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Atonic seizures commonly begin in childhood and can carry on into adulthood. These seizures are rare — about 1 percent to 3 percent of children living with epilepsy have atonic seizures.
Atonic seizures are also called astatic seizures, drop seizures, or drop attacks. They happen without warning and cause the muscles to suddenly relax and become limp. Infants and children will often have their heads drop, and adults may collapse or fall. However, atonic seizures are quite short, and people often recover quickly.
There are different types of seizures. Atonic seizures are generalized seizures — the seizure activity affects both sides of the brain. Unlike other types of generalized seizures that may lead to muscle contractions and stiffening, people with atonic seizures experience a sudden loss of muscle tone. Someone having an atonic seizure will be unresponsive and limp.
Atonic seizures are short and happen quickly. In some cases, a face or head injury may result from a seizure-related fall. If a person has hurt themselves during the seizure, it is important to provide first aid or seek medical attention.
Symptoms can vary from person to person, but most people having an atonic seizure will experience the seizure for a few seconds. In severe cases, the seizure can last several minutes. During this time, there is a sudden loss of muscle tone affecting the head, torso, or entire body. Infants who are unable to stand or sit on their own will only have their heads drop, whereas other people may experience falls. Other symptoms include:
The underlying cause of atonic seizures remains unknown, although several factors may play a role in its development. Possible causes and risk factors include:
If you have any symptoms of an atonic seizure, make sure to see your doctor. There are many diagnostic tools and tests that help doctors and specialists diagnose atonic seizures. During your visit, you will typically be asked about your medical history and family history. You will also likely be asked to undergo an electroencephalogram or other testing.
An electroencephalogram is a test in which electrodes placed on the scalp record the brain’s electrical activity. This test is useful in detecting any abnormal brain activity and differentiating among possible types of seizures. It is typically the first tool used to confirm an atonic seizure diagnosis.
Imaging tests such as MRI or CT scans can show lesions in the brain or other structural abnormalities, such as tumors, that may cause atonic seizures.
In some cases, your doctor may run blood tests to find biomarkers of epilepsy.
Treatment plans are typically based on a person’s age and symptoms. Many treatment and therapy options are available today, so speak with your doctor about the best options.
Antiepileptic drugs (AEDs) are effective in treating a variety of seizures, although people with atonic seizures typically do not respond well to AEDs. If AED medications aren’t effective, you and your doctor should discuss other options.
A high-fat and low-carbohydrate diet, such as the ketogenic diet or a modified Atkins diet, is an effective treatment option in children and adults. However, a ketogenic diet may be difficult to sustain, and constipation is a common side effect. Because of these limitations, it is important to work with a nutritionist or dietitian if you’re interested in following a high-fat, low-carb diet.
Vagus nerve stimulation (VNS) is an FDA-approved treatment for epilepsy. VNS uses a device that’s inserted under the skin in the chest. The device releases controlled electrical impulses that help stimulate the vagus nerve, which communicates with the brainstem and other areas of the brain to regulate electrical activity. This action may reduce the frequency of atonic seizures.
If atonic seizures do not respond well to AEDs or VNS, your doctor may consider a corpus callosotomy, also called callosal sectioning or brain-splitting. The corpus callosum is the middle structure of the brain that has nerve fibers connecting both sides of the brain. This structure sends signals between the brain’s hemispheres. A corpus callosotomy cuts the band of nerve fibers, which helps prevent seizure signals inside the brain. This surgery helps reduce the frequency and severity of atonic seizures.
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