April 2011
Oh YS, Kim JS, Chung SW, Song IU, Kim YD, Kim
YI, Lee KS
Background and purpose: Decreased visual
function is one of the non-motor dysfunctions of Parkinson’s disease
(PD). Recent evidences suggest that essential tremor (ET) is not ‘pure’
motor disorder and there is growing evidence that this disease is a
multiple-system disorder. In some cases, it is difficult to
differentiate ET from PD. In addition, there is considerable controversy
regarding the relationship between PD and ET. The objective of this
study was to compare color discrimination dysfunction amongst patients
with PD and ET and to investigate the clinical relevance.
Methods:
Case–control comparisons of 54 patients with PD, 36 patients with ET,
and 34 age-matched controls were performed. All cases underwent
Farnsworth–Munsell 100 Hue test (FMT) and clinical assessments on
medication. In addition, the association between color vision
abnormalities and motor handicaps was investigated.
Results:
There were significant differences in the total error scores (TES) of
the FMT amongst the three groups; patients with the PD had higher TES
than the patients with ET and the controls after adjustments for age. In
addition, the motor symptom severity in PD correlated with the FMT
abnormalities, especially with regard to the axial symptoms.
Conclusion:
The results of this study suggest that color vision abnormalities may
be one of the non-motor clinical characteristics of PD-related
dysfunction in contrast to ET. In addition, the severity of axial motor
symptoms was closely related to visual dysfunction. Confirmation of
these findings as well as the mechanisms underlying these results
requires further study.
