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PubMedDate not supplied

Quantitative comparison of cell loss and thiopental-induced EEG changes in human epileptic hippocampus.

Thiopental-induced EEG beta activity recorded from mesial and lateral temporal lobe sites was analyzed both visually and by computer in 30 patients with complex partial seizures. All patients later received anterior temporal lobectomy. Volumetric cell densities and percentage of principal cell loss relative to normal controls were determined in several different areas of each resected temporal lobe. The percentage of drug-induced beta activity was then compared with the percentage of cell loss by (a) making precise topographic correlations between induced beta and cell loss, (b) relating the overall degree of left/right beta asymmetry to cell loss averaged over wide regions, and (c) comparing the likelihood of left/right beta asymmetries in patients with and without extreme cell loss. The results obtained were consistently negative and were unaffected by whether EEG data were analyzed by computer or visual inspection. These results indicate that the well-known loss of drug-induced beta activity found in epileptogenic regions is not an indicator of the degree of cell loss or sclerosis. The underlying focal dysfunction measured by EEG beta activity remains unknown, and factors such as focal hypoperfusion, hypometabolism, and the microanatomic features of the cells remaining in the focus should be investigated.

Beta Rhythm↗

PubMed2004

Ictal neocortical slowing in temporal lobe epilepsy.

BACKGROUND: Temporal lobe epilepsy (TLE) may affect brain regions outside the temporal lobe, causing impaired neocortical function during seizures. METHODS: The authors selected 11 consecutive patients with mesial TLE and hippocampal sclerosis who underwent intracranial EEG monitoring and had no seizures during a follow-up period of at least 1 year after temporal lobe resection. Secondarily generalized seizures were excluded, and up to three seizures were analyzed per patient (31 seizures total). Electrode contacts were assigned to one of nine cortical regions based on MRI surface reconstructions. EEG during seizures was analyzed for specific patterns including low-voltage fast (LVF), rhythmic polyspike, spike-wave, irregular slowing, and postictal suppression. RESULTS: Mesial and lateral temporal contacts on the side of seizure onset showed significant increases in ictal patterns such as LVF and polyspike activity, followed by postictal suppression. Bilateral frontal and ipsilateral parietal cortex exhibited large amplitude irregular slow waves during seizures. This frontoparietal slowing persisted into the postictal period. Perirolandic and occipital cortex were relatively spared. These EEG patterns were accompanied by bland staring, minor automatisms, and unresponsiveness or amnesia in the majority of patients studied. CONCLUSIONS: Prominent irregular slowing occurs in bilateral frontal and ipsilateral parietal association cortex during and after temporal lobe seizures. EEG slowing in the frontoparietal association cortex may signify physiologic impairment that contributes to widespread altered cerebral function during partial seizures.

Adolescent↗

PubMed2006

Cognitive functioning following epilepsy surgery.

Temporal lobe resection is the most common surgery for intractable epilepsy because of its proven efficacy in seizure control. However, patients who may benefit from the procedure might be deterred from surgical evaluation due to concerns of postoperative cognitive decline. Recent reports on long-term follow-up indicate that, similar to findings within the year after surgery, cognition remains relatively stable in the years following right temporal resection. The verbal memory decline often observed 1 year after left temporal resection persists over time, yet is mitigated to some extent by good seizure outcome. Although memory decline observed on testing is not typically accompanied by functional decline, a small proportion of patients do experience reductions in occupational or academic status. Recent advances in functional imaging and refinements in preoperative mapping promise better prediction and protection of cognitive functioning. Additionally, results from studies comparing cognitive outcome among different surgical techniques suggest that more restricted resections benefit some patients, whereas more extended resections might be appropriate in a select group of well-defined patients. Preliminary reports on alternate treatments such as vagal nerve stimulation suggest no direct influence on cognition, although improvement in quality of life has been reported. The decision to pursue surgical treatment must balance the potential benefit of seizure control with the potential impact and probability of cognitive decline.

Anterior Temporal Lobectomy↗

PubMed2001

Psychiatric and neuropsychological problems in epilepsy surgery: analysis of 100 cases that underwent surgery.

