Two magneto-encephalographic epileptic foci did not coincide with the electrocorticographic ictal onset zone in a patient with temporal lobe epilepsy

To evaluate the usefulness and limitations of magneto-encephalography (MEG) for epilepsy surgery, we compared 'interictal' epileptic spike fields on MEG with ictal electrocorticography (ECoG) using invasive chronic subdural electrodes in a patient with intractable medial temporal lobe epilepsy (MTLE) associated with vitamin K deficiency intracerebral hemorrhage. A 19-year-old male with an 8-year history of refractory complex partial seizures, secondarily generalized, and right hemispheric atrophy and porencephaly in the right frontal lobe on MRI, was studied with MEG to define the interictal paroxysmal sources based on the single-dipole model. This was followed by invasive ECoG monitoring to delineate the epileptogenic zone. MEG demonstrated two paroxysmal foci, one each on the right lateral temporal and frontal lobes. Ictal ECoG recordings revealed an ictal onset zone on the right medial temporal lobe, which was different from that defined by MEG. Anterior temporal lobectomy with hippocampectomy was performed and the patient has been seizure free for two years. Our results indicate that interictal MEG does not always define the epileptogenic zone in patients with MTLE.

Effects of sevoflurane and isoflurane on electrocorticographic activities in patients with temporal lobe epilepsy

To compare the neuroexcitatory effects of sevoflurane and isoflurane, we recorded electrocorticograms (ECoG) during wakefulness and during sevoflurane and isoflurane anesthesia in six patients with temporal lobe epilepsy (TLE). These patients had subdural grid electrodes chronically implanted in the temporal region. During sevoflurane anesthesia at 1.5 minimum alveolar concentration (MAC) of the combination with 67% nitrous oxide (N2O), a marked increase in interictal paroxysmal activities was observed in four patients. Two patients had a slight increase in paroxysmal activities. Activated areas were widely distributed, not being confined to the ictal onset zone of spontaneous seizures. However, isoflurane anesthesia at 1.5 MAC of the combination with 67% N2O was associated with less increased paroxysmal activity. While the neuroexcitatory properties of sevoflurane proved greater than those of isoflurane, the widespread irritative response to sevoflurane administration was not helpful in localizing the epileptogenic area.

Phantom studies for estimation of defect size on cardiac (18)F SPECT and PET: implications for myocardial viability assessment

SPECT with (18)F-FDG has emerged as an alternative to dedicated PET for the assessment of myocardial viability. However, whether FDG SPECT can reliably quantify the extent of viable and scarred myocardium is uncertain. The aim of this study was to investigate whether SPECT with an (18)F-labeled agent would provide information on defect size similar to that provided by dedicated PET.

METHODS

Imaging was performed using an elliptic cylinder chest phantom with simulated bone, lung, mediastinum, liver, and heart. (18)F was administered into the myocardium, mediastinum, right and left ventricular cavities, and liver. Plastic inserts (n = 11) ranging in size from 2% to 60% of the myocardium were used to simulate transmural myocardial infarctions. The chest phantom was imaged with a dedicated PET camera and with a double-head SPECT camera equipped with ultra-high-energy collimators. Both SPECT and PET data were analyzed using a semiquantitative polar map approach. Defects were quantified using various cutoff thresholds ranging from 30% to 80% of peak activity and were expressed as a percentage of the left ventricular myocardium. Defect size as measured by SPECT or PET was compared with true defect size.

RESULTS

The measured SPECT defect size was highly variable depending on the cutoff used, whereas PET defect size was relatively constant over the range of cutoffs tested. The mean absolute difference between measured and true defect sizes was minimal at a cutoff of 50% of peak activity for both SPECT (3.3% +/- 3.3%) and PET (2.7% +/- 2.5%). For this threshold, both SPECT and PET measurements showed an excellent correlation with true defect size (r = 0.98 for SPECT and 0.99 for PET). The correlation between SPECT and PET measurements was also excellent (r = 0.99; P < 0.01).

