Reflex seizures induced by calculation, card or board games, and spatial tasks: a review of 25 patients and delineation of the epileptic syndrome

Nine patients had reflex activation of seizures by calculation, card and board games, or spatial tasks. The common denominator for these and the 16 others reported in the literature appears to be activity related to function of the parietal lobe. The clinical and EEG findings in all 25 patients support the diagnosis of primary generalized epilepsy. Seizures usually start during adolescence and consist of myoclonus, absences, and generalized convulsions. Specific inquiry about reflex activation should be carried out in patients with generalized epilepsy since this is rarely provided spontaneously. Attacks could be controlled satisfactorily in 89% of our patients. The genetic features are those of a primary generalized epileptic disorder without evidence for a specific inheritance of reflex sensitivity. Neuropsychological analysis of the stimuli points to parietal cortical dysfunction. These stimuli lead to activation of a generalized epileptic process analogous to the occipital cortical participation in the activation of generalized epileptic abnormality occurring in patients with photosensitive epilepsy.     

Reflex writing seizures in two siblings with juvenile myoclonic epilepsy

We report on two siblings who presented with juvenile myoclonic epilepsy, and in whom myoclonic jerks of the right arm and hand were also triggered by writing tasks. Both patients underwent intensive video-electroencephalography monitoring, with simultaneous neuropsychological tests. In both patients, reflex epileptic myoclonus was more easily triggered by writing that required a higher degree of concentration. Conversely, other cognitive tasks, such as reading, typing, thinking, or calculation never elicited any seizures or myoclonus. Valproate was effective in controlling both spontaneous and reflex epileptic seizures. The results of this study further support the notion that 'praxis-induced' reflex epilepsy precipitated by specific stimuli occurs in the context of idiopathic generalized epilepsy. Our results also illustrate that writing tasks are more effective in eliciting seizures when they require higher levels of concentration and mental elaboration.     

Cortical reflex myoclonus

Three patients with a type of myoclonus produced by intention and somatosensory stimulation were studied with electrophysiologic techniques. Each jerk typically affected only a few contiguous muscles; agonist and antagonist muscles were activated simultaneously with a simple electromyographic (EMG) burst lasting 10 to 30 msec. Cranial nerve muscles were activated in an order indicating that the signal to produce the myoclonus traveled down the brainstem. In action-induced jerks a negative transient in the electroencephalogram (EEG) from the contralateral sensorimotor cortex consistently preceded the jerk with a fixed latency. In reflex-induced jerks this negative transient could be recognized as a component of the sensory evoked potential. The types of myoclonus are reviewed and it is argued that this type of myoclonus is mediated in cerebral cortex and that the negative transient represents a paroxysmal depolarization shift (PDS). The myoclonus may result from hyperactivity of a component of the long-latency stretch reflex.     

Negative myoclonus in Creutzfeldt-Jakob disease.

OBJECTIVE: To describe electrophysiological findings in a patient with Creutzfeldt-Jakob disease (CJD) showing negative myoclonus. METHODS AND RESULTS: We studied this CJD patient electrophysiologically, in comparison with two patients with cortical reflex positive myoclonus due to benign adult familial myoclonic epilepsy (BAFME). Spontaneous negative myoclonus was associated with periodic synchronous discharges (PSDs) on the electroencephalogram, but negative myoclonus could also be induced by electrical stimulation of the median nerve in the CJD patient. This patient showed giant somatosensory evoked potentials (SEPs) and enhanced C reflexes, and the duration of the induced EMG silences was found to be significantly correlated with the amplitude of cortical SEPs. The duration of silent periods (SPs) produced by magnetic stimulation of the motor cortex was extremely long. The study of recovery function of SEPs suggested that the excitability of the somatosensory cortex was decreased during a long post-stimulus period. These findings were clearly different from those of patients with BAFME. CONCLUSIONS: This CJD patient had two types of negative myoclonus; one was associated with PSDs and the other was cortical reflex negative myoclonus. The long-lasting decrease in excitability of the sensorimotor cortices after stimulation could be related to the occurrence of both types of negative myoclonus.     

Electroclinical and genetic findings in a family with cortical tremor, myoclonus, and epilepsy

We report a five-generation family showing cortical tremor, myoclonus, and epilepsy, originating from Naples, Italy. Eleven members, aged 24-56 years (mean: 39.2 years), suffered from hand tremor and myoclonus, whereas generalized seizures occurred in six. Electrophysiological study confirmed the presence of cortical reflex myoclonus in all affected members. In addition, giant somatosensory-evoked potential components and enhanced long loop reflex I were found also in three presymptomatic members who manifested hand tremor and myoclonus at upper limbs after 1.5 years of follow-up. Genetic study of the pedigree revealed a significant linkage on chromosome 2p (maximum lod score = 5.9). Further observations are needed to clarify the pathophysiology of this condition.     