PURPOSE: For the past 20 years (1978-1997), a series of 100 cases of uncontrolled epilepsy had surgery in our department under the stated standard for surgical indications and were followed up for 2-22 years after surgery. METHODS: We evaluated 70 cases of temporal lobectomy, 20 cases of neocortical focal resection, and 10 cases of corpus callosotomy. RESULTS: Analysis of postoperative seizure control showed that 78 cases were class 1 or 2 (no or rare seizures), 14 cases were class 3 (worthwhile improvement), and eight cases were class 4 (no improvement). As generally accepted, temporal lobectomy was the most effective operative procedure, yielding excellent or good results in 87% of the 70 cases so treated. Among the nine cases in whom various psychiatric symptoms developed after surgery, four cases showed neurotic and five cases psychotic symptoms. Patients with psychosis had delusions of various types as a core symptom, combined with other symptoms such as anxiety, irritability, aggression, and depressive state. In two patients with psychosis who had episodes of delusions in the interictal phase before surgery, the symptoms were extremely resistant. The full IQ score of the Wechsler Adult Intelligence Scale-Revised (WAIS-R) was increased after temporal lobectomy in 75% of the cases (p < 0.01; n = 44). The general MQ score in 31 cases, however, showed a 50:50 split between increase and decrease postoperatively. In correlation with the dominance of language by the Wada test, the general MQ score in the 15 cases of nondominant temporal lobe resection showed a significant increase (p < 0.05); whereas the MQ in the 16 cases of dominant-side operation did not change. CONCLUSIONS: Our new test, in which hippocampal stimulation and supraspan learning are combined, seems to be efficient for estimating the postoperative outcome of memory function.

Adolescent↗

PubMed1998

Intraoperative magnetic resonance imaging with the magnetom open scanner: concepts, neurosurgical indications, and procedures: a preliminary report.

OBJECTIVE: Intraoperative magnetic resonance imaging (MRI) is now available with the General Electric MRI system for dedicated intraoperative use. Alternatively, non-dedicated MRI systems require fewer specific adaptations of instrumentation and surgical techniques. In this report, clinical experiences with such a system are presented. METHODS: All patients were surgically treated in a "twin operating theater," consisting of a conventional operating theater with complete neuronavigation equipment (StealthStation and MKM), which allowed surgery with magnetically incompatible instruments, conventional instrumentation and operating microscope, and a radiofrequency-shielded operating room designed for use with an intraoperative MRI scanner (Magnetom Open; Siemens AG, Erlangen, Germany). The Magnetom Open is a 0.2-T MRI scanner with a resistive magnet and specific adaptations that are necessary to integrate the scanner into the surgical environment. The operating theaters lie close together, and patients can be intraoperatively transported from one room to the other. This retrospective analysis includes 55 patients with cerebral lesions, all of whom were surgically treated between March 1996 and September 1997. RESULTS: Thirty-one patients with supratentorial tumors were surgically treated (with navigational guidance) in the conventional operating room, with intraoperative MRI for resection control. For 5 of these 31 patients, intraoperative resection control revealed significant tumor remnants, which led to further tumor resection guided by the information provided by intraoperative MRI. Intraoperative MRI resection control was performed in 18 transsphenoidal operations. In cases with suspected tumor remnants, the surgeon reexplored the sellar region; additional tumor tissue was removed in three of five cases. Follow-up scans were obtained for all patients 1 week and 2 to 3 months after surgery. For 14 of the 18 patients, the images obtained intraoperatively were comparable to those obtained after 2 to 3 months. Intraoperative MRI was also used for six patients undergoing temporal lobe resections for treatment of pharmacoresistant seizures. For these patients, the extent of neocortical and mesial resection was tailored to fit the preoperative findings of morphological and electrophysiological alterations, as well as intraoperative electrocorticographic findings. CONCLUSION: Intraoperative MRI with the Magnetom Open provides considerable additional information to optimize resection during surgical treatment of supratentorial tumors, pituitary adenomas, and epilepsy. The twin operating theater is a true alternative to a dedicated MRI system. Additional efforts are necessary to improve patient transportation time and instrument guidance within the scanner.

Adolescent↗

PubMed2001

Postictal diffusion-weighted imaging for the localization of focal epileptic areas in temporal lobe epilepsy.

