The role of presurgical EEG parameters and of reoperation for seizure outcome in temporal lobe epilepsy.

PURPOSE: After surgery for intractable mesiotemporal lobe epilepsy (mTLE) seizures recur in 30-40%. One predictor for seizure recurrence is the distribution of seizure onset and interictal epileptiform discharges (IED). Our study focused on lateralization and extent of epileptiform activity regarding postoperative seizure persistence and the effect of reoperation. METHODS: This study comprises 426 consecutive patients operated for intractable mTLE. Impact of preoperative seizure onset and IED on the persistence of seizures and results of reoperation were analyzed. RESULTS: One year after surgery, 27% of patients with mTLE experienced persistent seizures (Engel II-IV). Preoperative bilateral seizure onset in EEG was predictive for postoperative seizure recurrence (Engel II-IV: 64%). Seizure foci and IED exceeding the temporal lobe in the ipsilateral hemisphere were not found to be associated with worse seizure outcome (Engel I: 72% and 75%) compared to patients with seizure foci confined to the ipsilateral temporal lobe (Engel I: 75% and 76%). Moreover, IED exceeding the affected temporal lobe in the ipsilateral hemisphere or even bilateral IED did not negatively affect seizure freedom if seizure onset was strictly limited to the affected temporal lobe (Engel I: 85% and 65%, respectively). 60% of patients reoperated in the ipsilateral temporal lobe for persistent seizures became seizure free. CONCLUSIONS: Preoperative bilateral ictal foci are a negative predictor for seizure outcome. Contrarily, IED exceeding the affected temporal lobe in the ipsilateral hemisphere or even bilateral IED had favorable seizure outcome if seizure onset is strictly limited to the affected temporal lobe. Reoperation for seizure persistence constitutes a promising therapeutic option.

A realistic multimodal modeling approach for the evaluation of distributed source analysis: application to sLORETA.

OBJECTIVE: Electrical source localization (ESL) deriving from scalp EEG and, in recent years, from intracranial EEG (iEEG), is an established method in epilepsy surgery workup. We aimed to validate the distributed ESL derived from scalp EEG and iEEG, particularly regarding the spatial extent of the source, using a realistic epileptic spike activity simulator. APPROACH: ESL was applied to the averaged scalp EEG and iEEG spikes of two patients with drug-resistant structural epilepsy. The ESL results for both patients were used to outline the location and extent of epileptic cortical patches, which served as the basis for designing a spatiotemporal source model. EEG signals for both modalities were then generated for different anatomic locations and spatial extents. ESL was subsequently performed on simulated signals with sLORETA, a commonly used distributed algorithm. ESL accuracy was quantitatively assessed for iEEG and scalp EEG. MAIN RESULTS: The source volume was overestimated by sLORETA at both EEG scales, with the error increasing with source size, particularly for iEEG. For larger sources, ESL accuracy drastically decreased, and reconstruction volumes shifted to the center of the head for iEEG, while remaining stable for scalp EEG. Overall, the mislocalization of the reconstructed source was more pronounced for iEEG. SIGNIFICANCE: We present a novel multiscale framework for the evaluation of distributed ESL, based on realistic multiscale EEG simulations. Our findings support that reconstruction results for scalp EEG are often more accurate than for iEEG, owing to the superior 3D coverage of the head. Particularly the iEEG-derived reconstruction results for larger, widespread generators should be treated with caution.

Long-term outcome characteristics in mesial temporal lobe epilepsy with and without associated cortical dysplasia.

