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Results for “Temporal Lobe Resection”

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PubMed2002

Pre- and postoperative verbal memory in pediatric patients with temporal lobe epilepsy.

Outcome studies concerning memory after pediatric temporal lobe surgery in the treatment of epilepsy are rare and have not yielded consistent results. In the present study, 55 children and adolescents with temporal lobe epilepsy (TLE; 26 left, 29 right, 6-17 years) performed a verbal memory test before and 3 as well as 12 months after different types of temporal lobe resections (anterior lobectomy, amygdalo-hippocampectomy (AH), lesionectomy (LX)). Groups did not significantly differ before surgery. Three months after surgery, the left resected group showed a decline in learning and delayed recall, and performed significantly lower than the right resected group. Recoveries were evident 1 year after surgery. The postoperative memory declines were associated with a left-sided resection and a higher preoperative performance. Comparisons on the different resection types suggest a special risk in patients undergoing a left-sided AH. In summary, our results indicate a functional association of verbal memory functions with the left temporal lobe similar to findings in adult patients. Declines after left-sided temporal resections seem to be reversible at least for part of the children, perhaps due to the greater plasticity of the immature brain.

Adolescent↗

PubMed1999

Wallerian degeneration in the optic radiation after temporal lobectomy demonstrated in vivo with diffusion tensor imaging.

PURPOSE: Diffusion tensor imaging allows the quantitative assessment of the microstructural organization of tracts in vivo (MR tractography). We used the new technique of MR tractography to demonstrate the effects of temporal lobectomy on the optic radiation. METHODS: Spatially normalised maps encoding magnitude of the bias (anisotropy) of diffusion of three patients with temporal lobe resections were compared with spatially normalised diffusion maps of 22 control subjects. All three patients were operated on for the treatment of medically intractable temporal lobe epilepsy and had a normal neurologic examination before surgery. One patient had an amygdalocorticectomy. Two patients had standard en bloc resections, one of whom developed a homonymous hemianopia after surgery. RESULTS: In the patient with hemianopia, a significant reduction of diffusion anisotropy (greater than mean+/-2 SD) consistent with wallerian degeneration was demonstrated in the optic radiation on the side of the temporal lobectomy, extending from the temporal to the occipital lobe. In the other patient with standard en bloc resection but clinically no hemianopia, the optic radiation was only marginally affected. In the third patient (amygdalocorticectomy), the diffusion anisotropy was within the normal range in the expected position of the optic radiation. CONCLUSIONS: Our findings show that MR tractography may be a useful tool to demonstrate wallerian degeneration in the optic radiation after temporal lobectomy in patients with hemianopia. This is the first time that this new method has been applied in postoperative imaging; it enables us to visualise the morphologic correlate of dysfunctional pathways after epilepsy surgery in vivo. The potential for using MR tractography to study other aspects of epilepsy is discussed.

Anisotropy↗

PubMed1984

Distribution of pyramidal cell density and hyperexcitability in the epileptic human hippocampal formation.

Pyramidal cell densities in various regions of the anterior and posterior hippocampal formation were measured from en bloc temporal lobe resections and compared with presurgical stereoelectroencephalography (SEEG) data derived from depth electrodes in 12 patients with temporal lobe epilepsy. These data were compared with cell densities observed in four nonepileptic control patients. Patients who consistently exhibited anterior focal changes in the SEEG accompanying onset of ictus had cell densities that were selectively reduced in the anterior hippocampal formation but normal with respect to controls in the posterior hippocampal formation. Patients who exhibited more regional changes in the SEEG at onset of ictus had reduced cell densities in both the anterior and posterior hippocampal formation. Patients who exhibited focal spike activity in the anterior hippocampal formation as their predominant interictal SEEG pattern also had selectively reduced cell densities in the anterior hippocampal formation, while patients with widespread spiking throughout the hippocampal formation had reduced cell densities both anteriorly and posteriorly. These data support the concept that epileptogenesis occurs in or near those areas of epileptic hippocampus that are most damaged. Hippocampal sclerosis must be viewed as related to adjacent hyperexcitable or epileptogenic neurons and not solely as a passive result of repeated anoxia or ischemia.

Cerebral Cortex↗

PubMed1995

[Surgery for intractable epilepsy--selection and presurgical evaluation].

