Objectives: Recent studies have suggested a further differentiation of PSP in Richardson's Syndrome
(RS) and PSP-Parkinsonism (PSP-P). On clinical grounds, early PSP-P is hard to distinguish
from Idiopathic Parkinson's disease (IPD). Although vertical gaze palsy is one of
the core features in the diagnosis of progressive supranuclear palsy (PSP), it is
reported to occur later if at all in PSP-P compared to RS. The aim of this study was
to search for possibly early oculomotor abnormalities in the PSP-P subset out of a
sample of PSP patients via video-oculography (VOG) and to compare these findings with
those of RS and IPD patients and a control group.
Materials and Methods: Twelve cases of RS, 5 cases of PSP-P and 27 cases of IPD were examined by use of
VOGand compared to 39 healthy controls. In order to elicit possible correlations between
the clinical data and the oculomotor parameters, a clinical data sheet was designed
for all patients including the core symptoms of Parkinsonian syndromes as well as
the Hoehn & Yahr scale. For statistical analysis, all VOG parameters were subjected
to an ANOVA analysis and suspected differences between the groups were analyzed with
the Mann-Whitney-U test.
Results: VOG showed statistically significant differences of RS and PSP-P patients in comparison
with both IPD patients and normal controls. Thus, a clear-cut separation of both PSP
syndromes and IPD could be achieved based upon VOG. The oculomotor dysfunction, however,
did not differ between RS and PSP-P since PSP-P patients exhibited similar oculomotor
alterations as RS patients although they were still in an early stage of the disease.
A correlation of VOG data and clinical data could not be observed.
Conclusion: Via VOG, it was possible to measure a statistically significant slowing of reactive
saccades in PSP-P compared with patients and controls. Remarkably, these alterations
occured already in the early course of disease, when the clinical hallmarks of PSP-P
like lateralisation of rigidity and akinesia as well as levodopa responsivity were
still apparent. This finding can be considered as an early specific sign of gaze palsy
in PSP-P. Hence, in view of the difficulties in the early differentiation of PSP-P
and IPD on clinical grounds, VOG might play an important role in the diagnostics of
these entities. Further studies in larger samples will be necessary to analyse if
the observed early affection of eye movement in PSP-P is more common than yet expected.