OBJECT: The intention of our study was to identify predictive characteristics for long-term seizure control and running down phenomenon after surgical treatment of pharmacoresistant mesiotemporal lobe epilepsy (mTLE) with and without associated cortical dysplasia. MATERIALS AND METHODS: Our study comprises a consecutive series of 458 patients who underwent surgical treatment for intractable mTLE at the Epilepsy Center Freiburg. Data evaluated included semiology, duration and frequency of seizures, results of presurgical diagnostics including video-EEG monitoring, MRI, PET and SPECT as well as postoperative seizure outcome. Results were evaluated forming two groups: Group A consisted of isolated mesiotemporal lesions. Group B comprised patients with mTLE and additional focal cortical dysplasia (FCD). Statistical evaluation was based on the Kaplan Meier survival analysis, using log-rank-tests and a multivariate regression model. Postoperative running down phenomenon was defined as seizure freedom after a period of gradual reduction of postoperative seizure frequency. This was compared to patients with ongoing epilepsy. RESULTS: Complete seizure freedom was achieved in 65.0% of investigated patients at 1year and in 56.5% at long-term follow-up of ≥5 years after surgery. Corresponding results were 64.2% and 56.8% at 1 and ≥5 years, respectively in group A and 66.4% and 56.0%, respectively in group B. Predictive for favorable postoperative outcome in the total group were younger age at surgery, shorter duration of epilepsy, absence of secondarily generalized tonic-clonic seizures (SGTCS), presence of strictly ipsilateral temporal interictal epileptiform discharges (IEDs), complete resection of the lesion as well as absence of postoperative epileptiform activity and of early postoperative seizures. In subgroup analyses, patients of group A demonstrated longer postoperative seizure-free intervals with adolescent age at surgery, short duration of epilepsy before surgery and absence of SGTCS, whereas in patients of group B ipsilateral temporal seizure onset and strictly unilateral IEDs in EEG as well as complete resection were predictors for favorable seizure outcome. Furthermore, absence of early postoperative seizures and of spikes in EEG were predictive factors for long-term seizure-freedom in both subgroups. The running down phenomenon was found in 33 (7.2%) patients. None of the parameters evaluated demonstrated significant predictive power. Only late seizure onset and neoplastic lesions showed a trend for postoperative gradual seizure reduction in multivariate analyses. CONCLUSION: Depending on the presence or absence of focal cortical dysplasia in addition to mesiotemporal structural alterations, predictors of long-term seizure control differed regarding the relevant clinical and electrophysiological features. This is important for specific patient counseling in respective groups.

Management of cortical dysplasia in epilepsy.

Focal cortical dysplasias (FCD) are increasingly diagnosed as a cause of symptomatic focal epilepsy in paediatric and adult patients. Nowadays, focal cortical dysplasias are identified as the underlying pathology in up to 25% of patients with focal epilepsies. The histological appearance can vary from mild architectural disturbances to severe malformation containing atypical cellular elements like dysmorphic neurons and Balloon cells. Clinical presentation depends on the age at onset of epilepsy, the location and size of the lesion. In most patients seizures begin in early childhood and the course of epilepsy is often severe and pharmaco-resistant. For the majority of patients, epilepsy surgery is the only treatment option in order to become seizure free.In this review an overview on the literature of the last ten years is provided, focussing on histological appearance and classification, pathogenetic mechanisms and clinical presentation of cortical dysplasias. Recent developments in the presurgical diagnostic and outcome after operative treatment as well as prognostic factors are summarized. Finally, an outlook is given on the development of future novel treatment options that might be minimally invasive and help especially the patient group who is inoperable or has failed epilepsy surgery.

Randomized controlled trial of 2.5-cm versus 3.5-cm mesial temporal resection--Part 2: volumetric resection extent and subgroup analyses.

