Nobuyoshi Shibata

Bone mineral density of epileptic patients on long-term antiepileptic drug therapy: a quantitative digital radiography study

In order to assess the bone atrophy lesions of epileptic patients, the bone mineral densities (BMDs) of their lumbar spines and femoral necks were measured using quantitative digital radiography (QDR). The study groups were 44 patients on long-term medication for epilepsy and 62 healthy control subjects. We selected patients who had been taking phenytoin, barbiturates, and/or acetazolamide for at least 5 years. BMDs at both sites were significantly lower in the patient group than in the control group. No sex differences were found in BMDs. There were no significant correlations with the onset or the duration of illness and BMD. We compared BMD according to the type of epileptic drug being taken and theorized that phenytoin, barbiturates, and acetazolamide reduced BMD. BMDs of the 15 patients were measured again 7 years later, and were found to be significantly lower at both sites than in the previous examination. These results confirm the presence of bone atrophy lesions in epileptic patients on long-term antiepileptic drugs. Patients on antiepileptic therapy for long periods should have their BMDs checked, because they are prone to developing bone atrophy.

Valproic Acid‐Induced Hyperammonemic Encephalopathy with Triphasic Waves

Summary: Purpose: To examine a patient with valproic acid (VPA)‐induced hyperammonemic encephalopathy accompanied by triphasic waves.

Ictal brain hemodynamics in the epileptic focus caused by a brain tumor using functional magnetic resonance imaging (fMRI).

Using functional magnetic resonance imaging (fMRI) we were able to observe, in detail, ictal brain hemodynamics during epileptic seizure caused by a brain tumor. A 53-year-old man was experencing partial motor seizures of the left side of his face and neck. In a brain MR image a mass lesion was found in the subcortical area of the right frontal lobe. We found focal spikes in his right hemisphere, though dominantly in C4 and T4 regions. fMRI investigations were carried out at 1.5 T (GE Signa Horizon) using gradient-echo echo-planar neuroimaging. We were able to perform the ictal examination twice. The activated regions were focalized and clearly found only on the lateral side of the tumor base. The region was in agreement with the epileptic focus examined using an electrocorticogram (ECOG). The signal intensity in the seizure focus rapidly increased 30 seconds before the convulsion was observed. After the end of the convulsion it also took 30 seconds to restore the signal intensity to the baseline value. fMRI is a very useful tool for various studies such as the identification of the epileptic focus, the mechanism of epileptic seizure, and so on.

Non-convulsive status epilepticus induced by antidepressants

We report on a 27-year-old woman of non-convulsive status epilepticus (NSE) very probably induced by antidepressants. She has no history of febrile convulsions, or epileptic seizures. There are no genetic factors for epilepsy in her family. As she developed depressive illness, she consulted a doctor. Clomipramine 25 mg i.v. drip/day and maprotiline 75 mg/os/day were started. Recently she began to doze, so an EEG was performed. Continuous generalized 2-3 Hz spike and wave complexes were observed. Clomipramine and maprotiline were stopped the same day, and the patients drowsiness gradually improved. There are some case reports of NSE induced by antidepressants. However, the patients in these reports had received frequent electroconvulsive therapy (ECT) and were middle aged and may have been affected by an organic brain disorder. The present patient was young, and had not received ECT. It is therefore very likely that antidepressants may have been responsible for the occurrence of NSE in this patient. It is concluded that NSE should be considered an adverse effect of any antidepressant.

A study of the relationship between the seizure focus and 1H-MRS in temporal lobe epilepsy and frontal lobe epilepsy

Abstract Several studies of temporal lobe epilepsy (TLE) patients have investigated the relationship between the seizure focus and 1H magnetic resonance spectroscopy (1H‐MRS). There have also been a few reports in other types of partial epilepsy. We examined the relationship between the seizure focus and the reduction in N‐acetylaspartate : creatine (NAA : Cr) ratio using 1H‐MRS in both TLE and frontal lobe epilepsy (FLE) patients. We studied 21 patients with unilateral TLE and seven patients with unilateral FLE. We used a 1.5 Tesla magnetic resonance unit (Signa Horizon; General Electric). Approximately 15 × 15 × 20 mm3 voxel of interest (VOI) was placed over the anterior portion of the bilateral hippocampus in the TLE patients, and the anterodorsal position of bilateral frontal lobe in the FLE patients. The seizure focus was identified by interictal scalp electro‐encephalogram (EEG). In the TLE patients the NAA : Cr ratios were reduced in the seizure focus, while in the FLE patients they were not always reduced in the seizure focus. In the TLE patients the coincidence rate between the seizure focus and the reduction in the NAA : Cr ratio was 90% (19 of 21 patients), while in the FLE patients the coincidence rate was only 57% (four of seven patients).

