Taketoshi Maehara

Surgical outcome of corpus callosotomy in patients with drop attacks.

Summary:  Purpose: We examined presurgical factors that independently influence surgical outcome after corpus callosotomy. For adequate measurement of the surgical outcome, we analyzed seizure outcome of drop attacks, postoperative overall daily function, and family satisfaction.

Modification of Peri-insular Hemispherotomy and Surgical Results

OBJECTIVE We modified the peri-insular hemispherotomy technique devised by Villemure and Mascott. Our modified technique and the surgical results obtained with this method are presented. METHODS The frontoparietal operculum is resected, and the resection cavity is connected with the lateral ventricle. Through this cavity, a transventricular corpus callosotomy and resection of the medial temporal structures are performed. RESULTS This technique was used for 34 patients, with satisfactory surgical results. Cerebrospinal fluid shunt placement was necessary for five patients, and incomplete callosal sectioning was postoperatively detected in three cases. CONCLUSION Our modification of the peri-insular hemispherotomy can be safely and effectively used to treat epilepsy caused by hemispheric lesions, even in cases without ventricular dilation.

Postoperative development of children after hemispherotomy

We studied the postoperative development of 14 children with cortical dysgenesis who underwent modified functional hemispherectomy (hemispherotomy) at the age of 6 years or younger. At follow-up of 24-72 months (median of 47 months), six (43%) were seizure-free, six achieved>90% reduction, one achieved 50-90% reduction, and one achieved 0-50% reduction in seizure frequency. At the preoperative and final postoperative examinations, mean scores of developmental quotient (DQ) were as follows: 25.5 and 31.9 in total DQ, 26.0 and 33.7 in intellectual DQ, and 27.4 and 22.9 in motor DQ. Children scoring >50 points in preoperative intellectual DQ score obtained near-normal intellectual DQ postoperatively, while, those scoring <10 DQ preoperatively remained at a low developmental level. Among children with DQ scores in the range from 10 to 50, two children who obtained seizure-free outcome and were operated upon in the first 3 years of life achieved marked developmental progress. The present study indicated that high preoperative intellectual DQ and cessation of seizures seem to be associated with better postoperative intellectual development. However, long-term observation of postoperative development and an accumulation of more cases will be needed before we can reach a firm conclusion.

Cortical oscillations in human medial temporal lobe during wakefulness and all-night sleep

We have recorded human medial temporal lobe electrocorticogram during wakefulness and natural sleep in epileptic patients with subdural electrodes. From these recordings, we have found gamma (30-150 Hz) [Neuroscience 90 (1999) 1149] and beta-1 (10-20 Hz) [NeuroReport 10 (1999) 3055] activities during wakefulness in human medial temporal lobe. In this paper, we will report changes of these frequencies across wake and natural sleep. Electrocorticograms during wake, slow wave sleep and rapid eye movement (REM) sleep were subjected to fast Fourier transformation analysis. During wake two spectral enhancements, beta-1 and gamma, were consistently observed across subjects. In the raw signal, beta-1 was observed as a regular rhythmic oscillation. In slow wave sleep, the beta-1 peak disappeared but gamma remained, although slightly reduced in power. During REM sleep, beta-1 appeared again, but the peak frequency was significantly lower than during wake (mean frequency: wake=16.6, REM=12.8 Hz). The gamma peak was also present in REM sleep. It has been known that the rhythmic slow activity (RSA) or theta is observed in some animals. However, it is unclear whether the human hippocampus displays similar activity. Since human beta-1 appears during wake and REM sleep when RSA is observed in other species, and since beta-1 is also a regular rhythmic oscillation, we propose that beta-1 may be the functional equivalent of hippocampal RSA (theta) observed in some animals. Functional significances of the gamma activity should be further investigated.

Enhanced gamma (30–150 Hz) frequency in the human medial temporal lobe

We performed fast Fourier transformation power spectral analysis of the electrocorticogram in human medial temporal lobe during wakeful rest in six epileptic subjects. Compared with the electrocorticogram wave in the basal temporal lobe, which showed monotonic decline of spectral power across the frequency axis, the electrocorticogram wave in the parahippocampal gyrus was enhanced (or did not decline) in the gamma frequency range (30-150 Hz) in all subjects. Although it has been suggested that electrical oscillations of the hippocampus have functional roles in higher brain functions, namely learning and memory, the knowledge of hippocampal oscillations is largely limited to animal studies. The present results demonstrate that fast frequency oscillation is also present in the human medial temporal lobe, which has been reported in animal hippocampi. They also demonstrate the importance of recording very fast field potentials in human electrocorticograms. This fast oscillation is likely to play important functional roles related to learning and memory, possibly to induce long-term potentiation in the human medial temporal lobe.

