Abstracts

Rationale: To demonstrate that cognitive deterioration due to long-lasting Absence status may be correlated with dramatically impaired white matter integrity as assessed by fractional anisotropy (FA). Methods: Clinical case report including EEG documentation, neuropsychological testing, conventional MRI, and assessment of FA using diffusion tensor imaging (DTI). FA maps were compared with 63 age- and gender-matched healthy controls on a regions of interest (ROI) basis. DTI was acquired at 3 T, with 20 diffusion directions. Results: A 22 year old male with idiopathic generalized epilepsy was admitted due to obtunded-aggressive behaviour lasting two weeks. EEG revealed generalized spike-waves and delta slow, supporting diagnosis of Absence status. The patient suffered a series of generalized tonic-clonic seizures before status was terminated by lorazepam and valproate. However, behaviour remained severely impaired. Conventional MRI was normal except for a linear left frontal gliotic lesion. In contrast, FA was below 1st percentile in 5 out of 15 ROIs, compared with controls, with exceptionally severe decrease in the frontal lobes. At 2-month follow-up, FA was further reduced, with 12 out of 15 ROIs below 1st percentile. At 6-month follow-up, FA was below 0.1st percentile in 13 out of 15 ROIs, indicating an even more dramatic reduction. Neuropsychological testing at 2 months revealed verbal and figural memory, processing speed, and executive function scores below 10th percentile. The patient remained unable to work and to continue his technical apprenticeship. Conclusions: Despite its generally good prognosis, prolongated absence status lasting weeks may cause decline of intellectual functioning. This case demonstrates that FA assessed with DTI may reveal dramatic diffuse white matter changes although conventional MRI shows merely minimal lesions. White matter integrity may continue to decline within several months of follow-up despite termination of status epilepticus.