Giant somatosensory evoked potentials in children without myoclonic epilepsy

Sixteen of 1093 children 5-14 years of age with various neurological problems were detected showing giant somatosensory evoked potentials (GSSEP). These potentials were analysed and their enlarged components described. None of the 16 children had evidence of myoclonic epileptic seizures. Nine children had epileptic seizures, but 7 did not. The characteristics of GSSEPs in patients without myoclonic seizures are described. We conclude that in patients without myoclonic seizures GSSEPs occur and bear some similarity with those elicited in patients with myoclonic seizures. They may represent a form of hyperexcitability of the CNS.     

Neuropsychological disorders related to interictal epileptic discharges during sleep in benign epilepsy of childhood with centrotemporal or Rolandic spikes

Nine children (five males, four females; age range 6 years 1 month to 11 years 1 month) affected by benign epilepsy of childhood with centrotemporal or Rolandic spikes (BECRS) with EEG evidence of marked activation of interictal epileptic discharges (IEDs) during sleep, and nine unaffected control children matched for age, sex, and socioeconomic status, were enrolled in a prospective study. At the time of detection of IED activation during sleep, patients showed a mean Full-Scale IQ score within the normal range, but significantly below that of control participants; neuropsychological assessment revealed disorders in visuospatial short-term memory (Corsi's Block Tapping Test), attention, and cognitive flexibility (Trail Making Test and Stroop Color-Word Test), picture naming, and fluency (Benton's Naming Test and Word Fluency), visuoperceptual skill (Ghent-Poppelreuter and Street Gestalt Completion Tests) and visuomotor coordination (Bender Test). After detection of IED activation during sleep, children were followed up for 2 years. At the time of IED remission (T1), neuropsychological re-evaluation showed a notable increase in IQ score and a significant improvement (t-test: p<0.007) in visuomotor coordination, non-verbal short-term memory, sustained attention and mental flexibility, picture naming, and visual-perceptual performance. At T1, patients' performance did not differ from the controls (Mann-Whitney U test).     

Magnetoencephalographic analysis of roland discharges in benign childhood epilepsy

We report the detailed analysis of the generator and propagation of rolandic discharges in benign childhood epilepsy with centrotemporal spikes by means of 37-channel magnetoencephalography with neuromagnetic three-dimensional dipole localization. Equivalent current dipoles of prominent negative sharp waves of rolandic discharges appeared as tangential dipoles in the rolandic region, positive poles being situated anteriorly. These equivalent current dipoles showed a relatively limited localization and regular directions compared with other components. Equivalent current dipoles of preceding small positive waves, positive waves following negative sharp waves, and negative slow waves appeared in the vicinity of negative sharp waves. Equivalent current dipoles of rolandic discharges were located around the generator of somatosensory evoked magnetic fields stimulated at the lower lip. These findings suggest that rolandic discharges are generated through basically a mechanism similar to that for the middle-latency components of somatosensory evoked responses.     

Higher brain dysfunction in benign childhood epilepsy with centrotemporal spike and atypical benign partial epilepsy of childhood

Although some recent studies have reported various cognitive impairments and behavioral disorders in children having benign childhood epilepsy with centrotemporal spike (BCECT), it is still commonly believed that BCECT does not cause any definite neuropsychological impairment. In addition, reported impairments range over various cognitive functions, and there is no general agreement on this issue. We performed detailed neuropsychological tests in 17 children with BCECT and analyzed the profiles of their subtests. Atypical benign partial epilepsy of childhood (ABPE) is a type of BCECT in which patients have minor generalized seizures and their EEGs show continuous spike-waves during sleep. We also performed the same tests in five patients with ABPE, and compared the results in the two groups. Neuropsychological tests performed are as follows: Kaufman assessment battery for children (K-ABC), Wechsler intelligence scales for children-revised (WISC-R), Illinois test of psycholinguistic abilities (ITPA), Benton visual retention test (BVRT), Token test, calculation, figure copying task, letter copying task, line bisection task, and line cancellation task. Mental processing composite of the K-ABC and FIQ of the WISC-R were within normal limits in all children with BCECT and ABPE, but were generally lower in ABPE than in BCECT. On the other hand, the profiles of subtests of ITPA in children with BCECT revealed the significant feature of the lower scores on verbal expression (p = 0.013) and auditory sequential memory (p = 0.035). Considering the normal scores in the elementary cognitive functions, such as visual and verbal functions and long-term memory, disturbance in the process of executive functions such as flexibility, fluency, and working memory could cause this characteristic profile. ABPE also showed the similar profile in the subtests of ITPA to that of BCECT. It is likely that both groups of children share the common cognitive dysfunction.     

