end of the neural tube to close. It develops between the 23^rd and 26^th day of gestation. Children born with this condition often lack a major portion of the brain, skull and scalp and do not have a forebrain. This is the largest part of the brain and it contains the cerebrum, which is responsible for thinking and coordination. Patients with anencephaly usually cannot see or hear and are unconscious. As a result, they do not feel pain.
  
  It is one of the most common disorders of the central nervous system in fetuses. Between 1,000 and 2,000 babies are born every year with this condition, according to the National Institute of Neurological Disorders and Stroke. Females are affected more often than males. Most children diagnosed with anencephaly do not live past infancy, and death often occurs soon after birth. These babies may be stillborn. Spina bifida is another type of NTD.
  
  
• Colpocephaly. Abnormal enlargement of the rear portion of the lateral ventricles of the brain (occipital horns, at the back of the head near the base of the skull) caused by a lack of development or thickening of the white matter in the posterior cerebrum. It develops during the first or second trimester. Affected patients are mentally retarded and have an abnormally small head (microcephaly), motor problems, muscle spasms and seizures. The prognosis varies depending on the degree of abnormal brain development associated with colpocephaly.
  
  
• Holoprosencephaly. Occurs when the forebrain does not completely divide into the left and right halves of the brain (bilateral cerebral hemispheres). It occurs during the fifth or sixth week of gestation. Holoprosencephaly results in abnormalities of structure and function of the face and brain. There are three types, including alobar holoprosencephaly (brain fails to separate at all, causing severe facial anomalies) semilobar holoprosencephaly (brain separates slightly) and lobar holoprosencephaly (separation occurs that is almost, but not quite, normal). Severe cases can result in miscarriage, stillbirth or severe facial defects, such as development of just a single eye (cyclopia). Mild cases may result in lesser facial defects (such as a cleft lip) and normal brain development. Seizures and mental retardation also are associated with holoprosencephaly.
  
  
• Hydranencephaly. A rare, extreme form of porencephaly in which the cerebral hemispheres are absent. It usually occurs as a result of damage to the vascular system or trauma during the 12^th week of development. Sacs filled with cerebrospinal fluid usually take the place of the missing hemispheres, while the cerebellum and brainstem are normally formed. Children born with this condition often appear normal at birth, but may become irritable and show increased muscle tone (hypertonia) a few weeks after birth. Several months later, seizures and abnormally large head size (hydrocephalus) may develop. Other symptoms include visual impairment, lack of growth, deafness, blindness, paralysis and intellectual deficits. Prognosis is usually poor, with most children dying before their first birthday.
  
  
• Iniencephaly. A rare neural tube defect in which there is extreme backward bending (retroflexion) of the head and severe defects in the spine. This causes short stature with a disproportionately large head, with the skin of the face connected to the chest and the scalp connected to the skin of the back. The neck usually is absent. Affected patients may have associated conditions such as anencephaly, cephalocele (a disorder in which part of the cranial contents protrudes from the skull), hydrocephalus, cyclopia, absence of the mandible (lower jaw bone), cleft lip and palate, cardiovascular disorders, hernia of the diaphragm, and gastrointestinal malformation. Females are more often diagnosed with iniencephaly than males.  Prognosis is poor, with most patients living just a few hours after birth. The mother’s health also may be in jeopardy during delivery because of the distortion in the fetus’ body.
  
  
• Lissencephaly. Rare brain malformation marked by microcephaly and reduced number of normal folds in the brain. It occurs when nerve cells move from their place of origin to a new permanent location (defective neuronal migration). Symptoms include unusual facial appearance, difficulty swallowing, failure to thrive and severe slowing of movement directly related to brain activity (psychomotor retardation). Anatomical abnormalities of various organs (e.g., hands, fingers, toes), muscle spasms and seizures may occur. Prognosis varies depending on the degree of brain malformation. Some children may have near-normal development while many others die before age 2. Respiratory failure is a frequent cause of death.
  
  
• Megalencephaly (macrencephaly). Condition in which the brain is abnormally large and heavy and may not function properly. Head enlargement may be evident at birth, or may not occur until a few years later. Other symptoms include delayed development, corticospinal (brain cortex and spinal cord) dysfunction and seizures. Males are affected more often than females. The prognosis often depends on the underlying cause and associated neurological disorders. Megalencephaly may lead to macrocephaly in some cases. In rare cases, just one-half of the brain is affected (hemimegalencephaly). Prognosis for these patients typically is poor.
  
  
• Microcephaly. Neurological disorder marked by head circumference smaller than average given a child’s age and gender. It is also associated with Down syndrome. The condition sometimes is congenital, but it also may develop later within the first few years of life. Patients may have a large face, receding forehead, and loose, wrinkled scalp. As children with this disorder grow older, they often are underweight and lack proper stature. There may be delays in development of motor functions and speech. Other symptoms include hyperactivity, mental retardation and convulsions. Life expectancy may be reduced.
  
  
• Porencephaly. Very rare disorder of the central nervous system that may occur before or after birth. Cysts or cavities develop in one cerebral hemisphere, often as a result of destructive lesions or abnormal development. Symptoms include poor or absent speech development, epilepsy, hydrocephalus, spastic contractures (shrinkage or shortening of muscles), and mental retardation. Prognosis varies depending on the location and extent of the lesion. Some patients may have normal intelligence and minor neurological problems, while others may die before age 20.
  
