Search PubMed⌕ Search

Biomedical subjects

C Helmstaedter

Publications and source records attributed to C Helmstaedter.

At least 19 recordsLinked to original sources
PubMed2003

Hippocampal function and visual object processing in temporal lobe epilepsy.

Limbic event-related potentials related to verbal but not to visual recognition memory have been found to be attenuated within the epileptic hippocampus of patients with temporal lobe epilepsy (TLE). To identify hippocampal contributions to visual processing and memory we recorded intracranial ERPs directly from within the epileptic and the non-epileptic hippocampus in 12 patients with unilateral TLE during a visual object decision and naming task. While the non-epileptic hippocampus differentiated reliably between real and nonsense objects, this effect was completely eliminated within the epileptic mesial temporal lobe. This finding suggests that the hippocampus proper contributes to the semantic processing of visual objects and may help to explain visual memory deficits in TLE.

Adult↗
PubMed2002

Diagnostic delay in psychogenic nonepileptic seizures.

Delay to diagnosis was studied in 313 consecutive patients with psychogenic nonepileptic seizures (PNES). On average, patients with PNES were diagnosed 7.2 years after manifestation (SD 9.3 years). Younger age, interictal epileptiform potentials in the EEG, and anticonvulsant treatment were associated with longer delays. Other patient factors did not explain the great variability of the time to diagnosis, suggesting that physician factors contributed to delays.

Adolescent↗
PubMed2002

Neuropsychological Outcome in Children after Frontal Lobe Epilepsy Surgery.

We investigated the neuropsychological performance of children with frontal lobe epilepsy (FLE, n = 12) before and 1 year after surgery. Children with temporal lobe epilepsy (TLE, n = 12) were included as control group. Preoperatively, children with FLE had a significantly higher IQ than children with TLE, but were significantly more often impaired in manual motor coordination. Postoperatively, both groups improved in attention, short-term and long-term memory, and manual coordination, although the latter was not significant. Neuropsychological outcome in FLE patients was not better in seizure-free patients than in patients with continuing seizures. To avoid deterioration in language functions of patients in whom surgery involved left area 44, correspondence of results in cortical stimulation and intracarotid amytal test may be essential. All in all, our data indicate a favorable cognitive outcome in children 1 year after frontal lobe surgery.

Journal Article↗
PubMed2002

Effects of chronic epilepsy on declarative memory systems.

Memory is systematically affected by temporal lobe epilepsy. Since surgery is a promising alternative to pharmacological treatment the questions which memory system is affected and what the long-term prognosis of memory is are more relevant than ever. We address these issues by cross-sectional and longitudinal analysis of memory performance in large series of patients with temporal lobe epilepsy (TLE). The findings indicate that episodic memory rather than semantic memory is impaired in TLE, in particular in TLE with mesial temporal pathology. With the exception that mesial functions appear increasingly affected by chronic non-mesial TLE, memory decline in TLE is not different from that observed in healthy control subjects. However, since patients perform poorer than controls at any age, normal senescence brings patients to mnesic disability at a younger age. Semantic memory seems unaffected by this process but early cortical lesions appear to interfere with knowledge acquisition. Longitudinal data come to a different conclusion regarding the contribution of epilepsy/seizures to memory decline. Conservative treatment is associated with significant decline in figural memory and 37% of the patients experience some memory decline in the long run. Surgery partly anticipates the decline observed with conservative treatment, but losses are most marked after left temporal lobe surgery. After surgery, quite stable memory or even late recovery from surgery is indicated. Leaving aside the surgical intervention, the data provide evidence that the longitudinal memory outcome in TLE is determined by seizure control, seizure severity, mental reserve capacities, and the retest interval. Thus early and efficient seizure control and the prevention of any cerebral damage from the beginning of epilepsy are demanded.

Epilepsy↗
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↗
PubMed2002

Evidence of brain abnormality in patients with psychogenic nonepileptic seizures.

Markers of brain abnormalities in patients with psychogenic nonepileptic seizures (PNES) were studied to explore whether physical brain disorder is associated with an increased risk of PNES. Evidence of epileptiform EEG changes, MRI abnormalities, and neuropsychological (NPS) deficits was obtained from the records of 329 consecutive patients in whom the diagnosis of PNES was established at our center between 1991 and 2001. Two hundred six patients had PNES alone, and 123 PNES and epilepsy (PNES+E). In the PNES-only group, at least one marker of brain disorder was detected in 22.3% of patients (epileptiform potentials in 8.7%, MRI changes in 9.7%, NPS deficits in 9.7%). The actual prevalence of abnormalities is likely to be higher because 54.9% of the patients with only psychogenic seizures did not undergo MRI or neuropsychological testing. Evidence of brain abnormality was found more frequently in the PNES+E group (epileptiform potentials in 70.7%, MRI changes in 60.2%, NPS deficits in 52.8%). Although markers of brain abnormality were detected much less commonly in the PNES than in the PNES+E group, they were still found in a substantial proportion of patients with PNES alone. This suggests that physical brain disease plays a role in the development of PNES. Markers of physical abnormality were not more common in the right hemisphere.