Success in epilepsy surgery depends upon the exact localization of epileptogenic lesion identified by recordings of scalp and/or intracranial EEG and observation of clinical seizures in addition to the neuroimaging techniques such as CT, MRI, SPECT, PET. Thinking of the postoperative outcome in the literatures regarding epileptic seizures according to surgical procedure, main candidates for surgery are patients with intractable symptomatic localization-related epilepsies. Walker's criteria (1974) are generally agreed as selection criteria of candidate for epilepsy surgery. In our hospital, candidates for temporal lobe resection are selected according to the following criteria: 1) presence of an epileptogenic region presumably within the temporal lobe, 2) appropriate drug treatment for at least 5 years, 3) complex partial seizures more frequently than once a week, 4) adolescent or adult patients over 15 years of age with no persistent psychiatric symptoms, and 5) patients capable of social rehabilitation if recurrent seizures subside. Presurgical evaluation consists of noninvasive and invasive evaluation. Noninvasive evaluation includes neuro-psychological tests including Wada test, neuroimagings, interictal and ictal long-term intensive EEG/CCTV monitoring by the scalp EEG using 10/20 electrode placement as well as sphenoidal electrode to catch at least 3 spontaneous seizures. Invasive evaluation is interictal and ictal long-term intensive EEG/CCTV monitoring by intracranial electrodes for two weeks. The presurgical evaluation is performed by the team composed of neurosurgeon, neurologist, neuropsychiatrist, and neuropediatrician to decide the localization of epileptogenic lesions for resection. Outcome concerning seizure, neuropsychological aspects, and QOL is followed for more than 3 years after operation. Surgery for epilepsy should not be done without strict presurgical evaluation.

Adolescent↗

PubMed2004

Preoperative clinical evaluation, outline of surgical technique and outcome in temporal lobe epilepsy.

Temporal lobe epilepsy (TLE) is the most common type of refractory epilepsy. The mechanisms of epileptogenesis and seizure semiology of the mesial and neocortical temporal lobe epilepsy are discussed. The evaluation and selection of patients for TLE surgery requires team work: the different clinical aspects of neuropsychological evaluation, magnetic resonance and functional imaging (positron emission tomography, single photon emission computed tomography and magnetoenephalography) are reviewed. In our programme of epilepsy surgery at Kuopio University Hospital, Finland, we have performed 230 temporal resections from 1988 until 2002. Preoperative diagnostic EEG-videotelemetry often required intracranial monitoring and it has proved to be safe and efficient. The indications and technique for tailored temporal lobe resection with amygdalohippocampectomy used in our institution, as well as the complications, are described. Our analysis of outcome after temporal lobe surgery included 140 consecutive adult patients between 1988 and 1999; one year after the operation in unilateral TLE the Engel I-II outcome was observed in 68% of the patients. Outcome of surgery improved significantly after introduction of the standardised MR imaging protocol from 1993; 74% of patients with unilateral TLE achieved Engel I-II outcome.

Electroencephalography↗

PubMed2001

Rhythm and melody in children and adolescents after left or right temporal lobectomy.

Rhythm (a pattern of onset times and duration of sounds) and melody (a pattern of sound pitches) were studied in 22 children and adolescents several years after temporal lobectomy for intractable epilepsy. Left and right lobectomy groups discriminated rhythms equally well, but the right lobectomy group was poorer at discriminating melodies. Children and adolescents with right lobectomy, but not those with left temporal lobectomy, had higher melody scores with increasing age. Rhythm but not melody was related to memory for the right lobectomy group. In neither group was melody related to age at onset of non-febrile seizures, time from surgery to music tests, or the linear amount of temporal lobe resection. Pitch and melodic contour show different patterns of lateralization after temporal lobectomy in childhood or adolescence.

Adolescent↗

PubMed2001

Neuropathological findings in a patient with epilepsy and the Parry-Romberg syndrome.

PURPOSE: The Parry-Romberg syndrome is an unusual disorder frequently associated with epilepsy. The origin of this disease, and the cause of epilepsy, are unknown. This study is the first reported case of the Parry-Romberg syndrome, with intractable temporal lobe epilepsy, in which detailed microanatomic analyses have been performed on resected brain tissue obtained after surgical intervention. METHODS: Standard histopathologic methods and correlative light and electron microscopy, combined with immunocytochemical techniques, were used to study in detail the synaptic microorganization of the resected hippocampal formation. RESULTS: After surgery, the patient was seizure free (follow-up period of 4 years and 7 months). The resected temporal lobe showed a variety of dramatic microanatomic alterations (small groups of ectopic cells, neuronal loss, gliosis, and activated microglial cells) in mesial structures, including the entorhinal cortex, subiculum, and dentate gyrus. At the electron-microscopic level, we found that in the dentate gyrus, the number of synapses in the cell-sparse region adjacent to the ectopic mass of neurons was almost twice that found in the molecular and polymorph cell layers, indicating the intrusion of neuritic processes and synapse formation. In addition, the symmetrical axosomatic synapses characteristically found on granule cells, which are likely derived from gamma-aminobutyric acid (GABA)ergic inhibitory basket cells, were not observed. CONCLUSION: The complete seizure relief after surgery suggests that the pacemaker region(s) of seizure activity were within the resected tissue. However, we do not know which of the multiple neuropathologic findings reported here were the primary cause of seizure activity. Nevertheless, the changes found in the dentate gyrus circuitry appear to be among the most important alterations that would lead to epilepsy.