BACKGROUND: This paper is addressing outcome differences in interesting subgroups from a previous randomized controlled trial of the extent of mesial temporal lobe resection (TLR) for drug-resistant epilepsy, by looking at effects of randomization, intended resection group, center, and true resection extent on seizure outcome. METHODS: One hundred and seventy-nine cases with volumetrically assessed resection extent were used. Analyses of the extent of resection and subgroups and within subgroups for the two treatment arms will be performed, looking for confounding factors and using statistical methods (chi-square test, logistic regression analysis, and two-factorial ANOVA). RESULTS: True resection extent varied considerably. Outcome comparison for right versus left resections, subgroups with mesial temporal sclerosis (MTS), or largest and smallest resections revealed no remarkable difference, compared to overall class I outcome. The intent-to-treat analyses within these subgroups revealed differences for class I outcome, albeit lacking in significance, except for better TLR outcome. Small true resection volume differences or randomization into the two resection groups could not explain the outcome differences between the selective amygdalohippocampectomy (SAH) and TLR subgroups. Logistic regression analysis showed an interaction between intended resection length and surgery type, confirming the impression of different impacts of the intended resection length under the two surgery types. The outcome difference between SAH and TLR was more likely explained by a center effect. In a two-factorial ANOVA for resected hippocampal volume, Engel outcome class I, and resection type, the outcome was not found to be correlated with true resection volume. A multifactorial logistic regression showed a mild interaction between the resection type with center on the Engel outcome class, extent of resection, and surgery type interacted, as did the extent of resection and center. CONCLUSION: Patients with quite similar extent of resection can be seizure free or non-seizure free. In this cohort, seizure freedom rates fell again when the extent of mesial resection was maximized. Differences in class I outcome for SAH and TLR were not due to erroneous randomization, true resection extent, or presence of MTS, but were influenced by a center effect. Subgroup analyses did not help to provide arguments to favor one surgery type over the other.

Randomized controlled trial of 2.5-cm versus 3.5-cm mesial temporal resection in temporal lobe epilepsy--Part 1: intent-to-treat analysis.

BACKGROUND: Only one prospective randomized study on the extent of mesial resection in surgery for temporal lobe epilepsy (TLE) exists. This randomized controlled trial (RCT) examines whether 3.5-cm mesial resection is leading to a better seizure outcome than a 2.5-cm resection. METHODS: Three epilepsy surgery centers using similar MRI protocols, neuropsychological tests, and resection types for TLE surgery included 207 patients in a RCT with pre- and postoperative volumetrics. One hundred and four patients were randomized into a 2.5-cm resection group and 103 patients into a 3.5-cm resection group, i.e., an intended minimum resection length of 25 versus 35 mm for the hippocampus and parahippocampus. Primary outcome measure was seizure freedom Engel class I throughout the first year. The study was powered to detect a 20% difference in class I outcome. Seizure outcome was available for 207 patients, complete volumetric results for 179 patients. Outcome analysis was restricted to control of successful randomization and an intent-to-treat analysis of seizure outcome. RESULTS: The mean true resection volumes were significantly different for the 2.5-cm and 3.5-cm resection groups; thus, the randomization was successful. Median resection volume in the 2.5-cm group was 72.86% of initial volume and 83.44% in the 3.5-cm group. At 1 year, seizure outcome Engel class I was 74% in the 2.5-cm and 72.8% in the 3.5-cm resection group. CONCLUSIONS: The primary intent-to-treat analysis did not show a different seizure freedom rate for the more posteriorly reaching 3.5-cm resection group. It appears possible that not maximal volume resection but adequate volume resection leads to good seizure freedom.

Essentials and pitfalls in the treatment of CNS hemangioblastomas and von Hippel-Lindau disease.

Hemangioblastomas are rare CNS tumors, which are mostly located in the posterior fossa or spinal cord and occasionally in spinal nerves. They can occur sporadically or as a component tumor of von Hippel-Lindau (VHL) disease, an autosomal dominant tumor syndrome. The limited awareness of several pitfalls in the therapy of these rare lesions results in delayed or suboptimal treatment for many of these patients, especially those with VHL disease. The University of Freiburg serves as a reference center for patients with VHL disease and hemangioblastomas. The current therapeutic strategies for hemangioblastoma patients and typical pitfalls are presented here.

Preoperative depressive symptoms predict postoperative seizure outcome in temporal and frontal lobe epilepsy.

