Preservation of absolute pitch after right amygdalohippocampectomy for a pianist with TLE.

Absolute pitch (AP) ability is a rare musical phenomenon. In the literature, it has been suggested that the relative specialization for pitch processing is in the right temporal lobe in the non-AP population. Since the anatomic basis for absolute pitch is not fully understood and cases of temporal lobe epilepsy of AP possessors are extremely rare, applicability of resection as a treatment of epilepsy in this particular area should be evaluated with caution. In the present study, we examined an AP possessor who suffered from medically refractory temporal lobe epilepsy and underwent right selective amygdalohippocampectomy (SAH). The SAH procedure clearly avoided disturbing important structures for AP, inasmuch as postsurgically she preserved her AP ability and was seizure-free. She did well post-operatively in the test of pure sine wave tones with short reaction time, which could be identified as "true" absolute pitch.

Uneven interhemispheric connections between left and right primary sensori-motor areas.

To clarify the characteristics of interhemispheric connections, we investigated cortico-cortical evoked potentials (CCEP) in human. Fourteen patients with temporal lobe epilepsy who underwent invasive EEG monitoring with bilaterally implanted subdural electrodes were studied. Electric pulse stimuli were given in a bipolar fashion at two adjacent electrodes on and around the motor area (MA) or sensory area (SA), and CCEP responses were recorded by averaging electrocorticograms from the contralateral hemisphere. Seventy-two pairs of electrodes were stimulated, and 468 recordings were analyzed. Fifty-one of 468 recordings demonstrated CCEP responses. Of 51 responses, 16 consisted of an initial positive triphasic wave (Type 1), 27 had an initial negative biphasic wave (Type 2), and 8 showed an initial positive biphasic wave (type 3). The mean latencies of the earliest peaks were 13.1, 28.9, and 29.4 ms in Types 1, 2, and 3 responses, respectively. The responses were more frequently evoked by stimulating facial MA (f-MA) and nonfacial MA (nf-MA) than by stimulating SA or noneloquent area. In both f-MA and nf-MA stimulation, the responses were more frequently recorded at the contralateral f-MA than at the contralateral nf-MA or other areas. SA stimulation never evoked CCEP responses at the contralateral MA or SA. The amplitudes were maximal when f-MA was stimulated and responses recorded at the contralateral f-MA. These findings suggest that the interhemispheric connections are uneven. Both f-MA and nf-MA send dense interhemispheric connections to the contralateral f-MA. SA may have no or only rare direct connection with the contralateral MA or SA.

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

OBJECT: The goal in this study was to assess the role of longitudinal hippocampal circuits in the generation of interictal and ictal activity in temporal lobe epilepsy (TLE) and to evaluate the effects of multiple hippocampal transections (MHT). METHODS: In 6 patients with TLE, the authors evaluated the synchrony of hippocampal interictal and ictal epileptiform discharges by using a cross-correlation analysis, and the effect of MHT on hippocampal interictal spikes was studied. Five of the 6 patients were studied with depth electrodes, and epilepsy surgery was performed in 4 patients (anterior temporal lobectomy in 1 and MHT in 3). RESULTS: Four hundred eighty-two (95.1%) of 507 hippocampal spikes showed an anterior-to-posterior propagation within the hippocampus, with a fixed peak-to-peak interval. During seizures, a significant increase of synchronization between different hippocampal regions and between the hippocampus and the ipsilateral anterior parahippocampal gyrus was observed in all seizures. An ictal increase in synchronization between the hippocampus and ipsilateral amygdala was seen in only 24.1% of the seizures. No changes in synchronization were noticed during seizures between the hippocampi and the amygdala on either side. The structure leading the epileptic seizures varied over time during a given seizure and also from one seizure to another. Spike analysis during MHT demonstrated that there were two spike populations that reacted differently to this procedure--namely, 1) spikes that showed maximum amplitude at the head of the hippocampus (type H); and 2) spikes that showed the highest amplitude at the hippocampal body (type B). A striking decrease in amplitude and frequency of type B spikes was noticed in all 3 patients after transections at the head or anterior portion of the hippocampal body. Type H spikes were seen in 2 cases and did not change in amplitude and frequency throughout MHT. Type B spikes showed constantly high cross-correlation values in different derivations and a relatively fixed peak-to-peak interval before MHT. This fixed interpeak delay disappeared after the first transection, although high cross-correlation values persisted unchanged. All patients who underwent MHT remained seizure free for more than 2 years. CONCLUSIONS: These data suggest that synchronized discharges involving the complete anterior-posterior axis of the hippocampal/parahippocampal (H/P) formation underlie the spread of epileptiform discharges outside the H/P structures and, therefore, for the generation of epileptic seizures originating in the H/P structures. This conclusion is supported by the following observations. 1) Hippocampal spikes are consistently synchronized in the whole hippocampal structures, with a fixed delay between the different hippocampal areas. 2) One or two transections between the head and body of the hippocampal formation are sufficient to abolish hippocampal spikes that are synchronized along the anterior-posterior axis of the hippocampus. 3) Treatment with MHT leads to seizure freedom in patients with H/P epilepsy.