Journal Article↗
PubMed2002

The localizing value of ictal consciousness and its constituent functions: a video-EEG study in patients with focal epilepsy.

Using ictal neuropsychological testing in pre-surgical patients with focal epilepsies, we examined the localizing value of the constituent functions of consciousness as opposed to 'conscious behaviour' as a unitary variable. 'Conscious behaviour' was defined in terms of awareness and responsiveness. The constituent functions of consciousness examined included the orientation to the examiner, intentional behaviour demonstrated by expressive or receptive speech, and postictal memory. Frequency and patterns of impairment of constituent functions and 'conscious behaviour' were assessed. To achieve this, pre-surgical video-EEG (n = 40) or video-electrocorticography recordings (n = 76) of ictal neuropsychological assessments were reviewed retrospectively. Patients were divided into groups with frontal (n = 29), right temporal (n = 21), left temporal (n = 38) and bitemporal (n = 28) seizure activity. Consciousness was most commonly impaired in patients with bitemporal and left temporal seizure activity. There were different patterns of impairment of the assessed constituent functions in the four groups: patients with frontal seizure activity showed loss of orientation behaviour and expressive speech whereas patients with left temporal seizure activity had impairments of memory, expressive and receptive speech. Patients with seizure activity limited to the right temporal lobe rarely exhibited ictal impairment of any of the assessed functions. In contrast, patients with bitemporal seizure activity showed impairment of all examined functions. Hence, normal functioning of the left temporal lobe or both temporal lobes is necessary for the preservation of all constituent aspects of consciousness. The localizing value of patterns of impairment of constituent functions is superior to that of 'consciousness' as a whole.

Adolescent↗
PubMed2001

Self-Reported Mood Changes following 6 Months of Vagus Nerve Stimulation in Epilepsy Patients.

Vagus nerve stimulation (VNS) for treatment of drug-resistant epileptic seizures has been reported to have additional positive mood effects as obtained by psychiatric ratings. To avoid rater bias effects, this study used self-report questionnaires and examined changes in self-reported mood and health-related quality of life following 6 months of VNS treatment. From 40 adult patients treated with VNS since the beginning of the study, 28 patients (mean age: 35.4 years) with unchanged medication were included. Repeated-measures MANOVA revealed a significant general mood improvement. Post hoc univariate tests obtained improvements of tenseness and dysphoria but not of depression, level of activity, or health-related quality of life. Mood and seizure outcome were correlated. VNS may improve unspecific states of indisposition and dysphoria. Absolute seizure reduction contributes to this antidysphoric effect. Since baseline depression scores were low, findings do not contradict but complement earlier reports of an antidepressive effect of VNS.

Journal Article↗
PubMed2001

No evidence for cognitive side effects after 6 months of vagus nerve stimulation in epilepsy patients.

Vagus nerve stimulation (VNS) can reduce seizure frequency in epilepsy patients and may affect central mechanisms of brain functioning. Experimental studies have provided evidence of cognitive alterations during VNS on phases. This single-arm follow-up study evaluates the potential of VNS to affect cognitive performance following long-term treatment. Thirty-six adult patients with medication-resistant epilepsies enrolled. Cognition was assessed before and at least 6 months after implantation of the stimulation device by a comprehensive neuropsychological assessment battery comprising tests on attention, motor functioning, short-term memory, learning and memory, and executive functions. Neither multiple testing of single score changes nor multivariate testing of cognitive domains revealed significant pre-post changes. Improvements in attentional performance were completely explained by practice effects as is usually expected. In particular, no negative side effects were revealed. These findings are in line with the clinical impression that VNS does not affect cognitive performance.

Journal Article↗
PubMed2001

Memory alterations during acute high-intensity vagus nerve stimulation.

Left cervical vagus nerve stimulation (VNS) is an accepted add-on treatment for pharmacoresistant epilepsy. However, it also allows the investigation of the effects of peripheral nerve stimulation on central nervous functions. The impact of 4.5 min high intensity VNS (>1 mA) on material-specific memory and decision times was evaluated in an experimental 'box car' design in 11 patients with pharmacoresistant epilepsy. Results indicate reversible deterioration of figural but not verbal memory and a trend of accelerated decision times during VNS. Thus, further support of cognitive effects of VNS is provided. There are indications of a major projection of VNS to activating brain structures of and the right hemisphere. Significant cognitive side effects in clinical application are unlikely because of the reversibility of the effect and differences between experimental and therapeutic stimulation conditions. However, since the effectors and the direction of the cognitive effects of VNS seem to depend strongly on stimulation conditions, we recommend future experimental research covering a larger range of stimulation conditions.

