Diagnostic Tests

What are the most common diagnostic tests done on GRIN kids?

Depending on your child’s symptoms, your neurologist or pediatrician may recommend SOME or all of the following diagnostic tests: 

Electroencephalogram (EEG)

This is a test widely used in patients with epilepsy and/or sleep problems. With this test, the brain’s electrical activity is monitored in both, sleep and awake states. This way, it is possible to detect the type and location of the epileptic foci to better define, and later design the appropriate treatment of epilepsy.

In cases of sleep alterations, the EEG can also be done throughout the night (for a minimum of 18 hours), to verify if the sleep disturbances come from abnormal brain activity as there are also certain forms of epilepsy that only occur during sleep.

It has been shown that in some GRIN children the EEG can show altered brain wave patterns even without the child having epileptic seizures. In selected cases the initiation of medication may need to be considered in patients with abnormal EEG results, even without obvious epileptic crises. This is due to the high incidence of refractory epilepsy (i.e epilepsy that does not responds to treatment) in GRIN patients. It is certainly important to treat a kind of epilepsy that happens during sleep, called the continuous spike-waves during sleep (CSWS) because these waves can cause set backs in memory and learning processes. 

Lumbar puncture

During a lumbar puncture, cerebrospinal fluid is extracted. Cerebrospinal fluid is a clear, colourless body fluid that bathes the brain and the spinal cord. A lumbar puncture is usually performed before a GRIN diagnosis, to rule out infection or certain metabolic diseases as a possible cause for your child’s neurological symptoms. Also, a lumbar puncture can be done to determine whether your child’s brain can process/obtain certain metabolites, such as glucose, which, in some cases, could be added or substituted in their diet.  

Most likely your child will need heavy sedation or even full narcosis/anesthesia during the lumbar puncture. After the puncture, it is important that your child has sufficient (bed) rest for at least 24 hours to decrease the chances of getting a bad headache. It is considered a risky procedure and will only be done if the neurologist deems it necessary for the child’s diagnosis and treatment. 

Visual and auditory evoked potentials

These are special tests where tiny electrodes (needle like cables) are placed in the head to record the neuronal interactions after a sensory (auditory or visual) stimulus.  This test measures the communication between neurons and helps rule out central (brain) vs peripheral visual or hearing problems. This is done to determine the speed at which the neurons are connecting with each other and also to discriminate whether, for instance, a child is suffering from visual problems related to a defect in the eye or optic nerve vs a difficulty in the processing of the visual stimuli in the brain. 

Dysphagia test

This test is used to determine if your child has difficulty eating/swallowing. The most common test done is video fluoroscopy. This imagen test is done while the child is swallowing food and liquids. This test helps assess the risk a person might have of swallowing liquids or food wrongfully into the respiratory tract (lungs), something that could lead to aspiration pneumonia, a possibly life-threatening condition.

Magnetic resonance Imaging (MRI)

It is a diagnostic test which allows the doctors to see the brain structures. Generally, this test is done before the diagnosis of GRIN, to rule out other diseases that can cause brain structure changes. There is a small percentage of GRIN children who have brain malformations that could be detected with this diagnostic tool. Your child will need to be put under full narcosis/anesthesia for this procedure as this test requires your child to lie absolutely still for an extended period of time inside a narrow tube. Also, the MRI machine makes a lot of noise which can be very disturbing too for children.  The test normally lasts less than 1h. 

A few examples of MRI findings in GRIN disorders

(Polymicrogyria: https://academic.oup.com/brain/article/141/3/622/4911356

(Lissencephaly: https://www.nature.com/articles/ejhg2016163)