Electrophysiological and positron emission studies in a patient with cortical myoclonus, epilepsia partialis continua and motor epilepsy.

A patient is described who had a combination of stimulus-sensitive cortical myoclonus, epilepsia partialis continua, and Jacksonian motor epilepsy. He eventually required surgery because of the severity of his seizures. Electrophysiological recordings made before and during surgery, and PET scans performed before surgery identified an abnormal area of cerebral cortex in the postcentral parietal region. It is suggested that the stimulus-sensitive myoclonus arose because input into this region from peripheral sensory afferents produced an abnormal discharge which was fed forwards via cortico-cortical connections to the precentral motor cortex, to produce a reflex muscle jerk. The epilepsia partialis continua may have been caused by spontaneous discharges arising in the same region of parietal cortex. Both forms of jerking disappeared after resection of this part of the cortex.     

Cortical reflex myoclonus in patients with the mitochondrial DNA transfer RNALys(8344) (MERRF) mutation

Five patients from three families with the syndrome of myoclonic epilepsy and ragged red fibres (MERRF), associated with the mitochondrial DNA point mutation at position 8344, were studied neurophysiologically to determine the characteristics of their myoclonus. The findings were those of cortical reflex myoclonus, with enlarged cortical somatosensory evoked potentials and late reflex responses to peripheral nerve stimulation. Electroencephalography showed paroxysmal spike and polyspike and wave discharges, with photic sensitivity. This pattern of electrophysiological abnormalities was uniform, despite considerable variation in severity of myoclonus. Although a consistent finding, cortical reflex myoclonus is not specific to MERRF amongst myoclonic syndromes.     

Wilson's disease with myoclonus and white matter lesions

White matter lesions (WML) and epilepsy have been occasionally seen in Wilson's disease. No cases of generalized myoclonus have been reported so far. We present a patient with psychiatric symptoms starting at age 16, followed by tremor, generalized dystonia and severe generalized myoclonus. In addition to classical findings, the MRI showed also extensive WML in temporal, parietal and frontal regions, preserving interhemispheric fibers. Necropsy revealed marked alterations of white matter, cortex and basal ganglia. We subsequently review the literature concerning WML and myoclonus in Wilson's disease.     

Language-induced epilepsy, acquired stuttering, and idiopathic generalized epilepsy: phenotypic study of one family

PURPOSE: Language-induced epilepsy involves seizure precipitation by speaking, reading, and writing. Seizures are similar to those of reading epilepsy (RE). The nosologic position of language-induced epilepsy is not clear. We performed a clinical and neurophysiological study in a multigenerational family with the association of idiopathic generalized epilepsy (IGE) with ictal stuttering as a manifestation of reflex language-induced epilepsy. METHODS: Nine members on three generations were studied. All patients underwent video-polygraphic EEG recordings (awake and during sleep). A standardized protocol was applied to test the effect of language and non-language-related tasks. RESULTS: Six patients presented language-induced jaw jerking that mimicked stuttering and corresponded to focal myoclonus involving facial muscles. This was associated with an IGE phenotype in four of these patients. Focal EEG spikes were found in all six patients by visual analysis and/or back-averaging techniques. The focal spikes were either asymptomatic (when followed by a slow wave) or symptomatic of facial myoclonia (when isolated). Levetiracetam, used as add-on or monotherapy in four patients, suppressed ictal stuttering. One additional case only had a phenotype of IGE without focal features. CONCLUSIONS: This family study demonstrates the phenotypic heterogeneity of the association of IGE phenotype with ictal stuttering (language-related reflex seizure). Our data suggest that this particular form of reflex epilepsy related to language has more similarities with generalized epilepsies than with focal ones. Neurophysiological investigations should be performed more systematically in patients with acquired stuttering, especially if there is family history of IGE.     

Differences of cortical activation in spontaneous and reflex myoclonias.

Frontal and parietal components of somatosensory evoked potentials (SEPs) following median nerve stimulation and scalp potentials preceding myoclonic jerks (jerk-locked averaging, JLA) were compared in 6 patients with cortical reflex myoclonus. Giant potentials were found over the parietal cortex in both conditions. Prominent frontal activity was detected following median nerve stimulation which, however, was absent in jerk-locked averages. Therefore an identical generator of the giant SEP and the JLA is unlikely. As the frontal component is lacking in jerk-locked averaging, the spontaneous jerks produced in our experimental paradigm are believed to be due to spontaneous hyperactivity of the parietal cortex rather than to pathologically enhanced transcortical reflexes.