Epilepsia, 39(4):389-398, 1998 Lippincott-Raven Publishers, Philadelphia 0 International League Against Epilepsy Selective Amobarbital Test for the Determination of Language Function in Patients with Epilepsy with Frontal and Posterior Temporal Brain Lesions Marketa Hajek, *Anton Valavanis, TYasuhiro Yonekawa, Regula Schiess, $Alfred Buck, and Heinz Gregor Wieser Departments of Neurology, *Neuroradiology, ?Neurosurgery, and $Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland Summary: Purpose: Selective amobarbital tests with selective temporary inactivation of the left frontal operculum and/or the left parietotemporal cortex were performed in 5 patients with left-hemispheric epileptogenic lesions in or adjacent to classical Broca's and/or Wemicke's area. The aim was to assess language functions in these brain regions before surgery, to tailor the surgery according to the individual functional importance of these brain regions, and to predict postoperative outcome. Methods: Amobarbital was injected by transfemoral selective catheterization of the arteries supplying the target areas. Along with neuropsychological and neurological testing during the amobarbital procedure, EEG recordings were performed in all patients, and [99"Tc]HMPAO-single photon emission computed tomography (SPECT) in 2 patients. Results: After the amobarbital injection into the left frontal opercular region, there was no recognizable language dysfunction in 3 patients. In these 3 patients, the lesions in or adjacent to the frontal operculum were completely resected without postoperative language impairment. In the remaining 2 patients, temporary language impairment after the amobarbital injection into the left frontoopercular and Wemicke' s region, respectively, suggested language functions in these areas. Surgery was restricted to the left mesiotemporal lobe in 1 patient. In the other patient, the tumor infiltrating the frontal operculum was restrictively resected. Postoperatively, the f i s t patient had no language impairment, but the latter had transient global aphasia, from which she recovered. Conclusions: Selective temporary amobarbital inactivation of brain regions that may be associated with language has clearly indicated the presence or absence of language functions in these regions. The test contributed substantially to planning of the surgical approach in each patient. The predictive value of the amobarbital test was demonstrated by the postoperative outcome. Key Words: Language representation-Selective amobarbital memory test-Selective amobarbital language test-Presurgical epilepsy e~aluation-[~~"Tc]HMPAO single photon emission computed tomography. The intracarotid amobarbital procedure (IAP, Wada test) with anesthesia of one hemisphere is traditionally used to determine the laterality of language dominance (1) and to assess memory functions in candidates for epilepsy surgery (2). In Zurich, the inauguration of the selective amygdalohippocampectomy (AHE) (3) led to the search for new strategies to predict postoperative memory deficits. The aim was to modify the Wada test in such a way that (a) the amobarbital was delivered exclusively but thoroughly to the mesiobasal temporal lobe (TL) structures considered for surgery, and that (b) the extratemporal ipsilateral brain areas remained unaffected by the drug. The selective TL amobarbital memory (STLAM) test, used in Zurich since 1986, consists either of the anterior procedure with injection of amobarbital into (a) the anterior choroidal artery (acha); or (b) into the acha, the posterior communicating artery, and the ophthalmic artery after temporary balloon occlusion of the internal carotid artery distal to the origin of the acha (4-6); or of the posterior approach with injection of amobarbital into the P2 segment of the posterior cerebral artery (5-8). To date, 64 patients have received a STLAM test. In 41 patients, the amobarbital was injected directly into the acha; in 18 patients the test was performed using the balloon occlusion technique, and in 5 patients (in 3 of them in addition to the anterior STLAM)the posterior approach was chosen. In all these patients, the amobarbital procedure was performed ipsilaterally to the epileptogenic focus, and only 2 patients underwent bilateral STLAMtest. There were no compli- Accepted December 1, 1997. Address correspondence and reprint requests to Dr. M. Hajek at Neurological Department, University Hospital Zurich, Frauenklinikstr. 26, CH-8091 Zurich, Switzerland. 