Biomedical subjects

Tanja Ludwig

Publications and source records attributed to Tanja Ludwig.

3 recordsLinked to original sources

PubMed2003

Brain diffusion after single seizures.

PURPOSE: Diffusion-weighted magnetic resonance imaging (DWI) after focal status epilepticus has demonstrated focal alterations of the apparent diffusion coefficient (ADC) in the epileptogenic zone. We hypothesized that localized dynamic alterations of brain diffusion during the immediate postictal state will be detectable by serial DWI and correlate with the epileptogenic zone. METHODS: Nine adult patients (four men, five women) with medically intractable epilepsy were prospectively examined with a total of 25 DWI scans taken 2-210 min after a seizure. RESULTS: The interictal ADC was significantly (p < 0.05) elevated in the ictogenic hippocampus in all patients with temporal lobe epilepsy. The following postictal changes of the ADC were seen: (a) decreases by maximally 25-31%, which were most pronounced in the epileptogenic zone (n = 2); (b) generalized ADC changes after generalized seizures (n = 1) or prolonged complex partial seizures (n = 2); (c) no major changes after short-lived seizures or if the time to first DWI scan was >15 min or both (n = 3); and (d) widespread bilateral ADC increases after a flumazenil-induced seizure (n = 1). CONCLUSIONS: ADC changes seen during serial postictal DWI are complex and appear to reflect origin and spread of the preceding seizure. A delineation of the epileptogenic zone appears to be possible only in complex-partial seizures of >60 s duration that do not secondarily generalize.

Adult↗

PubMed2003

Presurgical evaluation of epilepsy by brain diffusion: MR-detected effects of flumazenil on the epileptogenic focus.

PURPOSE: After focal status epilepticus, focal alterations of the apparent diffusion coefficient (ADC) have been demonstrated in the epileptogenic zone by using diffusion-weighted magnetic resonance (MR)imaging (DWI). Effects of flumazenil on an epileptogenic focus have been demonstrated by EEG recordings, but not by functional MRI. We hypothesized that dynamic spatiotemporal alterations of brain diffusion of the epileptogenic focus after application of flumazenil will be detectable by DWI and correlate with the epileptogenic zone. METHODS: Twelve adult patients considered for epilepsy surgery with medically intractable temporal lobe epilepsy (TLE; n = 7), extratemporal lobe epilepsy (ETE; n = 2), and TLE+ETE (n = 3) were prospectively examined with DWI interictally (serving as baseline) and 10 min after application of 1 mg flumazenil i.v. RESULTS: The baseline interictal ADC was significantly elevated in the hippocampus on the ictogenic side in the patients with TLE (p = 0.002) as compared with healthy volunteers. The following changes of the mean ADC were seen in different regions of interest (ROIs) after injection of flumazenil: decreases in the hippocampus on the seizure-onset side by 14.8% (p = 0.005); decreases in the parahippocampal gyrus on both sides by 6.8% (epileptogenic side; p = 0.044) or 7.9% (nonepileptogenic side; NS), respectively; decreases in the cortex on the nonictogenic side by 7.9% (p = 0.047); and no significant changes of the ADC in the other ROIs. CONCLUSIONS: ADC decreases measured after application of flumazenil were seen in the seizure-onset zone as revealed by EEG and structural MRI and are an indicator of focus localization in patients with TLE.

Adult↗

PubMed2002

Brain diffusion during hyperventilation: diffusion-weighted MR-monitoring in patients with temporal lobe epilepsy and in healthy volunteers.

Hyperventilation (HV) can be used to provoke epileptiform activity and occasionally seizures in generalised and in focal epilepsies. Based on the hypothesis that HV might alter brain diffusion in the epileptogenic areas of patients with temporal lobe epilepsy (TLE), we examined these alterations using quantitative diffusion MR imaging (DI) in four patients with TLE and unilateral hippocampal sclerosis (TLE-HS) and six patients with TLE without hippocampal sclerosis (TLE-pure), and in 10 healthy volunteers. Brain diffusion was measured at baseline and immediately after 4 min of HV. In all patients with TLE HV was repeated two times, 4 min each, followed by subsequent DI. The apparent diffusion coefficient (ADC) was quantified in predefined regions of interest. In controls, the ADC did not differ between baseline and HV and between right and left side. Compared to controls TLE-HS patients showed significantly higher ADC at baseline in the hippocampus of the ictogenic side (111+/-13 vs. 87.5+/-4.26 x 10(-5) mm(2)/s, P=0.029). During HV ADC decreased significantly in the ictogenic hippocampus compared to controls (-17.3+/-7.1 vs. -3.34+/-8.7, P=0.004). In TLE-pure patients ADC of the ictogenic hippocampus was higher than in normals (99.3+/-14.2 vs. 87.5+/-4.26 x 10(-5) mm(2)/s, P=0.031) but there was no significant decrease during HV. Serial HV did not further enhance this decrease. No significant HV-induced changes were seen in other brain areas. In conclusion, our results show that HV can induce dynamic changes of brain diffusion in patients with sclerotic hippocampi but not in non-sclerotic hippocampi. These findings may be utilized for lateralisation of the epileptogenic hippocampus during presurgical evaluation of TLE.

Adult↗