Mesial Temporal Lobe Epilepsy in Childhood

Summary: To clarify the clinical picture of mesial temporal lobe epilepsy (MTLE) in childhood, we carried out a clinical, electroencephalographic, and neuroradiologic study of 19 patients. MTLE was noted in 19 (0.82%) of 2,319 epileptic patients with childhood onset. Three types of initial seizure were recognized: febrile convulsion, afebrile generalized convulsion, and complex partial seizure (CPS). As presumed causes, various prolonged convulsions (persisting for >30 min) were found in 12 (63.2%) cases. Regardless of the presence of preceding convulsions (febrile or afebrile), the clinical course was not uniform, with CPS in the early period temporarily controlled in some cases and intractable from the early period in others. Unilateral hippocampal abnormalities were confirmed on magnetic resonance imaging (MRI) before the age of 5 years in two cases, suggesting that mesial temporal sclerosis (MTS) is formed within a relatively short period in some cases. Seizures were controlled for >6 months in only two (10.5%) cases and persisted in 17. In four (21.1%) cases, surgical treatment was considered to be available.     

Quantification of Hippocampal Signal Intensity in Patients with Mesial Temporal Lobe Epilepsy

BACKGROUND: Refractory mesial temporal lobe epilepsy (MTLE) is frequently associated with hippocampal atrophy (HA) and an abnormal hippocampal signal (Hsig) on magnetic resonance imaging (MRI). OBJECTIVE: To quantify Hsig on MRI using a simplified technique. METHODS: The authors included 15 patients with refractory MTLE who underwent surgery and had preoperative MRI with hippocampal volumetry. Hsig was quantified on preoperative coronal T1-weighted and T2-weighted MRI using the NIH-Image program. Hsig was determined for the head, tail, and entire hippocampal extension. Abnormal Hsig was defined when values were above (for T2) or below (for T1) 2 standard deviations from the mean of normal control group. RESULTS: The lateralization of abnormal Hsig values was concordant with electroencephalograms and HA in all patients. There was a significant difference in ipsilateral T2 Hsig between patients and controls (P < .0001), but not for contralateral T2 Hsig. T1 Hsig showed bilateral abnormalities more frequently, whereas T2 Hsig could lateralize better hippocampal abnormalities. Overall, there were no differences when comparing T2 Hsig for the entire hippocampus, head, or tail only. However, there were some individual differences. T2 Hsig abnormalities involved the entire hippocampus in most patients but were restricted to the head in one patient and to the tail in another. CONCLUSIONS: This simplified method for the quantification of Hsig using NHI-Image is an efficient method for the identification and quantification of hippocampal abnormalities in patients with MTLE. The assessment of the entire extension of the hippocampal formation may provide important additional data, compared to T2 relaxometry maps limited to one segment of the hippocampus.     

Ictal Scalp EEG in Unilateral Mesial Temporal Lobe Epilepsy

Summary: Purpose: We wished to determine the predictive significance of unilateral hippocampal atrophy and interictal spikes on localization of ictal scalp EEG changes and assess whether ictal EEG provides information that might change treatment or influence prognosis in patients with such characteristics of epilepsy.
Methods: We analyzed EEG seizure patterns in 118 seizures in 24 patients with unilateral mesial temporal lobe epilepsy (MTLE) defined by typical clinical seizure semiology, unilateral hippocampal atrophy on magnetic resonance imaging (MRI) and unitemporal spikes on interictal EEG. Two blinded electroencephalographers independently determined morphology, location, and time course of ictal EEG changes.
Results: Lateralization was possible in 88.4–92.0% of seizures and always corresponded to the side of the interictal spike focus and of hippocampal atrophy on MRI. Although only 30.4–33.9% of seizures were lateralized at onset, a later significant pattern emerged (12.6–13.3 s after EEG seizure onset) that allowed lateralization in 82.4–91.O% of seizures with non-lateralized onset. Interobserver reliability for lateralization was excellent, with a K-value of 0.85. In most patients, either all (79.2–83.3%) or >50% (8.3–16.7%) of seizures were lateralized. In only a small proportion of patients (4.2–8.3%) were 40% of seizures lateralized. In 1 patient, no seizure could be lateralized by 1 electroencephalographer. The results of ictal EEG recordings did not alter the surgical approach and did not correlate with surgical outcome.
Conclusions: We conclude that unilateral hippocampal atrophy on MRI and unitemporal interictal spikes can predict localization of ictal scalp EEG changes with a high degree of reliability and that ictal EEG provides no additional localizing information in this particular patient group.     

