Critical care decisions in fetal and neonatal medicine: ethical issues
Appendix 4: Brain injury in the newborn baby
Diagnosis of brain injury in the newborn baby
There are three major tools used alongside clinical examination to assess the brain of a newborn baby for abnormalities:
- Ultrasound scanning sends high frequency sound waves into tissue and measures the reflection of sound back (similar to naval sonar). The scanner detects changes that indicate bleeding, enlargement of the normally slit-like fluid-filled spaces (ventricles), and areas of brain injury, often comprising cystic changes which represent areas where brain cells have died. Doppler ultrasound can also be used to measure the speed of blood flow inside blood vessels and is more useful in assessing brain injury in the term baby.
- Magnetic resonance imaging (MRI) involves placing the baby in a powerful magnetic field and reversing the polarity of the magnet, causing tiny radio signals to be emitted by the body which are picked up by a sensitive receiver. With MRI, doctors can now identify areas of injury due to lack of blood supply or lack of oxygen (infarction) with more definition than ultrasound and can better define the details of congenital malformations of the brain and spine.2
- Electroencephalography (EEG) measures the spontaneous electrical activity of the brain. In newborn babies EEG can accurately identify seizures and abnormalities in background brain electrical activity which relate to long-term outcome. In addition the cerebral function monitor (a simple form of EEG) is used to monitor EEG activity over a long period of time and these records have proved usefully predictive of later development.3
Other forms of clinical examination have been developed (some using long periods of video recording) that have proved helpful in predicting if a poor outcome is likely. Other techniques such as computerised (axial) tomography (CT) scanning (computerised scan involving a large dose of Xrays) and testing of specific brain pathways for vision, hearing, sensation and movement are occasionally used, although not in routine practice.
Footnotes
2 Biagioni E, Mercuri E, Rutherford M et al. (2001) Combined use of electroencephalogram and magnetic resonance imaging in full-term neonates with acute encephalopathy Pediatrics107: 461–8.
3 Ibid.