title: Cortical somatosensory magnetic responses in multiple sclerosis.
abstract: Somatosensory evoked magnetic fields (SEFs) to contralateral median and ulnar nerve stimulation were analyzed in 10 patients with multiple sclerosis and in 8 healthy controls. SEFs were recorded with a 24-channel SQUID gradiometer over both hemispheres. Seven patients showed abnormally large-amplitude SEF deflections at 60-80 msec; 5 of them had multiple lesions around lateral ventricles in magnetic resonance imaging. In 2 patients with plaques at the level of 3rd and 4th ventricles and medulla, the 30 msec responses were enlarged. The equivalent sources of 20 msec and 30-80 msec responses were in the primary hand sensorimotor cortex both in patients and in control subjects. The results suggest that early and middle-latency SEFs reflect parallel processing of somatosensory input. Recording of middle-latency evoked responses, electric or magnetic, may give additional information about the somatosensory function in multiple sclerosis.
authors.affiliation: Low Temperature Laboratory, Helsinki University of Technology, Espoo, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Karhu
authors.forename: R
authors.initials: R
authors.lastname: Hari
authors.forename: J P
authors.initials: JP
authors.lastname: Mäkelä
authors.forename: J
authors.initials: J
authors.lastname: Huttunen
authors.forename: J
authors.initials: J
authors.lastname: Knuutila
mesh_terms: D000328:Adult; D001931:Brain Mapping; D004558:Electric Stimulation; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000503:physiopathology*; D011930:Reaction Time / Q000502:physiology; D013003:Somatosensory Cortex / Q000503:physiopathology