Psychiatric Symptoms in Temporal Lobe Epilepsy with Left Mesial Hippocampal Sclerosis

A 16-year-old woman was referred to us for depression and persistent suicidal and homicidal ideation. From 2010, the patient visited a neurologist due to recurrent grand mal epilepsy, auditory and visual hallucinations, episodic memory loss, and persistent depression. Upon admission, it was revealed through clinical history taking that she had suffered from chronic bullying from same-sex peers and sexual abuse, twice, from an adult male in the neighborhood when she was 10 years old. A brain magnetic resonance imaging study showed left mesial hippocampal sclerosis. The patient exhibited improvement of her psychiatric symptoms after treatment with a combination of fluoxetine (30 mg) and aripiprazole (10 mg). Children and adolescents with epilepsy experience conflicts in the family, challenges at school, stigma, and psychosocial limitations or deprivations due to their comorbid psychiatric symptoms and hence, psychiatric evaluation and early intervention is important when treating these patients.     

Neuronal Cyclin Expression in the Hippocampus in Temporal Lobe Epilepsy

This study used immunocytochemistry to explore the expression of cyclins A, B, D, and E and the apoptosis-associated Bax protein in hippocampal subfields of 35 lobectomy specimens with medial temporal lobe sclerosis removed for the treatment of temporal lobe epilepsy (TLE), 2 age-matched controls, and 2 elderly patients suffering from drug-responsive epilepsy. Cyclins A and D were not detected at all in neuronal nuclei. Cyclin E was only rarely detected in neuronal nuclei in drug-controlled and TLE groups and in controls. Cyclin B was expressed in significantly more neuronal nuclei in the hippocampi in TLE than in the other groups studied. The nuclear expression of these proteins suggested that neurons had reentered the cell division cycle and reached the G₂phase. The nuclear expression of cyclin B in the hippocampus from these patients was accompanied by neuronal cytoplasmic expression of the death-related Bax protein. We interpret these neuronal findings as evidence of cell cycle disturbances and a possible apoptotic mechanism of hippocampal neuronal cell death in TLE.     

Changes in Central Auditory Processing in Patients with Mesial Temporal Lobe Epilepsy after Anterior Temporal Lobectomy with Amygdalohippocampectomy

MethodsFrequency-pattern, duration-pattern, and dichotic tests were performed before and after epilepsy surgery in 22 patients with normal hearing according to pure-tone audiometry.ResultsNo significant difference in CAP scores was detected between pre- and postoperative tests, but there was a strong association between surgery in the language-dominant temporal lobe and postoperative worsening in the non-dominant-side dichotic test (p<0.05). The probability of a decreased performance in a non-dominant-side dichotic test after surgery was 7.5-fold greater in patients who underwent surgery on the dominant temporal lobe compared with the nondominant temporal lobe. No significant association of postoperative worsening in CAP with the verbal, nonverbal intelligence quotient, or right- or left-side lobectomy was noted.ConclusionsThese results suggest that ATL-AH on the dominant side in patients with mTLE-HS worsens the CAP ability in the non-dominant-side dichotic test.     

