Search PubMed⌕ Search

Biomedical subjects

C Helmstaedter

Publications and source records attributed to C Helmstaedter.

At least 37 records · Page 2Linked to original sources
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↗
PubMed2000

Depression in patients with temporal lobe epilepsy is related to mesial temporal sclerosis.

Depression is a frequent psychiatric symptom in epilepsy and has been related to epilepsy of temporal origin, especially of left-sided foci. No study differentiated the precise localization of the epileptogenic lesion within the temporal lobe. Regarding this issue, we evaluated depression assessed by the Beck Depression Inventory in 60 patients with temporal lobe epilepsy, with particular consideration of morphological abnormalities within the temporal lobe (mesial temporal sclerosis (MTS) versus neocortical lesions) and lateralization of the lesion. Multivariate analyses indicated significant higher depression scores in MTS independent of the lateralization of the lesion. Depression was a good indicator for MTS but not vice versa. Hence, MTS can be discussed as a predisposing factor for the development of mood disorders in focal epilepsy.

Adult↗
PubMed2000

Behavioural disorders in children with epilepsy: early improvement after surgery.

OBJECTIVES: Epilepsy surgery has proved to be a successful intervention method to achieve freedom from seizures or seizure relief in children with pharmacoresistant epilepsy. Long term studies on operated children suggest that behavioural disorders, which are often seen before surgery, improve after surgery. However, the early postoperative development of behavioural problems has not been systematically evaluated. METHODS: Parents of 28 children with pharmacoresistant focal epilepsies completed the child behaviour checklist (CBCL) preoperatively and 3 months after surgery. Surgeries comprised 24 focal resections (13 temporal, 11 extratemporal), two hemispherectomies, and two callosotomies. Twenty eight conservatively treated children with comparable CBCL scores served as a control group. A repeated measurement multivariate analysis of variance (MANOVA) and a regression analysis were computed to compare the development of behaviour between both groups and to identify predictors of postoperative changes in behaviour. RESULTS: Preoperatively 39% of the children exhibited significant behavioural problems, a further 11% were within the borderline range. The MANOVA disclosed a significant interaction between time of examination and group (F=2.23, p<0.05). The surgery group showed significant improvements on the scales "internalising problems", "externalising problems", "attention problems", and "thought problems". Behavioural problems in the control group, however, remained unchanged. No changes were seen in social problems in both groups. The significant predictor of total behavioural improvement was a good seizure outcome (R(2)=0.11, p<0.05). Age, sex, onset, and duration of epilepsy, the site of the focus, and changes in antiepileptic drug regimen did not influence changes in behaviour. CONCLUSIONS: The data demonstrate an early improvement of behavioural problems after epilepsy surgery in children. The behavioural improvements can be assumed to result directly from the removal of the epileptic focus. They are not predictable on the basis of information available preoperatively, but depend on the seizure outcome.

Adolescent↗
PubMed2000

Neuropsychology of childhood epilepsy: pre- and postsurgical assessment.

Childhood epilepsy is one of the most prevalent forms of chronic and disabling childhood disorders. Because it disrupts brain maturation, it has long been thought to produce non-specific consequences such as mental deficiency and behavioral problems. However, advances in medical knowledge have shown that childhood epilepsy should not be considered as a single disorder, and it is now becoming apparent that various clinical entities have different cognitive expressions that yet need to be specified. The purpose of this paper is to provide an up-to-date analysis of this multi-faceted pathology. The first section is devoted to the characterization of the neuropsychological profile that accompanies focal epilepsies, as defined by the site of the epileptic process. We report the first group study of children with frontal lobe epilepsy. The results indicate that frontal lobe epilepsy produces symptoms (deficits of planning, attention and motor dexterity) that are akin to those found in frontal-lesioned adults. Similarly, like in adults, temporal lobe epilepsy produces memory impairment in children as well as behavioral and academic disturbances. Occipito-parietal lobe epilepsy is rare in children and its effects still need to be specified. The second section deals with the neuropsychological techniques used in presurgical evaluation. Finally, the various neurosurgical procedures that are increasingly being used as part of the arsenal of epilepsy treatment are described along with the neuropsychological findings that are associated with these interventions. It can be concluded that the beneficial effects of epilepsy surgery (callosotomy, hemispherectomy, temporal and extra-temporal resections) by far outweigh the few cognitive deficits that are occasionally reported following these interventions.

