Most people have experienced an abrupt jerk as they are falling asleep (normal sleep myoclonus) or have jumped when someone gives them a fright and this is similar to the jerk experienced by a child who has a myoclonic seizure. Myoclonic seizures are like being jolted by a mild electric shock. They are like single jolts which may occur frequently throughout the day. They can affect the whole body or just part of it. The jerk can be severe enough to make a child fall.

As the label myoclonic-astatic epilepsy (MAE) suggests, myoclonic seizures are one of the core seizure types associated with the disorder. In MAE, children usually have both myoclonic and myoclonic-astatic seizures. Myoclonic seizures can be serious because they may be difficult to control, occur frequently on a daily basis, and because they are only one manifestation of this mixed seizure disorder.

What happens?

Myoclonic seizures (myo meaning muscle, clonic meaning jerk) is a sudden involuntary contraction of muscle groups. In MAE, myoclonic jerks consist of symmetric, mostly generalised jerks, accentuated in the arms and in the shoulders and frequently simultaneously with a head nod; both the arms may fling out together and simultaneously a head nod may occur. Sometimes the entire body may jerk, just like a startle response. As is the case with all generalised seizures, the child is not conscious during the event but the seizure is so brief that the person appears to remain fully conscious. The intensity of these seizures is variable and ranges from violent myoclonic jerks with sudden falls to mild abortive forms presenting simply as short irregular twitches or head nods.

The jerk arises from deep structures in the brain stem that control posture and tone in the body. A sudden increase in tone in a muscle group will cause a sudden movement of that part of the body. An abrupt increase in tone in the flexor muscles will cause the body to bend forward at the waist, the head to drop down on the chest, the arms to bend at the elbow or the knees to come up to the chest. An abrupt increase in tone in the extensor muscles will cause the head to be thrown back, the back to arch, the legs to extend, the arms to stiffen. Any or all of these movements may occur during a myoclonic jerk. If they occur while a child is standing, he may be suddenly thrown backward to the ground, or he may suddenly be thrown forward to the ground, perhaps hitting his/her face, breaking a tooth, or causing a facial laceration.

u See also Seizures - Myoclonic-astatic seizures

u See also Safety - Protecting your child from injury

u See also Safety - Protective helmts

u See also Safety - Educating your caregiver

What to do

• Guide the child from danger
• Look for an epilepsy identity card or identity jewellery
• Attend to any injury which may have resulted

• Stay with the child until recovery is complete

• Be calmly reassuring

• Explain anything that they may have missed

Don't

• Restrain the child
• Act in a way that could frighten the child, eg abrupt movements or shouting at them
• Assume the person is aware of what is happening or what has happened
• Give the child anything to eat or drink until they are fully recovered
• Attempt to bring them round

Call an ambulance if....

• The seizure event continues for more than five minutes

• One seizure follows another seizure without the child regaining consciousness between them

• The child is injured during the seizure
• You believe the child needs urgent medical attention¨