Electroencephalogram‐triggered functional magnetic resonance imaging in focal epilepsy

Abstract  The high spatial resolution and cost performance of functional magnetic resonance imaging (fMRI) is useful for estimating focus localization in epilepsy, but this is difficult in the case of ictal fMRI because this is susceptible to motion artifacts. Electroencephalogram (EEG)‐triggered fMRI, which is interictal, can be performed without marked movement and is thought to be useful, but requires further investigation in order to establish a methodology. The authors studied EEG‐triggered fMRI in partial epileptic patients. Six patients were examined using a Nihon Kohden digital EEG recorder and Signa Horizon High Speed LX 1.5 T MRI scanner. Six electrodes were attached in the vicinity of the focus detected by scalp EEG. The fMRI scans were recorded after the discharges (activation) and scans without spikes (baseline). Equal numbers of activation and baseline scans were collected and analyzed using SPM99. In three of the six patients, an activated area was observed near the focus, but no activated areas were found in the other three subjects who tended to have a low number of spikes and low spike amplitude. Although various approaches focusing on improvement of the activation/non‐activation ratio are required, EEG‐triggered fMRI is a promising technique for detecting focal epileptic brain activity.

Study on the P300 of adult epileptic patients (unmedicated and medicated patients)

On cognitive function there have been few reports that examined the difference between unmedicated epileptics and normals. There have been relatively few reports in epileptic patients to use P300 (event-related potential) in order to assess cognitive function. We undertook this study to assess cognitive function in adult epileptic patients who were receiving or not receiving drug therapy and to investigate the factors causing their cognitive dysfunction by using P300. The subjects consisted of 46 unmedicated epileptic patients (the unmedicated group), 74 medicated epileptic patients (the medicated group), and 78 healthy subjects (the control group). The oddball paradigm was used in the measurement of P300. There were no significant differences in either latency or amplitude between the unmedicated group and the control group, but the latencies were significantly longer in the medicated group than in the control group. Significant positive correlations were found between the seizure frequency and latency prolongation, the number of drugs and latency prolongation, and the blood concentrations of all antiepileptic drugs (AEDs) administrated and latency prolongation, while no relationships were found with age at onset, duration of illness, or seizure type. These results suggest that the cognitive function of epileptic patients may be impaired by multidrug combination and high doses of AEDs, in addition to the possibility that it is impaired by frequently recurring seizures.

Estimation of Epileptic Foci Using the Dipole Tracing Method in Epileptic Seizures with Structural Lesions of the Brain

Abstract We estimated the position of the epileptic focus using the dipole tracing method (DTM) in three patients with epileptic seizures and structural lesions, and made comparisons between the foci and their lesions. Patient 1 had a large arachnoid cyst in the right temporal lobe, patient 2 had a tumor in the right hippocampus, and patient 3 had a tumor in the right amygdala. In patient 1, the epileptic focus was estimated to lie in the lateral portion of the right temporal lobe just outside the cyst; in patient 2, in the right hippocampus just under the tumor; and in patient 3, one in the right hippocampus just behind the tumor, another in the right superior temporal gyrus (rSTG). Except for the focus of patient 3 on rSTG, the epileptic foci in all three patients were estimated to lie near the lesions. These estimations correlated with past reports that most foci of seizures caused by brain lesions were located near the lesions. The results of ECoGs in patient 3 were in close correlation with those of DTM. Therefore, we conclude that DTM is a highly accurate method in the estimation of the foci in patients with brain lesions associated with epileptic seizures.

Mapping Epileptic Foci by the Dipole Tracing Method in a Brain Tumor Patient with Olfactory Seizures: Comparison with Intraoperative Electrocorticograms

We estimated the position of the epileptic foci in a case of brain tumor with olfactory seizures using the Dipole Tracing Method (DTM) and compared the results with electrocorticograms (ECoGs) recorded during surgical resection. The case was a 24-year-old male. Electroencephalograms (EEG) showed frequent focal spikes in the right temporal area. Magnetic resonance imaging revealed a tumor in the right hippocampus region. We analyzed the spikes using DTM with a CDT-1000 EEG analyzer. The locations of two independent foci were analyzed; one was thought to be in the right hippocampus and the other in the right superior temporal gyrus. When the ECoG was taken, the results were in very close correlation with those of DTM, demonstrating the accuracy of DTM in the estimation of the location of epileptic foci in epileptic seizures with brain lesions.

Mapping Epileptic Foci with the Dipole Tracing Method: A Comparison with Intraoperative Electrocorticograms

Purpose: To show the high accuracy of the dipole tracing method (DTM; Homma et al.Electroencephalogr Clin Neurophysiol 1994;91: 374–82), we estimated the position of the epileptic foci in two patients with epileptic seizures by using the DTM and compared the results with electrocorticograms (ECoGs) recorded during surgical resection.