Versive seizures in occipital lobe epilepsy: lateralizing value and pathophysiology.

To clarify the value of versive seizures in lateralizing and localizing the epileptogenic zone in patients with occipital lobe epilepsy, we studied 13 occipital lobe epilepsy patients with at least one versive seizure recorded during preoperative noninvasive video-EEG monitoring, who underwent occipital lobe resection, and were followed postoperatively for more than 2 years with Engel's class I outcome. The videotaped versive seizures were analyzed to compare the direction of version and the side of surgical resection in each patient. Moreover, we examined other motor symptoms (partial somatomotor manifestations such as tonic and/or clonic movements of face and/or limbs, automatisms, and eyelid blinking) associated with version. Forty-nine versive seizures were analyzed. The direction of version was always contralateral to the side of resection except in one patient. Among accompanying motor symptoms, partial somatomotor manifestations were observed in only five patients. In conclusion, versive seizure is a reliable lateralizing sign indicating contralateral epileptogenic zone in occipital lobe epilepsy. Since versive seizures were accompanied by partial somatomotor manifestations in less than half of the patients, it is suggested that the mechanism of version in occipital lobe epilepsy is different from that in frontal lobe epilepsy.

Clinical significance of ictal high frequency oscillations in medial temporal lobe epilepsy.

OBJECTIVE: To clarify the clinical significance of ictal high frequency oscillations (HFO) in the medial temporal lobe. METHODS: This study included 19 patients who underwent intracranial electrode implantation in bilateral temporal lobes and had at least one seizure recorded at 1kHz sampling rate. The characteristics of ictal HFO in the medial temporal lobe, and the relations between the presence of HFO, pathology, and postoperative seizure outcome were analyzed. RESULTS: Ictal HFO were detected from medial temporal structures in 11 patients with medial temporal lobe epilepsy (MTLE). Among eight patients without HFO, only three were diagnosed with MTLE. Ictal HFO were detected from unilateral medial temporal structures ipsilateral to the side of hippocampal sclerosis (HS). In one patient with bitemporal independent seizure onset, ictal HFO were detected only on the side of HS. HS was detected in all 11 patients with HFO, but in only one of four patients without HFO. Seizure outcome did not differ between patients with and without HFO. CONCLUSIONS: Ictal HFO in the medial temporal lobe may be a specific marker for MTLE with HS. SIGNIFICANCE: Recording of ictal HFO in the medial temporal lobe may be useful for presurgical evaluation of MTLE.

Ictal very low frequency oscillation in human epilepsy patients.

Using intracranial electroencephalographic recordings, we identified a distinct brain activity in 3 patients with refractory epilepsy characterized by very early occurrence from 8 minutes 10 seconds to 22 minutes 40 seconds prior to clinical seizure onset, periodical appearance of slow negative baseline shift, long interpeak interval of 40 to 120 seconds, and disappearance after clinical seizure. We named this activity "very low frequency oscillation" (VLFO), which reflected a dynamic process during the preictal state. This observation may render new insight into epileptogenesis and provide additional information concerning the epileptogenic zone as well as prediction of epileptic seizures.

