Klinische Neurophysiologie 2006; 37 - A221
DOI: 10.1055/s-2006-939304

Eye hand coordination in spinocerebellar ataxia type 17

P Trillenberg 1, A Sprenger 1, A Hiller 1, C Klein 1, G Weinberger 1, S Kruck 1, C Zühlke 2, A Rolfs 3, C Helmchen 1
  • 1Universitätsklinikum Schleswig-Holstein, Neurologie, Lübeck
  • 2Universitätsklinikum Schleswig-Holstein, Humangenetik, Lübeck
  • 3Universitätsklinikum Rostock, Neurologie, Rostock

Background/Aim:

SCA17 is caused by a trinucleotide expansion in the gene encoding the TATA binding protein (TBP). We intended to characterize combined eye-hand movements in this ataxic disorder by using hand pointing tasks.

Methods:

Subjects were included after molecular genetic diagnosis of SCA17. Hand pointing movements were recorded in 10 patients and 10 controls matched for age with an ultrasound based system (ZEBRIS). Eye movements were recorded with the video-based EYELINK II system. Subjects were asked to point towards targets at 8° and 12° to the left and to the right, respectively. In different conditions, they were supposed to simultaneously carry out saccades towards the target (condition „sac“) and to continue fixating a straight-ahead target while pointing to the lateral target („nosac“). In a third condition („blank“), the target was blanked once a saccade towards the target was initiated.

Results:

SCA17 mutation carriers (age range 19–53) showed a broad phenotypic spectrum (cerebellar, extrapyramidal signs). Hand movements in SCA17 subjects were characterized by reduced peak acceleration (group means 1442 and 814cm/s2 in control and patient group, respectively) and peak velocity (103 vs. 82cm/s). The latencies of peak acceleration (68 vs. 209 ms), peak velocity (162 vs. 322 ms) and peak deceleration (251 ms vs. 390 ms) were almost twofold increased in the mutation carriers. Pointing error was increased in the patient group (1.1cm vs. 3.3cm). The differences between the groups were not influenced by a simultaneous saccade or the blanking of the target.

Discussion:

The kinematic parameters (acceleration, velocity) of hand pointing movements were profoundly altered in SCA17 patients leading to hand dysmetria while approaching the target. Since hand pointing deficits did not differ in the condition without saccades they do not reflect an inherent eye-hand coordination deficit. They are compatible with cerebellar disease of other origin (Topka et al 1998).