OBJECTIVE: Recent research has pointed to the possibility of a bidirectional relationship between seizure frequency in epilepsy and depressive symptoms. The study described here investigated the relationship between preoperative depressive symptomatology and postoperative seizure outcome in a sample of patients with temporal (TLE) and frontal (FLE) lobe epilepsy. METHODS: A retrospective analysis was conducted on the data from 115 eligible patients with TLE (N=97) and FLE (N=18) and resections limited to one cortical lobe who were evaluated preoperatively and 1year after epilepsy surgery with respect to depressive symptoms (Beck Depression Inventory, BDI) and seizure outcome. The latter was assessed in terms of actual total seizure frequency as well as a dichotomous variable (seizure free vs. not seizure free) for the 1-year outcome. Repeated-measures analyses of variance and regression analyses were applied. RESULTS: Seizure-free patients had significantly lower BDI scores preoperatively as well as postoperatively than patients who were not seizure free. In the regression analyses, the preoperative BDI score was a significant predictor of postoperative seizure frequency as well as seizure freedom. When only patients with TLE were analyzed, the results for the association between preoperative BDI and postoperative seizure frequency and seizure freedom remained consistent. CONCLUSION: The present results provide evidence for a statistical bidirectionality of the relationship between depressive symptoms and postoperative seizure status in a mixed sample of patients with TLE and FLE. Possible reasons for this bidirectional association include an underlying common pathology in both depression and epilepsy, for example, structural changes or functional alterations in neurotransmitter systems.

The impact of extratemporal epilepsy surgery on quality of life.

Quality of life (QOL) with respect to seizure outcome, cognitive performance, and depressive symptoms was analyzed in 21 adult patients undergoing extratemporal epilepsy surgery (EXTLE). The Subjective Handicap of Epilepsy questionnaire was administered before and 1 year after surgery. Additionally, cognitive performance, depressive symptoms (Beck Depression Inventory), and seizure frequency were assessed. After surgery, seizure frequency decreased and various aspects of QOL significantly improved. Improvements in the domain of Work and Activities correlated with a reduction in complex partial seizure frequency. Alterations in the subscale change correlated with a decrease in simple partial seizure frequency. The present results provide detailed evidence that patients with extratemporal epilepsy benefit from epilepsy surgery.

[Quality of life following extratemporal epilepsy surgery]. / Lebensqualität nach extratemporaler Epilepsiechirurgie.

Extratemporal epileptic foci are increasingly treated successfully with surgery. This study assesses the effect of extratemporal epilepsy surgery on the subjective handicaps of epilepsy patients. Twenty-one adults with pharmacoresistant focal epilepsy undergoing extratemporal surgical interventions were analyzed compared to an age-, gender-, and IQ-matched patient group with temporal lobe epilepsy. A questionnaire on subjective handicaps was given prior to surgery and after 1 year of follow-up. There were significant postoperative improvements in the domains of work and activities, self perception, and judgement of changes in handicap. These changes were similar to those in patients undergoing temporal lobe surgery and not restricted to those achieving complete seizure remission. Epilepsy surgery thus improves not only seizure control but also quality of life in patients with extratemporal focus localization.

Epilepsy surgery in patients with multiple cerebral cavernous malformations.