Statistical analysis of transcallosal propagation of spikes arising from the mesial frontal area.

OBJECTIVE: To study the connections between bilateral mesial frontal (MF) regions. METHODS: We evaluated synchrony of spikes, recorded by subdural electrodes, arising from bilateral MF regions using cross correlation in MF epilepsy. A seven-year-old boy with intractable daily bilateral asymmetric tonic seizures and a normal MRI was investigated. To confirm the lateralization of epileptogenicity, subdural electrodes were implanted bilaterally. Only spikes of an amplitude of 400 µV or more were analyzed. RESULTS: Of 92.4% (194/210) of the left MF spikes recorded for 30 minutes, an approximately synchronous spike was also detected in the right MF region. Cross correlation analysis demonstrated that for 88.7% of the bilateral MF spikes (172/194, 88.7%) the left MF spike led the contralateral spikes with relative fixed peak-to-peak intervals (18.9 ± 11.1 ms) and high cross correlation values (0.81 ± 0.10). An estimated conduction velocity of 7.2 ± 9.8 m/sec was calculated (assuming no synaptic delay). After a second period of more extended invasive EEG monitoring, a left partial frontal lobectomy was performed and the patient immediately had a few brief seizures before remaining seizure-free for a follow-up period of 14 months. CONCLUSION: We conclude that the propagation of spikes between bilateral MF regions most likely occurs mainly through myelinated callosal fibres. In addition, this cross correlation method showed that the left MF spikes, most of the time, preceded the right MF spikes suggesting that the epileptogenic zone was localized in the left MF region.

The applications of time-frequency analyses to ictal magnetoencephalography in neocortical epilepsy.

PURPOSE: Ictal magenetoencephalographic (MEG) discharges convey significant information about ictal onset and propagation, but there is no established method for analyzing ictal MEG. This study sought to clarify the usefulness of time-frequency analyses using short-time Fourier transform (STFT) for ictal onset and propagation of ictal MEG activity in patients with neocortical epilepsy. METHODS: Four ictal MEG discharges in two patients with perirolandic epilepsy and one with frontal lobe epilepsy (FLE) were evaluated by time-frequency analyses using STFT. Prominent oscillation bands were collected manually and the magnitudes of those specific bands were superimposed on individual 3D-magnetic resonance images. RESULTS: STFT showed specific rhythmic activities from alpha to beta bands at the magnetological onset in all four ictal MEG records. Those activities were located at the vicinity of interictal spike sources, as estimated by the single dipole method (SDM), and two of the four ictal rhythmic activities promptly propagated to ipsilateral or bilateral cerebral cortices. The patients with FLE and perirolandic epilepsy underwent frontal lobectomy and resection of primary motor area, respectively including the origin of high-magnitude areas of a specific band indicated by STFT, and have been seizure free after the surgery. CONCLUSIONS: STFT for ictal MEG discharges readily demonstrated the ictal onset and propagation. These data were important for decisions on surgical procedure and extent of resection. Ictal MEG analyses using STFT could provide a powerful tool for noninvasive evaluation of ictal onset zone.

Very high frequency oscillations (over 1000 Hz) in human epilepsy.

OBJECTIVE: High frequency oscillations (HFO) of 100-500Hz have been reported in epileptic human brain. However, the questions of how fast these oscillations can reach, and which frequency range is clinically important remain unanswered. We recorded interictal and ictal very high frequency oscillations (VHFO) of 1000-2500Hz by subdural electrodes using 10kHz sampling rate. We describe the characteristics of VHFO, and discuss their underlying mechanism and clinical significance. METHODS: Five patients with neocortical epilepsy were studied. All patients underwent intracranial EEG monitoring with subdural electrodes. EEG recording with sampling rate of 10kHz was conducted. Histopathology revealed malformation of cortical development in all cases. RESULTS: In four of five patients, very high frequency activities of 1000-2500Hz were detected in highly localized cortical regions (one to four electrodes in individual patient). We named these activities "very high frequency oscillations (VHFO)". Interictally, VHFO appeared intermittently, and were interrupted by spikes. Sustained VHFO without spikes appeared around the start of seizures. CONCLUSIONS: Both interictal and ictal VHFO can be recorded by subdural electrodes. Compared to HFO previously reported, VHFO have much higher frequency, more restricted distribution, smaller amplitude, and different timing of onset. SIGNIFICANCE: Recording of VHFO may be useful for identifying the epileptogenic zone.

