Using eye saccade velocity to distinguish PSP-P and PD

This interesting research out of Germany looked at 12 cases of the RS (Richardson’s Syndrome) form of PSP, 5 cases of the PSP-P (PSP-Parkinsonism) form, 27 cases of Parkinson’s Disease, and 23 healthy controls. (It was just published on PubMed though the journal is dated Dec ’08 and the epub is dated 1/14/09.)

At the bottom of this post I’ve copied an abstract of an ’05 journal article explaining the terms RS and PSP-P. In short, “Cases of RS syndrome [make] up 54% of all cases, and [are] characterized by the early onset of postural instability and falls, supranuclear vertical gaze palsy and cognitive dysfunction.” “A second group of [32% are] characterized by asymmetric onset, tremor, a moderate initial therapeutic response to levodopa and were frequently confused with Parkinson’s disease (PSP-P).”

Because PSP-P and PD are so similar in symptoms, clinicians need a way to differentiate the two disorders. The German researchers conclude that video-oculography (VOG) can be used because of the “clear-cut separation between PSP-P and [PD] obtained by measuring saccade velocity.” Typically, a neuro-ophthalmologist has the equipment to conduct a VOG.

It should be noted that none of the patients had pathologically-confirmed diagnoses, so the results may change based upon that.


Journal of Neurology. 2008 Dec;255(12):1916-1925. Epub 2009 Jan 14.

Differential diagnostic value of eye movement recording in PSP-parkinsonism, Richardson’s syndrome, and idiopathic Parkinson’s disease.

Pinkhardt EH, Jürgens R, Becker W, Valdarno F, Ludolph AC, Kassubek J.
Dept. of Neurology, University of Ulm, Ulm, Germany.

Vertical gaze palsy is a highly relevant clinical sign in parkinsonian syndromes. As the eponymous sign of progressive supranuclear palsy (PSP), it is one of the core features in the diagnosis of this disease.

Recent studies have suggested a further differentiation of PSP in Richardson’s syndrome (RS) and PSP-parkinsonism (PSPP).

The aim of this study was to search for oculomotor abnormalities in the PSP-P subset of a sample of PSP patients and to compare these findings with those of (i) RS patients, (ii) patients with idiopathic Parkinson’s disease (IPD), and (iii) a control group. Twelve cases of RS, 5 cases of PSP-P, and 27 cases of IPD were examined by use of video-oculography (VOG) and compared to 23 healthy normal controls.

Both groups of PSP patients (RS, PSP-P) had significantly slower saccades than either IPD patients or controls, whereas no differences in saccadic eye peak velocity were found between the two PSP groups or in the comparison of IPD with controls.

RS and PSP-P were also similar to each other with regard to smooth pursuit eye movements (SPEM), with both groups having significantly lower gain than controls (except for downward pursuit); however, SPEM gain exhibited no consistent difference between PSP and IPD.

A correlation between eye movement data and clinical data (Hoehn & Yahr scale or disease duration) could not be observed.

As PSP-P patients were still in an early stage of the disease when a differentiation from IPD is difficult on clinical grounds, the clear-cut separation between PSP-P and IPD obtained by measuring saccade velocity suggests that VOG could contribute to the early differentiation between these patient groups.

PubMed ID#: 19224319 (see for this same abstract)

Here’s an abstract of an important paper on PSP in 2005 that introduced the terminology RS and PSP-P:

Brain. 2005 Jun;128(Pt 6):1247-58. Epub 2005 Mar 23.

Characteristics of two distinct clinical phenotypes in pathologically proven progressive supranuclear palsy: Richardson’s syndrome and PSP-parkinsonism.

Williams DR, de Silva R, Paviour DC, Pittman A, Watt HC, Kilford L, Holton JL, Revesz T, Lees AJ.
The Queen Square Brain Bank for Neurological Disorders, University College London, UK.

The clinical diagnosis of progressive supranuclear palsy (PSP) relies on the identification of characteristic signs and symptoms. A proportion of pathologically diagnosed cases do not develop these classic features, prove difficult to diagnose during life and are considered as atypical PSP. The aim of this study was to examine the apparent clinical dichotomy between typical and atypical PSP, and to compare the biochemical and genetic characteristics of these groups. In 103 consecutive cases of pathologically confirmed PSP, we have identified two clinical phenotypes by factor analysis which we have named Richardson’s syndrome (RS) and PSP-parkinsonism (PSP-P). Cases of RS syndrome made up 54% of all cases, and were characterized by the early onset of postural instability and falls, supranuclear vertical gaze palsy and cognitive dysfunction. A second group of 33 (32%) were characterized by asymmetric onset, tremor, a moderate initial therapeutic response to levodopa and were frequently confused with Parkinson’s disease (PSP-P). Fourteen cases (14%) could not be separated according to these criteria. In RS, two-thirds of cases were men, whereas the sex distribution in PSP-P was even. Disease duration in RS was significantly shorter (5.9 versus 9.1 years, P < 0.001) and age at death earlier (72.1 versus 75.5 years, P = 0.01) than in PSP-P. The isoform composition of insoluble tangle-tau isolated from the basal pons also differed significantly. In RS, the mean four-repeat:three-repeat tau ratio was 2.84 and in PSP-P it was 1.63 (P < 0.003). The effect of the H1,H1 PSP susceptibility genotype appeared stronger in RS than in PSP-P (odds ratio 13.2 versus 4.5). The difference in genotype frequencies between the clinical subgroups was not significant. There were no differences in apolipoprotein E genotypes. The classic clinical description of PSP, which includes supranuclear gaze palsy, early falls and dementia, does not adequately describe one-third of cases in this series of pathologically confirmed cases. We propose that PSP-P represents a second discrete clinical phenotype that needs to be clinically distinguished from classical PSP (RS). The different tau isoform deposition in the basal pons suggests that this may ultimately prove to be a discrete nosological entity.

PubMed ID#: 15788542 (see for abstract only)

If you want to read the full paper published in Brain ’05, it’s available online for free here:
I have found that articles that are available for free are not always left online for free access. So if you want to save a copy of this article on your hard drive, do so now.