What is a sign of an atonic seizure?

An atonic seizure, often referred to as a "drop seizure," is characterized by a sudden loss of muscle tone. This results in moments where the individual may become limp and may even collapse. Slackening of the jaw is a clear manifestation of this loss of muscle tone, as the muscles responsible for maintaining muscle tension in the jaw relax abruptly.

In contrast, other seizure types exhibit different muscle responses. For example, sudden muscle tightening is more indicative of a tonic seizure, where there is a strong and sustained contraction of muscles. An increased heart rate may occur during various types of seizure activity due to autonomic responses, but it is not a specific indicator of atonic seizures. Extended posture is often seen in tonic seizures or during some types of focal seizures but does not represent the hallmark of an atonic seizure, where posture is typically lost, and collapse occurs.

Thus, the slackening of the jaw is the most relevant and accurate sign associated with atonic seizures.