Epileptic negative myoclonus: a combined study of EEG and [123I]iomazenil (123I-IMZ) single photon emission computed tomography indicating involvement of medial frontal area.

Negative myoclonus (NM) is a sudden brief atonia in muscle that causes jerky lapses of posture. This study employed an electrophysiological technique (silent-period-locked-averaging (SPLA) electroencephalography (EEG)) and a pharmacodynamic imaging technique (123I-IMZ-SPECT) to examine epileptic NM (ENM). Delayed-phase 123I-IMZ-SPECT images, which reflect the specific binding of the tracers to GABA-A receptors, exhibited significant decrease in the left medial frontal area. The deficit in GABA-A receptors indicated that abnormal synchronization was mediated by the lack of inhibitory postsynaptic mechanism. The SPLA-EEG recorded spike-like notches superimposed on the slope of negative slow activity in the contralateral fronto-central region. The slow activity started around 100 ms before and the peak of the spike-like component was 30 ms before the onset of ENM. Since the 123I-IMZ-SPECT shows the actual distribution of the tracers, the abnormal area associated with ENM in this particular patient was supposed to be on the left medial frontal lobe. Scalp EEG, though it cannot always accurately locate the abnormal area, was highly sensitive to be able to detect electrical activities transmitted through neuronal network or volume conductor. Combined use of the two methods provided high resolution both in spatial and temporal domain.

Very high-frequency oscillations (over 1000 Hz) of somatosensory-evoked potentials directly recorded from the human brain.

The aims of this study were to record high-frequency oscillations (HFOs) associated with somatosensory-evoked potentials from subdural electrodes and to investigate their generators and clinical significance. Six patients who underwent long-term subdural electrode monitoring were studied. Somatosensory-evoked potentials were recorded directly from the subdural electrode after stimulation of the median nerve. Bandpass filter was 10 to 10,000 Hz for conventional somatosensory-evoked potential and 500 to 10,000 Hz for HFO. Three types of HFO were recorded. The first component was early HFO (407-926 Hz), which occurred before N20 peak. The second component was late HFO (408-909 Hz), which occurred after N20 peak. In addition, a novel component was recorded with a range from 1,235 to 2,632 Hz, and this component was termed very HFO. Early and late HFOs were recorded from relatively wide areas centering around the primary motor and primary sensory areas, whereas very HFO was localized around the primary sensory areas. In this study, at least three components of HFO could be identified. Only very HFO was localized around primary sensory areas, suggesting a possibility that very HFO may provide an effective method of identifying the central sulcus.

Neural connection between bilateral basal temporal regions: cortico-cortical evoked potential analysis in patients with temporal lobe epilepsy.

OBJECTIVE: In patients with temporal lobe epilepsy, invasive electroencephalographic study has shown that epileptic activities arising from the unilateral temporal lobe often propagate to the contralateral temporal lobe. Which commissural pathways are responsible for this spreading remains controversial. Some previous studies, however, have suggested that interhemispheric connections between bilateral basal temporal regions (BTR) might have a significant role in propagation of epileptic activities. METHODS: We attempted to elucidate the neural connections between bilateral BTRs using the cortico-cortical evoked potential (CCEP) method. Five consecutive patients with temporal lobe epilepsy who underwent intracranial electroencephalographic monitoring were studied. RESULTS: CCEP responses were recorded from a total of 24 electrodes after stimulation of the contralateral BTRs (24 CCEPs/720 recordings; 3.33%). There were 3 types of CCEP waveform: type N-P (16 of 24; 66.7%) consisting of an initial negative peak followed by a positive peak; type N (4 of 24; 16.7%) showing a negative peak only, and type P (4 of 24; 16.7%) showing a positive peak only. The latencies ranged from 48.2 to 102.3 ms (mean, 65.5 ms) for negative peaks and 70.2 to 122.0 ms (mean, 95.2 ms) for positive peaks. In all patients, the basal temporal language area was associated with at least 1 CCEP, either as a stimulated region or a recorded region (11 of 24; 45.8%). CONCLUSION: These data indicate that there is a neural connection between bilateral BTRs. In consideration of the involvement of the basal temporal language area, we speculate that these responses may reflect some physiological connections between bilateral BTRs.