Adult↗
PubMed1999

Sex differences in material-specific cognitive functions related to language dominance: an intracarotid amobarbital study in left temporal lobe epilepsy.

Population-based studies of material-specific cognitive functions yield evidence of sex differences: women are superior on verbal tasks whereas men are superior on figural and visuo-spatial tasks. Although there is still no direct evidence, these sex differences have been assumed to be related to a different cerebral organisation of language and nonlanguage functions, i.e. language in women is suggested to be more bilaterally organised than in men. We investigated this issue with respect to verbal/nonverbal memory functions in 42 men and 43 women with left temporal lobe epilepsies who all underwent intracarotid amobarbital testing for language dominance. The results indicate that atypical language dominance is not significantly more frequent in women than in men (44% vs 33%). Atypical dominance was related to an onset of epilepsy before puberty and appeared to be a consequence of the left hemisphere pathology rather than being naturally predisposed. Furthermore, women indeed showed the expected advantage with respect to verbal memory, and men showed an advantage in figural memory. With consideration of language dominance, however, the sex difference in verbal memory was observed particularly with atypical dominance, whereas the sex difference in figural memory was observed with left dominance.

Journal Article↗
PubMed1999

Pre- and postoperative neuropsychological profiles in children and adolescents with temporal lobe epilepsy.

PURPOSE: To evaluate the neuropsychological performance of children before and after temporal lobe resection (TLR). METHODS: Memory, attention, language, and visuoconstructive abilities were examined in 20 children (age 10-16 years) before, and 3 and 12 months after TLR (right, n = 10; left, n = 10; two-thirds anterior resection, n = 16; amygdalohippocampectomy, n = 4). Preoperative performance was compared with data of 30 age-matched healthy children; changes in performance after surgery were determined by repeated-measurement multivariate analysis of variance (MANOVA) and by use of reliable change indices (RCI). RESULTS: Preoperatively, no differences were observed between patients and controls in verbal and figural memory performance. Children with temporal lobe epilepsy (TLE), however, and particularly those with a left temporal focus, showed significantly reduced language performance. Repeated-measurement statistics indicated that memory performance did not change after surgery, whereas language performance and attention significantly improved 3 months and 1 year after surgery, respectively. Individual evaluations of memory showed gains in five children and deterioration in four children. Poor seizure control appeared the decisive variable characterizing children with losses in memory. CONCLUSIONS: Compared with adults, pre- and postoperative memory data suggest less pronounced hemispheric differences in school-age children with TLE. The results raise the possibility that children have a lower risk of memory deterioration after TLR, which may be due to their larger potential for cerebral plasticity.

Adolescent↗
PubMed1999

Surgical outcome in a group of low-IQ patients with focal epilepsy.

PURPOSE: Because a low IQ score indicates global brain damage, several authors consider it a contraindication for resective epilepsy surgery. This study reports the postoperative results of a small group of subaverage-intelligence patients with epilepsy who underwent focal resections. METHODS: We report on 16 patients who underwent focal resections (no callosotomy or hemispherectomy). All had IQ's <85 and were >13 years of age at the time of surgery. Low IQ was psychometrically assessed (mean IQ = 70) and confirmed by the patients' educational/occupational status. Clinical characteristics, findings from the preoperative workup, and the surgical treatment are described in detail. Postoperative outcome was evaluated with respect to seizure relief and cognitive/ socioeconomic development. RESULTS: Three months after surgery, 14 (87%) of 16 patients were completely seizure free, and nine (64%) of 14 were seizure free at the 1-year follow-up. Patients' cognitive abilities and socioeconomic status were mostly unchanged and in some cases improved. Seizure outcome was not related to IQ level, and there was no evidence of multiple epileptic foci in the patients with continued seizures. CONCLUSIONS: A low IQ level does not entail the presence of extended epileptogenic regions or multiple epileptic foci. Seizure-relief rates in our group concurred with the rates in patients of average intelligence, and the cognitive/socioeconomic outcome was favorable. We conclude that focal surgery in intellectually impaired patients can be recommended if the preoperative diagnostics confirm a circumscribed seizure onset.

