Background: Recently, polyneuropathy has been been described in higher proportions for patients
with Parkinson’s disease (PD) than in normal population. This finding was hypothesized to be related
to the elevation of plasma homocysteine, following the management of PD with levodopa. We
conducted this study to clarify the clinical value of elevated plasma homocysteine in PD patients for
their relation to polyneuropathy.
Methods: A total of 37 PD patients without neuropathy (PD control) and 41 PD patients with polyneuropathy
(PDP), who were recruited for this study, were compared with age and sex matched 48 healthy
controls. All PD patients performed electrophysiological tests, including nerve conduction study, to
diagnose polyneuropathy. Plasma homocysteine levels were measured in all subjects and compared
between each groups.
Results: The homocysteine of PDP showed higher homocysteine level than those of PD control and
healthy controls. However, there was no significant difference in homocysteine levels between PD
control and healthy controls. In each group of PD control and PDP, there were no intercorrelations
between daily levodopa dose, duration of PD symptoms and PD treatment or motor severity with
homocysteine levels.
Conclusions: We could cautiously assume that plasma homocysteine level may be related with the
involvement of peripheral nerve of PD patients in this study. The pathophysiologic role of homocysteine
and the relationship between plasma homocysteine level and levodopa in PDP need to be confirmed.



KEYWORDS
Homocysteine,
Parkinson’s disease,
Polyneuropathy