Myoclonic Seizure - An Overview

Introduction

A sudden change or abnormalities in the brain’s electrical activity can result in seizures. Myoclonic seizures result in sudden movements or jerks in a muscle or a group of muscles. They occur briefly and only last for a few seconds. Mostly the cause of this condition is unknown. Myoclonic seizures are mostly controlled with medications. This article discusses myoclonic seizures, their causes, symptoms, and treatment options.

What Is a Myoclonic Seizure?

Myoclonic seizure is a type of seizure indicated by a brief episode of sudden movements in a muscle or a muscle group lasting one or two seconds or occurs in a cluster with episodes of two to three in a row without affecting the level of consciousness in the patient. They might occur without any cause or as a symptom of an underlying condition or a type of epilepsy. Other types of seizures mostly accompany them. It primarily affects one side of the body. In severe cases, they tend to occur in the broader body areas.

How Common Is a Myoclonic Seizure?

Myoclonic seizures occur commonly in people with familial history of epilepsy, previous history of seizures, or stroke. In people with focal seizures (seizures originating from the brain due to abnormalities in the brain's electrical activity), myoclonic seizures tend to affect one side of the body. Myoclonic seizure is a common type of seizure occurring most commonly in the myoclonic epilepsy of infants and Juvenile myoclonic epilepsy. Myoclonic seizure is the primary symptom of Juvenile myoclonic epilepsy, with an occurrence rate of about five to ten percent of all epilepsy cases.

What Are the Epileptic Conditions Associated With Myoclonic Seizures?

Myotonic seizures are involved in certain epileptic conditions, such as.

• Lennox-Gastaut Syndrome: It is a rare and severe form of epilepsy that occurs more commonly in childhood between the ages of two to four. Multiple recurrent seizures with a specific pattern of brain activity characterize the syndrome. Along with myoclonic seizures, this syndrome is accompanied by various other types of seizures.

• Juvenile Myoclonic Epilepsy: This condition is characterized by multiple, rapid, and sudden seizures that occur commonly between the age of 12 to 18 up to adulthood. This is the common type of epilepsy commonly associated with a positive familial history.

• Myoclonic Epilepsy of Infancy: This rare condition occurs before three years and is characterized by brief myoclonic seizures. They are popularly called benign myoclonic epilepsy in infants.

• Progressive Myoclonic Epilepsy: This syndrome is characterized by a group of rare and inherited disorders. They cause myoclonic seizures and progressive brain deterioration, including memory loss and impaired thinking ability.

• Myoclonic-Astatic Epilepsy: This condition is also called Down’s syndrome, characterized by developing myoclonic seizures on both sides of the body.

• Infantile Spasms: This is a rare epileptic seizure primarily seen in the first year of life.

What Are the Causes of Myoclonic Seizures?

Myoclonic seizures occur commonly when an underlying condition affects normal brain functioning. Causes of myoclonic seizure include

• Brain or spinal cord injury.

• Hereditary.

• Brain tumor.

• History of stroke.

• Drug intoxication.

• Cerebral hypoxia (lack of oxygen to the brain)

• Trauma.

• Encephalitis or meningitis.

• Alcohol withdrawal.

• Infections involving the brain.

• Liver or kidney failure.

What Are the Symptoms of Myoclonic Seizures?

The symptoms of myoclonic seizures include brief, sudden muscle jerks or twitches of a muscle or a muscle group. They only last for a few seconds; however, in some people, they may occur in clusters of episodes in a row. The symptoms resemble a sensation of electric shock, and they are mistaken for a nervous reaction. They often result in muscle weakness and sometimes sudden falls, referred to as the Drop attack.

How Is Myoclonic Seizure Diagnosed?

Most commonly, the symptoms of myoclonic seizures are accompanied by other conditions. Therefore the healthcare provider will obtain a detailed history of the patient and the signs of the seizures. The doctor will receive information on the familial history of the patient. The doctors will perform additional tests on the patient to rule out other conditions.

• The primary test for diagnosing the condition is the electroencephalogram (EEG). The painless test measures the brain's electrical activity by placing small sensitive electrodes over the scalp.

• Radiographic investigations of myoclonic seizures are done using a Computed Tomography scan or Magnetic Resonance Imaging (MRI) to identify any abnormalities in the brain that might have triggered the seizure.

• Blood tests are obtained for electrolyte abnormalities, glucose, liver, thyroid, and renal functions.

• Sometimes, they may perform a spinal fluid examination by placing a lumbar puncture to withdraw a cerebrospinal fluid sample to look for abnormalities affecting normal brain functions.

How Are Myoclonic Seizures Treated?

Treatment of myoclonic seizures mainly depends on the underlying cause or the epileptic condition. If the seizure is caused due to the presence of any surgically removable tumor or drug intoxication, It can be treated by correcting the underlying cause. They are rarely managed with a single treatment and require multiple treatment options. Considering the side effects of the medications, the healthcare provider will prescribe a combination of drugs to reduce the episodes of seizures.

• Anticonvulsant drugs such as valproate are prescribed. This is the most effective drug in treating myoclonic seizures; however, considering its teratogenicity, it is contraindicated in pregnant women.

• Other anti-epileptic medications, such as benzodiazepine, lamotrigine, levetiracetam, topiramate, and zonisamide, might be prescribed.

• Patients whose seizures are caused due to lack of sleep or alcohol consumption are advised to avoid consuming alcohol and get proper and adequate sleep without interference.

• Vagus nerve stimulation might be performed in some patients that involve using a device to stimulate the vagus nerve to alter the electrical signals in the brain.

• Dietary changes such as a low-carbohydrate or keto diet may be advised for the patients.

Conclusion

Myoclonic seizures are a mild type of seizure that is characterized by the occurrence of sudden, brief jerks or twitching in the muscles or muscle group. They are accompanied by other types of seizures and often cause muscle weakness. The episodes of seizures last for only a few seconds and sometimes occur as a cluster of episodes in a row. This condition is mainly inherited, and the specific cause of the condition is difficult to diagnose. Managing this condition requires lifelong treatment since there is evidence of recurrence after withdrawal from therapy.