PURPOSE: Diffusion-weighted MR imaging (DWI) is a novel technique to delineate focal areas of cytotoxic edema of various etiologies. We hypothesized that DWI may also detect the epileptogenic region and adjacent areas during the ictal and early postictal periods in patients with temporal lobe epilepsy (TLE). METHODS: We studied patients with intractable TLE (n = 9), due to hippocampal sclerosis (HS, n = 7), left mesial temporal lobe tumor (n = 1), and of unknown etiology (n = 1). Informed consent was obtained before inclusion in the study. All patients with single short seizures were scanned immediately after EEG-documented seizures (between 45 and 150 min); one of two patients in status was scanned 14 h after cessation of seizures. DWI results were analyzed visually and by calculating apparent diffusion coefficient (ADC) maps. RESULTS: We found significant decreases in ADC postictally in one of six patients with TLE due to HS and single short seizures. One patient with an incompletely resected temporal lobe tumor also exhibited ADC abnormalities. One patient in focal status epilepticus revealed a decrease in ADC, and one patient with a continuous aura had no DWI abnormality. CONCLUSIONS: Postictal DWI technique may occasionally help delineate epileptic areas in some patients with TLE. Yield is low in patients with HS and single short seizures: it may be higher in patients with tumor or status epilepticus.

Adolescent↗

PubMedDate not supplied

Focal cortical dysplasia and intractable epilepsy in adults: clinical, EEG, imaging, and surgical features.

PURPOSE: The clinical features of focal cortical dysplasia (FCD) in adults are poorly understood. The purpose of this report is to describe the clinical, electrographic, and neuroimaging characteristics of adults with FCD undergoing surgical resection for intractable epilepsy. METHODS: Case series of 55 patients, aged 17-57 years, with a histopathological diagnosis of FCD. Medical history, neurological examination, non-invasive video-EEG, neuroimaging, and surgical outcome data were analyzed retrospectively. RESULTS: There were 36 patients with temporal, 19 with extra-temporal lobe resections. Mean age at surgery was 29 years. Mean age at epilepsy onset was 10 years. Dual pathology was seen in 56% of patients, with 68% of these having hippocampal sclerosis (HS). Epilepsy risk factors included febrile seizures (16%), head trauma (16%), CNS infections (11%), and perinatal stroke (4%). Interictal EEG showed regional epileptiform activity in 89% of patients. Only 24% were diagnosed with FCD pre-operatively. Of those with dual pathology, only 6% were suspected of having FCD pre-operatively. Of those patients with >12 months follow-up, surgical outcomes were as follows: 65% seizure-free, 19% significant improvement, 16% without significant improvement. CONCLUSIONS: In this series of adult patients with intractable epilepsy and FCD, a significant number have other seizure risk factors, normal neurological examinations and neuroimaging, and regional EEG findings. Dual pathology was common in patients with FCD. FCD should be considered as an etiology of epilepsy even in patients whose evaluation suggests other mechanisms.

Adolescent↗

PubMed2004

[Surgical treatment of epilepsy].

In this article the possibilities, indications, methods and results of surgery in epilepsy are summarized in general with the Hungarian experience emphasized. Surgery may provide effective treatment in about 5-10% of the epileptic population. Surgical solution nowadays became an essential treatment in medial temporal epilepsy, if hippocampal sclerosis or other lesion is present, in therapy resistant lesional extratemporal epilepsies and in catastrophic childhood epilepsies if the epileptic disorder is restricted to one hemisphere (Rasmussen syndrome, hemimegalencephaly, Sturge-Weber disease and posttraumatic or postencephalitic hemispherial epilepsies). The algorithms of the presurgical evaluation and the current methods for study the pacemaker area, forbidden zones, and hemispherial functions are treated. The currently used type and techniques of surgery, such as lesionectomy, temporal lobe resections, hemispherotomy, callosotomy, multiple subpial transsections and their indications are described. The newest surgical approaches, as deep brain stimulation, vagal nerve stimulation, and irradiation techniques are also briefly touched. Lastly, we deal with prognostical factors of the surgical outcome, reasons of surgical failures and complications. In a brief chapter the importance of postsurgical rehabilitation is emphasized.

Algorithms↗

PubMed1997

Is 11C-flumazenil PET superior to 18FDG PET and 123I-iomazenil SPECT in presurgical evaluation of temporal lobe epilepsy?

