Biomedical subjects

Edgar Kockelmann

Publications and source records attributed to Edgar Kockelmann.

5 recordsLinked to original sources

PubMed2006

Cognitive outcomes in patients with chronic temporal lobe epilepsy.

Cognitive impairment is frequent in temporal lobe epilepsy (TLE). In particular, specific deficits in temporal lobe related functions occur, but deficits in extratemporal lobe functions and global intelligence are also found. The degree and type of the impairment are first determined by structural damage and functionally dynamic factors. Most cognitive problems in TLE are already detectable at, or even before, the onset of the epilepsy. Accumulation of damage during the course of chronic epilepsy may add to this. This additional damage may be caused directly by severe seizures, head trauma, intoxication etc., or indirectly by interference of the epilepsy with mental development. Surgical treatment of TLE may also affect the cognitive outcome of patients with chronic TLE, with a risk of additional impairments on the one hand and functional recovery due to seizure control on the other hand. With regard to patient-associated factors, better baseline performance, younger age, cerebral plasticity, and good mental reserve capacities are associated with a better outcome. With regard to treatment-associated factors, prevention of additional brain dysfunction/damage and successful seizure control are important.

Chronic Disease↗

PubMed2005

Rhinal-hippocampal connectivity determines memory formation during sleep.

Compared with waking state attention, volition and semantic processing play a minor role during sleep. Thus, investigating declarative memory formation during sleep may allow us to isolate mnemonic core processes. The most feasible approach to memory formation during sleep is the analysis of dream memories. Lesion and imaging studies have demonstrated that encoding of declarative memories, i.e. consciously accessible events and facts, depends on operations within the rhinal cortex and the hippocampus, two substructures of the medial temporal lobe. Successful memory formation is accompanied by a transient rhinal-hippocampal interaction. Consequently, the ability to memorize dreams may be related to mediotemporal connectivity. Therefore, we recorded EEG during sleep from rhinal and hippocampal depth electrodes implanted in 12 epilepsy patients (eight women, mean age 41.1 +/- 6.4 years). They were awakened during rapid eye movement sleep (REM) and asked to recall their dream. Via coherence analyses we show that rhinal-hippocampal connectivity values are approximately twice as large for patients with good dream recall versus those patients with poor recall. This suggests that rhinal-hippocampal connectivity is a key factor in determining declarative memory formation.

Adult↗

PubMed2004

Cognitive profile of topiramate as compared with lamotrigine in epilepsy patients on antiepileptic drug polytherapy: relationships to blood serum levels and comedication.

RATIONALE: This retrospective study was conducted to identify cognitive domains affected by topiramate (TPM), and to evaluate the role of blood serum levels of TPM and comedication in the etiology of TPM-induced cognitive impairment. METHODS: Forty-two patients on AED polytherapy containing topiramate and a random sample of 42 patients with lamotrigine as the corresponding agent underwent extensive neuropsychological testing. Current blood serum levels of TPM were correlated with test scores. RESULTS: Patients on TPM scored significantly worse in phonematic verbal fluency, memory spans, and working memory; language and memory function were not affected per se. In few cognitive domains, serum levels of TPM and performance were correlated before correction for multiple testing. Drug load of additional medication did not account for differences between or within groups. DISCUSSION: Consistent with previous reports, patients on AED polytherapy including TPM display a cognitive pattern with specific impairment in executive functions. The severity of the cognitive side effects of TPM may be related to dosing to a certain extent, but this relationship may be disclosed only with larger sample sizes. Accordingly, TPM dosage does not appear to be a good indicator of TPM-related cognitive side effects in the individual patient.

Adult↗

PubMed2003

Significant improvement in frontal lobe associated neuropsychological functions after withdrawal of topiramate in epilepsy patients.

RATIONALE: Topiramate (TPM) is a highly effective anticonvulsant drug, but a comparably high rate of cognitive adverse effects have been reported. In this study, we investigated changes in frontal lobe associated cognitive measures after TPM withdrawal in epilepsy patients hospitalized for presurgical evaluation. METHODS: Twenty epilepsy patients were administered a brief neuropsychological test battery before and after withdrawal of TPM. Neuropsychological evaluation included a verbal fluency task, verbal (Wechsler's digits) and spatial spans (Corsi block-tapping) and Trail Making Test (TMT, parts A and B). Median baseline dosage of TPM was 237.5mg/d, the median retest-interval was 8 days. Results were compared to a matched group of patients, who had been tested and retested before and after reduction of AEDs other than TPM at comparable time intervals. RESULTS: After TPM withdrawal, group performance appeared significantly improved in five of six tests administered. The scores of the control patients remained largely unchanged after drug reduction. After withdrawal, the scores of the TPM group did not differ significantly from the results of the control group whereas pronounced differences had been observed before. Individual improvement became apparent in the majority of patients. Cognitive performance was not correlated to current daily dosages/current blood serum levels of TPM. CONCLUSION: Withdrawal of TPM causes significant improvement in frontal lobe associated measures like verbal fluency and working memory. As withdrawal was part of the preoperative work-up, and not initiated because of patients' complaints or hints of intoxication, cognitive impairment due to TPM appears to be easily overlooked and underestimated.

Adult↗

PubMed2003

Rhinal-hippocampal EEG coherence is reduced during human sleep.

The deficiency of declarative memory compared with waking state is an often overlooked characteristic of sleep. Here, we investigated whether rhinal-hippocampal coherence, an electrophysiological correlate of declarative memory formation, is significantly altered during sleep as compared with waking state. For this purpose, we analysed recordings of intracranial EEG activity during sleep obtained directly from within the medial temporal lobe in patients with unilateral temporal lobe epilepsy. We found a general reduction of rhinal-hippocampal EEG coherence during sleep compared with waking state, which was most pronounced within the upper gamma bands (average decrease up to 56%). The observed coherence changes clearly differ from findings reported for surface EEG data and thus appear to be specific for the medial temporal lobe. The decrease of rhinal-hippocampal EEG coherence from waking state towards sleep may yield an electrophysiological explanation for the sleep-related deficiency of declarative memory.

Adult↗