Adolescent↗
PubMed1999

Clinical relevance of amygdala sclerosis in temporal lobe epilepsy.

OBJECT: The goal of this study was to define the incidence and clinical significance of amygdala sclerosis (AS) in patients with temporal lobe epilepsy (TLE). METHODS: Surgical specimens of the lateral amygdaloid nucleus and the hippocampus excised from 71 patients who were treated for medically intractable TLE were quantitatively evaluated using a computer-assisted image-analysis system and compared with 10 normal autopsy specimens. Densities of neurons and reactive astrocytes in the patients with TLE were correlated with clinical, neuropsychological, and depth-electroencephalography data. The neuron counts of the lateral amygdaloid nucleus did not correlate with various presumed etiological factors of TLE including hereditary seizures, birth complications, febrile convulsions, traumatic brain injury, infections, seizure semiology, and epileptological outcome. However, patient age at surgery was significantly higher (mean difference 10 years) when AS was present, as compared with patients without AS (p < 0.01). Seizure origin, as determined by using amygdalohippocampal depth electrodes, did not correlate with the presence or absence of AS. Neuropsychologically, there was a significant correlation between the neuronal densities of the lateral amygdaloid nucleus and both preoperative visual recognition and postoperative deterioration of short-term verbal memory performance (p < 0.05). CONCLUSIONS: Except for the relatively long history of epilepsy, the presence of AS is not associated with specific clinical or electrocorticographic features of mesial TLE. However, patients without AS are particularly at risk for deterioration of short-term verbal memory following amygdalohippocampectomy.

Adolescent↗
PubMed1998

Limbic ERPs predict verbal memory after left-sided hippocampectomy.

Surgical removal of the dominant medial temporal lobe regions runs a considerable risk of verbal memory deficits which may be compensated for postoperatively by corresponding regions in the non-dominant medial temporal lobe. We examined this possibility by recording event-related potentials (ERPs) to words from the medial temporal lobes of patients with left-sided temporal lobe epilepsy (TLE) undergoing presurgical evaluation. N400 amplitudes in the right anterior medial temporal lobe predicted the postoperative verbal recall performance of individual patients with surprising accuracy, indicating that intracranial recordings can be used to quantify the functional capacities of the right hemisphere that can compensate for the verbal memory deficits after loss of medial temporal lobe structures in the left hemisphere.

Adolescent↗
PubMed1998

Verbal novelty detection within the human hippocampus proper.

Animal studies and neuropsychological tests of patients with temporal lobe epilepsy have demonstrated the importance of human medial temporal lobes for memory formation. In addition, more recent studies have shown that the human hippocampal region is also involved in novelty detection. However, the exact contribution of the hippocampus proper to these processes is still unknown. To examine further its role we compared event-related potentials recorded within the medial temporal lobes in 29 temporal lobe epilepsy patients with and 21 without hippocampal sclerosis. While in patients with extrahippocampal lesions but without hippocampal sclerosis event-related potentials to first presentations and repetitions of words were reduced on the side of the epileptogenic focus, in patients with hippocampal sclerosis only those to first presentations but not to repetitions were affected. Because sclerosis of the hippocampus proper selectively reduced event-related potentials to new but not old verbal stimuli, it can be concluded that the human hippocampus proper contributes to verbal novelty detection.

Adolescent↗
PubMed1998

Neuropsychological consequences of epilepsy surgery in frontal lobe epilepsy.