Adolescent↗
PubMed2001

Long-term seizure outcome and antiepileptic drug treatment in surgically treated temporal lobe epilepsy patients: a controlled study.

PURPOSE: To evaluate the long-term impact of surgical treatment on seizure outcome and antiepileptic drug (AED) use in patients with pharmacoresistant temporal lobe epilepsy (TLE). METHODS: Comparison of seizure outcome and AED us in operated-on TLE patients (n=148) and nonsurgically treated TLE patients (n=94) at a baseline visit and a follow-up visit after a mean period of 4.8 years. RESULTS: At follow-up, 44.6% of the surgical patients and 4.3% of the nonsurgical patients had been continuously seizure- free since the baseline visit (including the immediate postoperative period). A further 17.6% of the operated-on and 3.2% of the not operated-on patients had been seizure-free for at least the previous year; 37.8% of the surgical and 92.5% of the nonsurgical patients had had seizures during the previous 12 months (p < 0.001). Of the surgical patients, 8.8% versus none of the nonsurgical patients were AED free at follow-up; 55.4% versus 20.2% were receiving monotherapy, and 35.8% versus 79.8% were receiving polytherapy (p < 0.001). Mean number of AEDs and mean change in number of AEDs were significantly more favorable in operated-on than in non-operated-on patients. Further subgroup analysis revealed that not only the continuously seizure-free surgical patients, but also the operated-on patients with ongoing seizures took fewer AEDs than their respective non-operated-on counterparts. CONCLUSIONS: This controlled study for the first time provides comprehensive information on long-term seizure outcome and AED use in surgical TLE patients. It shows a more favorable seizure outcome and AED use in the surgically treated patients. The latter holds true even for the not seizure-free patient subgroup.

Adult↗
PubMed2001

Memory and epilepsy: characteristics, course, and influence of drugs and surgery.

Memory processing in humans is essential for consciousness, cognitive-behavioral development and individual biography. In epilepsy, declarative memory functions show characteristic patterns of impairment when mesiotemporal and associated neocortical structures are affected by lesions, ongoing epileptic activity, or the undesired effects of conservative or operative treatment. Major issues are thus the etiology, onset and course of memory impairment, as well as the prevention of further memory decline during treatment. New input in the field has resulted from improved imaging techniques, sophisticated experimental study designs, more selective surgical approaches, and new antiepileptic drugs.

Animals↗
PubMed2001

Combined systemic and intraventricular chemotherapy in primary CNS lymphoma: a pilot study.

The objective was to evaluate response rate, response duration, and toxicity after systemic and intraventricular chemotherapy in primary CNS lymphoma (PCNSL). From September 1995 to September 1998, 20 consecutive patients with PCNSL (median age 64, range 27 to 71 years) were enrolled in a pilot study evaluating chemotherapy without radiotherapy. A high dose methotrexate (MTX) (cycles 1, 2, 4, 5) and cytarabine (ara-C) (cycles 3, 6) based systemic therapy (including dexamethasone, vinca alkaloids, ifosfamide, and cyclophosphamide) was combined with intraventricular MTX, prednisolone, and ara-C. Complete response was achieved in 11 and partial remission in two patients; in one response could not be determined. Four patients showed progressive disease and two (70, 71 years) died from treatment related complications. Observation time was 2 to 59 months (median 31.5 months). Kaplan-Meier estimate for median time to treatment failure (TTF) was 20.5 months, and for median survival 54 months. Systemic toxicity was mainly hematological. Ommaya reservoir infection occurred in four patients and acute transient MTX induced encephalopathy in two (subacute in another). Cognitive dysfunction possibly due to treatment was seen in only one patient after relapse and after a total of 12 cycles (six at relapse). In conclusion, primary chemotherapy based on high dose MTX and ara-C is highly efficient in PCNSL. Toxicity is manageable in patients younger than 70 years.

Adult↗
PubMed2000

Limbic encephalitis not associated with neoplasm as a cause of temporal lobe epilepsy.

