Epilepsy with Myoclonic-Atonic seizures: EMAtS
What is EMAtS?
Epilepsy with myoclonic-atonic seizures (EMAtS), also known as Doose syndrome, is a rare type of epilepsy that typically begins in early childhood and accounts for 1-2% of all childhood epilepsies. It is characterized by the occurrence of myoclonic seizures, which are brief and sudden muscle jerks, as well as atonic seizures, which cause the individual to lose muscle tone and fall down. These seizures can occur several times a day and may be accompanied by other types of seizures, such as generalized tonic-clonic seizures, absence seizures, and non-convulsive status epilepticus.
Approximately 50% of patients with this condition will enter a “stormy phase” in the first year after diagnosis. The stormy phase is characterized by development of three or more seizure types that rapidly become resistant to medical therapy. Patients can also go into prolonged seizures, with or without convulsions (called non-convulsive status epilepticus). Although 60% of patients are ultimately developmentally normal and seizure free, up to 40% will end up with mild-to-moderate developmental delays and medically refractory epilepsy. More natural history studies are needed in this condition to afford a well-designed clinical trial. The exact cause of EMAtS is unknown.
How is EMAtS diagnosed?
The diagnosis of EMAtS typically involves a combination of the following steps:
Medical history: The doctor will take a detailed medical history, including information about the onset and frequency of seizures, any associated symptoms, and any relevant family history. There is a small but clinically significant family history of febrile seizures in about 25% of patients. Also, many patients first start with a generalized tonic-clonic seizure. Since a myoclonic atonic seizure is a mandatory seizure type for diagnosis of this condition, diagnosis is sometimes unclear until a patient develops such a seizure type.
Neurological examination: The doctor will perform a physical examination to assess motor function, reflexes, and other neurological symptoms. Typically, the neurological examination in children with EMAtS is normal.
Electroencephalogram (EEG): This test records the electrical activity of the brain and can help identify any abnormal patterns of activity that may be associated with seizures. In individuals with EMAtS, the EEG may show characteristic patterns of spikes or slow waves.
Imaging studies: The doctor may order imaging tests such as an MRI (magnetic resonance imaging) scan to rule out any underlying structural abnormalities in the brain that may be contributing to the seizures. Imaging studies in EMAtS are typically normal.
Blood tests: Blood tests may be done to check for any underlying metabolic or genetic conditions that may be contributing to the seizures. Genetic tests are often unrevealing when diagnosing this condition.
Once all the information has been gathered, the doctor will consider the individual's medical history, physical examination, and test results to make a diagnosis of EMAtS. In some cases, a definitive diagnosis may not be possible without long-term EEG monitoring, which may involve spending several days in a specialized epilepsy center to have seizures captured and recorded.
It's important to note that the diagnosis of EMAtS can be challenging and may require the involvement of several specialists, including a neurologist, a neuropediatrician, and a geneticist. A definitive diagnosis is important for guiding appropriate treatment and management of the condition.
What is the treatment for EMAtS?
There is currently no one best therapy for EMAtS, but treatment is aimed at reducing the frequency and severity of seizures and improving quality of life. The treatment options for EMAtS include:
Anti-seizure medications (ASMs): ASM’s are the mainstay of treatment for EMAtS and are typically used to control seizures. The choice of ASMs will depend on the individual's specific needs and the type of seizures they experience. Common ASMs used to treat EMAtS include valproate, lamotrigine, benzodiazepines (like clobazam or clonazepam), and levetiracetam.
Dietary therapy: A special diet called the ketogenic diet, which is high in fat and low in carbohydrates, has been shown to be effective in reducing seizures in some individuals with EMAtS. The diet works by producing a metabolic state called ketosis, which has been shown to have anticonvulsant effects. A recent study showed that irrespective of when the ketogenic diet is started, it is likely to be effective in up to 72% of patients treated with the diet.
Surgery: In some cases, surgery may be recommended for individuals with EMAtS who do not respond to medical treatment. The type of surgery will depend on the specific location of the seizures within the brain and may include procedures such as corpus callosotomy and vagus nerve stimulation.
Supportive therapies: Physical therapy, speech therapy, and behavior therapy may also be recommended to help individuals with EMAtS maintain optimal function and improve quality of life.
The treatment plan for EMAtS will vary depending on the individual's specific needs and should be tailored to their specific circumstances. In general, the goal of treatment is to provide the best possible seizure control and improve quality of life, while minimizing any side effects of treatment. Close collaboration between the individual and their healthcare team is important for achieving these goals.
What is the prognosis for someone with EMAtS?
The prognosis for someone with EMAtS is generally good, but it can vary widely depending on the severity of seizures and the individual's response to treatment. Some individuals with EMAtS may have only mild seizures that can be well controlled with medication, while others may experience more frequent and severe seizures that are difficult to control.
In general, the outcome for individuals with EMAtS is influenced by several factors, including the age of onset, the frequency and severity of seizures, and the individual's response to treatment. With appropriate treatment and management, many individuals with EMAtS can lead productive and fulfilling lives. However, some individuals may experience developmental delays, intellectual disability, or behavioral problems, and may require ongoing support and care.
Ultimately the prognosis for EMAtS is unique to each individual and can change over time. Close collaboration between the individual and their healthcare team is important for monitoring the course of the condition and adjusting treatment as needed to ensure the best possible outcome.