CONCLUSION

If an appropriate threshold is used to define a defect, SPECT with an (18)F-labeled agent can accurately measure defect size similarly to the manner of PET.

[An operated case of medial temporal lobe epilepsy associated with schizencephaly]

A 24-year-old male of medial temporal lobe epilepsy associated with schizencephaly was presented. He developed complex partial seizure after head trauma at the age of a year and 7 months, which became intractable at the age of 13 year. MRI demonstrated a schizencephalic cleft in the right peri-Rolandic area, cortical dysplasia in the right medical parietal and occipital lobes, and right hippocampal atrophy. Scalp-recorded EEG failed to localize the ictal onset zone. Interictal FDG-PET and ECD-SPECT indicated hypometabolism and hypoperfusion of the right entire temporal lobe, and ictal ECD-SPECT increased perfusion of this area. Chronic subdural electrode recording clearly demonstrated that ictal onset zone was located not on the schizencephalic cleft or its surrounding cortex but on the right medial temporal lobe. Following right anterior temporal lobectomy with hipppocampectomy, seizure control became easy. For the identification of the epileptogenic zone in patients with schizencephaly, chronic subdural electrode recording is mandatory.

Neuromagnetic assessment of epileptogenicity in cerebral arteriovenous malformation

Magnetoencephalographic (MEG) activities were recorded in five patients with cerebral arteriovenous malformation (AVM) who presented with epilepsy and no clinical history of intracranial hemorrhage, using a 37-channel DC superconducting quantum interference device (SQUID) system. While scalp-recorded electroencephalograms (EEG) failed to reveal paroxysmal discharge, MEGs demonstrated localized high frequency magnetic activity (HFMA). Magnetic source imaging (MSI) depicted the accumulation of equivalent current dipole (ECD) originating from HFMA around the nidus, and the ECD localization agreed well with spike localization on intraoperative electrocorticography (ECoG). These areas corresponded with the areas of hypoperfusion on single photon emission tomography and the intraoperative laser Doppler flow meter. We discussed the application of MEG in estimating interictal paroxysmal activity sources in patients with AVM and addressed the questions of its reliability and validity in source localization.

[Transurethral microwave thermotherapy for benign prostatic hyperplasia]

The clinical efficacy of transurethral microwave thermotherapy using the PROSTCARE apparatus was evaluated in 60 patients with bladder outlet obstruction associated with benign prostatic hyperplasia. All of the 60 patients received a single thermal session for 60 minutes with an average intraprostatic temperature of 45 degrees C. They were evaluated by analyzing the international prostate symptom score (IPSS), quality of life (QOL) index, maximum urinary flow rate and prostate volume at 2 months after the treatment to estimate criteria for efficacy of treatment in BPH. Both IPSS and QOL index improved significantly. The maximum urinary flow rate improved but there was no significant change. There was no significant change in prostate volume. The rates of improvement in IPSS, QOL index and maximum flow rate were 73%, 78% and 47% of the patients respectively. The rate of overall improvement was 78% of the patients. As a complication after the treatment, 2 patients complained of ejaculation disturbance.

Temporal lobe epilepsy: a clinicopathological study with special reference to temporal neocortical changes

The number of patients undergoing surgical treatment for pharmacoresistant temporal lobe epilepsy is rapidly increasing. While there have been many clinicopathological studies concerning the medial structures of the temporal lobe in temporal lobe epilepsy, its lateral structures have received little attention. To examine the nature and frequency of lateral temporal lobe abnormalities that occur in temporal lobe epilepsy, 22 patients who underwent standard anterior temporal lobectomy with hippocampectomy for intractable temporal lobe epilepsy were studied. The mean ages at the onset of seizure and at surgery were 15.9 years and 27.7 years, respectively. The electroclinically determined epileptogenic zones were the medial structures of the temporal lobe in 16 patients and the lateral in six. There was histologic evidence of hippocampal sclerosis in 12 of the 16 patients with medial onset seizures and in three of the six patients with lateral onset seizures. The lateral structures of the temporal lobe showed variable degrees of histological abnormalities in 21 patients. Among these abnormalities, heterotopic white matter neurons were observed in six of the 16 medial patients and in all the lateral patients. Glial changes were also common abnormalities, and often glial fibrillary acidic protein (GFAP)-positive astrocytes were present over the entire temporal lobe. In addition to hippocampal sclerosis, cerebral microdysgenesis and gliosis in the lateral structures of the temporal lobe may have a significant role in epileptogenesis of temporal lobe epilepsy.

