Diagnosing Epilepsy in Children - How Much Do You Know?

Author: Yuan Leilei, deputy chief physician, Beijing Tiantan Hospital, Capital Medical University

Reviewer: Zhang Chun, Chief Physician, Xuanwu Hospital, Capital Medical University

"Doctor, my child is twitching, rolling his eyes, and can't be woken up. Is he suffering from epilepsy? Why did he get this disease? Can it be cured?"

Many parents of children with epilepsy often panic when they first encounter this situation. They don't know what to do. Even after seeing the doctor and coming out of the clinic with a pile of examination sheets, they still look confused and at a loss, not knowing what these examinations are for. Today, let's talk about the use of auxiliary examinations that children with epilepsy often need.

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"Epilepsy" or "epilepsy" is the popular name for epilepsy, which is one of the common diseases of the nervous system caused by various causes. The incidence of epilepsy in children is significantly higher than that in the general population. More than half of the new epilepsy patients in my country each year are children and adolescents. Due to people's lack of correct understanding of it, they often "turn pale when talking about epilepsy", and some parents even deliberately conceal it to protect their children's self-esteem, so that their children cannot receive timely diagnosis and treatment and delay the disease. Although common seizures of childhood epilepsy have similar manifestations, mainly absence seizures with brief loss of consciousness - "petit mal" or generalized tonic-clonic seizures with systemic convulsions and loss of consciousness - "grand seizures", there are many causes of childhood epilepsy. If neurologists only rely on symptoms and physical examinations, they cannot accurately determine the location and nature of the epileptic lesions, and they cannot formulate effective treatment plans. Therefore, some "eagle-eyed" examinations are needed to tell us what is going on in the child's brain, how to treat it next, and how likely it is to be cured.

1. Electroencephalogram

Epilepsy is characterized by abnormal discharges of brain neurons causing dysfunction of the central nervous system. Therefore, children are often called "electric angels". Electroencephalogram (EEG) is a non-invasive method of reading brain electrical activity. It uses precision electronic instruments to amplify the spontaneous biopotential of the brain (the current generated by the brain itself) from the scalp and record it in a graphic. Doctors can judge whether there is abnormal discharge in the child's brain and the location of abnormal discharge based on the graphic. The EEG itself does not discharge and has no radiation. Video EEG adds a camera to the conventional EEG, and synchronously records the patient's behavior during brain wave monitoring. Therefore, it is also called video EEG monitoring. Doctors can observe the symptoms of the patient's disease attack at the same time based on the video EEG, and the diagnosis result will be more accurate. For example, a patient who is stunned may have a problem with the hippocampus in the temporal lobe of the brain, and a convulsion in the left limb may be a problem with the right central area, etc. If the video shows the EEG during the attack and also records abnormal graphics in the corresponding brain area, it is very likely that these are the epileptic brain areas. Intracranial electrode EEG is an EEG monitoring procedure that is performed for several to dozens of days with the help of surgery. It eliminates the influence of the scalp, skull, and dura mater, and has a higher positive detection rate.

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2. Imaging Examination

Relying only on EEG, we still don’t know what disease the brain area with abnormal discharge has. Among the many causes of epilepsy (genetic, structural, metabolic, immune, infectious and unknown factors), focal lesions can often be cured by surgical resection, such as benign and malignant tumors that children are prone to, focal cortical dysplasia, focal brain herniation, etc. Imaging examination methods can provide us with clear objective evidence, so that "seeing is believing".

1. Magnetic resonance imaging

Magnetic resonance imaging (MRI) is a routine examination method for examining structural changes in the brain. Its tissue resolution is much higher than that of CT, so it is also a necessary examination item. In order to clearly display suspicious lesions, the examination of epilepsy has relatively high requirements for MRI equipment and scanning sequences. Some special sequences are often required to display, exclude or identify lesions as much as possible. This is why the doctor still asks for another MRI examination after an MRI examination has been done. In addition, since birth, as the brain develops, the MRI signal of the child's brain will also change. Some congenital lesions may not be obvious in infancy, and some lesions need to be dynamically observed to clarify their nature or determine the appropriate time for surgery, so regular MRI reviews may be required.

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2. 18 F-FDG PET/**** ( CT/MRI )

Some patients may ask: "Doctor, we have already done EEG and MRI, why do we need to go to the nuclear medicine department for PET/(CT/MRI) examination? What is the difference between this and CT and MRI?"

This is because PET is a test that can reflect changes in brain function, and functional changes always precede structural changes. Therefore, PET examination can help find epileptogenic foci sensitively and early and reflect changes in overall brain function, especially in the diagnosis and treatment of latent epilepsy (no lesions found on MRI). PET examination is incomparable to other methods. In addition, we all know that different lesions require different treatments and require appointments from different departments. Unfortunately, these lesions show similar signal changes on MRI and are difficult to identify, which greatly increases the difficulty of diagnosis. At this time, the advantages of PET are highlighted, especially the advanced integrated PET/MRI that can simultaneously observe changes in brain structure and function.

For example, two children with psychiatric seizures came to the hospital's neurology department for treatment. After the doctor examined them, he initially diagnosed them with epilepsy originating from the temporal lobe based on symptoms and EEG. However, further examination and treatment plans were needed to determine what disease caused the psychiatric seizures. So both children underwent PET/MRI examinations: MRI examinations of both children showed swelling of the left hippocampus and high signals on the Flair; the first child's PET examination showed low metabolism, and the imaging doctor comprehensively considered a low-grade glioma, so he needed to visit the neurosurgery department to choose the right time for surgery to remove it; the second child's PET performance was the opposite of the first, showing high metabolism, and was diagnosed with autoimmune encephalitis. It was recommended to further test cerebrospinal fluid antibodies, and to go to the neurology department for drug treatment after the diagnosis was confirmed. It can be seen that PET examinations are very helpful for patients to accurately choose the department to visit.

In addition to its role in locating latent epilepsy and identifying the nature of epileptic lesions, PET also plays a major role in evaluating the prognosis of the disease and the efficacy of treatment. For example, children with epilepsy who have diffusely reduced brain PET metabolism may not recover well after surgery, and patients with encephalitis who have high metabolism and are more affected may relapse.

PET imaging also has some disadvantages, such as a small amount of radiation, but currently the radiation from PET/MRI is greatly reduced compared to PET/CT; in addition, PET imaging is expensive, and in some areas it is a self-funded project.

3. Others

When the diagnosis is unclear or further differential diagnosis is needed, further examinations such as cerebrospinal fluid, gene monitoring or genetic metabolic screening are required according to the patient's specific situation. For example, cerebrospinal fluid testing is required for suspected encephalitis, lactate and pyruvate testing is required for suspected genetic metabolic diseases, and genetic testing is required for suspected genetic-related diseases.

In short, when patients visit the doctor, they need to fully explain their condition to the doctor, which will help the doctor prescribe the necessary tests and develop the most appropriate treatment method based on the medical history and various test results.