Current Case: Summer 2019

Contributed by Jun T. Park, MD, FAES
Pediatric epileptologist; Associate professor; UH Rainbow Babies & Children’s Hospital; Case Western Reserve University School of Medicine

Clinical Presentation

A 32-year-old man who was previously diagnosed with epilepsy as a teenager presented to the emergency department (ED) after an epileptic seizure that had aborted after administration of intravenous lorazepam en route. He intermittently answered questions in the ED. A routine EEG was obtained and shown below is the finding. No clinical event occurred during this EEG event.

Question 1: What conclusion can be drawn from this EEG finding? (sensitivity 5uV; time constant 0.1 second; high frequency filter 70Hz)

  1. This is a generalized electrographic seizure characterized by initial polyspikes followed by 3 Hz-spike-and-wave discharges which evolve into generalized alpha frequency activity.
  2. The patient has juvenile myoclonic epilepsy, which is supported specifically by the presence of generalized polyspikes and 3 Hz spike-and-wave complexes.
  3. The EEG shows an interictal finding supportive of a generalized epilepsy syndrome.
  4. This is a photoparoxysmal response showing 3 Hz spike/polyspike wave discharges.
Answer: (click here)

A1: Correct answer: C. The EEG shows an interictal finding supportive of a generalized epilepsy syndrome.

Question 2: In which of the following epilepsy syndromes is a photo paroxysmal response most likely

  1. Juvenile myoclonic epilepsy
  2. Juvenile absence epilepsy
  3. Childhood absence epilepsy
  4. Temporal lobe epilepsy
Answer: (click here)

A2: Correct answer: A. Juvenile myoclonic epilepsy

This EEG shows a burst of generalized polyspikes lasting ~1 sec leading into 2.5 Hz generalized spike wave discharges lasting ~1 sec. This finding supports a diagnosis of genetic generalized epilepsy in the appropriate clinical setting. This is not specific for juvenile myoclonic epilepsy and may be seen in other genetic generalized epilepsy syndromes.Absence epilepsy is characterized by 3 Hz-spike-and-wave pattern, although the spike-wave frequency can vary during a discharge, averaging 3.4-4.5 Hz at the onset and gradually slow to an average of 2.5-2.8 Hz by the end of the paroxysm. In juvenile myoclonic epilepsy, associated interictal EEG findings are polyspikes and polyspike-wave discharges followed by high-voltage, irregular 2-to 5 Hz slow waves and intermixed spikes. Diagnosis of a specific generalized epilepsy syndrome requires correlation of EEG findings with clinical history specifically, age of onset and the type of seizures (absence, myoclonic and generalized tonic clonic).

There is no seizure on this 15-second page of EEG as there was no clinical correlate associated with EEG and the duration of discharges is less than 10 seconds to qualify for an electrographic seizure.

What follows the 2.5 Hz spike- and-wave discharges is photic driving at 12 Hz stimulation. This is not a photoparoxysmal response as the polyspikes start before the start of photic stimulation at 12 Hz. Although a photoparoxysmal response (PPR) is seen frequently in patients with juvenile myoclonic epilepsy (JME) (38% in one study of 181 patients with JME), PPR can be seen in other forms of generalized epilepsy.

 

References

  1. Aicardi’s epilepsy in Children. 3rd Ed. Alexis Arzimanoglou, Renzo Guerrini, Jean Aicardi. Pg 76-78; 107-109. ISBN 0-7817-2698-0.
  2. Dalby MA. Epilepsy and 3 per second spike and wave rhythms. A clinical, electroencephalographic and prognostic analysis of 346 patients. Acta Neurol Scand 1969:suppl 40:43.
  3. Jans D. Epilepsy with impulsive petit mal (juvenile myoclonic epilepsy). Acta Neurol Scan 1985;72:449-459.
  4. Janz D, Durner M. Juvenile myoclonic epilepsy. In: Engel J Jr. Pedley TA, eds. Epilepsy: a comprehensive textbook. Philadelphia: Lippicott-Raven Publishers, 1997:2389-2400.