[Occipital encephalocele and epilepsy]

We report the incidence of epilepsy in 7 patients with occipital encephalocele (meningocele: 6 cases, meningoencephalocystocele: 1 case). Two cases had epilepsy and a case without the history of epileptic seizure had an epileptic pattern on the EEG. All these 3 cases had cortical dysplasia(CD) such as schizencephaly and subcortical gray matter, and two of them were associated with mental retardation. The location of the prominent CD was correlated with the EEG abnormalities and clinical epileptic pattern in each case. Associated hydrocephalus and placement of VP shunt had no significant influence on the occurrence of the epilepsy. Thus, complicated CD is thought to be epileptogenic in patients with occipital encephalocele.

[Surgical treatment for temporal lobe epilepsy in childhood]

We retrospectively analyzed 5 children (11-15 year) with intractable temporal lobe epilepsy (TLE) who underwent the anterior temporal lobectomy with hippocampectomy. Cases 1-3 had medial TLE (MTLE) with histologically verified hippocampal sclerosis, Case 4 had lateral TLE, and Case 5 had MTLE with old hemorrhagic lesion in the lateral temporal lobe. In Cases 3-5, chronic invasive electrocorticography recording using subdural electrodes was obtained, while in Cases 1 and 2, the epileptogenic region was defined by noninvasive preoperative evaluation. Postoperatively, Cases 1-3 became seizure free. All patients had psychosocial problems after the onset of their epilepsy, which was not improved even after the surgical control of epilepsy. Since most patients had morphological change and perfusional and metabolic disturbance outside the hippocampus at the time of surgery, earlier surgical consideration may be necessary.

Magnetoencephalographic analysis of periodic lateralized epileptiform discharges (PLEDs)

OBJECTIVE

To clarify the spatial and temporal distribution of the electroencephalographic (EEG) pattern termed 'periodic lateralized epileptiform discharges' (PLEDs), we performed magnetoencephalography (MEG) to analyze PLEDs in a patient with a right parietal metastasis associated with meningeal carcinomatosis.

METHODS

A 37-channel biomagnetometer was used to simultaneously record the EEG and MEG. Equivalent current dipole (ECD) source localization was calculated based on a single-dipole model and mapped onto a magnetic resonance image. Single-photon emission computed tomography with technetium-99-hexamethyl-propyleneamine oxime (HMPAO-SPECT study) was also performed during both presence and absence of PLEDs according to an EEG monitor.

RESULTS

By EEG the PLEDs, predominantly right-sided, consisted of a typical negative triphasic spike followed by a slow negative wave. By MEG the PLEDs had a sequence with 3 distinct components. ECDs in the 3 components were localized to the cortex around the lesion, although exact localization and dipole direction varied between components. HMPAO-SPECT demonstrated hypoperfusion of the lesion and adjacent cortex during both quiescence and appearance of PLEDs.

CONCLUSION

Our results indicate that PLEDs originated from the hypoperfused cortex surrounding the lesion.

[Schizencephaly: clinical and MRI features]

We report the clinical and neuroimaging features of 4 cases with schizencephaly. Case 1 had bilateral schizencephaly with open-lip on the right and closed-lip on the left. Case 2 had unilateral schizencephaly with closed-lip on the left and subcortical heterotopia on the right. Case 3 had unilateral schizencephaly with closed-lip on the left. Case 4 had bilateral closed-lip schizencephaly. Although all cases except for Case 3 had bilateral lesions, neurodevelopmental outcome was generally good; Case 1 and 3 had mild hemiparesis. All patient have epilepsy which are well-controlled with antiepileptic drugs. Thus, the clinical presentation of schizencephaly, even if bilateral lesions, are quite variable.

