Phase coupling between rhythmic slow activity and gamma characterizes mesiotemporal rapid-eye-movement sleep in humans.

In the human sleep literature there is much controversy regarding the existence and the characteristics of hippocampal rhythmic slow activity (RSA). Generally the human RSA is believed to occur in short bursts of theta activity. An earlier study, however, reported mesiotemporal RSA during rapid-eye-movement (REM) sleep that instead of theta fell in the delta frequency band. We conjectured that if this RSA activity is indeed a human analogue of the animal hippocampal theta then characteristics associated with the animal theta should also be reflected in the human recordings. Here our aim was to examine possible phase coupling between mesiotemporal RSA and gamma activity during REM sleep. The study relied on nine epilepsy surgery candidates implanted with foramen ovale electrodes. Positive half-waves of the 1.5-3 Hz RSA were identified by an automatic algorithm during REM sleep. High-frequency activity was assessed for 11 consecutive 20 Hz-wide frequency bands between 20 and 240 Hz. Increase in high frequency activity was phase coupled with RSA in most frequency bands and patients. Such a phase coupling closely resembles that seen between theta and gamma in rodents. We consider this commonality to be an additional reason for regarding delta rather than theta as the human analogue of RSA in animals.

Electrode manipulation automatism during temporal lobe seizures.

OBJECTIVE: To describe clinical characteristics and lateralizing value of peri-ictal electrode manipulation automatism (EMA) in patients with temporal lobe epilepsy (TLE) and compare our data with ictal manual automatisms described in the literature. METHODS: Two-hundred and five videotaped seizures of 55 consecutive patients with refractory TLE and postoperatively seizure-free outcome were analyzed and EMA (tugging, scratching or adjusting the electrodes and cables) were monitored. RESULTS: Twenty-eight (51%) patients showed EMA during 47 (23%) seizures. Ictal start was noted in 22 seizures and in 19/22 cases EMA finished before the end of seizure. Ictal EMAs were always associated with automotor seizure components. During 25 seizures, exclusively postictal EMAs were observed. Electrode manipulation was presented during 24/112 left-sided and 23/93 right-sided seizures (p = 0.742). Peri-ictal EMA was unilateral (completed by one hand) in 24/47 seizures (10 ictal, 14 postictal); it was done by the hand ipsilateral to the seizure onset zone in 17/24 and by contralateral hand in 7/24 cases (p = 0.064). We observed concomitant contralateral dystonic posturing during 3/10 seizures with unilateral ictal EMA. Unilateral hand automatism, temporally independent from the EMA appeared in 30 (64%) of the 47 seizures. CONCLUSION: Peri-ictal EMA is a frequent phenomenon but shows no lateralizing value in TLE. The mechanism of EMA is in many ways dissimilar from that of earlier described manual automatisms.

Lateralizing value of postictal automatisms in temporal lobe epilepsy.

PURPOSE: To describe clinical characteristics and lateralizing value of postictal automatisms in patients with temporal lobe epilepsy (TLE). METHODS: One hundred and ninety-three videotaped seizures of 55 consecutive patients with refractory TLE and postoperatively seizure-free outcome were analyzed. Ictal as well as postictal (manual, oral and speech) automatisms were monitored. RESULTS: Thirty-four (62%) of the 55 patients showed PA at least once during their seizures. Postictal automatism was observed in 70 (36%) attacks as manual (21%), oral (13%) or speech (9%) automatisms. Fifteen seizures contained a combination of two different postictal automatisms. The presence of postictal oral automatisms did not lateralize the seizure onset zone (p=0.834). Speech automatisms (repetitive verbal behavior) occurred more frequently after left-sided seizures (p=0.002). Postictal unilateral manual automatism showed no lateralizing value occurring by the ipsilateral hand in 10 and the contralateral upper limb in 6 seizures (p=0.454). CONCLUSION: : Postictal automatism is a relatively frequent phenomenon in TLE. Postictal speech automatism lateralizes the seizure onset zone to the left hemisphere. Our observation can help the presurgical evaluation of TLE because verbal perseveration frequently occurs spontaneously, even in seizures without appropriate postictal language testing.

Postoperative interictal spikes during sleep contralateral to the operated side is associated with unfavourable surgical outcome in patients with preoperative bitemporal spikes.