OBJECTIVE: To determine the contribution of 18FDG PET, 11C-flumazenil PET, and 123I-iomazenil SPECT to the presurgical evaluation of patients with medically intractable complex partial seizures. METHODS: Presurgical evaluation was performed in 23 patients, who were considered candidates for temporal lobe resective surgery (14 females and nine males with a median age of 34 (range 13 to 50) years). The presurgical diagnosis was based on seizure semiology as demonstrated with ictal video recording, ictal and interictal scalp EEG recordings, and MRI. RESULTS: Eighteen patients had convergent findings in clinical semiology, interictal and ictal EEG with scalp and sphenoidal electrodes, and MRI that warranted surgery without depth EEG (DEEG). In five patients with insufficient precision of localisation, DEEG with intracerebral and subdural electrodes was performed. MRI showed abnormalities in 22 out of 23 patients. Of these 22, 18 had mesial temporal sclerosis. This was limited to the mesial temporal lobe in four and more widespread in the temporal lobe in 14 patients. In one patient only enlargement of the temporal horn was found and in three others only white matter lesions were detected. 18FDG PET showed a large area of glucose hypometabolism in the epileptogenic temporal lobe, with an extension outside the temporal lobe in 10 of 23 patients. Only in one of these patients DEEG showed extratemporal abnormalities that were concordant with a significant extratemporal extension of hypometabolism in 18FDG PET. 18FDG PET was compared with the results of scalp EEG: in none of the patients was an anterior temporal ictal onset in scalp EEG related to a maximum hypometabolism in the mesial temporal area. By contrast, the region of abnormality indicated by 11C-flumazenil PET was much more restricted, also when compared with DEEG findings. Extension of abnormality outside the lobe of surgery was seen in only two patients with 11C-flumazenil and was less pronounced compared with the intratemporal abnormality. Both 18FDG PET and 11C-flumazenil PET reliably indicated the epileptogenic temporal lobe. Thus these techniques provide valuable support for the presurgical diagnosis, especially in patients with non-lesional MRI or non-lateralising or localising scalp EEG recordings. In those patients in whom phase 1 presurgical evaluation on the basis of classic methods does not allow a localisation of the epileptogenic area, PET studies may provide valuable information for the strategy of the implantation of intracranial electrodes for DEEG. Previous studies have suggested that 11C-flumazenil binding has a closer spatial relationship with the zone of ictal onset than the area of glucose hypometabolism, but this study suggests rather that the decrease in the 11C-flumazenil binding simply reflects a loss of neurons expressing the benzodiazepine-GABA receptor. 11C-flumazenil PET did not prove to be superior to 18FDG PET. CONCLUSION: In 21 patients sufficient material was obtained at surgery for a pathological examination. In 17 mesial temporal sclerosis, in one an oligodendroglioma grade B, in another a vascular malformation and in two patients no abnormalities were found. Although all 21 patients with pathological abnormality showed hypometabolic zones with 18FDG PET and a decreased uptake in 11C-flumazenil binding, there was no strong correlation between pathological diagnosis and functional abnormal areas in PET. Grading of medial temporal sclerosis according to the Wyler criteria showed no correlation with the degree of hypometabolism in either 18FDG or 11C-flumazenil PET. The interictal 123I-iomazenil SPECT technique was highly inaccurate in localising the lobe of surgery.

Adolescent↗

PubMed2004

Intraoperative diffusion-tensor MR imaging: shifting of white matter tracts during neurosurgical procedures--initial experience.

PURPOSE: To prospectively evaluate the location of white matter tracts with diffusion-tensor imaging (DTI) during neurosurgical procedures. MATERIALS AND METHODS: Ethical committee approval and signed informed consent were obtained. A 1.5-T magnetic resonance imager with an adapted rotating surgical table that is placed in a radiofrequency-shielded operating theater was used for pre- and intraoperative imaging. DTI was performed by applying an echo-planar imaging sequence with six diffusion directions in 38 patients (20 female patients, 18 male patients; age range, 7-77 years; mean age, 45.6 years) who were undergoing surgery (35 craniotomy and three burr hole procedures). Color-encoded maps of fractional anisotropy were generated by depicting white matter tracts. A rigid registration algorithm was used to compare pre- and intraoperative images. RESULTS: Intraoperative DTI was technically feasible in all patients, and no major image distortions occurred in the areas of interest. Pre- and intraoperative color-encoded maps of fractional anisotropy could be registered; these maps depicted marked and highly variable shifting of white matter tracts during neurosurgical procedures. In the 27 patients who underwent brain tumor resection, white matter tract shifting ranged from an inward shift of 8 mm to an outward shift of 15 mm (mean shift +/- standard deviation, outward shift of 2.5 mm +/- 5.8). In 16 (59%) of 27 patients, outward shifting was detected; in eight (30%), inward shifting was detected. In eight patients who underwent temporal lobe resections for drug-resistant epilepsy, shifting was only inward and ranged from 2 to 14 mm (9 mm +/- 3.3). In two of the three patients who underwent burr hole procedures, outward shifting occurred. CONCLUSION: Intraoperative DTI can depict shifting of major white matter tracts that is caused by surgical intervention.

