JLE

Epileptic Disorders

MENU

Neurophysiology of myoclonus and progressive myoclonus epilepsies Volume 18, supplément 2, September 2016

Figure 1

Patient with Unverricht-Lundborg disease. Polygraphic recording with the patient at rest showing fragmentary multifocal myoclonus without overt EEG correlate (EMG artefacts due to myoclonic jerks involving the face are superimposed onto the EEG trace).

Figure 2

Patient with PME associated with SCARB2 mutation, at disease onset. Left panel: the patient is at rest; EEG shows preserved background activity without epileptiform abnormalities; on the EMG channels, erratic multifocal myoclonic jerks without EEG correlate are evident. Right panel: the patient keeps her arms outstretched; the EMG channels show continuous rhythmic cortical myoclonic activity at a frequency around 12-20 Hz.

Figure 3

EMG recording from two antagonist muscles of the right wrist (RW) showing the presence of synchronous EMG bursts with an irregular (A) and quasi-rhythmic (B) course.

Figure 4

TVAR analysis of a movement-activated myoclonus in a patient with Unverricht-Lundborg disease (A) and sialidosis (B). Note in the coherence spectrum (B), the presence of significant EEG-EMG coherence in the beta and gamma bands remaining consistent throughout the movement, in contrast with the intermittent course in the ULD patient. (C and D) Mean coherence (the dotted line indicates the 95 per cent confidence limit) and phase spectra obtained from TVAR analysis. The estimated time lag was fitted with a cortico-spinal time transfer.

Figure 5

Left panel: EEG-EMG polygraphic recording in a patient with PME manifesting positive myoclonus in the hands at rest. Note that most myoclonic jerks were associated with a spike-and-wave complex on EEG, and the upward negativity recorded from the ipsilateral earlobe electrode. ECR: extensor carpi radialis muscle; 1stDI: first dorsal interosseous muscle; Rt: right. Right panel: Records of jerk-locked back-averaging obtained from the same patient. The onset of the EMG discharge from the right thenar muscle was used as a trigger pulse to back-average multichannel EEGs. EEG was recorded from the ipsilateral earlobe electrode. A positive-negative, biphasic EEG spike is observed maximally near the midline vertex, slightly shifted to the left (C1-Cz), and widespread over the scalp. Note that the myoclonic EMG discharge, which was also averaged with respect to the same fiducial point, spreads rapidly from the proximal muscles to the distal ones (Modified from Shibasaki & Hallett [2005]).

Figure 6

Somatosensory evoked potential (SEP) waveforms following electrical stimulation of the left median nerve (LMN Stim) of the wrist in a patient with Lafora disease presenting with PME (upper panel), with scalp topography consisting of two peaks (lower panel). Four peaks are clearly distinguishable: N20/P20, P25, N30/P30, and N35. N30/P30 shows a similar distribution to N20/P20 (not shown here), although with opposite polarity. A1: left earlobe electrode. Note the upward negativity. (From Ikeda et al., [1995]).

Figure 7

Giant SEP recorded in a patient with Lafora body disease showing an enlarged N20-P25 component and extremely enhanced P25-N33, merged into a very large middle-latency wave.

Figure 8

Graphic representation of N20 latency (A), LLR latency (B) and cortical relay time (C), comparing healthy controls with patients with Unverricht-Lundborg disease (EPM1) or Lafora body disease (EPM2).

Figure 9

Graphic representation of interaction between peripheral somatosensory stimuli and transcranial magnetic stimulation (TMS). Note the different profiles between controls and both PME groups indicating the amplification of the effect of sensory stimulus on motor cortex excitability. Moreover, Lafora patients show a larger and long-lasting excitatory interaction.