PURPOSE: To correlate the persistence of contralateral spikes during sleep after unilateral surgery with seizure outcome in a temporal lobe epilepsy (TLE) population and to test the existing hypotheses about the origin of the contralateral spikes in temporal lobe epilepsy. METHODS: In the 19 patients selected for this study unilateral temporal lobe surgery was performed. To investigate the course of bilateral interictal epileptiform discharges observed before surgery in awake or sleep over the temporal lobe contralateral to surgery, 24 h mobile 12 channel EEG recording was performed at minimum two, in average 4.6 (2-10) years after the surgery. RESULTS: The association of postoperative contralateral spikes and non-seizure free outcome was highly significant. The existence of unilateral pathology before surgery was highly predictive for good outcome and disappearance of contralateral spikes. The association between good seizure outcome, disappearance of contralateral spikes and the existence of unilateral pathology before surgery was also significant. Our data partially satisfies the expectations of both the "seizure induced" and mirror type secondary epileptogenesis hypotheses concerning origin of contralateral spikes, but were not completely congruent with either of them. CONCLUSIONS: Unfavourable surgical outcome in a temporal lobe epilepsy group with preoperative independent bilateral interictal spikes was associated with the persistence of postoperative contralateral spikes and lack of unilateral pathology. Compared with seizure outcome the presence/absence and distribution of postoperative interictal spikes in NREM sleep not entirely fit to the predictions of existing secondary epileptogenesis hypotheses.

Intentional seizure interruption may decrease the seizure frequency in drug-resistant temporal lobe epilepsy.

We investigated the nature of preictal subjective phenomena and whether they had any effect on the seizure frequency in 95 adult patients with medial temporal lobe epilepsy. Seventy-three (77%) patients indicated that they experienced seizure-provoking factors. Ten patients (11%) had prodromas independent of auras, while auras occurred in 89%. Forty-four patients (46%) reported that that they had tried to stop their seizures in the presence of prodroma or aura and this action had resulted in success at least once. Twenty-one patients (22%) regularly tried to stop their seizures because this effort was often successful according to their interpretation. Patients who reported that they could frequently inhibit their seizures had 1.8 +/- 1.6 seizures/month, a significantly lower mean seizure frequency than those 74 patients who did not do it regularly (4.6 +/- 4.8 seizures/month, P<0.001). Patients who reported regular experience in inhibiting intentionally their seizures more often had affective (P=0.05) and vertiginous auras (P<0.01) as well as isolated auras (P<0.05). Patients who experienced provoking factors showed the same seizure frequency as those who did not. Our results suggest that intentional seizure inhibition had an impact on the severity of drug-resistant epilepsy.

Clinical differences in patients with unilateral hippocampal sclerosis and unitemporal or bitemporal epileptiform discharges.

PURPOSE: To investigate factors determining the presence of bilateral interictal epileptiform discharges (IEDs) in temporal lobe epilepsy (TLE) with unilateral hippocampal sclerosis (HS). METHODS: We analysed data of 243 TLE patients with unilateral HS who had long-term video-EEG. Eighty-one patients (33%) had bitemporal IEDs. RESULTS: We categorised patients into a unilateral group (UG), a bilateral group (BG) according to presence of bitemporal IEDs. We found no difference between UG and BG regarding epilepsy duration, secondarily generalised seizures, and history of febrile seizures. Mean seizure frequency was significantly higher in the BG (UG: 7.7+/-14.7 seizures/month; BG: 13+/-35 seizures/month, P=0.01). We found a significant correlation between late epilepsy onset and the presence of bitemporal IEDs. The mean age at epilepsy onset in UG was 10.1+/-7.9 years, while in BG it was 13+/-9.2 years (P=0.02). CONCLUSIONS: The traditional concept of the evolution of mirror focus cannot apply for humans because the duration of epilepsy does not influence the evolution of bitemporal IEDs. Other factors, i.e. age at onset and seizure frequency may play a role in this process. The association between the higher seizure frequency and mirror foci indicates that the development of mirror focus depends on seizures and not on a progressive 'interictal' epileptogenesis.

Misleading lateralization by ictal SPECT in temporal lobe epilepsy-- a case report.

