Atonic seizure is a type of generalized seizure and comprise of sudden loss of muscle tone resulting in the patient going limp and falling to the ground. Atonic seizures are also known as astatic seizure, drop attack and drop seizure. Atonic seizures occur rarely; however, they commonly occur in children than adults. Atonic seizures are commonly present in children who also have other types of seizures, such as myoclonic seizures or tonic seizures. Atonic seizure can occur in any age groups, however, commonly occur in children and continue into adulthood.
When a person sits or stands, there is slight contraction of the muscles, which help us in being upright. Patient loses this tension or contraction of the muscles in atonic seizures causing him/her to suddenly fall down and drop things. In the beginning of an atonic seizure, the patient may experience one or more myoclonic jerks. However, there are various types of seizures where the child can fall down, such as tonic seizures. The difference being, the patient falls straight to the ground in atonic seizures; whereas in tonic seizures he/she is pushed forward or backward due to muscle contractions.
Signs & Symptoms of Atonic Seizure
- There is sudden loss of the muscle tone in atonic seizures.
- The patient suffering from atonic seizure becomes limp and falls to the ground.
- The patient may be conscious or may lose consciousness briefly.
- There is drooping of the eyelids in patients suffering from atonic seizures.
- There is nodding of the head.
- In atonic seizure, the patient loses the muscle tone and goes limp and falls straight to the ground. It is difficult to identify an atonic seizure if the patient is lying down or sitting as he/she will not fall.
- Atonic seizures commonly appear as a head drop in babies who are not able to stand up.
- The duration of the seizure is commonly less than 15 seconds, however, some may last for several minutes also.
- Atonic seizure patient may suffer from one seizure or have several one after the other.
- Atonic seizures are also seen in syndromes like Lennox Gastaut syndrome.
- After the Atonic seizure attack, the child rapidly becomes conscious and alert once again.
Causes of Atonic Seizures
The exact cause of atonic seizures is not understood yet. Atonic seizures are commonly seen in different types of symptomatic epilepsy and very rarely in idiopathic epilepsy.
Investigations for Atonic Seizures
Diagnosis is made on the basis of the description of these seizures. Some tests like EEG are done to confirm the diagnosis. Other tests, such as ECG are done to look for any changes in the heart rhythm or in the blood pressure and also to exclude other causes of patient falling down.
Treatment of Atonic Seizures
- Anti-epileptic drugs are used to treat atonic seizures. Patient may not always respond well to them.
- Ketogenic diet can also benefit in atonic seizures.
- Vagus nerve stimulation is also done for treating atonic seizures.
- Corpus callosotomy is a surgical procedure done for treating atonic seizures.
- Patient may also need treatment for any injury incurred after falling down in these seizures.
- Atonic seizures are also known as "drop attacks" because the patient suddenly falls down if he/she is standing at the onset of the seizure. For this reason, if it is known that the patient suffers from atonic seizures then helmet can be worn to protect the head from any injury.
Prognosis of Atonic Seizures
The prognosis for Atonic Seizures depends on the diagnosis of the syndrome. There are some epilepsy syndromes, which will recede gradually as the child grows up. In some cases, lifelong anti-epileptic medicines need to be taken.