PURPOSE: Cerebral cavernous malformations (CCMs) are frequently associated with intractable epilepsy. Whereas surgery indication in single CCMs is clear, data regarding the efficacy of epilepsy surgery in patients with multiple CCMs are scarce. We sought to clarify diagnostic requirements and postoperative outcome in patients with multiple CCMs and refractory epilepsy. METHODS: Retrospective analysis of clinical records of hospitalized patients who underwent comprehensive diagnostic work-up including long-term video-EEG monitoring. RESULTS: From a total of 63 consecutive patients with CCMs and medically refractory epilepsy, 11 (17%) had multiple CCMs and underwent epilepsy surgery. There were three females and eight males. Mean age at epilepsy onset was 28.3 years (S.D. 12.3), and at epilepsy surgery, 40.7 years (S.D. 10.3). On average, each patient had 3.7 (S.D. 2.2) supratentorial CCMs. In all cases we identified only one epileptogenic zone. The epileptogenicity was higher for the CCMs located within the temporal lobe. At 2 years follow-up, the outcome according to the Engel classification was Ia (seizure-free) in nine patients (81.8%) and IIb (rare seizures) and IVc (worsening) in two patients, respectively. In one patient, a dual pathology was present and, in another case, de novo appearance of CCMs was demonstrated. CONCLUSIONS: Our results show that postoperative outcome in patients with multiple CCMs can be as good as in those with single malformations if proper presurgical identification of the epileptogenic CCMs is done. The possibility of the novo appearance of CCMs or dual pathology may occur and may affect long-term outcome negatively.

Factors influencing surgical outcome in patients with focal cortical dysplasia.

A total of 120 patients with histologically proven focal cortical dysplasias (FCD) were retrospectively analysed for prognostic factors for successful epilepsy surgery. Multivariate data analyses showed that older age at epilepsy surgery, occurrence of secondarily generalised seizures and a multilobar extent of the dysplasia were significant negative predictors. In univariate analyses, longer duration of epilepsy, need for intracranial EEG recordings and incomplete resection of the FCD were factors which significantly reduced the chance of becoming seizure free. Histological subtype of the FCD and age at epilepsy onset had no significant predictive value. These findings strongly suggest early consideration of epilepsy surgery in FCD patients.

Efficacy and frequency of cerebrospinal fluid drainage in operative management of thoracoabdominal aortic aneurysms.

BACKGROUND: Paraplegia remains the most dreaded complication following thoracoabdominal aortic repair. We investigated the efficacy of cerebrospinal fluid drainage as a spinal cord-protecting modality. We also evaluated the correlation between the frequency of cerebrospinal fluid drainage and the Crawford classification. METHODS: Spinal cord function was monitored during 20 open surgical procedures (group I) and 27 stent-graft implantations (group II). Evoked potentials and intracranial pressure were monitored in each operation. If intracranial pressure exceeded 15 mmHg, cerebrospinal fluid was drained. RESULTS: Cerebrospinal fluid drainage was necessary in 75 % of patients in group I (Crawford type I: 33 %, type II: 40 %, type III: 20 %, type IV: 7 %) and in 22 % of patients in group II (Crawford type I: 33 %, type II: 66 %). Evoked potential alterations correlated with an increase in intracranial pressure. Timely cerebrospinal fluid drainage reversed these changes in 72 %. Three patients remained paraplegic. CONCLUSION: Cerebrospinal fluid drainage is a valuable neuroprotective interventional tool to lower the risk of spinal cord ischemia. The combination of neurophysiological monitoring and cerebrospinal fluid drainage optimizes the prevention of paraplegia during aortic repair.

Thoracoabdominal aortic aneurysm repair: interplay of spinal cord protecting modalities.