Generators of tibial nerve somatosensory evoked potential: recorded from the mesial surface of the human brain using subdural electrodes.

The generators of the initial cortical component of somatosensory evoked potentials in response to tibial nerve stimulation (Tib-somatosensory evoked potentials) are still uncertain. The purpose of this study is to localize the generators of it. A 15-year-old boy with intractable parietal lobe epilepsy was studied. Subdural electrodes were chronically implanted for presurgical evaluation of epilepsy surgery, covering the primary motor, primary sensory, and supplementary sensorimotor areas of the right leg. Tib-somatosensory evoked potentials were recorded from these areas. Highly localized prominent positive activities were recorded from electrodes on the primary motor area of the leg at 32.4 to 34.0 milliseconds. No corresponding large negative peak was recorded in any other electrodes. Weak negative activities distributed widely around the postcentral area at 33.2 to 33.6 milliseconds, accompanied by similar but positive activities in the precentral area at 32.8 to 33.2 milliseconds. There was an independent positive field on supplementary sensorimotor areas at 34.0 to 34.8 milliseconds. A small negative peak was also recorded but only from a single electrode within supplementary sensorimotor areas at 34.0 milliseconds. Our data suggest that the initial response of Tib-somatosensory evoked potentials has at least three independent generators: a radial dipole on the primary motor, a tangential dipole on the primary sensory area, and a dipole on the supplementary sensorimotor areas oriented perpendicularly to the mesial hemispheric surface.

Symptomatic laughter in a patient with orbitofrontal seizure: A surgical case with intracranial electroencephalographic study: case report.

OBJECTIVE: A rare case of orbitofrontal lobe epilepsy manifesting gelastic seizure is reported. CLINICAL PRESENTATION: A 49-year-old woman had developed weekly complex partial seizures consisting of nonverbal vocalization and unresponsiveness followed by laughter. Magnetic resonance imaging revealed a round tumorous lesion at the posterior side of the right rectal gyrus and medial orbitofrontal gyrus. Neuroimaging studies and electrophysiological examinations, including intracranial electroencephalographic monitoring, suggested the existence of an epileptogenic zone in the ipsilateral orbitofrontal gyrus, including the lesion. INTERVENTION: After partial right prefrontal lobectomy including lesionectomy, the patient became seizure-free during a follow-up period of 33 months. We speculated that the limbic system, including the orbitofrontal lobe and temporal structures, which have a strong connection with the pontine nuclei, might be involved in this patient's gelastic seizure. CONCLUSION: Except for impaired consciousness, the clinical manifestations did not correspond to the characteristics of orbitofrontal seizure described by the International League Against Epilepsy. Symptomatic laughter in epilepsy that originates from the orbitofrontal lobe is very rare. Intracranial electroencephalographic findings and ictal symptomatology associated with epileptogenesis in this rare case are discussed.

Early seizure propagation from the occipital lobe to medial temporal structures and its surgical implication.

Intracranial EEG documentation of seizure propagation from the occipital lobe to medial temporal structures is relatively rare. We retrospectively analyzed intracranial EEG recorded with electrodes implanted in the medial temporal lobe in patients who underwent occipital lobe surgery. Four patients with occipital lesions, who underwent intracranial EEG monitoring with intracerebral electrodes implanted in the medial temporal lobe prior to occipital lobe surgery, were studied. Subdural electrodes were placed over the occipital lobe and adjacent areas. Intracerebral electrodes were implanted into bilateral hippocampi and the amygdala in three patients, and in the hippocampus and amygdala ipsilateral to the lesion in one. In light of the intracranial EEG findings, the occipital lobe was resected but the medial temporal lobe was spared in all patients. The follow-up period ranged from six to 16 years, and seizure outcome was Engel Class I in all patients. Sixty six seizures were analyzed. The majority of the seizures originated from the occipital lobe. In complex partial seizures, ictal discharges propagated to the medial temporal lobe. No seizures originating from the temporal lobe were documented. In some seizures, the ictal-onset zone could not be identified. In these seizures, very early propagation to the medial temporal lobe was observed. Interictal spikes were recorded in the medial temporal lobe in all cases. Intracranial EEG revealed very early involvement of the medial temporal lobe in some seizures. Seizure control was achieved without resection of the medial temporal structures.