389 cations, and the predictive value for postoperative memory functions in patients with mesiobasal TLE was good (6). The long-standing experience with the selective memory Wada test encouraged us to apply selective amobarbital strategies in patients with neocortical epileptogenic lesions affecting the classical language areas, i.e., Broca's and Wernicke's language area of the left hemisphere. Noninvasive neuropsychological methods (tachistoscopic lexical decision task) demonstrated unclear or left hemispheric language dominance in these patients. The rationale for the selective strategy instead of a global hemispheric strategy was that in presence of an epileptogenic lesion the language function might have shifted in the same hemisphere from the classic language areas to other remote ones. Because hemispheric inactivation would not be able to show this, a spatially restricted and topographically precise delivery of the amobarbital to the target structures was intended. The frontoopercular region was temporarily inactivated by an amobarbital injection into the left frontoopercular branch of the middle cerebral artery; the temporal parietal region was inactivated by application of the barbiturate into the ramus temporalis superior of the left middle cerebral artery. To date, we have performed the selective extratemporal amobarbital test in 4 patients with left hemispheric epileptogenic foci involving the frontal operculum and in 1 patient with a presumably epileptogenic lesion in the left temporoposterior neocortex. We report our f i s t results of this newly developed amobarbital language test. The clinical course of the patients, the role and procedures of selective amobarbital testing, the surgery performed, and the postoperative outcome are described. PATIENTS AND METHODS Patient 1 Since age 6 months, patient 1, a 15-year-old lefthanded girl had had epilepsy with complex partial seizures (CPS) and tonic seizures with tonic-clonic convulsions. Magnetic resonance imaging (MRI) showed cortical dysplasia of the left superior frontal gyrus. [* 8 F ] F l u ~ r ~ d e ~ ~ x y g l ~ ~ ~ ~ e -emission p o s i t r otomogran phy (["FIFDG-PET]) showed focal left frontobasal hypometabolism. As shown with invasive EEG monitoring using nine subdural strips and two bilateral four-contactforamen ovale (FO) electrodes, the CPS originated in the left frontopolar cortex. The generalized tonic-clonic seizures (GTCS) had onset with bilateral synchronous spike waves. The left frontal resection was tailored by intraoperative electrocorticography (ECoG) with recording of one seizure, which yielded, in addition to confirmation of the frontoorbital onset zone, a second epileptogenic region in the inferofrontal gyrus situated near the frontal operculum. The epileptogenic and the lesional zones Epilepsia, Vol. 39, No. 4, 1998 could be resected, since in this patient selective amobarbital inactivation of the left frontal opercular area had no detectable effect on language function. The histopathological findings showed abnormal migration with nodular cortical heterotopias, focal cortical dysplasia, and gyral synechy. The surgery caused no additional neurological or neuropsychological deficits and the girl was completely seizure-free for the entire 23-month followup period. Patient 2 Patient 2, a 28-year-old right-handed female had had CPS since age 6 years. MRI showed multiple cortical and subcortical parenchymal ischemic lesions in the left anterior middle temporal gyrus and in the ternporoposterior cortex. [18F]FDG-PETdisclosed no signs of focal hypometabolism. Proton magnetic resonance spectroscopy (['HIMRS) with volume of interest (VOI) in the left hippocampus indicated disturbed glial metabolism with slightly increased inositol and increased glutamate and its derivates (Glx). The seizures recorded with FO electrodes showed seizure onset in the mesiobasal TL structures with strong involvement of the temporolateral neocortex. Due to transient aphasia immediately after the amobarbital inactivation of the sensory language area (Table l), surgery was restricted to the mesiobasal TL structures, leaving the lesion untouched. The histopathological findings showed gliosis. Postoperatively, the patient was completely seizure-free for the 43-month follow-up period and had no language deficits but did have moderate impairment of verbal memory. Patient 3 At age 27 years, the patient, a 29-year-old righthanded woman, had presented with CPS with epigastric aura, subjective weakness of the right arm associated with stiffness of the right hand, and vegetative signs. MRI showed a lesion in the left frontal operculum (Fig. 1). Selective amobarbital inactivation of the frontal opercular area had no detectable effect on language functions. Therefore, the