Differenzierung zwischen axonaler und demyelinisierender Schädigung bei Patienten mit Multipler Sklerose durch Untersuchung der hochfrequenten SEP-Komponenten nach Medianus-Stimulation
High-frequency (600 Hz) oscillations (HFOs) are superimposed onto the primary cortical response (N20) in human median nerve somatosensory evoked potentials (SEPs). HFOs are generated both in deep axon segments of thalamo-cortical projection neurons and at the primary somatosensory cortex. To test the hypothesis that HFOs might be more sensitive to temporal dispersion caused by demyelinating lesions than the low-frequency N20, we compared HFOs in bilaterally tested median nerve SEPs in 50 patients with definite multiple sclerosis (MS) vs. 30 healthy controls. Three patterns of SEP alterations were found: (1) abolished HFOs with either normal N20 (11% of stimulated limbs) or delayed N20 (16%), reflecting a predominantly demyelinating process; (ii) an attenuated N20 amplitude with preserved HFOs (13%), indicating a mainly axonal lesion pattern; and (iii) mixed SEP alterations pointing to a combined axonal/demyelinating process (21%). Thus, HFOs provide a functional tool to distinguish axonal vs. demyelinating MS lesions. Furthermore, the combination of normal N20 with abolished HFOs points to an additional sensitivity of HFOs in comparison to routine SEP parameters for the detection of slight demyelinating processes which might be of interest, for example, in treatment monitoring.
info:eu-repo/classification/ddc/610, Medizin, Multiple Sklerose, somatosensibel evozierte Potentiale
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