BACKGROUND: The purpose of this study was to assess the complementary use of different methods of measuring spinal cord perfusion during thoracoabdominal aortic surgery. METHODS: The spinal cords of 28 patients undergoing surgery on the thoracoabdominal aorta were monitored with transcranial electrical stimulation (tcMEP) and somatosensory-evoked potentials (SSEP). Available approaches of spinal cord-protection included: Moderate systemic hypothermia, constant cerebrospinal fluid (CSF) drainage and pressure monitoring, reimplantation of segmental arteries, cardiopulmonary bypass (CPB), and staged clamping. RESULTS: Fourteen of 19 patients (75%) undergoing open surgical treatment (Group I) exhibited loss of tcMEP after proximal aortic clamping. In nine cases (47%), we observed recovery of tcMEP after intraoperative interventions, while two patients subsequently developed paraplegia and three died. Seventeen of 19 patients showed loss of SSEP, with recovery in 12 cases (63%). During stent-graft implantation (Group II), one of nine patients (11%) demonstrated tcMEP loss with intraoperative, intervention-related recovery. The SSEP-recording course remained stable. CONCLUSIONS: tcMEP/SSEP monitoring has proved to be an excellent means of detecting spinal cord ischaemia during surgery on thoracoabdominal aortic aneurysms. The prognostic value of tcMEP monitoring should be considered superior to that of SSEP measurements, because of its direct and rapid response to spinal malperfusion. Through combined neurophysiological monitoring, vital parameter balancing and intraoperative interventions, spinal cord perfusion improves and recovery of tcMEP and SSEP is achievable, reducing the prevalence of postoperative paraplegia.

[Impaired cerebral autoregulation in asymptomatic patients with carotid artery stenosis: comparison of acetazolamide-SPECT and transcranial CO(2)-dopplersonography]. / Störung der zerebralen Perfusionsreserve.

PURPOSE: The indication for operation in patients with asymptomatic high-grade carotid artery stenosis is still under debate. Since impaired cerebrovascular autoregulation is associated with an increased risk for ischaemic events, assessment of cerebral vascular reactivity might be a valuable selection criterion for surgery. The aim of our study was therefore to evaluate the incidence of impaired autoregulation in asymptomatic patients with acetazolamide-single photon emission computed tomography (ACZ-SPECT) and transcranial CO (2)-dopplersonography (CO (2)-TCD). Furthermore, both methods were compared in regard to results and clinical practicability. METHODS: In 42 patients with high-grade (> 70 %) asymptomatic carotid artery stenosis, cerebral perfusion and vascular reactivity were assessed with resting and ACZ-enhanced SPECT scans. In 31 of these patients the CO (2) reactivity of cerebral perfusion was determined by TCD and expressed as normalized autoregulation reserve (NAR). RESULTS: Cerebral perfusion was decreased in 14.3 %. In ACZ-SPECT 26 % and in CO (2)-TCD 28 % revealed an impaired vascular reactivity. Conformity of both methods was high (kappa = 0.93). TCD was superior in practicability, but only applicable in 81 % due to a missing temporal bone window for insonation. CONCLUSION: In accordance ACZ-SPECT and CO (2)-TCD could detect impaired vascular reactivity in a quarter of asymptomatic patients. Both TCD and SPECT could be of value for preoperative selection in this group of patients, whereby sonography is recommended for daily diagnostic work-up.

Cannabinoid CB1 receptor-mediated modulation of evoked dopamine release and of adenylyl cyclase activity in the human neocortex.

1. The present study investigated the binding characteristics of various ligands to cannabinoid CB(1) receptors in human neocortex and amygdala. In addition, the functionality of CB(1) receptors in the human neocortex was assessed by examining the effects of CB(1) receptor ligands on evoked [(3)H]-dopamine (DA) release in superfused brain slices and on synaptosomal cAMP accumulation. 2. Saturation-binding assays in human neocortical and amygdala synaptosomes using a radiolabelled cannabinoid receptor agonist ([(3)H]-CP55.940) revealed pK(d) values of 8.96 and 8.63, respectively. The numbers of binding sites (B(max)) were 3.99 and 2.67 pmol (mg protein)(-1), respectively. 3. Various cannabinoid receptor ligands inhibited [(3)H]-CP55.940 binding with rank order potencies corresponding to those of previous studies in animal tissues. 4. Electrically evoked [(3)H]-DA release from human neocortical slices was inhibited by CP55.940 (IC(50) 6.76 nm, I(max) 65%) and strongly enhanced by the cannabinoid receptor antagonist AM251. However, [(3)H]-DA release was not influenced in rat neocortex. In human tissue, the estimated endocannabinoid concentration in the biophase of the release-modulating CB(1) receptors was 1.07 nm, expressed in CP55.940 units. 5. K(+)-evoked [(3)H]-DA release in the presence of tetrodotoxin (TTX) was strongly inhibited by CP55.940 in humans, but not in rats. 6. In human tissue, CP55.940 inhibited forskolin-stimulated cAMP accumulation (IC(50) 20.89 nm, I(max) 35%). AM251 blocked this effect and per se increased forskolin-stimulated cAMP accumulation by approximately 20%. 7. In conclusion, cannabinoids modulate [(3)H]-DA release and adenylyl cyclase activity in the human neocortex. CB(1) receptors are located on dopaminergic nerve terminals and seem to be tonically activated by endocannabinoids.

