To determine whether there are non-motor regions of cerebellum in which sizeable infarcts
have little or no impact on motor control.
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.
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.
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.