Distribution of brainstem somatosensory evoked potentials following upper and lower limb stimulation

OBJECTIVE

Because somatosensory evoked potentials (SEP) to lower limb stimulation have not been recorded from the brainstem to the extent that upper limb SEPs have been studied, we compared brainstem recordings in response to both median nerve (MN) and posterior tibial nerve (PTN)stimulation.

METHODS

SEPs were recorded directly from the dorsal surface of the brainstem in four patients with fourth ventricle tumors.

RESULTS

Following MN stimulation, medullary SEPs were characterized by a major negativity (N1) preceded by a small positivity (P1) and followed by a large positivity (P2). In the pons, triphasic waves with predominant negativity were obtained. With PTN stimulation, similar medullary SEPs with a P1'-N1'-P2' configuration and pontine SEPs with a triphasic waveform were obtained.

CONCLUSIONS

Since the distribution of PTN SEP was identical to that of MN SEP, PTN SEPs are thought to be generated by mechanisms similar to those for MN SEP. Thus, the P1' and N1' of medullary SEP would be generated by the dorsal column fibers that terminate in the nucleus, with P2' possibly arising postsynaptically in the nucleus. The triphasic PTN SEP from the pons reflects an axonal potential generated in the medial lemniscal pathway.

[Temporal lobe epilepsy associated with old intracerebral hemorrhage due to capillary telangiectasis in the temporal lobe: case report]

A case of 45-year-old female, who presented with temporal lobe epilepsy was reported. The patient was found to have old intracerebral hemorrhage due to capillary telangiectasis in the temporal lobe. On the intraoperative electrocorticography, frequent paroxysmal activities were recorded independently both on the medial and lateral aspects of the temporal lobe. Even after resection of the lateral temporal lobe, frequent paroxysmal discharges were noted on the hippocampus. Histologically, there are astrogliosis and hemosiderin deposits in the white matter around the telangiectasis and the old hematoma. It is postulated that the hippocampus gained secondary epileptogenicity.

Immunohistochemical expression of trk receptor proteins in focal cortical dysplasia with intractable epilepsy

Focal cortical dysplasia (FCD), which is often associated with intractable epilepsy, is a form of abnormal structure of the cerebral cortex caused by a disorder of normal neocortical development. In such cerebral lesions obtained from four patients (two male, two female; average age 32.3 years at operation), the immunohistochemical expression of Trk receptors, which interact with neurotrophins and result in both growth and maturational changes in neuronal cells, was investigated in relation to the possible histogenesis of these lesions. In all cases, a derangement of the cortical laminar structure, dysplastic cytomegalic neurones, and large round balloon cells were the characteristic histological features. Immunohistochemically, the TrkA expression was localized in large dysplastic cytomegalic neurones, and TrkB expression was observed in large dysplastic and relatively small neuronal cells within the affected cortex. Although the exact roles of neurotrophins and their receptors in the pathogenesis of FCD remain uncertain, its development might be governed by such neurotrophic influences, and thus possibly prevent the death of abnormal neuronal cells. In addition, Trk receptors in FCDs may also play a role in establishing in the intrinsic epileptogenicity of FCDs.