Adolescent↗

PubMed1992

[Temporal lobe epilepsy--psychiatric aspects and surgical treatment].

The prevalences and types of psychiatric disorders connected with temporal lobe epilepsy and surgical treatment hereof are discussed. Studies comparing psychiatric morbidity among surgically treated patients and less selected groups of patients with epilepsy, respectively, are desired. Previous follow-up studies of patients undergoing temporal lobe resection point to a high prevalence of psychiatric disorders pre- and postoperatively, in terms of personality disturbances (especially aggression) and various psychotic disorders. On the basis of older studies, postoperative psychoses are believed to appear in 7-10% of surgically treated patients. New Brain Imaging and neurophysiological techniques permit a more precise focal diagnosis. Thus more selective surgical procedures have been introduced, e.g. resection of the amygdala and hippocampus. Together with an increased awareness of the importance of psycho-social factors and the absence of severe psychiatric disturbances for a good postoperative outcome this means that results of older studies may no longer apply. Studies reflecting present day conditions are needed.

Epilepsy, Temporal Lobe↗

PubMed1998

Waterjet dissection of the brain: experimental and first clinical results. Technical note.

Control of bleeding during dissection is a problem that is still not completely resolved in neurosurgical procedures. To overcome this problem in some settings, the authors, in close collaboration with their institution, developed a new device for blunt dissection of brain tumors that is based on a waterjet technique. This report describes their first experimental and clinical experience with this new method. Numerous cutting experiments were performed in porcine cadaver brains. The best results were obtained using pressures from 4 to 6 bars with a 100-microm tip, which produced very small, precise cuts. Histological evaluation showed no disruption or vacuolization of the surrounding tissue. The authors have used the new device in nine patients (seven with gliomas and two undergoing temporal lobe resections for epilepsy), and no complications have been observed. The waterjet device allowed dissection of the brain tissue while even small exposed vessels were spared injury. The instrument was found to be easy to use. Future investigations will concentrate on adapting this new method to endoscopic surgery and evaluating fluids with low surface tension to avoid foaming and bubbling during open surgery.

Animals↗

PubMed1996

Intractable epilepsy in children.

Although most children with epilepsy have a good prognosis, a small but significant minority have seizures that either do not respond to conventional antiepileptic drugs (AEDs) or have significant adverse reactions to AEDs. Many children may benefit from epilepsy surgery. Surgical treatment of epilepsy is becoming a well-established therapy for infants and young children with severe, medically intractable seizures. As in older children and adults, the presurgical evaluations of possible surgical candidates typically consist of a detailed history, neurologic and neuropsychologic examination, and anatomic and functional neuroimaging. The "gold standard" test, however, is the recording of ictal events by using simultaneous EEG and videomonitoring. Although temporal lobe resection is the most commonly performed surgery in older children and adults, nontemporal lobe resection, corpus callosotomy, and hemispherectomy are commonly performed in younger children. Efficacy of surgery in children compares favorably with results from adult patients. In addition, because the immature brain is more plastic than the mature brain, recovery of function is often greater after surgery in children than in adults. Early surgery in children with intractable epilepsy is recommended.

Adult↗

PubMedDate not supplied

Lack of pathologic changes in human temporal lobes after transcranial magnetic stimulation.

Most animal studies have failed to demonstrate pathologic changes in the brain after transcranial magnetic stimulation (TMS). Nevertheless, vacuolar lesions in the cortex of rats after TMS have been reported. We report the first histopathologic studies of human brains after TMS in 2 patients with epilepsy who underwent temporal lobectomies. They had been involved in a study to determine the speech-dominant hemisphere by TMS and had received approximately 2,000 stimuli centered over the resected temporal lobe. Histologic study of the surgical specimens did not show any lesions attributable to TMS in these 2 patients.

Adult↗

PubMed1996

A proposed modification of the Wada test for presurgical assessment in temporal lobe epilepsy.

We report experience with a modification of the Wada test used before temporal lobe resection in patients with drug-resistant epilepsy. Our procedure consists of injection of amytal via a microcatheter into the anterior choroidal artery or the P2 segment of the posterior cerebral artery and simultaneous presentation of verbal and figural memory test material before, during and after the injection. Pros and cons of the modification and inherent shortcomings of the amytal test are discussed on the basis of the results in ten patients.