OBJECTIVE: To describe four patients with temporal lobe epilepsy with limbic encephalitis unrelated to neoplasm. METHODS: The authors performed a retrospective evaluation of patient data obtained during presurgical evaluation, with additional CSF analyses, serum analyses, and histopathologic investigations. RESULTS: The patients shared the following clinical features: onset of the disease in young adulthood with subacute onset or exacerbation of frequent intractable temporal lobe seizures, verbal and visual memory deficits, and affective abnormalities. MRI showed variably extended areas of increased T2 signal in limbic structures and adjacent areas. In the histopathologic investigation, chronic inflammation was observed without evidence of a viral origin. There was no evidence of an underlying malignancy. CONCLUSIONS: Nonparaneoplastic limbic encephalitis should be included in the differential diagnosis of adult patients with temporal lobe epilepsy.

Adult↗
PubMed2000

Synaptic plasticity in the human dentate gyrus.

Activity-dependent plasticity is a fundamental feature of most CNS synapses and is thought to be a synaptic correlate of memory in rodents. In humans, NMDA receptors have been linked to verbal memory processes, but it is unclear whether NMDA receptor-dependent synaptic plasticity can be recruited for information storage in the human CNS. Here we have for the first time analyzed different forms of synaptic plasticity in human hippocampus. In human subjects who show a morphologically intact hippocampus that is not the primary seizure focus, NMDA receptor-dependent long-term potentiation (LTP) and forskolin-induced long-lasting potentiation are readily induced at the perforant path-dentate gyrus synapse. In this group, long-term potentiation could be partially depotentiated by low-frequency stimulation. Because patients with a hippocampal seizure focus showed a marked reduction in verbal memory performance in previous studies, we asked whether synaptic plasticity is similarly affected by the presence of a hippocampal primary seizure focus. We found that the amount of potentiation induced by high-frequency stimulation or perfusion of forskolin is dramatically reduced in this patient group. In addition, low-frequency stimulation is not effective in inducing synaptic depression. In summary, we show that activity-dependent synaptic plasticity with properties similar to the rodent is available for information storage in the human hippocampus. Because both verbal memory processes and synaptic plasticity are impaired by a hippocampal seizure focus, we suggest that impaired synaptic plasticity may contribute to deficient declarative memory in human temporal lobe epilepsy.

1-Methyl-3-isobutylxanthine↗
PubMed2000

[Temporal lobe epilepsy: longitudinal clinical, neuropsychological and psychosocial follow-up of surgically and conservatively managed patients].

Little is known about the differential long-term outcome from surgical and nonsurgical therapy in patients with chronic epilepsy. In the present study, 161 surgically or nonsurgically treated patients with drug-resistant temporal lobe epilepsy (TLE) were re-evaluated according to a detailed clinical, neuropsychological, and psychosocial protocol with a mean follow-up interval of 58 months. Freedom from seizures was achieved in 64% of the surgical group; yet 23% of the nonsurgical patients became seizure-free as a result of modifications in drug therapy. Generally, socioeconomic development was poorer in nonsurgical than in surgical patients. Freedom from seizures, employment, and the absence of depression were significant determinants of better quality of life. As for neuropsychological outcome, verbal memory impairment was common after left-sided temporal resection; however, there was no evidence of a marked progression of cognitive impairment after the first postoperative year. In nonsurgical patients, too, cognitive capacities were surprisingly stable over time, although persisting seizures and good baseline performance predicted a poorer neuropsychological outcome.

Adult↗
PubMed2000

Behavioral markers for self- and other-attribution of memory: a study in patients with temporal lobe epilepsy and healthy volunteers.

OBJECTIVES: The correlation between clinical measures of memory and subjectively reported memory is often poor. Regarding this we investigated in patients with temporal lobe epilepsy (TLE) whether there is evidence that persons mistake other cognitive performances for memory due to subjective memory theories. METHODS: a neuropsychological test battery comprising measures of attention, verbal/figural memory and other visual or language related functions was applied in patients with left (L-TLE, n=24) or right temporal lobe epilepsy (R-TLE, n=21) and healthy volunteers (n=20). In addition, subjective self- and other-reported memories were assessed by the subjective memory questionnaire (SMQ). RESULTS: subjective measures as well as objective measures indicate significant cognitive impairment in TLE and in L-TLE in particular. Self-reports and other-reports are interrelated but only self-reported memory correlates significantly with objective memory performance. Regression analysis indicates that self-reported memory is best predicted by word fluency followed by verbal memory and vocabulary, and other-reported memory is best predicted by word fluency, vocabulary, confrontation naming, and verbal recognition memory. DISCUSSION: The results suggest that attribution of memory refers to a subjective view of memory which is wider than its neuropsychological definition. It furthermore differs dependent on the observer's point of view. Memory is preferentially concluded from verbal behaviors. These reflect language skills and access to vocabulary rather than declarative memory. Consideration of subjective memory theories and associated attribution processes can significantly contribute to our understanding of the often-poor relationship between objective test results and subjective impairment in TLE.

Adolescent↗