tumor was completely resected. There was no postoperative language impairment. The histopathological findings showed a ganglioglioma of World Health Organization category 1 (WHO I). The patient has been completely seizure-free without neurological deficits for the 55-month follow-up period. Patient 4 Patient 4, a 30-year-old left-handed man, had had an unremarkable history until age 30 years. Occurrence of secondarily generalized seizures led to a neurological evaluation with MRI findings of a tumor in the left inferoposterior frontal gyrus (Fig. 1). The EEG was normal. Tachistoscopically treated language dominance was unclear. Fortunately, in this patient, selective amobarbital inactivation of both the motor and the sensory lan- 15281167, 1998, 4, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/j.1528-1157.1998.tb01391.x, Wiley Online Library on [11/04/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License M. HAJEK ET AL. 390 TABLE 1. Assessment of memory, frontal functions, and language Patientlage(yr)lsex ~~ Parameter 1/15/F Tachistoscopically Unclear tested language dominance Neuropsychological Preoperative tests R4VLT 210 Recall 313 RVDLT ND Recall ND Rey CF Test ND Verbal Fluency 11512 Test" Figural Fluency 31111 Ted Weigl-type ND sorting test, two-group test Stroop Color-Word ND Test' AAT No deficits ~ 21281~ Unclear Preoperative ~~ ~ ~ Left hemispheric Postoperative Preoperative 1510 aio 1210 1310 1310 1110 191014 310 1010 1010 910 411116 301010 Left hemispheric Postoperative Preoperative Postoperative Preoperative 610 1610 l9lOI2 661011 I a1012 510 410 3011 No deficits 1510 1310 1510 1410 1410 1310 1010 1010 2a1010 ND 1010 201010 291010 241010 301010 241012 231010 40/010 ND 310 510 510 410 ND 2410 2110 2711 1711 3611 2911 2610 No deficits No deficits No deficits No deficits No deficits Oligophrenia, Slight Impaired frontal impairment verbal dysfunction of frontal memory functions Social status Special schooling for mentally retarded No change aio 1310 1010 Postoperative 1010 1110 1010 910 1010 231010 Results 1110 1010 5/30/F 4130/M Right (?) hemispheric 1510 1310 1210 1110 1510 191010 Housewife ~ 3129IF 1110 Slight Slight Normal Normal impairment impairment of right of left frontal frontal functions functions Fully No change Auxiliary Training for employed worker office as work technician ND - Naming, 89; Naming comprehension, difficulties 91; Token Test, 94 Naming Discrete difficulties naming apparent in difficulties spontaneous speech Disability pension Fully employed as nurse RAVLT, Rey Auditory Verbal Learning Test ( 1 1 ) ; RVDLT, Rey Visual Design Learning Test (12); CF, Complex Figure (12); AAT, Aachener Aphasie Test (16). The numbers separated by a slash designate comctlincorrect answers, numbers separated by two slashes designate correctlrule hreaktrepetition, Patient 1 did not undergo any neuropsychological testing. This mentally retarded girl was carefully examined postoperatively by 2 neurologists(H.G.W. and M.H.), who noted overall improvement in her mental and cognitive abilities. a From Rey (12). bFrom Pemt (13). From Regard et al. (14). guage areas did not cause any language deficit; therefore, the tumor (astrocytoma WHO 11) was removed radically. The patient was seizure-free during the 20-month followup period with no language or neurological deficits. Patient 5 At age 24 years, a 30-year-old right-handed woman had presented with simple partial seizures (SPS) with an olfactory aura and short lasting CPS. The diagnostic procedures showed a tumor (astrocytoma WHO 11) in the left insular region, which was radically removed. Postoperatively, the patient was seizure-free with no postoperative deficit for 30 months. Recurrence of tumor infiltrating the left frontal operculum, the frontal pole, the frontobasal regions, as well as the insula and the mesiobasal temporal lobe structures, required reoperation. Selective amobarbital inactivation of the opercular region caused transient aphasia. Therefore, tumor resection was limited to the temporal lobe, with preservation of the frontal lobe to avoid postoperative language deficits. Despite the limited resection, the patient had transient global aphasia postoperatively. The aphasia diminished in the 12-month follow-up period, with persistence of some anomic disturbance. During the 12 months, the patient experienced two focal sensory Jacksonian seizures. Results of the pre- and the postoperative neuropsychological testing and the social status of all patients are shown in Table 1. Amobarbital test procedure Amobarbital application was performed according to our sTLAMprocedure (4-6). In the first