Requirement of longitudinal synchrony of epileptiform discharges in the hippocampus for seizure generation: a pilot study

Umeoka, Shuichi; Lüders, Hans; Turnbull, John; Koubeissi, Mohamad Z.; Maciunas, Robert J.

doi:10.3171/2011.10.jns11261

Cited by 30 publications

(30 citation statements)

References 35 publications

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“…Although the role of the VH in the generation of epileptiform activity (EA) is significant, the importance of connections between DH and VH for full seizure development should not be underestimated. Recent clinical and basic research studies show that hippocampal longitudinal synchrony of EA is required for seizure generation and transection of the hippocampal longitudinal epileptic circuits is effective in suppressing seizures (Imamura et al, 2001; Shimizu et al, 2006; Umeoka et al, 2012). However the premise for the increase of hippocampal longitudinal synchronization in epileptic brain is not fully understood.…”

Section: Introductionmentioning

confidence: 99%

Status epilepticus results in region-specific alterations in seizure susceptibility along the hippocampal longitudinal axis

Isaeva¹,

Romanov²,

Holmes³

et al. 2015

Epilepsy Research

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Temporal lobe epilepsy (TLE) is the most common epilepsy syndrome in adults. In particular, the hippocampus is highly susceptible to abnormal synchronization. Recent advances in the surgical treatment of patients with refractory TLE have shown that multiple hippocampal transections can effectively control seizures. It has been suggested that in TLE the synchrony in the longitudinal connections is required for seizure generation; however the physiological background for the increase in hippocampal synchronization along the longitudinal axis is not fully understood. The hippocampus varies in seizure susceptibility along its longitudinal axis with the ventral hippocampus (VH) region being more seizure-prone and susceptible to neuronal damage than the dorsal hippocampus (DH). In the present study we studied seizure susceptibility along the longitudinal axis of the hippocampus following pilocarpine-induced status epilepticus (SE). In control conditions the VH generates epileptiform activity (EA) more frequently than the DH when exposed to a low Mg2+/1Ca2+/5K+ solution. Following SE the probability of inducing epileptiform actvitiy (EA) is similar in the VH and DH slices. This SE-induced change is due to an increase in the proportion of DH slices responding to the low Mg2+/1Ca2+/5K+ solution with EA. Moreover, both the VH and DH show similar responses to a low Mg2+/1Ca2+/5K+ solution. These findings indicate that the hippocampus undergoes significant functional changes following SE, which may provide the necessary increase of synchrony along the longitudinal axis to generate seizures in TLE.

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Section: Introductionmentioning

confidence: 99%

Status epilepticus results in region-specific alterations in seizure susceptibility along the hippocampal longitudinal axis

Isaeva¹,

Romanov²,

Holmes³

et al. 2015

Epilepsy Research

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“…Therefore, the EEG recording is the optimal method to study neuronal bioelectrical activity [20]. During ictal and interictal periods, there are over-synchronized discharges in the cerebral cortex [21]. Furthermore, it has been shown that EEG recordings demonstrate that kainic acid-induced epilepsy is a useful model for epilepsy research [22].…”

Section: Discussionmentioning

confidence: 99%

Dynamic expression of CX36 protein in kainic acid kindling induced epilepsy

Wang

Hao

et al. 2017

Translational Neuroscience

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Connexin (Cx) 36 is known to be a component of gap junctions, and has been suggested to play an important role in epilepsy. In order to determine dynamic changes of Cx36 protein expression in epilepsy and investigate the role of Cx36 in electroencephalographic activity and pathogenesis, we utilized kainic acid (KA) to induce epileptogenesis. We found that epileptic discharges began 71.8 ± 23.7 s after KA administration. Spike frequency and amplitude of epileptiform activity reached maximal levels at 30 ± 5.2 min. The maximum level of spike frequency and amplitude of epileptiform activity was 13.9 ± 0.3 Hz and 198 ± 14.3mV respectively. Employing Western blotting and immunohistochemistry, we demonstrated that hippocampal Cx36 protein expression was significantly increased 6 h after KA kindling compared to control or sham groups, but decreased in 3 d and 7d groups. Our results suggested that the dynamic change of Cx36 expression may play an important role inepilepsy, and the specific manipulation of Cx36 expression may be a potential target for the treatment of epilepsy.

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“…22,23 Although the concept of HT was a proposed hypothesis, not an accepted doctrine, recent studies have described detailed electrophysiological observations in humans 25 and memory preservation in rat models 12 that support the theory and efficacy of HT. However, in the previous literature, the important processes of the surgery and the depth and extent of transection were ambiguous.…”

Section: Discussionmentioning

confidence: 99%

“…15,25 On the other hand, we modified the original HT approach and adopted a transsylvian approach to access the inferior horn of the lateral ventricle. In the transsylvian approach, there are some potential risks of cortical damage to the temporal and frontal opercula when splitting the sylvian fissure.…”

Section: Discussionmentioning

confidence: 99%

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Transsylvian hippocampal transection for mesial temporal lobe epilepsy: surgical indications, procedure, and postoperative seizure and memory outcomes

Uda¹,

Morino²,

Ito³

et al. 2013

JNS

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Object Amygdalohippocampectomy is a well-established, standard surgery for medically intractable mesial temporal lobe epilepsy (MTLE). However, in the case of MTLE without hippocampal atrophy or sclerosis, amygdalohippocampectomy is associated with decreased postoperative memory function. Hippocampal transection (HT) has been developed to overcome this problem. In HT the hippocampus is not removed; rather, the longitudinal hippocampal circuits of epileptic activities are disrupted by transection of the pyramidal layer of the hippocampus. The present study describes a less invasive modification of HT (transsylvian HT) and presents the seizure and memory outcomes for this procedure. Methods Thirty-seven patients with MTLE (18 men and 19 women; age range 9–63 years; 19 with surgery on the right side and 18 with surgery on the left side; seizure onset from 3 to 34 years) who were treated with transsylvian HT were retrospectively analyzed. All patients had left-side language dominance, and follow-up periods ranged from 12 to 94 months (median 49 months). Seizure outcomes were evaluated for all patients by using the Engel classification. Memory function was evaluated for 22 patients based on 3 indices (verbal memory, nonverbal memory, and delayed recall), with those scores obtained using the Wechsler Memory Scale–Revised. Patients underwent evaluation of the memory function before and after surgery (6 months–1 year). Results Engel Class I (completely seizure free) was achieved in 25 patients (67.6%). Class II and Class III designation was achieved in 10 (27%) and 2 patients (5.4%), respectively. There were differences in memory outcome between the sides of operation. On the right side, verbal memory significantly increased postoperatively (p = 0.003) but nonverbal memory and delayed recall showed no significant change after the operation (p = 0.718 and p = 0.210, respectively). On the left side, all 3 indices (verbal memory, nonverbal memory, and delayed recall) showed no significant change (p = 0.331, p = 0.458, and p = 0.366, respectively). Conclusions Favorable seizure outcome and preservation of verbal memory were achieved with transsylvian HT for the treatment of MTLE without hippocampal atrophy or sclerosis.

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Requirement of longitudinal synchrony of epileptiform discharges in the hippocampus for seizure generation: a pilot study

Cited by 30 publications

References 35 publications

Status epilepticus results in region-specific alterations in seizure susceptibility along the hippocampal longitudinal axis

Status epilepticus results in region-specific alterations in seizure susceptibility along the hippocampal longitudinal axis

Dynamic expression of CX36 protein in kainic acid kindling induced epilepsy

Transsylvian hippocampal transection for mesial temporal lobe epilepsy: surgical indications, procedure, and postoperative seizure and memory outcomes

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