Correlation of Hippocampal Neuronal Density and FDG-PET in Mesial Temporal Lobe Epilepsy

Summary: Purpose: Interictal [¹⁸F]fluorodeoxyglucose (FDG) positron emission tomography (PET) reveals regional hypometabolism in 60–80% of patients with mesial temporal lobe epilepsy (MTLE). The extent of hypometabolism generally extends beyond the epileptogenic zone. The pathophysiology underlying this widespread change is unknown. This study evaluated the relation between hippocampal neuronal loss and hypometabolism in patients with MTLE.
Methods: Forty-three patients with MTLE after anterior temporal lobectomy were included. Pathology demonstrated mesial temporal sclerosis (n = 41) or endfolium sclerosis (n = 2). Interictal FDG-PET scans were graded by visual analysis on a scale ranging from normal (grade 1) to severe (grade 5) hypometabolism. Neuronal counting was performed in the subiculum, hippocampal subfields, and dentate granular cell layer (DG). Neuronal density of patients was compared with that of seven autopsy controls. Data were compared by using Student's t tests and Kruskal-Wallis one-way analysis of variance (ANOVA).
Results: Significant neuronal loss in CA1 through CA4 and DG was found in patients compared with controls. Neuronal density in the subiculum, CA1, CA4, and DG did not correlate with severity of hypometabolism. However, patients with abnormal FDG-PET had higher neuronal density in CA2 and CA3 versus patients with normal studies.
Conclusions: This study supports a previous observation that degree of FDG-PET hypometabolism does not parallel severity of hippocampal neuronal loss in MTLE.     

经颞下沟选择性杏仁核海马切除术治疗内侧颞叶癫痫

目的探讨经颞下沟侧脑室入路选择性杏仁核海马切除术治疗内侧颞叶癫痫的手术方法、效果及并发症。方法确诊为药物难治性内侧颞叶癫痫的30例患者,在无框架神经导航指引下,经颞部锁孔开颅,显微镜下分开一小段颞下沟,切开侧脑室壁,进入颞角前外侧区,选择性切除杏仁核海马。结果30例患者术后随访至少2年时间（24—59个月）,神经功能改善,无严重手术并发症,23例（76．7％）癫痫发作完全消失（EngelⅠ级）。结论经颞下沟侧脑室入路选择性杏仁核海马切除术是治疗内侧颞叶癫痫的有效方法,在神经导航辅助下手术创伤小,可妥善保护语言区和视放射,安全性高。     

Properties of a Delayed Rectifier Potassium Current in Dentate Granule Cells Isolated from the Hippocampus of Patients with Chronic Temporal Lobe Epilepsy

Summary: Purpose: Properties of potassium outward currents were investigated in human hippocampal dentate gyrus granule cells from 11 hippocampal specimens obtained from patients with temporal lobe epilepsy (TLE) during resective surgery. Methods: Dentate granule cells were isolated enzymatically and outward currents analyzed by using the whole-cell configuration of the patch-clamp method. Hippocampal specimens were classified neuropathologically with respect to severe segmental cell loss, gliosis, and axonal sprouting (Ammon's horn sclerosis, AHS), or the presence of a focal lesion in the adjacent temporal lobe. Results: A delayed rectifier outward current (I), but not an A-type potassium current (I_k) or inwardly rectifying potassium currents, was observed in all cells. The average current density of I_k, the time-dependent decay of I_k, and the resting membrane characteristics were not significantly different between patients with and without AHS. The voltage of half-maximal activation V_1/2(act) was 5·4 ± 1·8 mV in AHS compared with ?2·9 ± 1·8 mV in lesion-associated epilepsy (NS). In contrast, V_1/2(inact) was shifted in a hyperpolarizing direction in AHS (?67·7 ± 0·6 mV) compared with that in hippocampi not showing AHS (?47·7 ± 2·6 mV; p = 0·0017). Conclusions: The altered steady-state voltage-dependence of I_k, may result in abnormal excitability of dentate granule cells in AHS and exert a marked influence on input-output properties of the dentate gyrus.