Interhemispheric connection of motor areas in humans.

We attempted to clarify functional interhemispheric connections of motor cortex (MC) by investigating cortico-cortical evoked potentials from human brains in vivo. Three patients with intractable epilepsy who underwent invasive EEG monitoring with subdural electrodes as presurgical evaluation were studied. Electric pulse stimuli were delivered in a bipolar fashion to two adjacent electrodes on and around MC. Cortico-cortical evoked potentials were recorded by averaging electrocorticograms from the contralateral hemisphere. An initial positive triphasic or an initial negative biphasic wave was recorded when the contralateral MCs were stimulated. When the non-MC electrodes were stimulated, no response was recorded. The latencies ranged from 9.2 to 23.8 ms for the initial positive peak, and 25.4 to 39.4 ms for the initial or the second negative peak. The cortico-cortical evoked potentials responses were maximal around the homonymous electrodes with the stimulated electrodes. Our results directly demonstrate the presence of the functional interhemispheric connections originating in MC. The interhemispheric transit time is indicated. The homotopic distribution of the responses indicates that motor coordination of the bilateral bodies is, at least partially, controlled within MC.

Extraoperative functional mapping of motor areas in epileptic patients by high-frequency cortical stimulation.

OBJECT: The aim of this study was to investigate the usefulness of a short train of high-frequency (500 Hz) cortical stimulation to delineate the primary motor cortex (MI), supplementary motor area (SMA), primary somatosensory cortex (SI), supplementary sensory area (SSA), negative motor area (NMA), and supplementary negative motor area (SNMA) in patients with epilepsy who were undergoing functional mapping. METHODS: Seventeen patients were studied, all of whom underwent functional mapping using 50-Hz electrical stimulation. After these clinical evaluations, cortical stimulations with a short train of electrical pulses at 500 Hz were performed through subdural electrodes placed at the MI, SMA, SI, SSA, NMA, and SNMA, which had been identified by 50-Hz stimulation, and surrounding cortical areas, while surface electromyography readings were recorded. RESULTS: Stimulation of the MI elicited motor evoked potentials (MEPs) in contralateral muscles. Stimulation of the SMA also induced MEPs in contralateral muscles but with longer latencies compared with the MI stimulation. Stimulation of the SMA did not elicit MEPs in ipsilateral muscles. Stimulation of the SI, SSA, NMA, and SNMA did not induce MEPs in any muscle. In one patient, MEPs were elicited without seizure induction by 500-Hz stimulation of the electrodes, whereas a 50-Hz stimulation of the same electrodes induced his habitual seizures. CONCLUSIONS: Extraoperative high-frequency stimulation with MEP monitoring is a useful complementary method for cortical mapping without inducing seizure. Stimulation of SMA induces MEPs in contralateral muscles, with longer latencies compared with the stimulation of MI. This finding may be useful for the differentiation between MI and SMA, especially in the foot motor areas.

Posterior cortex epilepsy secondary to ulegyria: is it a surgically remediable syndrome?