Adult↗

PubMed1993

High-resolution (2.6-mm) PET in partial complex epilepsy associated with mesial temporal sclerosis.

Eleven patients with medically refractory partial seizures underwent positron emission tomography (PET) with a 600-crystal tomograph and fluorine-18 fluorodeoxyglucose. All patients had been selected for temporal lobe resection, and the side of the epileptogenic focus had been demonstrated with electroencephalography (EEG). Only patients in whom structural lesions had been excluded with magnetic resonance (MR) imaging were studied. Ten of 11 patients were found to have temporal cortical hypometabolism on the same side as the focal abnormality that was demonstrated with EEG. In two patients, PET showed hypometabolism in the mesial temporal cortex only. There were no incorrectly lateralizing PET results. MR imaging showed an abnormality in the corresponding temporal lobe in seven patients. In one patient, both PET and MR images were normal. All patients underwent anterior temporal resection, and histologic examination of resected tissue showed mesial temporal sclerosis in all cases.

Adult↗

PubMed2000

Anatomy of optic nerve radiations as assessed by static perimetry and MRI after tailored temporal lobectomy.

AIMS: To determine the course of optic nerve radiations in the temporal lobe, especially their retinotopic organisation and the anterior limit of the Meyer's loop. METHODS: 18 adult patients who had undergone a tailored temporal lobectomy for epilepsy were included in this study between 1994 and 1998. The rostrocaudal extent of the lateral temporal lobe resection assessed intraoperatively by the surgeon and by postoperative MRI was compared with the postoperative visual fields determined by automated static perimetry (ASP). RESULTS: 15 patients (83%) presented a postoperative visual field deficit (VFD) confined to the superior homonymous field contralateral to the side of the resection. All degrees from a minimal upper field loss to a complete quadrantanopia were observed. The VFDs were somewhat stereotyped, predominating along the vertical meridian. The smallest anteroposterior resection resulting in a VFD was limited to 20 mm from the tip of the temporal lobe. A relation was observed between the extent of the lateral resection in front of the second and third convolutions and the occurrence and extent of postoperative VFDs. No patient reported persisting subjective visual impairment. CONCLUSION: The high frequency of postoperative VFDs appears to be due to the greater sensitivity of ASP. The characteristics of the stereotyped VFDs allow new conclusions about the course and retinotopy of optic nerve radiations. The anterior limit of Meyer's loop is likely to be located more rostrally than previously believed.

Adult↗

PubMed1995

Significance of spikes recorded on electrocorticography in nonlesional medial temporal lobe epilepsy.

Whether spikes recorded by intraoperative electrocorticography imply active epileptogenicity has not been adequately addressed. We performed preresection and postresection electrocorticography on 47 patients with nonlesional medial temporal lobe epilepsy who were undergoing surgery for the treatment of medically refractory epilepsy. A standard anteromedial temporal lobectomy was performed on all patients, with no additional resection, regardless of electrocorticographic findings. Patients were divided into two groups: Group I (no seizures or rare seizures) and Group II (recurrent seizures). Recorded spikes were analyzed for distribution and spike discharge rate. On preresection electrocorticography, 83% of Group I and 82% of Group II had spikes in the anterior temporal lobe. The spike discharge rate was equally distributed between high frequency and low frequency for both groups (not significant). Although spikes localized to the posterior temporal neocortex were seen more in Group II (64%) than Group I (39%), this was not a significant difference (p > 0.1). Most of these patients had a low-frequency spike discharge rate. On postresection electrocorticography, 80% of Group I and 75% of Group II had residual spikes. The majority of these had a low-frequency spike discharge rate and were localized to the margin of resection. We found no correlation between residual spikes on preresection and postresection electrocorticography and outcome. These findings do not support the role of intraoperative electrocorticography in guiding mesial temporal lobe resection.

Adolescent↗

PubMed2005

Functional magnetic resonance imaging for assessment of language and memory in clinical practice.

