title: Motor cortex activation is preserved in patients with chronic hemiplegic stroke.
abstract: Many central nervous system conditions that cause weakness, including many strokes, injure corticospinal tract but leave motor cortex intact. Little is known about the functional properties of surviving cortical regions in this setting, in part because many studies have used probes reliant on the corticospinal tract. We hypothesized that many features of motor cortex function would be preserved when assessed independent of the stroke-affected corticospinal tract. Functional MRI was used to study 11 patients with chronic hemiplegia after unilateral stroke that spared regions of motor cortex. Activation in stroke-affected hemisphere was evaluated using 3 probes independent of affected corticospinal tract: passive finger movement, a hand-related visuomotor stimulus, and tapping by the nonstroke index finger. The site and magnitude of cortical activation were similar when comparing the stroke hemisphere to findings in 19 control subjects. Patients activated each of 8 cortical regions with similar frequency as compared to controls, generally with a smaller activation volume. In some cases, clinical measures correlated with the size or the site of stroke hemisphere activation. The results suggest that, despite stroke producing contralateral hemiplegia, surviving regions of motor cortex actively participate in the same proprioceptive, visuomotor, and bilateral movement control processes seen in control subjects.
authors.affiliation: Department of Neurology, University of Washington, 1959 NE Pacific Street, Room RR650, Box 356465, Seattle, WA 98195-6565, USA. cramers@u.washington.edu
authors.forename: Steven C
authors.initials: SC
authors.lastname: Cramer
authors.forename: Angela
authors.initials: A
authors.lastname: Mark
authors.forename: Kristin
authors.initials: K
authors.lastname: Barquist
authors.forename: Hoang
authors.initials: H
authors.lastname: Nhan
authors.forename: Keith C
authors.initials: KC
authors.lastname: Stegbauer
authors.forename: Robert
authors.initials: R
authors.lastname: Price
authors.forename: Kathleen
authors.initials: K
authors.lastname: Bell
authors.forename: Ib R
authors.initials: IR
authors.lastname: Odderson
authors.forename: Peter
authors.initials: P
authors.lastname: Esselman
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Maravilla
mesh_terms: D000368:Aged; D001931:Brain Mapping; D002908:Chronic Disease; D035061:Control Groups; D005260:Female; D005385:Fingers / Q000503:physiopathology; D006429:Hemiplegia / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009068:Movement; D011597:Psychomotor Performance; D020521:Stroke / Q000150:complications*