Relationship between the biodistributions of radioactive metal nuclides in tumor tissue and the physicochemical properties of these metal ions

This study was undertaken to elucidate the relationship between the biodistribution of radioactive metal nuclides in tumor tissue and its physicochemical properties. Potassium analogs (86Rb, 134Cs, 201Tl) were taken up into viable tumor tissue, although 22Na concentrated in necrotic tumor tissue. 67Ga and 111In were more predominant in inflammatory tissue than in the viable and necrotic tumor tissue. 169Yb and 167Tm accumulated in viable tumor tissue and tissue containing viable and necrotic tumor tissue. 67Ga, 111In, 169Yb and 167Tm were bound to the acid mucopolysaccharide with a mol. wt. of about 10,000 daltons in the tumor tissue. 46Sc, 51Cr, 95Zr, 181Hf, 95Nb, 182Ta, and 103Ru were highly concentrated in inflammatory tissue and were bound to the acid mucopolysaccharides with a mol. wt. exceeding 40,000 daltons. 65Zn and 103Pd concentrated in viable tumor tissue and were bound to the protein in the tissue. The results suggest that the difference in intra-tumor distribution of these elements is caused by a difference in the binding substances (or status) of these elements in the tissues, and the binding substance is determined by physicochemical properties of the elements. We therefore conclude that the biodistribution of radioactive metal ions in tumor tissue is determined by its own physicochemical properties.

Intrinsic epileptogenicity of focal cortical dysplasia as revealed by magnetoencephalography and electrocorticography

Focal cortical dysplasia (FCD) is often associated with severe partial epilepsy. In this study, we performed magnetoencephalography (MEG) and electrocorticogrsphy (ECoG) on four patients with FCD-associated epilepsy to confirm the 'intrinsic' epileptogenicity of FCD. In all patients, we determined the three-dimensional locations of the magnetic sources of the interictal paroxysmal activities by a single dipole model, and then the estimated dipole localization was superimposed on the magnetic resonance image. The dipole clusters were located in the T2-prolonged lesions, namely in the FCD lesions themselves. All patients underwent surgery for their medically intractable epilepsy, and the acute and/or chronic ECoG were thereafter recorded. Either frequent or continuous paroxysmal activities were recorded from the ECoG electrodes which were placed over the surface of the FCD lesion, while few paroxysmal activities were observed on the normal appearing adjacent cortex. Intraoperative depth recordings were performed in a patient with the needle electrode inserted into the FCD lesion and they revealed these paroxysmal foci to be located not on the cortical surface but at a depth of 15 mm from the cortical surface where both abnormal giant neurons and bizarre large eosinophilic cells (so-called balloon cells) were also prominently observed on the postoperative histological sections. Following a lesionectomy combined with the removal of the underlying white matter, three patients demonstrated a favorable seizure outcome. Our findings thus suggest the FCD lesions to be highly and intrinsically epileptogenic lesions.

[Clinical experience of image-guided neurosurgery with a frameless navigation system (StealthStation)]

We have applied the frameless navigation system (StealthStation) to various neurosurgical procedures to examine its usefulness. The system consists of a UNIX based workstation that creates triplanar and 3-dimensional images; an infrared optical digitizer with camera array; a reference-light-emitting diode (LED) array (e.g., reference array); and pointer probe modified by the addition of LEDs. This system was used to assist in placing a minimal skin incision and craniotomy in 4 cases, to determine the tumor/brain interface in 2 cases, to target the subcortical lesion in one case, and to correlate bony structure with a skull base tumor in 3 cases. The combined use with magnetic source imaging of the somatosensory cortex allowed a fast orientation of eloquent areas in 2 cases with peri-Rolandic tumor. This system, thus, was proved to be a useful adjunct to open-tumor biopsy or resection.

[Carbamazepine induced hyponatremia]

Carbamazepine (CBZ) is a drug which can induce the syndrome of inappropriate antidiuretic hormone (SIADH). Until 1980's, there were reports regarding CBZ-induced SIADH, but it is rarely reported these days. We here report two cases of CBZ-induced SIADH. Hyponatremia in these cases was rapidly improved by withdrawal of administration of CBZ. According to the previous reports, the rate of hyponatremia in patients receiving CBZ is not small. It ranges from 48% to 31%. As CBZ is frequently used for patients with epilepsy and neuralgia, not only their blood CBZ concentration but also their serum Na level should be monitored.

