An EEG is the main diagnostic test required for West Syndrome. It’s not necessary for the infant to experience a seizure while having the EEG because an irregular, high voltage pattern known as hypsarrythmia will be seen while the spasms are not taking place. Other arrhythmic patterns may also be seen on the EEG. The electrodes on the scalp monitor electrical output within the brain during both activity and also during sleep. It is during sleep that hypsarrythmia is most frequently observed.
A lack of hypsarrythmia is not sufficient to conclusively rule out West Syndrome as a diagnosis because in some cases there can be a lag between clinical presentation and EEG abnormalities. For this reason, longer term EEG monitoring, during the night is far preferable to the standard 20 minute EEG appointment slot.
Brain scans such as CT and MRI may also be utilised as a means of confirming the diagnosis. CT images often aren’t clear enough to use on their own but can be excellent at showing areas which have become calcified. This can be an indicator for West Syndrome.
If the diagnosis of West Syndrome cannot be confirmed on an EEG or CT, an MRI scan may be carried out. This provides a far more detailed image of the brain and its activity. Cross-section slices of the brain can be captured by taking advantage of the magnetic elements of the brain atoms.
A lumbar puncture as well as urine and blood tests may also be carried out to identify any infections which could be the cause of West Syndrome.
If tuberous sclerosis is being considered as a possibility, the use of a Wood’s lamp can help to identify colourless lesions on the skin.
Molecular genetic testing is offered for any cases which are suspected to be due to either tuberous sclerosis or an X-linked West Syndrome. Conditions such as nonketotic hyperglycemia and mitochondrial diseases may require a sample of CSF fluid to be taken to check for the presence of glycine and lactate respectively.
Aside from colic, myoclonus can be a differential diagnosis and can present with involuntary contractions of the muscle groups. Like West Syndrome, myoclonus can be caused by a variety of causes including malignancy, asphyxia, viruses, metabolic disorders, drugs and lesions in the central nervous system. It may also be genetic. The above investigations and precise clinical presentation will help to exclude myoclonus as a cause.
Introduction to West Syndrome
Causes of West Syndrome
Diagnosis of West Syndrome
Treatment & prognosis of West Syndrome