PURPOSE OF REVIEW: There has been considerable interest in the role that functional magnetic resonance imaging (fMRI) may play in the assessment of patients with epilepsy. This review considers recent progress in this field and the current role of fMRI in the preoperative assessment of language and memory function. RECENT FINDINGS: Many studies have compared fMRI with the intracarotid amytal test for establishing language dominance, with most showing over 90% concordance between the two tests. Atypical dominance is greater in patients with left temporal lobe epilepsy and has been shown to be associated with increased epileptic activity. Preoperative fMRI has been used to predict language deficits following left anterior temporal lobe resection. A variety of paradigms have been used to assess memory function, and novel paradigms have demonstrated robust medial temporal lobe activation. Different patterns of encoding activity have been observed between patients with unilateral temporal lobe epilepsy and control individuals. SUMMARY: The application of fMRI paradigms used in cognitive neuroscience to patients with epilepsy is complicated by several factors. Although fMRI is increasingly being used clinically to establish language dominance, further work is required to localize accurately those specific language functions that are most at risk following surgery. Memory paradigms are not yet validated for use in surgical planning, although methodological and technical advances should make this possible in the near future. Further studies looking at the reorganization of language and memory function after surgery are also required.

Epilepsy↗

PubMed2002

Distractibility after unilateral resections from the frontal and anterior cingulate cortex in humans.

The prefrontal and anterior cingulate cortex figure prominently in current models of directed attention. The efficacy of selective attention was studied in a distractibility study carried out with patients who had unilateral surgical excisions from the frontal cortex with or without involvement of the cingulate gyrus, patients with unilateral anterior temporal resections, and normal control subjects. In Task A, participants responded to target stimuli presented at the foveal location in the presence or absence of distracting peripheral stimuli that appeared 200 ms before the target's onset. The presence of a distractor caused a comparable increase in reaction times to targets across all groups. In Task B, a distractor appeared during every trial but it appeared at a new location on 12% of the trials. A comparable transient increase in reaction times was observed in patients with frontal cortical resections that spared the anterior cingulate gyrus, patients with anterior temporal lobe resections, and the normal control group. Thus, lesions restricted to the prefrontal cortex need not impair the ability to attend and respond to a target event in the presence of distraction. Interestingly, no distracting effect was observed during Task B in patients with lesions that invaded the anterior cingulate gyrus, suggesting that this cortical region is involved in responding to or habituating to environmental stimuli.

Adult↗

PubMed1996

Treatment of epilepsy with multiple subpial transections: an acute histologic analysis in human subjects.

Multiple subpial transection (MST) is a new surgical technique for treating seizures that arise from functionally critical cortical areas. It has a reported efficacy comparable to that of standard temporal lobe resections. Although the mechanism through which MST works is unknown, the carefully controlled lesions, placed 5 mm apart at the midlevel of the cortical gyri, could produce fiber damage that would prevent horizontal synchronization and spread of epileptic discharges while allowing normal cortical functions such as those related to movement or speech to be preserved. We studied the acute neuropathological features associated with MST in 8 patients with intractable temporal lobe epilepsy. Transections were made along major temporal gyri just before standard lobectomy was performed. After resection, tissue was processed by conventional histological and immunocytochemical techniques. Macroscopically, subpial transections (STs) were perpendicular to the main gyral axis and had an appropriate spacing. Microscopically, most of the lesions were perpendicular and at midlevel. However, many transections involved the lateral aspects of the small gyri, resulting in oblique or deep STs, some of which reached the gray-white matter junction due to the complex microscopic neocortical architecture, in which small gyri are superimposed on major lobar gyri, and to the variable cortical thickness. Extensive acute pyknosis and tissue edema were also evident adjacent to the transections. These changes were variable and extenDed 1-3 mm laterally as irregular columnar blocks. In the deep lesions, myelin pallor and decreased neurofilament immunoreactivity were observed in the white matter. Based on the distribution of STs and their adjacent parenchymal injury, we conclude that this technique produces block-type lesions that probably disrupt propagation of epileptogenic activity. In most instances, midlevel horizontal fibers are damaged; one third of the cases showed additional deep injury that would sever afferent and efferent axons. Therefore, in addition to horizontal desynchronization, a deafferentation mechanism involving different fiber systems may contribute to the anti-seizure effects of MST. We hypothesize that preservation of cortical function is mediated by cortex remaining in the sulcus and gyral crown and possibly by reorganization of tissue adjacent to transections.

Adult↗

PubMed1984

Right-hemisphere language dominance in right-handed epileptic patients.