  
• Schizencephaly. Rare form of porencephaly in which abnormal clefts form in the cerebral hemispheres. When clefts appear in both hemispheres, patients may experience delayed speech and language skills, and corticospinal dysfunction. Smaller clefts that appear in just one hemisphere may cause weakness on one side of the body, but many patients have average or near-average intelligence. Other symptoms include microcephaly, mental retardation, paralysis affecting one side of the body or affecting all four extremities, or reduced muscle tone (hypotonia). Seizures are common, and some patients have hydrocephalus. Prognosis varies depending on brain cleft size and degree of neurological deficit.

Less common types of cephalic disorders include:

• Acephaly. Parasitic twin fetus is attached to the intact fetus. The second fetus lacks a head and a heart.
  
  
• Exencephaly. Brain is located outside of the skull. In most cases, the fetus is miscarried.
  
  
• Octocephaly. Marked by agnathia, a developmental anomaly characterized by total or virtual absence of the lower jaw. The condition is lethal due to a poorly functioning airway.
  
  
• Brachycephaly. Diameter of the skull from front to back is shorter.
  
  
• Oxycephaly. Involves premature closure of the coronal suture that connects the front, top and sides of the skull.
  
  
• Plagiocephaly. Premature unilateral fusion (joining of one side) of the coronal or lambdoid sutures that connect the top and sides to the back of the skull.
  
  
• Scaphocephaly. Premature fusion of the sagittal suture that connects the sides of the skull.
  
  
• Trigonocephaly. Premature fusion of the metopic suture (part of the frontal suture that joins the two halves of the frontal bone of the skull).

In most cases, cephalic disorders result from a disturbance that occurs very early in fetal neurological development. As the nervous system develops, it transforms from a small plate of cells into a neural tube. During the third and fourth weeks of pregnancy, this narrow sheath closes to form the brain and spinal cord.

However, in some cases difficulties arise during this formative period of the nervous system. These can result in cephalic disorders. Such a disorder often occurs as a result of a combination of factors, such as a hereditary or genetic condition. Exposures to certain environmental factors also can contribute to the development of cephalic disorders. For example, certain medications taken by the mother during pregnancy may be a contributing factor. Nutritional deficiencies in the mother may also be a factor. Other environmental factors include toxins, maternal infections and exposure to radiation.

Potential causes of specific cephalic disorders include:

In some cases, cephalic disorders in one child can portend an increased risk of similar disorders in future children of the same parents. For example, if a child is born with an opening in the neural tube such as anencephaly, subsequent children in the family have up to a 10 percent increase in risk of being born with anencephaly or a similar condition such as spina bifida.

Signs and symptoms of cephalic disorders vary depending on the nature and severity of the disorder. Mild cases of cephalic disorder may produce few if any symptoms. Patients may have mild facial deformities or slight impairment of cognitive abilities.

More significant cases of cephalic disorder may result in severe physical abnormalities and profound cognitive impairment. In many cases, the embryo or fetus is miscarried. Children with significant cephalic disorders do not live long. For specific signs of cephalic disorders, see the Types and Differences section.

Although cephalic disorders generally cannot be prevented, parents who have prenatal screenings often can learn information that will help them prepare for their child’s condition. Parents with a fetus whose prognosis is extremely poor may consider pregnancy termination. Parents facing such circumstances are urged to discuss their options with a physician.

Some cephalic disorders cannot be treated, such as anencephaly, holoprosencephaly, hydranencephaly and microcephaly. If the child survives such conditions, care can consist of managing related symptoms. Prognosis for those with these disorders is usually poor.

Some symptoms of these cephalic disorders can be treated with a variety of techniques. For example, hydrocephalus may be treated with a shunt, while anticonvulsant medication may be used to control seizures. Patients who have feeding difficulties may require a gastrostomy tube. Physical therapy and special education also is beneficial for many patients with cephalic disorders.

Experts believe that women of childbearing age who take folic acid can significantly reduce their risk of neural tube defects such as anencephaly and iniencephaly. For this reason, organizations such as the National Institute of Neurological Disorders and Stroke recommend that women of childbearing age take 0.4 milligrams of folic acid daily.

Women with diabetes who maintain control of their blood sugar levels during pregnancy may lower the risk of hydranencephaly in their children.

Preparing questions in advance can help parents to have more meaningful discussions with healthcare professionals regarding their child's condition. Parents may wish to ask their doctor the following questions related to cephalic disorders:

1. Genetic abnormalities run in our family. Do you recommend genetic counseling before trying to conceive?
   
   
2. How accurate are ultrasounds in screening for cephalic disorders?
   
   
3. Should I have an amniocentesis?
   
   
4. If my unborn child has a cephalic disorder, what steps need to be taken to care for my child?
   
   
5. What should I watch for during my child’s early years that might indicate the presence of a cephalic disorder?
   
   
6. What kind of cephalic disorder does my child have?
   
   
7. How serious is the cephalic disorder likely to be?
   
   
8. What types of treatments are available?
   
   
9. What is the long-term prognosis?
   
   
10. If I’ve had a child with a cephalic disorder, what are the odds that this may occur in a future child?
    
    
11. What steps can I take to lower the risk of cephalic disorder in my unborn child?