Differentiating between benign and less benign: epilepsy surgery in symptomatic frontal lobe epilepsy associated with benign focal epileptiform discharges of childhood

Benign focal epileptiform discharges of childhood are a genetically determined electroencephalographic trait. Assessment of their clinical relevance in children with epilepsy may be difficult if imaging reveals a lesion congruent or incongruous with the focus of the benign focal epileptiform discharges of childhood. This article reports a boy with parietooccipital benign focal epileptiform discharges of childhood in whom videoelectroencephalography and magnetic resonance imaging disclosed symptomatic frontal lobe epilepsy. Surgical removal of a focal cortical dysplasia in the left frontal lobe yielded freedom from seizures and positive behavioral and cognitive development. Nocturnal benign focal epileptiform discharges of childhood persisted until puberty (follow-up, 50 months). Early diagnostic differentiation of idiopathic syndromes such as idiopathic benign focal epilepsy of childhood from symptomatic focal epilepsies with a potentially less benign course is important. In symptomatic frontal lobe epilepsy, epilepsy surgery may yield an excellent outcome despite the presence of concurrent benign focal epileptiform discharges of childhood.     

Stormy onset of benign childhood epilepsy with occipital paroxysmal discharges

We studied six children with ages ranging from 4 to 10 years who were affected by childhood epilepsy with occipital paroxysms and presented after a stormy onset with prolonged loss of consciousness for 6–14 h. In all these patients, seizures were preceded by visual symptoms in the form of colored circular disks. A CT scan was performed immediately after the onset of symptoms and was normal in all patients. Routine laboratory and cerebrospinal fluid examinations were normal in all patients. The interictal EEG was characterized by continuous or subcontinuous occipital spike wave discharges, which disappeared after the patients’ eyes opened. We carried out a 7-year follow-up of all these patients. Only two patients were treated with antiepileptic drugs. The therapy (phenobarbital, clobazam) in the two patients did not induce changes in the EEG pattern. The first did not suffer any further seizures. The second patient had two more seizures (at 8 and 18 months from the onset) with phosphenes, confusional state, and involuntary movements followed by loss of consciousness. Among the other four patients, who did not receive any treatment, only one had any other seizures. The stormy onset of the syndrome described in our six patients emphasizes the extreme variability in the presentation of this type of childhood epilepsy. Our follow-up confirms the good prognosis of this epilepsy even when it has a stormy onset. Received: 21 July 1998 Revised: 19 April 1999     

Sequential occurrence of benign partial epilepsy and childhood absence epilepsy in three patients

We first report 3 patients who experienced absence epilepsy (mean age at onset: 6.3 years; range: 4–9) 1–4 years after recovering from an electroclinical picture characteristic of benign childhood partial epilepsy (BCPE). All patients were put on monotherapy with sodium valproate, and their long-term course was excellent with remission of absences and normalization of EEG recordings. The exceptionality of our observation favors the hypothesis that BCPE and absence epilepsy are distinct entities.     

A study on epileptic negative myoclonus in atypical benign partial epilepsy of childhood

Objective. To investigate the clinical and neurophysiological characteristics, particularly therapeutic considerations, of epileptic negative myoclonus (ENM) in atypical benign partial epilepsy (ABPE) of childhood. Methods. From 1998 to 2006, 14/242 patients with benign children epilepsy with centrotemporal spikes (BECTS) were diagnosed as having ABPE with ENM. In all 14 patients, we performed video-EEG monitoring along with tests with the patient’s arms outstretched; 6/14 patients were also simultaneously underwent surface electromyogram (EMG). ENM manifestations, electrophysiological features, and responses to antiepileptic drugs were analyzed. Results. In all cases, ENM developed after the onset of epilepsy and during antiepileptic drug therapy, and the appearance of ENM were corresponding to EEG findings of high-amplitude spikes followed by a slow wave in the contralateral motor areas with secondary generalization. This was further confirmed by time-locked silent EMG. During ENM occurrence or recurrence, habitual seizures and interictal discharges were exaggerated. In some patients, the changes in antiepileptic drug regimens in relation to ENM appearance included add-on therapy with carbamazepine, oxcarbazepine, and phenobarbital or withdrawal of valproate. ENM was controlled in most cases by administration of various combinations of valproate, clonazepam, and corticosteroids. Conclusion. The incidence of ENM or ABPE in our center was approximately 5.79%. A combination of video-EEG monitoring with the patient’s arms outstretched and EMG is essential to identify ENM. The aggravation of habitual seizures and interictal discharges indicate ENM. Some antiepileptic drugs, such as carbamazepine, oxcarbazepine, and phenobarbital, may be related to ENM occurrence during spontaneous aggravation of ABPE. Various combinations of valproate, benzodiazepines, and corticosteroids are relatively effective for treating ENM that occurs in ABPE.     