A 28-year-old woman with temporal lobe epilepsy underwent presurgical evaluation. Scalp-EEG showed non-localizing seizure patterns. MRI revealed a right hippocampal sclerosis. Ictal HMPAO-SPECT showed a marked left temporal hyperperfusion. Video-EEG monitoring with foramen ovale electrodes (FOE) showed an initial seizure pattern which appeared in the right FOE and which shifted to the left 8 s after clinical onset. Three years after a right temporal lobectomy, the patient is seizure-free. In conclusion, although the ictal SPECT suggested a left temporal seizure focus, the intracranial EEG and the postoperative seizure-freedom confirmed the right-sidelocation of the epileptogenic region. A rapid right-left seizure spread explains the mechanism of falsely lateralizing ictal SPECT.

[Surgically treatable epilepsy--a review]. / Mútéttel gyógyítható epilepszia--összefoglaló tanulmány.

20-25% of epileptic patients do not become seizure free on adequate drug therapy. In 25-50% of patients with intractable epilepsy, the brain area responsible for seizures is well localizable and does not involve eloquent regions. In these patients, the surgical excision of the epileptic focus may lead to relief from seizures. In Hungary, there may be 5-6000 patients who needs an epilepsy surgery, but till now only 200 patients with chronic epilepsy underwent a surgical procedure. In the surgically remediable epilepsies, the operation is not a "ultima ratio". Concerning these syndromes, if 2-3 adequate antiepileptic drugs do not lead to seizure freedom within 1-3 years after the epilepsy onset, then a presurgical evaluation is necessary. The most common surgically remediable epilepsy is the temporal lobe epilepsy in which 60-90% of drug-resistant patients could be surgically cured. In lesional neocortical epilepsies 50-80% of patients become postoperatively seizure free. In childhood hemispheric epilepsies, the surgery could lead to seizure freedom in 70-80% of patients. The basic tools of the presurgical evaluation are the detailed history, the high resolution-MRI, the video-EEG monitoring, and the neuropsychological assessment. These investigation methods are usually enough to evaluate the necessity of the surgery and the postoperative outcome as well as to plan the localization and the extension of the resection. In some cases, ictal SPECT, PET, or video-EEG monitoring with intracranial electrodes could also be necessary in order to localize the epileptic focus.

Hippocampal malrotation with normal corpus callosum: a new entity?

Among 527 MRI examinations of patients with a suspicion of epilepsy in 5 years, we found 32 cases of hippocampal malrotation (HIMAL). The characteristic features are: incomplete inversion of the hippocampus with and abnormally round shape; unilateral involvement of the whole hippocampus; normal signal intensity and size; blurred internal structure; an abnormal angle of collateral sulcus; abnormal position and size of the fornix; normal size of the temporal lobe; enlargement and particular configuration of the temporal horn, typical of corpus callosum agenesis; and a normal corpus callosum. In 7 cases (22%) HIMAL occurred together with developmental disorders. It was predominantly seen in men. The clinical features were varied. Based on some MRI features, the presence of developmental disorders, the male predominance, the frequently positive family history, and a review of the literature, we think HIMAL may be the consequence of a mild hemisphere developmental disorder. It is probably not the basic cause of epilepsy in such varied clinical setting, but may be a sign of a developmental disorder and can help in selecting patients for more meticulous investigation. It also may give some new understanding of brain development.

Disabling erratic myoclonus during lamotrigine therapy with high serum level--report of two cases.

We present two patients with epilepsy who experienced disabling myoclonic jerks during lamotrigine treatment. Both were young males who had intractable cryptogenic generalized epilepsy since childhood. They received a lamotrigine-valproate combination resulting in an excellent improvement; however, after 2-3 years of therapy, both patients were hospitalized because of continuous disabling myoclonic jerks. The dosage of lamotrigine was the same before and at the onset of myoclonus. When the severe myoclonus started, both patients had a higher serum lamotrigine level (16.5 and 17.7 mg/L, respectively) than in previous findings. Disabling myoclonus was also present during lamotrigine monotherapy with 15 mg/L serum level. Lamotrigine may severely worsen myoclonic phenomena in generalized epilepsies, in which adverse events may be dependent on drug serum level.

Propagation of focal epilepsies and the timing and targeting of surgical interventions. Illustrative case reports.

The mirror focus conception assumes propagation of epileptic excitation towards a homotopic area of the contralateral hemisphere inducing secondary focal discharges. Later, independent discharges can be initiated by this new area of epileptogenesis but initiation of seizures of the same or altered symptomatology--and not only interictal discharges--from a mirror focus has yet not been proved. Three cases will be presented where dynamism of the development of temporal lobe mirror focus have been followed. All cases give rise to several questions concerning selection and timing of surgical approach.