Hemispheric language dominance, as determined by intracarotid amobarbital sodium injections, and handedness, as reflected by writing and drawing preference, were evaluated in a select group of patients with intractable seizures who had documented focal epilepsy originating from one temporal lobe. Of the patients with left temporal lobe seizure focus, an unusually high percentage of right-handed patients (4/26 [15%]) had right hemisphere language dominance. Pathologic findings of the resected temporal lobe in these patients revealed microscopic damage (hippocampal sclerosis) of the hippocampus in three of three cases; one patient also had a small hamartoma in the midtemporal gyrus. We hypothesize that crossed dominance resulted from disruption by epileptiform activity during early development of selective areas of the left hemisphere.

Adolescent↗

PubMed1993

Amygdaloid sclerosis in temporal lobe epilepsy.

Hippocampal sclerosis is the sole abnormality found in approximately 65% of all temporal lobe specimens resected for intractable temporal lobe epilepsy. Up to 27% of en bloc temporal lobectomy specimens, however, show no definitive pathological changes. The lateral amygdaloid nucleus from 8 consecutive patients who underwent temporal lobectomy in whom no definitive hippocampal pathology was present and corresponding tissue from 8 consecutive patients with hippocampal sclerosis were subjected to quantitative estimation of neuronal density and astrogliosis. As compared to amygdaloid tissue from autopsy control subjects with no history of neurological disease, both the patient group with and that without hippocampal sclerosis consistently exhibited severe neuronal loss and gliosis with no quantitative differences between the two groups. Blinded clinical review of both groups of patients revealed that the development of hippocampal sclerosis was associated with a history of early brain insult; this history was absent in patients with isolated amygdaloid sclerosis. Neuropsychological testing prior to surgery demonstrated that patients with hippocampal sclerosis displayed a greater degree of memory impairment than did those without hippocampal sclerosis. We conclude that amygdaloid sclerosis occurs in the absence of hippocampal sclerosis, and that these patients form a distinct group with no history of early brain insult and milder memory impairment than that seen in patients afflicted with hippocampal sclerosis.

Adult↗

PubMed1992

Ictal spikes: a marker of specific hippocampal cell loss.

Spontaneous seizures recorded from mesial temporal depth electrodes in the human are commonly manifested by one of two onset patterns: a high frequency discharge or a periodic spike discharge morphologically similar but clearly distinguished from ongoing interictal activity. We categorized medial temporal lobe seizure onset for the presence of periodic ictal spikes at a frequency of less than 2 Hz lasting for more than 5 sec to investigate the relationship of this ictal pattern to anatomical changes in the resected temporal lobe tissue. Fifty-one patients had hippocampal depth electrode recordings of spontaneous seizures, subsequent hippocampal resection, and quantitative cell counts of hippocampal subfields. Thirty-two of these patients had ictal spikes lasting at least 5 sec in more than 50% of their seizures. The presence of ictal spikes was significantly correlated with decreased cells in CA1 only (P = 0.015). The correlation of a common ictal pattern with focal cell loss in the hippocampus suggests that electrophysiological manifestations of seizures provide a clue to the underlying pathological substrate. Ictal spikes may be a cause or result of the cell loss. These observations should be correlated with independent investigations in humans and animal models that reflect the CA1 cell loss associated with temporal lobe epilepsy.

Electroencephalography↗

PubMed1999

Glial cell changes in the white matter in temporal lobe epilepsy.

Temporal lobe gliosis and neuronal loss are pathological hallmarks of complex partial seizures. However, the specificity of glial cell changes is not clear. To assess this we studied surgically resected temporal lobes containing either medial temporal sclerosis (MTS) or temporal lobe epilepsy with tumour (TLET) and compared them with idiopathic epilepsy cases and normal controls. We quantitatively assessed glial cell density and mean nuclear volume in the white matter of various temporal gyri and the deep white matter. There was an increase in mean glial cell nuclear volume in MTS and TLET cases in the white matter of superior temporal gyrus, parahippocampal gyrus and deep white matter but not in the white matter of the middle temporal gyrus. In contrast, the densities of glial cells immunopositive for glial fibrillary acidic protein in the MTS and TLET groups were reduced in all white matter regions when compared with the controls. These changes may indicate that glial cells in the white matter have an active role to play in epilepsy pathogenesis.

Adolescent↗

PubMed1981

Selection of patients with chronic drug-resistant epilepsy for resective surgery: 5 years' experience.

Selection criteria are the key to success in resective surgery for intractable epilepsy. Using such criteria about 50% of patients admitted for assessment are considered unsuitable, half of these for neurophysiological reasons or because there is evidence of more than one area of structural abnormality. Selection for a good result from temporal lobectomy can be judged, both on the proportion of positive pathological lesions in the resected temporal lobes and on a high degree of seizure relief together with a low incidence of side effects. The same holds for other resections. The relationship between these factors is reviewed.

Chronic Disease↗