Shutting down operating theater ventilation when the theater is not in use: infection control and environmental aspects.

OBJECTIVE: In hospital operating rooms (ORs), specially conditioned air is supplied to protect patients from airborne agents that may cause infections. This study investigated whether it is hygienically safe to shut down the air supply at night if measures are taken to ensure a timely restart before surgery is performed. DESIGN: Experimental study. SETTING: Neurosurgical OR of a German university hospital. METHODS: The ventilation system was switched off and restarted after 10 hours. Particles suspended in the air near the operating table were counted, OR temperature was measured, and settle plates were exposed and incubated. RESULTS: In 13 investigations, a median of 1.3 x 10(4) particles 0.5 microm/m3 or greater (range, 5.8 x 10(3) to 1.1 x 10(5)) were documented immediately after restart in the morning. After 10 minutes and subsequently, no test showed a particle count exceeding the threshold limit of 1.0 x 10(4) particles 0.5 microm/m3 or greater recommended by the German Society of Hygiene and Microbiology. Only a few colony-forming units (CFU) were detected per settle plate (median, 0 CFU/60 cm2; range, 0 to 8) and OR temperatures quickly reached normal levels. CONCLUSIONS: Shutting down OR ventilation during off-duty periods does not appear to result in an unacceptably high particle count or microbial contamination of the OR air shortly after the system is restarted. Because substantial energy and cost savings are likely, this should be considered in hygienically safe heating, ventilation, and air conditioning systems. However, normal ventilation should be established at least 30 minutes before surgical activity.

Evidence for strychnine-sensitive glycine receptors in human amygdala.

Recent studies suggested the existence of strychnine-sensitive glycine-receptors in mammalian amygdala. In the present study, we investigated the amino acid concentrations as well as immunocytochemical and pharmacological properties of glycine-receptors in fresh human amygdala tissue obtained from epilepsy surgery. High pressure liquid chromatography revealed a considerable amount of glycine and its precursors and glycine-receptors agonists L-serine and taurine in this tissue. Immunohistochemistry using the monoclonal antibody mAb4a, recognizing an epitope common to all alpha-subunit variants of glycine receptors, displayed a specific labeling at the soma and on proximal dendrites of mostly tripolar, large-sized neurons of irregular distribution and arrangement. To elucidate the pharmacological properties of the glycine-receptors found slices of human amygdala were preloaded with [(3)H]-choline and superfused. Glycine induced an overflow of [(3)H]-acetylcholine, which was inhibited by strychnine in a concentration-dependent manner. Furthermore, the glycine-induced release of [(3)H]-acetylcholine was significantly inhibited by furosemide, indicating glycine-induced actions to be attributed to chloride channels. These actions of glycine were not influenced by MK-801, D-CP-Pene or bicuculline. Thus, the effects of glycine did not seem to be mediated through NMDA or GABA receptors. These observations indicate that strychnine-sensitive, chloride-conducting glycine receptors, which elicit the release of [(3)H]-acetylcholine, are present at the soma and on proximal dendrites of neurons in human amygdala. It is hypothesized that glycine may display a regulatory role in amygdaloid functions, probably via cholinergic interneurons.