Cerebellar stroke without motor deficit: clinical evidence for motor and non-motor domains within the human cerebellum.
OBJECTIVE
To determine whether there are non-motor regions of cerebellum in which sizeable infarcts have little or no impact on motor control.


METHODS
We evaluated motor deficits in patients following cerebellar stroke using a modified version of the International Cooperative Ataxia Rating Scale (MICARS). Lesion location was determined using magnetic resonance imaging (MRI) and computerized axial tomography (CT). Patients were grouped by stroke location-Group I, stroke within the anterior lobe (lobules I-V); Group 2, anterior lobe and lobule VI; Group 3, posterior lobe (lobules VI-IX; including flocculonodular lobe, lobule X); Group 4, posterior lobe but excluding lobule VI (i.e. lobules VII-X); Group 5, stroke within anterior lobe plus posterior lobe.


RESULTS
Thirty-nine patients were examined 8.0+/-6.0 days following stroke. There were no Group 1 patients. As mean MICARS scores for Groups 2 through 5 differed significantly (one-way analysis of variance, F(3,35)=10.9, P=0.000 03), post hoc Tukey's least significant difference tests were used to compare individual groups. Group 2 MICARS scores (n=6; mean+/-SD, 20.2+/-6.9) differed from Group 3 (n=6; 7.2+/-3.8; P=0.01) and Group 4 (n=13; 2.5+/-2.0; P=0.000 02); Group 5 (n=14; 18.6+/-12.8) also differed from Group 3 (P=0.009) and Group 4 (P=0.000 02). There were no differences between Groups 2 and 5 (P=0.71), or between Group 3 and Group 4 (P=0.273). However, Group 3 differed from Group 4 when analyzed with a two-sample t-test unadjusted for multiple comparisons (P=0.03). Thus, the cerebellar motor syndrome resulted from stroke in the anterior lobe, but not from stroke in lobules VII-X (Groups 2 plus 5, n=20, MICARS 19.1+/-11.2, vs. Group 4; P=0.000 002). Strokes involving lobule VI produced minimal motor impairment.


CONCLUSIONS
These findings demonstrate that cerebellar stroke does not always result in motor impairment, and they provide clinical evidence for topographic organization of motor versus nonmotor functions in the human cerebellum.
Schmahmann
J D
JD
Ataxia Unit, Cognitive/Behavioral Neurology Unit, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Suite 340, Charles River Plaza South, 175 Cambridge Street, Boston, MA 02114, USA. jschmahmann@partners.org
Macmore
J
J
Vangel
M
M
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001931:Brain Mapping; D002531:Cerebellum / Q000473:pathology*; D004185:Disability Evaluation; D005260:Female; D005625:Frontal Lobe / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009069:Movement Disorders / Q000209:etiology* / Q000473:pathology; D011446:Prospective Studies; D011597:Psychomotor Performance / Q000502:physiology; D012720:Severity of Illness Index; D020521:Stroke / Q000150:complications* / Q000473:pathology*; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods; D055815:Young Adult