[Two cases of mesial temporal lobe epilepsy associated with old intracerebral hemorrhage in the lateral temporal lobe without "dual pathology"]

Two cases of intractable temporal lobe epilepsy associated with old intracerebral hemorrhage in the lateral temporal lobe were reported. Although preoperative magnetic resonance imaging (MRI) failed to reveal hippocampal atrophy with T2 hyperintensity, electrocorticographic (ECoG) recording with chronic invasive subdural electrodes indicated the mesial temporal lobe to be an ictal onset zone. After anterior temporal lobectomy involving the lesion and hippocampectomy, the patients became seizure-free. Hippocampal sclerosis, namely "dual pathology", was not noted on histological examination. Careful ECoG recording with chronic subdural electrodes is mandatory even when the preoperative MRI does not demonstrate the radiological hippocampal sclerosis.

[Efficacy of the fluid attenuated inversion recovery (FLAIR) sequence of MRI as a preoperative diagnosis of hippocampal sclerosis]

A newly advanced MRI pulse sequence, the FLAIR (fluid attenuated inversion recovery) imaging, in which a long TE spin echo sequence is used with suppression of the CSF with an inversion pulse, displays the CSF space as a no-signal intensity area. There have been only a few reports on the FLAIR pulse sequence of temporal lobe epilepsy (TLE) as yet. We examined 9 cases of intractable TLE by FLAIR images and analyzed the advantages and disadvantages of the FLAIR pulse sequence for decision making on temporal lobectomy. All patients underwent anterior temporal lobectomy with hippocampectomy, and the diagnoses were confirmed histologically after surgery. Abnormally high T2 signals (HT2S) were more conspicuous with the FLAIR sequence than with any of the conventional sequences. Tilted axial plane, orientated along to the long axis of the hippocampal body, clearly demonstrated hippocampal atrophy (HA). Selection of a FLAIR sequence into the routine MR examination of patients with TLE is recommended.

[Dual isotope SPECT with 99mTc and 123I using four-energy-window (FEW) method]

We devised "four-energy-window" (FEW) method which permits simultaneous acquisition for dual isotope single photon emission tomography (SPECT) studies using 99mTc and 123I of which photopeak is in close vicinity to each other. This acquisition method requires a total of four energy windows: two main windows for 99mTc (126-143 keV) and 123I (156-175 keV), respectively, and two 5% sub-windows which are set below the 99mTc window and above the 123I window, respectively. Two virtual windows (5%) are additionally set above the 99mTc and below the 123I window, respectively, to apply the triple-energy-window (TEW) method for the scatter correction. A phantom study demonstrated that photocounts from the two radionuclides could be completely separated from each other and that SPECT images obtained had preferable property for quantitative analysis. This method was applied to clinical, dual-radionuclide myocardial studies using 99mTc-MIBI and 123I-BMIPP, and was found to provide excellent images each tracer.

[Effectiveness of the radioactive strontium (89Sr) chloride agent, SMS.2P for pain palliation in patients with metastatic bone tumor in phase III multicenter clinical trial]

The phase III clinical trial of strontium-89 chloride agent (SMS.2P) was performed in 90 patients with painful bone metastases secondary to prostate (53), breast (18) and other types of cancer (19). Some patients experienced a transient increase in pain or nausea and vomiting. However both symptoms subsided and serious side effects were not observed in any of the patients. As reported, we confirmed some abnormal changes in peripheral blood picture. A decrease in the number of white blood cells and platelets was considered to be partly a result of bone marrow suppression due to 89Sr irradiation. Pain was substantially improved after 89Sr therapy in 58% of the patients and there was some alleviation in 12%. The release from pain was accompanied by an improved quality of life for these patients including sleep patterns and morbidity. Some patients were able to resume their former life styles. Most of the improved patients experienced pain relief from days to one week following 89Sr therapy and in half cases, this remained effective for 2 or 3 months. There were even cases in which the pain relief continued over an observation period of time of clinical study.