12 - Congenital defects of the nervous system

Summary

A congenital disorder is a medical condition that starts long before birth. This category includes conditions in which the brain and nervous system of a baby growing in the womb have been damaged or have not developed as they should. Most of these deaths occur in childhood, but a few occur in adulthood, resulting in an average age at which deaths occur of 13 years.

This is a very rare cause of death, accounting for, on average, 260 deaths per year over the 24 years studied. The geographical pattern for this group of causes of death is not very strong. From the map it appears that slightly higher ratios can be seen in the northern and western parts of the country; lower rates are found within London.

These causes of death include anencephalus (the absence at birth of all or part of the brain with death occurring within days), spina bifida (a spinal cord defect) and microcephaly (a neurological disorder in which the brain is small or squashed by the skull). The word ‘microcephaly’ derives from the Greek for small head. Microcephaly may be congenital or it may develop in the first few years of life.

Spina bifida, which accounts for approximately a third of deaths in this category, is a condition whereby a baby is born with a damaged spinal cord due to incomplete closing of the spine around it. This can cause difficulty walking and incontinence of urine and faeces. It is a common reason for a child needing to use a wheelchair; the child is not impaired above the level of the spinal defect. Many cases of spina bifida are due to inadequate intake of folic acid by the mother; taking folic acid around the time of conception can significantly reduce the incidence of spina bifida.

Congenital hydrocephalus, sometimes known as ‘water on the brain’, is when there is an abnormal accumulation of cerebrospinal fluid in the cavities of the brain, causing pressure and leading to enlargement of the head.

The remainder of deaths in this category are due to several other congenital defects of the nervous system which are often not specified further in the records.