step, the arteries supplying the target brain areas were identified by a diagnostic angiogram of the internal carotid arteries (percutaneous transfemoral catheterization technique). The arteries into which the amobarbital was to be injected were then selectively catheterized and visualized by contrast medium (Fig. 2). Finally, with the catheter tip remaining in the same position as during the selective angiogram, the amobarbital was injected. Immediately after the injection, the patient was tested for focal motor deficits, visual field defect, and sensory neurological deficits. Language abilities were assessed by testing for naming, comprehension, reading, and word repetition. The test procedure was monitQred by video; EEG was performed simultaneously with scalp electrode recordings accordEpilepsia, Vol. 39,No.4, 1998 15281167, 1998, 4, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/j.1528-1157.1998.tb01391.x, Wiley Online Library on [11/04/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License 391 SELECTIVE AMOBARBITAL LANGUAGE TEST FIG. 1. Patients 3 and 4. Preoperative (preop) and postoperative (postop) magnetic resonance imaging (MRI) scans showing the tumor located in the left frontal operculum and the extent of the resection. Right: Patient 5. Postoperative MRI shows the only partially removed frontotemporal tumor. Histology: Patient 3, ganglioglioma World Health Organization category I (WHO I); patients 4 and 5, astrocyloma WHO II. 15281167, 1998, 4, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/j.1528-1157.1998.tb01391.x, Wiley Online Library on [11/04/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License FIG. 2. Angiograms of our 5 patients showing the left internal carotid artery and/or its selectively filled branches. Position of the catheter tip is indicated by an arrow. Patient 7. Anteroposterior (AP) view (top left) of internal carotid artery and AP (right) and lateral (bottom) views of the selectively filled anterior and middle cerebral arteries. Patient 2. Lateral view of the internal carotid artery with its branches (top right). Selectively filled anterior choroidal artery and ramus temporalis superior of the middle cerebral artery (bottom right); Patients 3 and 5.Lateral view of the internal carotid artery angiogram (left) and the frontoopercular branch (right). Patient 4. Lateral view of the internal carotid artery (middle), the frontoopercular artery (left), and the ramus temporalis superior of the middle cerebral artery (right). 15281167, 1998, 4, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/j.1528-1157.1998.tb01391.x, Wiley Online Library on [11/04/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License 15281167, 1998, 4, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/j.1528-1157.1998.tb01391.x, Wiley Online Library on [11/04/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License d ing to the International 10/20 System (Fig. 3). In patient 2, in addition to the scalp EEG, the EEG of the mesiobasal TL structures was recorded with bilateral fourcontact FO electrodes. In patients 1, 3, and 5 the lefthemispheric opercular region was temporarily inactivated by injection of the amobarbital into the left frontoopercular branch of the middle cerebral artery. In patients 2 and 4, two different selective amobarbital tests were performed. In patient 2, in addition to selective inactivation of the presumed posterior sensory language region with injection of amobarbital into the ramus temporalis superior of the left middle cerebral artery, memory functions were evaluated by sTLAM with injection of amobarbital into the left acha (4-6). In patient 4, the first selective amobarbital test was aimed at inactivation of the presumed frontal motor language area. The second test was aimed at inactivation of the posterior temporoparietal language region. Because the effect of amobarbital lasts -6-8 min (17), an interval of 30 min between the two injections ensured no interference between performance of the two procedures. The second amobarbital procedure was started after the patient recovered completely and after return of the patient’s EEG to baseline. In patients 1 and 2, [99m]technetium-hexamethy1propylene-aminoxime single photon emission tomography ([99mTc]HMPAO-SPECT)was performed 1 h after completion of the neuropsychologicaltest with a rotating gamma camera (Picker Prism 3000, Bedford Heights, OH, U.S.A.; 120 projections, high-sensitivity, parallelbeam collimator, 64 x 64 matrix) (Table 2). The [99mTc]HMPA0 was coinjected with the amobarbital (intraarterially); therefore, the HMPAO distribution corresponded to the brain