Biomedical subjects

A Overby

Publications and source records attributed to A Overby.

15 recordsLinked to original sources

PubMed2000

Computerized posturography analysis of progressive supranuclear palsy: a case-control comparison with Parkinson's disease and healthy controls.

BACKGROUND: Progressive supranuclear palsy (PSP) is a neurodegenerative disorder that is frequently mistaken for Parkinson's disease (PD) in its early stages. OBJECTIVE: To compare balance measures using computerized posturography in patients with early PSP and early PD. METHODS: We performed computerized posturography (SMART Balance Master; NeuroCom International, Inc, Clackamas, Ore) in 20 patients with clinically diagnosed mild to moderate PSP (ambulatory) and compared results with those from 20 patients with PD of similar age and disease duration who were not receiving medications, and from 20 healthy age- and sex-matched controls. Sensory organization testing (SOT), limits of stability (LOS), and toes-up perturbations (4 degrees at 50 degrees per second) were tested while receiving and not receiving a combination of oral carbidopa (25 mg) and levodopa (250 mg) in the PSP group. Clinical assessment included Unified Parkinson's Disease Rating Scale, Performance-oriented assessments, and functional reach. RESULTS: When compared with the PD and control groups, total LOS time (P < .001) and path sway (P < .001) were significantly prolonged in PSP. Total SOT showed significantly worse scores in PSP compared with PD and control groups (F(2,57) = 29.6; P < .001). Univariate follow-up tests comparing PSP and PD showed differences in the following conditions: eyes open and visual sway (P = .003), eyes open and platform sway (P = .003), eyes closed and platform sway (P < .001), and eyes open and platform and visual sway (P < .001). Medium- and long-latency responses to perturbation were similar, but a larger number in the PSP group lacked short-latency responses (chi(2) = 11.3; P = .002). Levodopa administration did not significantly improve any aspect of posturography testing in PSP. In differentiating PSP from PD, LOS time and SOT condition of eyes open and platform and visual sway were nearly 100% sensitive and 100% specific (canonical correlation, 0.91). CONCLUSIONS: Computerized posturography testing reliably differentiated early PSP from early PD and age-matched controls. The PSP group demonstrated severely contracted limits of stability with probable deficits in motor programming. Results of SOT in PSP suggested a vestibular pattern and overreliance on visual cues, even when incorrect. The absence of short-latency responses (monosynaptic reflex arch) suggests an additional disturbance in the spinal cord or peripheral nervous system. Arch Neurol. 2000;57:1464-1469

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PubMed2000

Postural control in Parkinson's disease after unilateral posteroventral pallidotomy.

Postural control changes were studied in 27 patients with Parkinson's disease after unilateral posteroventral pallidotomy (PVP). Patients were evaluated before PVP and at 3, 6 and 12 months post-PVP, both 'off' and 'on' parkinsonian medications, with selected evaluation tools representing functional performance, functional balance and posturographic components of balance. The majority of variables in the 'off' state were significantly improved at 3 months post-PVP. Improvement was maintained at 6 months but had declined for some variables by the 12 month follow-up. Standing up from a chair (P = 0.009), the balance and gait sections of the Performance-Oriented Assessment (P < or = 0.0004), and the limits of stability (LOS) posturography variables (P < 0.0005) of the average time to reach a target, the number of targets missed and the initial excursion distance to the target (P = 0.029) retained significant improvement at the 12 month follow-up. When the patients were in the 'on' state, LOS posturography variables of average time to target, average path length deviation, and the number of targets missed were the only variables significantly improved at 3 months post-PVP (P = -0.013) and this improvement was maintained at 12 months post-PVP (P = 0.012-0.041). Unilateral PVP improves axial symptoms of Parkinson's disease involved in functional performance such as gait disturbance as well as improving postural stability in the 'off' state. Generally, the maximum improvement is seen at 3 months post-PVP with many variables remaining significantly improved at 12 months post-PVP. Axial dyskinesias in the 'on' state are also significantly reduced with the improvement maintained at 12 months post-PVP. These findings suggest that unilateral pallidotomy is not only effective in abolishing levodopa-induced dyskinesias, but that it also improves the axial signs of Parkinson's disease.

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PubMed1997