About Atonic Seizure Disorder

Atonic seizures are one of four types of generalized seizures experienced by patients with epilepsy. Epilepsy is a condition in which brain cells in certain parts of the brain keep firing rather than emitting electrical energy in a controlled manner, and can result in momentary confusion, twitching of the arms and legs, or unconsciousness. This results in seizures that affect a part of the brain or all of the brain, depending on the characteristics of the seizure. While seizures can last up to one or two minutes, atonic seizures can be very brief in duration. Thorough medical testing is the only way to ascertain what type of seizure a patient has experienced.

What Is a Generalized Seizure?

• Generalized seizures, including atonic seizures or "drop attacks," involve all of the brain. Other generalized seizures include absence seizures (petit mal) in which a patient experiences a period of "staring" and slight body movement, and in some cases, loss of consciousness, and myoclonic seizures, which present as sudden jerking and twitching of the limbs. Tonic-clonic seizures, described as the most intense of all generalized seizures, involve loss of consciousness, stiffening and quivering of the body and even loss of continence. Generalized seizures such as atonic seizures differ from partial seizures, which involve only a part of the brain and result in an alteration of mood or perception of smell, taste and sound, involuntary jerking of one arm or leg, loss of awareness that causes trance-like staring, and repetitive movements such as chewing, swallowing and hand-rubbing.

Characteristics of the Atonic Seizure

• Atonic seizures are also called astatic or akinetic seizures. An atonic seizure occurs without warning and presents as sudden drooping of the eyelids, head drop, loss of posture and collapse while standing due to sudden loss of muscle tone. These seizures typically last about 15 seconds and may or may not result in unconsciousness.

Risks of Atonic Seizures

• Many people who experience atonic seizures fall while standing and do so full force. The injuries that result from such a fall pose additional risks such as head and face injury and extreme bruising. Those who experience atonic seizures often choose to wear protective headgear to protect the head in the event of a sudden fall.

Diagnosing Epilepsy

• Patients suspected of having epilepsy undergo rigorous medical testing that begins with an in-office neurological and behavioral examination, in which a doctor--usually a neurologist--assesses motor abilities, behavior and intellectual capacity. In addition to blood testing to rule out underlying conditions such as anemia or diabetes that can cause seizures, tests to detect abnormalities of the brain are conducted. The most common test to diagnose epilepsy is the electroencephalogram (EEG), which assesses the pattern of a patient's brain waves. Other tests might include the use of computerized tomography (CT scan), magnetic resonance imaging (MRI) and positron emission tomography (PET scan).

Treatment of Atonic Seizures

• Unfortunately, atonic seizures are resistant to conventional drug therapy. According to the research conducted by the International League Against Epilepsy (ILAE) in 2004, newer medicines such as lamotrigine, felbamate and topiramate have reduced the frequency of atonic seizures in some patients. According to the ILAE, valproic acid used in conjunction with lamotrigine is considered the "treatment of choice" for atonic seizures. A surgical procedure known as a callosotomy is an alternative for patients who are unresponsive to medication. Information from ILAE reveals that patients with tonic and atonic seizures experienced an 80 percent decrease in frequency of seizures post-callosotomy.