regions irrigated by the amobarbital (Fig. 4). In patient 2, who underwent two amobarbital procedures, the [99mTc]HMPA0injection was combined with the amobarbital application into the left acha to visualize amobarbital distribution in the mesiobasal TL regions. Selective extratemporal Wada test results The IAP with selective inactivation of the frontoopercular and the parietotemporal brain regions proved effective in all our patients. Selective amobarbital inactivation of the left-hemispheric frontoopercular region produced no language deficits in patients 1, 3, and 4. Surgical resection of the left frontooperculum or adjacent brain regions left these patients with unimpaired lan- TABLE 2. Details of amobarbital procedure in 5 patients Patient injected artery (amobarbital) Dosage of amobarbital (mg) Motor deficits Neuropsychology 1 Left anterior and middle cerebral arteries 100 Right hemiparesis No language impairment 2 Left anterior choroidal artery 65 Slight paresis of the right arm No memory decline Ramus temporalis superior of the left middle cerebral artery Left frontoopercular branch Left frontoopercular branch Ramus temporalis superior of the left middle cerebral artery Left frontoopercular branch 65 Right hemianopsia Language impairment 110 40 Paresis of the right arm No deficits 40 Right hemiparesis No language impairment No language impairment No language impairment 3 4 5 80 No deficits Global aphasia EEG changes after amobarbital injection 7 s postinjectionpseudorhythmic sharp waves for 13 s with left frontal accentuation, then bifrontal delta waves for 13 s, followed by suppression burst panern lasting 160 s Questionable slowing in left FO electrode for -20 s after the injection; 64 s postinject-occurrence of 1-1.5/s sharp waves in the left FO electrode ,” without changes in EEG activity in right FO or in surface electrodes ’ 100 s postinjection-l.5-3/~ sharp waves in the left FO electrode with no other EEG changes No changes HMPAO-SPECT Regional tracer distribution left frontal Regional tracer distribution of the left mesiobasal TL structures ND No changes ND 7 s postinjection-left ND hemispheric delta waves with a duration of 56 s No changes ND SPECT, single photon emission computed tomography; FO, foramen ovale (10). Epilepsia, Vol. 39, No. 4, 1998 15281167, 1998, 4, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/j.1528-1157.1998.tb01391.x, Wiley Online Library on [11/04/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License 395 SELECTIVE AMOBARBITAL LANGUAGE TEST FIG. 4 . T r a n s v e r s e sections of [g8mTc]HMPAO-singlephoton emission computed tomography of patient 1 (with corresponding magnetic resonance imaging slices) showing HMPAO distribution in the left frontal lobe after simultaneous intraarterial coinjection of amobarbital and of 5 MBq [QQmT~]HMPAO into the left anterior and middle cerebral arteries. guage functions, demonstrating the reliability of the amobarbital procedure. Inactivation of the posterotemporoparietal region in patient 2 caused naming, comprehension, and word-repetition deficits. Therefore, in this patient, the epileptogenic area in the mesiobasal TL structures was removed, since the risk of postoperative language deficits that might have resulted from a temporolateral cortical resection was considered too high. Postoperatively, patient 2 did not develop language deficit and was seizure-free. Temporary amobarbital inactivation of the left frontooperculum in patient 5 resulted in transient global aphasia. Therefore, the frontoopercular tumor was partially resected. Despite the limited tumor resection, patient 5 developed global aphasia immediately after surgery. Except for naming difficulties, the aphasia in patient 5 resolved in the postoperative course. The amobarbital procedure is described in further detail in Table 2. DISCUSSION In the traditional IAP, the effect of the temporary anesthesia is routinely validated by confirmatory tests such as testing for the presence of neurological deficits, monitoring of EEG changes (18-20), and more recently, by SPECT (21-23). Despite the rather small target brain areas perfused by the amobarbital in our patients, the proper temporary inactivation could be demonstrated by at least one concomitant test performed during the procedure. Of seven tests performed in our 5 patients, the drug caused temporary neurological deficits in five, and induced EEG changes in four procedures (Table 2 and Fig. 3). The sharp wave activation in patient 2, which occurred >1 min after injection of the drug into the left acha, must be interpreted with caution, however. Amobarbital-induced EEG responses