Recurrent mutations of CD79B and MYD88 are the hallmark of primary central nervous system lymphomas

Primary central nervous system lymphoma (PCNSL) manifest aggressive clinical behaviour and have poor prognosis. Although constitutive activation of the nuclear factor‐κB (NF‐κB) pathway has been documented, knowledge about the genetic alterations leading to the impairment of the NF‐κB pathway in PCNSLs is still limited. This study was aimed to unravel the underlying genetic profiles of PCNSL.

Surgical Treatment of a Case of Early Infantile Epileptic Encephalopathy with Suppression-Bursts Associated with Focal Cortical Dysplasia

Summary: We report a surgically treated case of early infantile epileptic encephalopathy (EIEE) with supression‐bursts associated with focal cortical dysplasia. Tonic‐clonic seizures followed by a series of spasms occurred about a hundred times a day at a few days of age. Interictal electroencephalogram (EEG) revealed a suppression‐burst pattern that was predominant in the left hemisphere. Magnetic resonance imaging (MRI) suggested focal cortical dysplasia in the left prefrontal area. Combination therapies with antiepileptic treatments showed only partial efficacy. The patient underwent lesionectomy at age 4 months, after which he gradually showed psychomotor development and a decrease of spasms to 0‐2 series daily. In cases of EIEE with focal cortical dysplasia, surgical treatment may have beneficial effects on both psychomotor development and seizure control.

Usefulness of [11C]methionine PET in the diagnosis of dysembryoplastic neuroepithelial tumor with temporal lobe epilepsy.

Summary:  Purpose: We assessed the diagnostic value of [11C]methionine (MET) positron emission tomography (PET) in the differential diagnosis of dysembryoplastic neuroepithelial tumors (DNETs) among benign tumors associated with temporal lobe epilepsy (TLE).

Presence of human herpesvirus 6 and herpes simplex virus detected by polymerase chain reaction in surgical tissue from temporal lobe epileptic patients

Abstract We investigated the presence of human herpesvirus 6 (HHV‐6) and herpes simplex virus (HSV) in surgical tissue from temporal lobe epileptic patients. A total of 17 cases were studied, including eight males and nine females. The mean age was 24.9 ± 11.1 years and the mean age of onset was 11.1 ± 5.4 years. Five patients were diagnosed as encephalitis/meningitis and another three had a history of suspected encephalitis/meningitis, but no patient showed any obvious neurological symptom or mental handicap. Mesial and lateral temporal tissues were examined by polymerase chain reaction. Among six patients positive for HHV‐6 (35%), the mesial temporal lobe was positive in four and the lateral temporal lobe was positive in three. Herpes simplex virus was positive in only one patient. Three of the six patients positive for HHV‐6 did not show any apparent causes. Mild encephalitis/meningitis induced by HHV‐6, a condition sometimes not recognized as encephalitis/meningitis, may be one of the most frequent causes of temporal lobe epilepsy.

Theta oscillation in the human anterior cingulate cortex during all-night sleep: An electrocorticographic study

Ten epileptic patients each with subdural electrodes surgically attached to the anterior cingulate cortex (ACC; two cases), the orbitofrontal cortex (OFC; seven cases), or both (one case) were included in this study. We recorded each patients ACC or OFC electrocorticogram (ECoG) during the time period that the patient was awake and naturally asleep. We performed a Fast Fourier Transformation (FFT) power spectral analysis on each ECoG to examine its frequency component. We found that the ACC showed regular and continuous theta oscillation (5-7Hz) during wakefulness and rapid eye movement (REM) sleep, but not during slow wave sleep. Theta waves observed in REM sleep were not as distinct as those found in wakefulness. We also discovered that the orbitofrontal signals represented spectral peaks in the theta band only during wakefulness. This suggests the coexistence of theta oscillation in the ACC. Considering our previous observations of gamma and beta oscillations in the human hippocampus, we hypothesize that the human limbic system manifests two oscillatory activities. The results obtained in this study suggest that electrophysiological activity in the ACC could be related to particular psychological functions in wakefulness and in REM sleep. These results are useful in elucidating the human brain mechanism.