When is an individual considered to have microcephaly?

Answer 1

What is Microcephaly?

Microcephaly is a medical condition in which the circumference of the head is smaller than normal because the brain has not developed properly or has stopped growing.

Microcephaly can be present at birth or it may develop in the first few years of life. It is most often caused by genetic abnormalities that interfere with the growth of the cerebral cortex during the early months of fetal development. It is associated with Down's syndrome, chromosomal syndromes, and neurometabolic syndromes.

Babies may also be born with microcephaly if, during pregnancy, their mother abused drugs or alcohol, became infected with a cytomegalovirus, rubella (German measles), or varicella (chicken pox) virus, was exposed to certain toxic chemicals, or had untreated phenylketonuria (PKU). This can also be caused by the mother having the Zika virus during pregnancy.

Babies born with microcephaly will have a smaller than normal head that will fail to grow as they progress through infancy. Depending on the severity of the accompanying syndrome, children with microcephaly may have mental retardation, delayed motor functions and speech, facial distortions, dwarfism or short stature, hyperactivity, seizures, difficulties with coordination and balance, and other brain or neurological abnormalities.

Some children with microcephaly will have normal intelligence and a head that will grow bigger, but they will track below the normal growth curves for head circumference.

Is there any treatment? There is no treatment for microcephaly that can return a child's head to a normal size or shape. Treatment focuses on ways to decrease the impact of the associated deformities and neurological disabilities.

Children with microcephaly and developmental delays are usually evaluated by a pediatric neurologist and followed by a medical management team. Early childhood intervention programs that involve physical, speech, and occupational therapists help to maximize abilities and minimize dysfunction. Medications are often used to control seizures, hyperactivity, and neuromuscular symptoms. Genetic counseling may help families understand the risk for microcephaly in subsequent pregnancies.

What is the prognosis? Some children will only have mild disability. Others, especially if they are otherwise growing and developing normally, will have normal intelligence and continue to develop and meet regular age-appropriate milestones.

What research is being done? The National Institute of Neurological Disorders and Stroke (NINDS) conducts research relating to microcephaly in its laboratories at the National Institutes of Health (NIH) and supports additional research through grants to major medical institutions across the country. A small group of researchers studying a rare neurometabolic syndrome (3-PGDH), which causes microcephaly, have successfully used amino acid replacement therapy to reduce and prevent seizures.

Answer 2

An individual is considered to have microcephaly when their head circumference is significantly smaller than average for their age and sex. This condition typically indicates that the brain has not developed properly, which can lead to various developmental challenges. Microcephaly can be diagnosed at birth or later in infancy.

Answer 3

that which is either two or three standard deviations (a statistical measure of variability) below the normal average head circumference for the age, gender, and race of the child.