usually occur 6-12 s after drug application, substantially earlier than the sharp wave activation observed in patient 2 in the course of STLAM (Table 2) (18,20,24). Therefore, proper inactivation of mesial TL structures in patient 2 and the predictive value of the memory test is questionable. Indeed, Epilepsia, Vol. 39, No. 4, 1998 patient 2 displayed a decline in verbal memory functions after AHE, which contradicts the preoperative finding of intact memory during the IAP. The results of subsequently performed test with amobarbital injection into Wernicke's area were valid. The HMPAO distribution overlapped exactly the brain region perfused by the amobarbital (Fig. 4) in patients 1 and 2. Since 1994, [99"Tc]HMPAO- or [99"Tc]ethylcysteinate-dimer (ECD)-SPECT has been routinely included in our STLAM test protocol and proved to be worthwhile for validation of amobarbital delivery to the mesiobasal TL structures (6). The confirmatory SPECT evidence is of particular importance, because former [99mTc]HMPA0 studies performed after conventional IAP indicated incomplete hemispherical barbiturate perfusion with considerable intraindividual variation (21,22). In particular, the mesiobasal TL structures showed inconsistent barbiturate perfusion, varying between 72 and 18% after the IAP. Therefore, Coubes et al. (21) and Jeffery et al. (22) emphasized the need for caution in the use of the IAP to predict neuropsychological outcome after removal of mesiobasal TL structures. An alternative approach to study language representation is preoperative (25) or intraoperative (26) electrical cortical stimulation. However, despite their high reliability, these methods have several limitations. Whereas the presurgical Wada test contributes to the decision to recommend epilepsy surgery, intraoperative cortical mapping can be applied only in patients for whom a decision for surgical intervention has already been made. Moreover, the latter method is limited to highly cooperative patients who can tolerate brain surgery without general anesthesia. Our results indicate that selective temporary inactivation of brain regions, which may be associated with language functions, can be safely and effectively performed. In our 5 patients, the functions of the irrigated target areas could be clearly determined and the effect of the amobarbital was confirmed in 4 of the 5 patients (80%) by at least one concomitant test performed during the 15281167, 1998, 4, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/j.1528-1157.1998.tb01391.x, Wiley Online Library on [11/04/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License M.HAJEK ET AL. 396 procedure. In 3 patients, the selective amobarbital test with inactivation of the frontal operculum suggested no language function of this classic motor language area and thus allowed radical surgery without risk of postoperative language impairment. In patient 5, the fibrillary astrocytoma invading Broca’s region was not removed completely because of the amobarbital-verified language functions present in that brain region. Despite the limited resection, patient 5 had a transient complete aphasia postoperatively. Because language function improved postoperatively, the global aphasia in patient 5 might have been caused at least to some degree by postoperative edema. Without the preoperatively acquired knowledge of the left frontal language representation in patient 5 , a more radical tumor resection would probably have caused permanent and severe language deficits. The Wernicke’s language region remained surgically untouched in patient 2, whose lesion was in the temporoposterior neocortex. Fortunately, removal of the epileptogenic zone located in the mesiobasal TL structures led to complete relief of seizures. Because of the small number of patients in our study, our results with regard to selective amobarbital inactivation of presumed language areas are preliminary. Despite the favorable results in our patients, caution must be used in administering the selective amobarbital tests because they carry all potential risks of an invasive procedure. Therefore, use of these procedures should be restricted to a highly selected group of patients. The complication rate in the conventional IAP is -0-5% (27). The selective posterior TL amobarbital procedure has been associated with such serious complications (8) that it has been discontinued at some epilepsy centers (28). Although no complications resulted from the posterior TL amobarbital procedure in our center, indication for its use is restricted in our institution as well. 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