Ann Clin Neurophysiol.  2017 Jul;19(2):136-140. 10.14253/acn.2017.19.2.136.

Myoclonic status epilepticus in hypoxic ischemic encephalopathy which recurred after somatosensory evoked potential testing

• Kim S
• Kim Y
• Kim S
• Lee SY

• KMID: 2387235
• DOI: http://doi.org/10.14253/acn.2017.19.2.136

Abstract

A 77-year-old male with amyotrophic lateral sclerosis had a hypoxic event. After resuscitation, generalized myoclonus appeared and resolved after two days. Five days after the hypoxic event, myoclonic seizures re-emerged right after performing a somatosensory evoked potential and persisted for ten days. Electroencephalogram revealed frequent bi-hemispheric synchronous spike and waves in the central areas. We suggest that somatosensory evoked potential testing may trigger myoclonic status epilepticus. Underlying cortical degeneration associated with amyotrophic lateral sclerosis could attribute to this phenomenon.

Keyword

Myoclonus; Status epilepticus; Somatosensory evoked potential

MeSH Terms

Aged
Amyotrophic Lateral Sclerosis
Electroencephalography
Evoked Potentials, Somatosensory*
Humans
Hypoxia-Ischemia, Brain*
Male
Myoclonus
Resuscitation
Seizures
Status Epilepticus*

Figure

• 

  Fig. 1 Electroencephalography (EEG) recorded at three hours after hypoxic event. Background EEG shows diffuse arrhythmic delta slowing low to moderate amplitude. Thick arrows indicate large potential changes associated with generalized myoclonus. Artifactual components obscured authentic EEG potential. Sharp waves with maximum amplitudes in bilateral frontal area synchronously (thin arrows) were occasionally observed.

• 

  Fig. 2 Electroencephalography (EEG) recorded at three days after hypoxic event. Generalized small spikes or polyspikes were semiperiodically seen, predominantly in bilateral frontocentral area. During this EEG, visible myoclonus occurred only occasionally in face.

• 

  Fig. 3 Electroencephalography (EEG) after somatosensory evoked potential testing. (A) EEG recorded during frequently multifocal myoclonus in face and limbs at eleven days after hypoxic event. Generalized high amplitude spikes or polyspikes were semiperiodically seen, predominantly in bilateral frontocentral area. It is not discernible whether they are only artifacts or epileptic activities mixed with artifactual components. (B) EEG recorded after myoclonic movements were abolished by vecurnoium injection. Semiperiodic spikes were disclosed on C3 and C4 synchronously.

Reference

1. Wijdicks EF, Hijdra A, Young GB, Bassetti CL, Wiebe S; Quality Standards Subcommittee of the American Academy of Neurology. Practice parameter: prediction of outcome in comatose survivors after cardiopulmonary resuscitation (an evidence-based review): report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2006; 67:203–210.

2. Shibasaki H. Neurophysiological classification of myoclonus. Neurophysiol Clin. 2006; 36:267–269.

3. Hallett M. Myoclonus: relation to epilepsy. Epilepsia. 1985; 26:Suppl 1. S67–S77.

4. Hallett M, Chadwick D, Adam J, Marsden CD. Reticular reflex myoclonus: a physiological type of human post-hypoxic myoclonus. J Neurol Neurosurg Psychiatry. 1977; 40:253–264.

5. Werhahn KJ, Brown P, Thompson PD, Marsden CD. The clinical features and prognosis of chronic posthypoxic myoclonus. Mov Disord. 1997; 12:216–220.

6. Van Cott AC, Blatt I, Brenner RP. Stimulus-sensitive seizures in postanoxic coma. Epilepsia. 1996; 37:868–874.

7. van Zijl JC, Beudel M, vd Hoeven HJ, Lange F, Tijssen MA, Elting JW. Electroencephalographic findings in posthypoxic myoclonus. J Intensive Care Med. 2016; 31:270–275.

8. Hui AC, Cheng C, Lam A, Mok V, Joynt GM. Prognosis following postanoxic myoclonus status epilepticus. Eur Neurol. 2005; 54:10–13.

9. Young GB, Gilbert JJ, Zochodne DW. The significance of myoclonic status epilepticus in postanoxic coma. Neurology. 1990; 40:1843–1848.

10. Madison D, Niedermeyer E. Epileptic seizures resulting from acute cerebral anoxia. J Neurol Neurosurg Psychiatry. 1970; 33:381–386.