Atonic Seizures
Overview
A seizure happens when electrical activity in the brain surges suddenly. Atonic seizures are a type of seizure that causes sudden loss of muscle strength. These seizures are also called akinetic seizures, drop attacks or drop seizures.
The sudden lack of muscle strength, or tone, can cause the person to fall to the ground. The person usually remains conscious, and may not always fall down. Their head may drop, their eyelids may droop, and they may drop anything they were holding.
These types of seizures often begin in childhood and may last into adulthood. Sometimes they are linked to other conditions, such as Lennox-Gastaut syndrome.
Symptoms
Atonic seizures result in a sudden loss of muscle strength while the seizure is occurring. Other symptoms may include:
- Going limp and falling to the ground
- Remaining conscious
- Experiencing a brief loss of consciousness
- Drooping eyelids
- Head nods
- Jerking
Because these seizures often result in a fall, the patient may need first aid once the seizure is over. Some people who have these seizures often may choose to wear protective gear, like a helmet.
Causes and Risk Factors
The cause of atonic seizures is often unknown. Some patients may be more likely to have seizures because of changes in their genes.
Atonic seizures most often affect children but can occur in patients of any age.
Rapid breathing (hyperventilation) and flickering lights can trigger seizures.
Diagnosis
The most useful test in diagnosing seizures is an electroencephalogram (EEG). This records electrical activity in the brain. EEG can show unusual electrical activity patterns. Different types of seizures can be identified with these patterns.
Magnetic resonance imaging (MRI) and computed tomography (CT) scans may be used to study the condition. These images can also show where the seizure is happening in the brain. The scans can also rule out other possible causes such as a stroke.
Treatment
Patients may need to wear helmets to prevent head injuries during seizures if falling is common.
Medication is the most common treatment. Anti-seizure (or anti-epileptic) medications can be very helpful. It may take a few tries to find the right drug and the right dose. The doctor will monitor for side effects to find the best option. These medications include:
- Ethosuximide (Zarontin) is most often used as the first drug treatment.
- Valproic acid (Depakene) is another option. It is not recommended for women who are pregnant or want to become pregnant as it can increase the risk of birth defects.
- Lamotrigine (Lamictal) has fewer side effects than the other two medications but may also be less helpful.
- Clobazam (Onfi).
Certain types of seizures may be controlled with a ketogenic diet. This is a high-fat, low-carbohydrate diet used most often for children who have not responded to medications.
A vagus nerve stimulator (VNS) is sometimes implanted and used along with anti-epileptic medication to reduce seizures. The VNS is a device placed under the skin of the chest that sends electrical energy through the vagus nerve in the neck to the brain.
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