Electrophysiological and positron emission studies in a patient with cortical myoclonus, epilepsia partialis continua and motor epilepsy (original) (raw)
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Neurophysiology of myoclonus and progressive myoclonus epilepsies
Epileptic disorders : international epilepsy journal with videotape, 2016
The high temporal resolution of neurophysiological recordings makes them particularly suited to faithfully describing the time course of rapid events such as myoclonus and to precisely measure its time relationship with other related activities. In progressive myoclonus epilepsies (PMEs) polygraphy with simultaneous EMG-EEG recordings is a crucial tool for defining the characteristic of myoclonic jerks their topography over different muscles (namely antagonists), their time course and relationship with vigilance muscle activation and stimulations. Moreover on polygraphic recordings it is possible to detect EEG activities associated to myoclonic jerks and define their time relationship with myoclonus thus differentiating cortical types of myoclonus from subcorticallly generated ones. Tanks to the back averaging technique non obvious time-locked EEG potentials can be detected on polygraphy , furthermore in stimulus sensitive myoclonus the analysis can include the potential evoked by t...
Cortical reactivity in progressive myoclonus epilepsy
Electroencephalography and Clinical Neurophysiology, 1994
We studied 4 patients with progressive myoclonus epilepsy (Unverricht-Lundborg disease; ULD). Somatosensory evoked fields (SEFs), auditory evoked fields (AEFs), and spontaneous activity over the somatomotor cortex were recorded with a 24-channel SQUID gradiometer. All patients had "giant" 20-45 msec median nerve SEFs at the first somatomotor cortex, with 2-6 times larger amplitudes than the healthy control subjects. Later deflections were not similarly enhanced. The dependence of SEF amplitudes on interstimulus interval (0.2-4 sec) and on successive ulnar-median nerve stimulation (stimulus interval 40 msec) was comparable to that in controls. Cortical AEFs were attenuated and delayed. In 3 patients, the spontaneous activity consisted of 6-8 Hz mu rhythm, which originated within 2 cm from the sources of SEFs and was abolished by clenching of the contralateral fist. Control subjects had major spectral peaks around 10 and 20 Hz. The SEF amplitudes and the strength of the 6-10 Hz mu correlated strongly, suggesting that some components of evoked and spontaneous activity obtain contributions from overlapping neuronal populations. The results imply that ULD is associated with thalamo-cortical hyperreactivity in the sensorimotor but not in the auditory system.
Negative myoclonus induced by cortical electrical stimulation in epileptic patients
2006
Negative myoclonus (NM) is a motor disorder characterized by a sudden and abrupt interruption of muscular activity. The EMG correlate of NM is a brief (<500 ms) silent period (SP) not preceded by any enhancement of EMG activity (i.e. myoclonus). This study investigated the role of premotor cortex (PMC), primary motor cortex (MI), primary somatosensory area (SI) and supplementary motor area (SMA) in the pathophysiology of cortical NM by means of intracerebral low frequency (1 Hz) electrical stimulation. In three drug-resistant epileptic patients undergoing presurgical evaluation, we delivered single electric pulses (stimulus duration: 3 ms; stimulus intensity ranging from 0.4 to 3 mA) to PMC (2 patients), MI (1 patient), SI and SMA through stereo-EEG electrodes; surface EMG was collected from both deltoids. The results showed that (i) the stimulation of PMC or MI could evoke a motor evoked potential (MEP) either at rest or during contraction, in this latter case followed by an SP; however, in two patients, at the lowest stimulus intensities (0.4 mA), 50% of stimuli could induce a pure SP, i.e. not preceded by an MEP; raising the intensity of stimulation (0.6 mA), the SPs showed an antecedent MEP in >80% of stimuli; (ii) the stimulation of SI at low stimulus intensities (from 0.4 to 0.8 mA) induced in two patients only SPs, never associated with an antecedent MEP, whereas in the third subject the SPs could be inconstantly preceded by an MEP; by incrementing the stimulus intensity (up to 3 mA), in all three patients the SPs tended to be preceded, although not constantly, by an MEP; stimulus intensity affected SP duration (i.e. the higher the intensity, the longer the SP), without influencing the latency of onset of the SPs; (iii) the stimulation of SMA induced only pure SPs, at all stimulus intensities up to 3 mA; as for SI, increment of stimulus intensity was paralleled by an increase in SP duration, without influencing the onset latency of SPs. We conclude that single electric pulse stimulation of PMC, MI, SI and SMA through stereo-EEG electrodes can induce pure SPs, not preceded by an MEP, which clinically appear as NM, suggesting therefore that these cortical areas may be involved in the genesis of this motor phenomenon. However, it must be pointed out that SMA stimulation induced only pure SPs, regardless of the stimulus intensity, whereas occurrence of pure SPs following stimulation of PMC, MI, and SI depended mainly on the intensity of stimulation.
