Diagnosis

Diagnosis is the process by which health professionals determine the underlying cause of any medical condition affecting an individual. Making a diagnosis is a two step process. The first is deciding upon the most probable cause, based on the history and clinical appearance.  The second step is confirming the likely cause, using specifically directed investigations, to give the diagnosis.  

The EEG is a diagnostic tool which can be used in all age groups.  It is safe, quick to apply, painless, and can be performed at the bedside with minimal inconvenience to patients.  It can provide clinicians with considerable information about brain function, brain maturity and certain neurological conditions, and is increasingly being used to monitor newborn babies who are thought to be at risk for various conditions affecting the central nervous system.  In fact, EEG is considered the “gold standard”, or best test, to diagnose some conditions, such as seizures in newborns.

In order to improve our ability to diagnose certain neonatal neurological conditions, we must study the EEG’s response to impaired brain function and identify specific EEG patterns that are associated with particular brain disorders.  The presence of these patterns on the newborn EEG can then be used to diagnose neonatal neurological conditions rapidly and cost effectively.

We are currently studying the use of EEG features and quantitative EEG features for diagnosing seizure disorders and hypoxic ischaemic encephalopathy (HIE) (injury caused by inadequate supply of blood and oxygen to the brain) in the newborn.

Seizures are the most common neurological emergency in the newborn period and are a worrying sign for parents and clinicians. The incidence of seizure in babies born at full term (40 weeks) is 1.5-3.0 per 1,000 births: the incidence is higher in the more vulnerable group of premature babies, with estimates ranging from 50-150 per 1,000 live births. Most neonatal seizures are only accompanied by very subtle clinical signs and the only way to accurately diagnose a seizure disorder in the newborn period is to use EEG monitoring.

Accurate and early diagnosis of HIE is important as medical interventions such as total body cooling must be administered within the first six hours after birth. However, only a certain category of newborns with HIE will benefit from this method of treatment so the correctly identification of these newborns is critical. Quantitative analysis of newborn EEG has a potential to simplify this process and make it more accurate.

We are also investigating diagnostic methods that do not involve EEG, in particular blood biomarkers. We are researching alternate diagnostic methods as very few neonatal units in Ireland currently have 24 hour access to EEG facilities, or to experts in neonatal EEGs who can interpret them.  Alternate methods of diagnosis are, therefore, required until accurate, automated EEG diagnostic systems become widely available to the neonatal intensive care unit.

Biomarkers have many definitions, but in essence they are any substance which can be objectively measured to gain information on a biological process.  We are interested in various chemicals and proteins in the blood, to see if they can provide an early diagnosis of HIE. The diagnosis will be based on a small sample of blood taken from the placenta shortly after the baby and placenta have been delivered.

Further Information on diagnosis of HIE can be found in;

1. A. Malone, C.A. Ryan, A. Fitzgerald, L. Burgoyne, S. Connolly, G.B. Boylan. "Interobserver agreement in neonatal seizure identification".  Epilepsia, vol. 50(9), pp. 2097-2101, September 2009.
2. D.M. Murray, G.B. Boylan, I. Ali, C.A. Ryan, B.P. Murphy, and S. Connolly. "Defining the gap between electrographic seizure burden, clinical expression and staff recognition of neonatal seizures".  Archives of Disease in Childhood: Fetal Neonatal Edition, vol. 93(3), pp. F187-191, May 2008.
3. D.M. Murray, Boylan GB, Fitzgerald AP, Ryan CA, Murphy BP, S. Connolly . "Persistent lactic acidosis in neonatal hypoxic-ischaemic encephalopathy correlates with EEG grade and electrographic seizure burden".  Archives of Disease in Childhood: Fetal Neonatal Edition, vol. 93(3), pp. F183-186, May 2008.
4. D.M. Murray, C.A. Ryan, G.B. Boylan, A.P. Fitzgerald, S. Connolly. "Prediction of seizures in asphyxiated neonates: correlation with continuous video-electroencephalographic monitoring". Pediatrics, vol. 118(1), pp. 41-46, July 2006.
5. Murray DM, Boylan GB, Ryan CA, Connolly S.  Early continuous video-EEG in acute near-total intrauterine asphyxia.  Pediatric Neurology. vol. 35(1), pp. 52-56, July 2006.