The present study investigated the effect of frontal lobe surgery on "cognitive functions", which have previously been shown to be discriminative in the evaluation of non-resected patients with frontal lobe epilepsy (FLE). The cognitive outcome was evaluated with particular consideration of the side (left/right), the site (lateral, orbital, mesial, premotor/SMA), the type of surgery (resections vs. resections plus multiple subpial transections; MST), and seizure outcome. The evaluation is based on 33 patients with left (n = 17) or right (n = 16) frontal surgery. Forty-five patients who underwent successful left (n = 21) or right (n = 24) temporal lobectomy served as controls. The neuropsychological examination covered speed/attention, motor sequencing/coordination, response maintenance/inhibition, short-term memory, and language. With the exception of short-term memory, the chosen tests were discriminative in determining preoperative frontal lobe dysfunctions but they did not differentiate patients with a different lateralization or localization of the frontal focus. At the 3 month follow-up examination, patients with temporal lobectomy had improved frontal functions, whereas patients with frontal lobe surgery showed a mild deterioration. Within the frontally resected group, completely seizure-free patients had significantly improved short-term memory. Further consideration of the side, site and the type of the frontal resection indicated that patients with premotor/SMA surgery and patients with precentral/central MST had additional impairment after surgery. Premotor/SMA resections led to a deterioration in response maintenance/inhibition and if performed left sided also to deteriorated language functions. The latter impairment could be clearly related to transient aphasia directly after surgery. Irrespective of pareses observed immediately after surgery, patients with MSTs of the precentral/central areas displayed additional problems in motor coordination at the follow-up examination. In this group the seizure outcome was also less favourable. In summing up, frontal lobe surgery does not cause any considerable additional impairment in the short-term follow-up. However, caution is recommended when surgery or MST affect functional relevant cortex (here the prefrontal/SMA and precentral/central area). Finally, a release of functions associated with frontal areas not affected by surgery is suggested, when seizures are successfully controlled by surgery.

Adult↗
PubMed1998

Neuropsychological consequences of epilepsy surgery in frontal lobe epilepsy.

The present study investigated the effect of frontal lobe surgery on "cognitive functions", which have previously been shown to be discriminative in the evaluation of non-resected patients with frontal lobe epilepsy (FLE). The cognitive outcome was evaluated with particular consideration of the side (left/right), the site (lateral, orbital, mesial, premotor/SMA), the type of surgery (resections vs resections plus Multiple Subpial Transections), and seizure outcome. The evaluation is based on 33 patients with left (n = 17) or right (n = 16) frontal surgery. Forty-five patients who underwent successful left (n = 21) or right (n = 24) temporal lobectomy served as controls. The neuropsychological examination covered speed/attention, motor sequencing/coordination, response maintenance/inhibition, short-term memory, and language. With the exception of short term memory, the chosen tests were discriminative in determining preoperative frontal lobe dysfunctions but they did not differentiate patients with a different lateralization or localization of the frontal focus. At the three month follow-up examination, patients with temporal lobectomy had improved frontal functions, while patients with frontal lobe surgery showed a mild deterioration. Within the frontally resected group, completely seizure free patients had significantly improved short-term memory. Further consideration of the side, site and the type of the frontal resection indicated that patients with premotor/SMA surgery and patients with precentral/central MST had additional impairment after surgery. Premotor/SMA resections led to a deterioration in response maintenance/inhibition and if performed left sided also to deteriorated language functions. The latter impairment could be clearly related to transient aphasia directly after surgery. Irrespective of pareses observed immediately after surgery, patients with MST's of precentral/central areas displayed additional problems in motor coordination at the follow-up examination. In this group the seizure outcome was also less favorable. In summing up, frontal lobe surgery does not cause any considerable additional impairment in the short term follow-up. However, caution is recommended when surgery or MST affect functional relevant cortex (here the prefrontal/SMA and precentral/central area). Finally, a release of functions associated to frontal areas not affected by surgery is suggested, when seizures are successfully controlled by surgery.

Adolescent↗