Clemens Eder

Symmetry of post-movement beta-ERS and motor recovery from stroke: a low-resolution EEG pilot study.

The inter‐hemispheric symmetry of electroencephalographic (EEG) post‐movement beta‐event‐related synchronization (PMBS) after movements on a drawing board was studied in eight acute stroke subjects with mild hemiparesis and eight normal subjects. A follow‐up testing was conducted 3 months after the initial recordings with a twofold purpose: (1) to validate the reproducibility of the experimental protocol in normal subjects; and (2) to study changes of inter‐hemispheric PMBS‐symmetry as a response to recovery of motor function. PMBS values were calculated and their topographic distributions illustrated at various time instances following movement offset. Significant PMBS patterns were present in all normal subjects, with only minor differences within consecutive recordings. The side of hemiparesis in acute stroke subjects could be distinguished (P = 0.04) on the basis of the signed symmetry index, a quantitative measure of lateralization. The follow‐up testing on three recovered stroke subjects revealed a trend of changes in the lateralization towards the contralateral side of movement, an indication that the cortical organization of movement following recovery turned out as reported for normal subjects. Further clinical investigations need to be carried out to evaluate the relationship between recovery and PMBS symmetry on a large number of subjects, using the method presented here.

Chronic cuff electrode recordings from walking Göttingen mini-pigs

We present data from cuff electrode recordings from a mixed sensory-/motor nerve as expressed during walking in chronically implanted Göttingen mini-pigs. Our results show that it is possible to filter out residual electromyographic interference and that the energy content of the resulting electroneurographic (ENG) signals modulate clearly with gait. The approach may be used to detect heel strike from cuff electrode measurements to control the timing of stimulation in implantable foot drop correction systems.

Drawing test for assessment of arm functionality

Goal: We recently introduced the Drawing Test (DT) for the determination of coordination abilities in upper extremities (Eder et al., 2005; Popovic et al., 2002). The aim of the present study was to assess contributions of modified spatial frameworks to the kinematics of tracking movements by individuals with hemiplegia. The side of infarction and the dexterity before stroke are crucial in the rehabilitation treatment. Methods: Twenty acute and sub-acute individuals with cerebro-vascular infarction tracked the outline of a 20 · 20 cm square presented on a digitizing tablet with both arm (DT). The kinematics of the hand trajectory was compared to the outline of square. Results: Ninety percentage of patients (9 out of 10) with hemiplegia in their non-skilled arm had kinematic parameters in skilled arm similar to the desired one, while 60% of patients (6 out of 10) were unable to draw the square with their skilled arm affected with hemiplegia. Conclusions: Drawing test could be used in clinical settings to assess skilled arm functionality. Acknowledgements: Danish National Research Foundation, Denmark and the Ministry of Science and Environmental Protection of Serbia.