A 6 year old girl is easily distracted in class and exhibits poor scholastic performance. Seizures are precipitated by hyperventilation. What is the probable diagnosis?
Typical absence seizures are characterized by sudden, brief lapses of consciousness without loss of postural control. The seizure typically lasts for only seconds, consciousness returns as suddenly as it was lost, and there is no postictal confusion. Although the brief loss of consciousness may be clinically inapparent or the sole manifestation of the seizure discharge, absence seizures are usually accompanied by subtle, bilateral motor signs such as rapid blinking of the eyelids, chewing movements, or small-amplitude, clonic movements of the hands. Typical absence seizures are associated with a group of genetically determined epilepsies with onset usually in childhood (ages 4-8 years) or early adolescence and are the main seizure type in 15-20% of children with epilepsy. Since the clinical signs of the seizures are subtle, especially to parents who may not have had previous experience with seizures, it is not surprising that the first clue to absence epilepsy is often unexplained "daydreaming" and a decline in school performance recognized by a teacher. Hyperventilation tends to provoke these electrographic discharges and even the seizures themselves and is routinely used when recording the EEG. Ref: Lowenstein D.H. (2012). Chapter 369. Seizures and Epilepsy. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison's Principles of Internal Medicine, 18e.
Myoclonic seizures
Absence seizures
Atonic seizures
Myoclonia