The Egyptian Journal of Neurology, Psychiatry and Neurosurgery
Background Electrophysiological techniques have been used for discriminating myoclonus from other hyperkinetic movement disorders and for classifying the myoclonus subtype. This study was carried out on patients with different subtypes of myoclonus to determine the electrophysiological characteristics and the anatomical classification of myoclonus of different etiologies. This study included 20 patients with different subtypes of myoclonus compared with 30 control participants. Electrophysiological study was carried out for all patients by somatosensory evoked potential (SSEP) and electroencephalography (EEG) while the control group underwent SSEP. SSEP was evaluated in patients and control groups by stimulation of right and left median nerves. Results This study included 50 cases with myoclonus of different causes with mean age of 39.3 ± 15.7 and consisted of 23 males and 27 females. Twenty-nine (58%) of the patients were epileptics, while 21 (42%) were non-epileptics. Cases were c...
Journal of Neuroimaging, 1998
The dipole sources of interictal spike activity were localized and the myoclonus activity back‐averaged by combined magnetoencephalography and surface electromyographic measurements in a child who had epilepsia partialis continua without a structural brain lesion. Dipole sources were matched with metabolic information obtained from interictal 5‐fluoro‐o‐glucose positron emission tomography (PET) and superimposed onto highresolution magnetic resonance images. Dipole sources of interictal epileptic discharges clustered within the inferior parietal cortex, which also showed a regional hypermetabolism on PET scans. The dipole sources of reafferent activity following myocloni in the postcentral gyrus were associated with a local hypometabolism.
Electrophysiological signs of peripheral nerve dysfunction in progressive myoclonus epilepsy
Acta Neurologica Scandinavica, 2009
Electrophysiological findings were analysed in a group of 24 patients with progressive myoclonus epilepsy (PME) without Lafora bodies. Denervation activity in needle E M G and diminution of motor and sensory responses pointed out a mild axonal degeneration. We observed a significant slowing of motor and sensory conduction velocities in all the limb nerves examined, but distal motor latencies were not significantly increased. H-reflex latency of the posterior tibia1 nerve was prolonged. These results yielded the suggestion that there is a systemic peripheral nerve membrane dysfunction in PME.
Perioral Reflex Myoclonias: A Controlled Study in Patients with JME and Focal Epilepsies
Epilepsia, 2006
Purpose: Perioral reflex myoclonias (PORM) are obvious, frequent, but often unobserved focal seizures in different epileptic syndromes and the leading seizure type in reading epilepsy. PORMs remain often undiagnosed because the patients are not aware that these are epileptic seizures and fail to report them. Their semiology is not fundamentally different in various epileptic syndromes.
Blink reflex in progressive myoclonic epilepsies
Seizure, 2015
Progressive myoclonic epilepsies (PME) include a heterogeneous group of disorders. The brainstem is involved in these disorders, as demonstrated by neuroimaging and autopsy studies. The blink reflex (BR) is characteristically elicited after supraorbital electrical stimulation. The BR has two components, an ipsilateral R1 and bilateral R2 (R2 and R2c). The central generator of the BR is the brainstem. In this study, we aimed to investigate the functional status of the brainstem using the BR in PME cases with different etiological factors. Methods: We prospectively included 17 patients with a diagnosis of PME (8 male, 47.1%) who were examined between June 2009 and June 2012. For comparison, we included 41 healthy volunteers (18 male 43.9%) who did not have any neurological or systemic diseases. We recorded responses bilaterally over the orbicularis oculi muscles after supraorbital stimulation in all participants. Results: The R1 and R2 components of the BR were obtained in all healthy subjects with normal latencies, whereas abnormalities in the R2 and R2c components were observed at significantly higher rates in the PME patients. The mean latencies of the bilateral R2 and R2c components were significantly prolonged, and the amplitudes were diminished in the PME patients. Disease duration and the use of multiple antiepileptic drugs were related to abnormal R2s. Conclusion: The abnormalities of the R2 and R2c components of the BR confirmed the inhibition of the reticular formation. The findings are probably related to disease processes and partially due to the use of multiple antiepileptic drugs.
Journal of …, 2002
The authors investigated a 38-year-old patient with focal cortical dysplasia in the right precentral cortex using positron emission tomography and functional magnetic resonance imaging to localize the hand and finger motor representations. The patient presented clinically with epilepsia partialis continua, supposed to originate from the perirolandic area harboring the cortical malformation. Both methods revealed an abnormal bilateral activation of motor cortex during left-hand finger movements. The results suggest that the so-called eloquent but nevertheless pathological dysplastic cortex accommodates motor representations.