Adolescent↗

PubMedDate not supplied

Nuclear magnetic resonance imaging, a new approach to the investigation of refractory temporal lobe epilepsy.

Nuclear magnetic resonance is a noninvasive technique of imaging the brain using signals produced by magnetic fields and radiowaves. Sixteen patients with refractory temporal lobe epilepsy (TLE) had magnetic resonance imaging (MRI) during investigation for possible surgical management. These images plus those of 10 normal controls, were interpreted blind and the results from the TLE patients compared to the EEG and computerized tomographic (CT) scan findings. Fourteen patients compared with one normal control had one or more of the following: small temporal lobe, small mesial temporal structures, small hemisphere, and focal mesial temporal prolonged spin-spin relaxation time. These findings correlated with the electrographically determined seizure focus in 11 patients. Enlarged or asymmetrical temporal horns were seen with equal frequency in patients and controls and did not correlate with the seizure focus. CT scans were less likely to show these changes than MRI. Correlation of the MRI changes with histopathology of resected temporal lobes was poor. MRI reveals structural and possibly functional alterations which may aid in the localization of the seizure focus in the temporal lobes of patients with refractory complex partial seizures.

Adolescent↗

PubMed2005

Cerebral perfusion changes in mesial temporal lobe epilepsy: SPM analysis of ictal and interictal SPECT.

We examined cerebral perfusion changes in mesial temporal lobe epilepsy (mTLE) by the statistical parametric mapping of brain single photon emission computed tomography (SPECT) images of 38 mTLE patients and 19 normal controls. Ictal and interictal SPECTs were compared with control SPECTs by independent t test, and ictal and interictal SPECTs by paired t test. We evaluated the number of heterotopic neurons in temporal lobe white matter, white matter changes of the anterior temporal lobe (WCAT) and ictal hyperperfusion of the temporal stem (IHTS). Left mTLE showed interictal hypoperfusion in the ipsilateral hippocampus, bilateral thalami, and paracentral lobules. Right mTLE showed hypoperfusion in bilateral hippocampi, contralateral insula, bilateral thalami, and paracentral lobules. Both mTLEs showed ictal hyperperfusion in bilateral temporal lobes with ipsilateral predominance, and in the anterior frontal white matter bilaterally. By paired t test, ictal hyperperfusion was found in the ipsilateral temporal lobe, temporal stem, hippocampus, thalamus, putamen, insula, and bilateral precentral gyri, whereas ictal hypoperfusion was found in bilateral frontal poles and middle frontal gyri. Fifteen patients showed WCAT and 19 showed IHTS, a weak correlation was observed between WCAT and IHTS (r = 0.377, P = 0.02). WCAT was found to correlate with an early seizure onset age. In 35 patients, heterotopic neurons were found in the white matter of the resected temporal lobe, but the number of heterotopic neurons did not correlate with WCAT or IHTS. In summary, the cerebral perfusion patterns of mTLE suggest interictal hypofunction and ictal activation of the cortico-thalamo-hippocampal-insular network and ictal hypoperfusion of the anterior frontal cortex.

Adolescent↗

PubMed1999

Repetitive transcranial magnetic stimulation of the dominant hemisphere can disrupt visual naming in temporal lobe epilepsy patients.

We used repetitive transcranial magnetic stimulation (rTMS) to study visual naming in 14 patients with temporal lobe epilepsy. Ten had left hemisphere language by Wada testing and all experienced speech arrest with rTMS of the motor speech area in the left frontal lobe. One left-hander had speech arrest with stimulation of sites on both sides. Subjects were asked to name pictures or read words presented on a computer monitor. rTMS was delivered on half of the trials. Stimulation sites were the motor speech area in the left frontal lobe, the mirror site on the right, and the left and right mid superior and posterior temporal lobes. rTMS at left hemisphere sites caused more naming errors than did right hemisphere rTMS. All individual subjects, except two who had temporal lobe resections and the one with bilateral speech arrest, produced more naming errors with rTMS of left hemisphere sites. There was no significant effect on word reading. rTMS at the left hemisphere and right frontal sites produced reductions in reaction time for picture naming, but not for word reading. This was observed for both correct and incorrect responses. This study shows that left hemisphere rTMS can disrupt visual naming selectively.

Adult↗