Rolandic discharges: Clinico-neurophysiological correlation

Objective

The aim of this study was to analyze neurophysiologic aspects of rolandic discharges.

Methods

We reviewed 45 electroencephalograms of patients divided into two groups: those with benign childhood epilepsy with centrotemporal spikes (BCECTS) and symptomatic partial epilepsy (SPE), following ILAE criteria (1989). The EEG data analyzed were: horizontal dipole discharges, double spike phenomenon, the extension of epileptiform discharges and background activity.

Results

There was a predominance of horizontal dipole between patients with BCECTS compared with patients with SPE; however, this difference was not statistically significant. There was also no statistically significant difference between the two groups when the double spike phenomenon and the extension of discharges beyond the rolandic area were considered. The slower background activity in the SPE group was the only variable with statistical significance.

Conclusions

This study revealed similarities between rolandic discharges of two different epilepsy groups. The only reliable parameter to differentiate the groups was the background activity.

Significance

Our findings suggest that most EEG rolandic features are not pathognomonic of BCECTS, as they are related to the area of the discharges and not to the epileptic syndrome itself.     

Early somatosensory evoked potentials.

The early somatosensory evoked potential secondary to median nerve stimulation in the human had an onset latency of 9--12 msec when recorded from scalp electrodes at vertex-to-mastoid, vertex-to-inion or at the base of the skull. Similar latencies were observed from responses recorded over the cervical dorsal columns during neurologic surgery. A latency difference of 1.5 msec was observed between the early response and the responses recorded from the junction of medial lemniscus and nucleus ventralis posterior lateralis of the thalamus during human stereotaxic surgery. Cervical cord transections and transection at the midpontine levels of the monkey showed that the evoked potential was due to generators between these levels. Depth recording of the monkey indicate that the early evoked potential originates in the region of dorsal column nuclei, while the later components are secondary to generators in cerebral cortex.     

Extreme somatosensory evoked potentials (ESEPs) elicited by tapping of hands or feet in children: a somatosensory cerebral evoked potentials study

Six children with tactile-evoked spikes in the EEG, also defined as extreme somatosensory evoked potentials (ESEPs), underwent an SEPs study in order to define the characteristics of such evoked potentials. Short-latency SEPs showed normal mean latency and amplitude values. Mid- or long-latency SEPs of abnormally high amplitude were recorded after stimulation of one or more extremities. Such extreme responses which showed the same reactivity proper to normal long-latency SEPs could be considered to correspond to the evoked spikes in the EEG.     

Pain-Related somatosensory evoked potentials.

The authors reviewed basic and clinical reports of pain-related somatosensory evoked potentials (SSEP) after high-intensity electrical stimulation [pain SSEP(E)] and painful laser stimulation [pain SSEP(L)]. The conduction velocity of peripheral nerves for both pain SSEP(E) and pain SSEP(L) is approximately 10 to 15 m/second, in a range of Adelta fibers. The generator sources are considered to be the secondary somatosensory cortex and insula, and the limbic system, including the cingulate cortex, amygdala, or hippocampus of the bilateral hemispheres. The latencies and amplitudes are clearly affected by vigilance, attention-distraction, and various kinds of stimulation applied simultaneously with pain. Abnormalities of pain SSEP(L) reflect an impairment of pain-temperature sensation, probably relating to dysfunction of A5 fibers of the peripheral nerve and spinothalamic tract. In contrast, conventional SSEP after nonpainful electrical stimulation reflects an impairment of tactile, vibratory, and deep sensation, probably relating to dysfunction of Aalpha or Abeta fibers of the peripheral nerve and dorsal column. Therefore, combining the study of pain SSEP(L) and conventional SSEP is useful to detect physiologic abnormalities, and sometimes subclinical abnormalities, of patients with peripheral and central nervous system lesions.     

Segmentally specific somatosensory evoked potentials

The recording of segmentally specific somatosensory evoked potentials (SEPs) is time-consuming and the findings have generally been clinically unhelpful. This article critically evaluates the role of these SEPs in patients with disorders of the spinal cord or nerve roots.