Abnormalities of optokinetic nystagmus in progressive supranuclear palsy

Abstract

Objectives: To measure vertical and horizontal responses to optokinetic (OK) stimulation and investigate directional abnormalities of quick phases in progressive supranuclear palsy (PSP). Methods: Saccades and OK nystagmus were studied in six PSP patients, five with Parkinson's disease (PD), and 10 controls. The OK stimulus subtended 72˚horizontally, 60˚vertically, consisted of black and white stripes, and moved at 10-50˚/s. Results: All PSP patients showed slowed voluntary vertical saccades and nystagmus quick phases compared with PD or controls. Small, paired, horizontal saccadic intrusions (SWJ) were more frequent and larger in PSP during fixation. Vertical saccades were transiently faster at the time of SWJ and horizontal saccades in PSP. During vertical OK nystagmus, small quick phases were often combined with horizontal SWJ in all subjects; in PSP the vector was closer to horizontal. Vertical OK slow phase gain was reduced in PSP but, in most PD patients, was similar to normals. The average position of gaze shifted in the direction of vertical OK stimulus in PSP patients with preserved slow phase responses but impaired quick phases. Conclusions: Vertical OK responses in PSP show impaired slow phase responses, and quick phases that are slowed and combined with SWJ to produce an oblique vector. SWJ facilitate vertical saccades and quick phases in PSP, but it is unclear whether this is an adaptive process or a result of the disease. A large OK stimulus is useful to induce responses that can be quantitatively analysed in patients with limited voluntary range of vertical gaze.

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

“…In contrast, both PSP subgroups were significantly slower than controls and, noticeably, also significantly slower than IPD, while being mutually indistinguishable in terms of velocity. In line with clinical observations and eye movement studies [1,4], slowing was particularly evident in vertical Fig. 3 Population median values of horizontal (a) and vertical (b) saccade peak velocity as a function of saccade amplitude; note that for every direction and amplitude, peak velocities of IPD patients and controls are almost indistinguishable from each other whereas those of both PSP groups are considerably smaller direction where large saccades reached less than 30 % (RS) and 35 % (PSP-P) of the normal value, respectively, whereas horizontal saccades reached about 60 % (RS) and 70 % (PSP-P), respectively.…”

Distinctive Features of Saccadic Intrusions and Microsaccades in Progressive Supranuclear Palsy

“…Future research should moreover establish whether SWJs made by patients with other parkinsonian disorders, such as multiple system atrophy (Rascol et al, 1991; Pinnock et al, 2009), or cerebellar conditions such as Friedreich's ataxia, can be distinguished on this basis. Such studies seem justified (Rascol et al, 1991; Garbutt et al, 2004; Antoniades et al, 2007; Pinnock et al, 2009). In our analyses, the most powerful discriminator – evident during ROC analysis (Figure 5), was the size of vertical components of saccades.…”

Corticobasal degeneration

“…Thus, some patients with CBD may be mistakenly thought to have ophthalmoplegia if not given suffi cient time or stimulation to generate a saccade. Unequivocal slowing of vertical saccades (often best demonstrated by testing optokinetic nystagmus) or vertical supranuclear ophthalmoplegia early in the course suggests PSP rather than CBD [21].…”