Neuro-ophthalmology of late-onset Tay-Sachs disease (LOTS).

Department of Neurology, Veterans Affairs Medical Center and University Hospitals, Case Western Reserve University, Cleveland, OH 44106-5040, USA.
Neurology (Impact Factor: 8.3). 12/2004; 63(10):1918-26. DOI: 10.1212/01.WNL.0000144275.76658.F4
Source: PubMed

ABSTRACT Late-onset Tay-Sachs disease (LOTS) is an adult-onset, autosomal recessive, progressive variant of GM2 gangliosidosis, characterized by involvement of the cerebellum and anterior horn cells.
To determine the range of visual and ocular motor abnormalities in LOTS, as a prelude to evaluating the effectiveness of novel therapies.
Fourteen patients with biochemically confirmed LOTS (8 men; age range 24 to 53 years; disease duration 5 to 30 years) and 10 age-matched control subjects were studied. Snellen visual acuity, contrast sensitivity, color vision, stereopsis, and visual fields were measured, and optic fundi were photographed. Horizontal and vertical eye movements (search coil) were recorded, and saccades, pursuit, vestibulo-ocular reflex (VOR), vergence, and optokinetic (OK) responses were measured.
All patients showed normal visual functions and optic fundi. The main eye movement abnormality concerned saccades, which were "multistep," consisting of a series of small saccades and larger movements that showed transient decelerations. Larger saccades ended earlier and more abruptly (greater peak deceleration) in LOTS patients than in control subjects; these changes can be attributed to premature termination of the saccadic pulse. Smooth-pursuit and slow-phase OK gains were reduced, but VOR, vergence, and gaze holding were normal.
Patients with late-onset Tay-Sachs disease (LOTS) show characteristic abnormalities of saccades but normal afferent visual systems. Hypometria, transient decelerations, and premature termination of saccades suggest disruption of a "latch circuit" that normally inhibits pontine omnipause neurons, permitting burst neurons to discharge until the eye movement is completed. These measurable abnormalities of saccades provide a means to evaluate the effects of novel treatments for LOTS.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Eye movements in essential tremor (ET) are poorly described and may present useful information on the underlying pathophysiology of the disorder. Sixty patients with ET, including 15 de novo untreated patients, and 60 age-matched controls constitute the study population. A video-based eye tracker was used to assess binocular eye position. Oculomotor function was assessed while subjects followed random horizontally and vertically step-displaced targets. For all reflexive saccades, latencies were increased in ET subjects by a mean of 16.3% (p<0.01). Saccades showed reduced peak velocities with a lengthy, wavering velocity plateau, followed by slowed decelerations. For larger 30°+ saccades, peak velocities were decreased by a mean of 25.2% (p<0.01) and durations increased by 31.8% (p<0.01). The frequency of square wave jerks (SWJs) in patients was more than triple that of controls (p<0.0001). Despite frequent interruptions by SWJs, fixations were otherwise stable and indistinguishable from controls (root mean square [RMS] velocity, p = 0.324). The abnormal eye movement parameters were independent of disease duration, tremor severity, and medication therapy. In contrast to normally swift onset and efficient acceleration/deceleration movements, saccades in ET are characterized by abnormally prolonged latencies and slowed velocity profiles. Although ET subjects maintain highly stable fixations, they are interrupted by increased numbers of SWJs. This study reveals novel oculomotor deficits in ET, which are distinct from the eye movement dysfunction of other movement disorders, supporting a role for eye tracking to assist in the differential diagnoses of not only atypical, but also more common movement disorders.
    01/2013; 3.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Recently, we have concerned the strategic optimization on logistic network design problems and developed an efficient two-level solution method using a meta-heuristic method like tabu search. To cope with extremely large-scale problems, in this paper, we propose an extended algorithm for the parallel computing that utilizes the analogy between the algorithm and the master-worker configuration of PC cluster. To enhance the efficiency, we developed a modified discrete algorithm of particle swarm optimization (PSO) that can deal with binary decision variables. Then, we applied it to a parallel procedure that requires only very small overhead for the parallel computing. Finally, we confirmed that the proposed method can bring about high performance for the parallel computing that is suitable for the present goal and circumstance through numerical experiments.
  • American Journal of Ophthalmology 03/2007; 143(3):543. DOI:10.1016/j.ajo.2007.01.007 · 4.02 Impact Factor

Full-text (2 Sources)

Available from
May 27, 2014