PURPOSE: To examine whether surgery is indicated for posterior cortex epilepsy secondary to ulegyria. PATIENTS AND METHODS: Ten patients who underwent surgery for posterior cortex epilepsy with ulegyria and were followed for more than 2 years were included. All patients underwent comprehensive presurgical evaluations. Five patients underwent intracranial electroencephalography (EEG) studies. The posterior cortex including the magnetic resonance imaging (MRI) lesion was resected in all patients. Postoperative follow-up period was 2-12 (mean 6) years. RESULTS: Nine patients had a history of perinatal distress including asphyxia and prolonged labor. Age at seizure onset was 5-11 years, except one patient. Three patients had visual field defects preoperatively. Ulegyria was unilateral in four patients and bilateral but unilateral-predominant in six patients. In most of the cases, the lesions were in the posterior cerebral artery area or the watershed area between middle cerebral and posterior cerebral arteries. In four of five patients who underwent intracranial EEG, seizure onset zones extended outside the lesions. Postoperative seizure outcome was Engel's class I in seven cases, and class III in three cases. Three of four patients whose seizure onset zones were not completely resected achieved class I outcome. Four of six patients with bilateral lesions achieved class I outcome. CONCLUSION: Ulegyria due to perinatal distress is considered to be a major cause of posterior cortex epilepsy. Long-term postoperative seizure outcome is favorable. Resection of MRI lesion is important for seizure relief. Bilateral lesions should not be excluded from surgical indication. The usefulness of intracranial EEG may be limited.

Intracranial EEG findings in patients with lesional lateral temporal lobe epilepsy.

PURPOSE: Intracranial EEG in patients with lesional lateral temporal lobe epilepsy is rarely reported. Therefore, the number of patients with seizures arising independently from ipsilateral mesial structures or contralateral hemisphere has not been clarified. We analyzed the intracranial EEG of cases with localized lesion in the lateral temporal cortex. METHODS: We studied 15 patients who satisfied the following criteria: (1) MRI depicted a lesion less than 4cm in diameter located lateral to the collateral sulcus and at least 3cm posterior to the temporal pole; (2) intracranial EEG with electrodes placed on bilateral temporal lobes captured at least one complex partial seizure; and (3) postoperative follow-up period of 2 years or longer. The mean age of seizure onset was 16.6 years (range, 11-25) and that at surgery was 26.7 years (range, 16-36). RESULTS: A total of 147 complex partial seizures, 51 simple partial seizures, 16 secondarily generalized seizures, and over 80 subclinical seizures were recorded. On the lesional side, many clinical seizures were recorded from the lateral cortex. Independent of the lateral temporal onset seizures, ictal discharges originating from the mesial temporal structures were recorded in 7 of 15 patients (47%). Moreover, onset of ictal discharges from the contralateral temporal lobe was recorded in 7 of 15 patients (47%). Interictal spikes from ipsilateral mesial structures were recorded in all patients. The presence of ipsilateral mesial onset seizures was not associated with hippocampal neuron losses. CONCLUSION: Intracranial EEG analysis revealed that approximately one-half of the patients with structural lesions in the lateral cortex showed independent epileptogenic areas in ipsilateral mesial structures. Although ictal discharges originating from the contralateral temporal lobe were recorded in a half of these patients, this finding does not constitute a contraindication of resective surgery. Interictal spike is not an indicator of whether mesial structures should be resected.

Bilateral symmetric tonic posturing suggesting propagation to the supplementary motor area in a patient with precuneate cortical dysplasia.

We report a patient manifesting seizures with bilateral symmetric tonic posturing, which were markedly reduced after resection of the left precuneus. A 16-year-old man had sudden onset, complex partial seizures with bilateral symmetric tonic posturing since the age of eight years. Magnetic resonance fluid-attenuated inversion-recovery imaging revealed a hyperintense lesion in left precuneus. In almost all focal seizures recorded during an invasive EEG evaluation, ictal onset was detected from the inferomesial aspect of the lesion, but fast paroxysmal discharges from the ipsilateral supplementary motor area (SMA) were observed just before the clinical onset. After surgical excision of the EEG onset zone, including the lesion, seizure frequency was markedly (> 95%) reduced. By the 20th month after surgery, there were only brief nocturnal seizures involving slight elevation of both shoulders and slight abduction of both arms, with preservation of consciousness occurring once every few days. Invasive EEG findings and surgical outcome suggested that the epileptic activity originating from the epileptogenic zone may have propagated to the symptomatogenic zone including mainly the ipsilateral SMA. In summary, we report an interesting case of bilateral symmetric tonic posturing suggesting propagation to the SMA. MRI and invasive EEG confirmed the epileptogenic focus as a precuneate cortical dysplasia lesion.[Published with video sequences].