Neck Myoclonia With Absence Seizures: Report of 3 Cases

Absence seizures associated with myoclonic phenomena can be seen in typical absences, myoclonic absences, eyelid myoclonia, and perioral myoclonia, all of which have diagnostic electroclinical features. The authors report 3 patients who encountered prominently rhythmic neck myoclonias with and without absences (loss of awareness). The descriptive symptoms of attacks by witnesses were head shaking or turning repeatedly instead of absences. The seizures were induced by hyperventilation in all 3 cases. Two cases had a history of previous febrile seizures. In all patients, video-electroencephalography showed a one-to-one correspondence relationship between the 2.5- to 3.5-Hz generalized spike and wave discharges and the rhythmic myoclonic jerks of the neck, which was further confirmed by sternocleidomastoideus electromyography recording in 1 patient. Seizures had been controlled by 1 or 2 antiepileptic drugs. Neck myoclonia with absences might be classified either as 1 special subtype of typical absence or as an independent seizure type. Paying close attention to the special phenomenon will help to clarify the clinical spectrum of this seizure.