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Proprioceptive reflexes in patients with reflex sympathetic dystrophy
A C Schouten1, W J T Van de Beek, J J Van Hilten
1Delft University of Technology, Department of Mechanical Engineering, Man Machine Systems and Control, Mekelweg 2, 2628 CD Delft, Leiden, The Netherlands. a.c.schouten@wbmt.tudelft.nl
Experimental Brain Research
|May 14, 2003
Summary
Reflex sympathetic dystrophy (RSD) impairs spinal circuits, affecting motor control. This study found reduced reflex gains in RSD patients, particularly those with dystonia, suggesting altered inhibitory pathways.
Area of Science:
- Neuroscience
- Motor Control
- Clinical Neurology
Background:
- Reflex sympathetic dystrophy (RSD) is a post-injury syndrome with sensory, autonomic, and motor deficits.
- Tonic dystonia, a motor feature of RSD, arises from impaired spinal inhibitory interneuronal circuits.
- Understanding proprioceptive reflex modulation in RSD is crucial for explaining motor dysfunction.
Purpose of the Study:
- To quantitatively assess proprioceptive reflex modulation in shoulder muscles of RSD patients.
- To investigate differences in reflex gains between RSD patients with and without dystonia compared to controls.
- To explore the role of spinal interneuronal circuits in RSD-associated motor impairments.
Main Methods:
- Quantitative assessment of shoulder muscle proprioceptive reflexes in 19 RSD patients and controls.
- Application of two force disturbance types: fixed low frequency/variable bandwidth and small bandwidth/prescribed center frequency.
- Measurement of reflex gains for velocity and position feedback.
Main Results:
- RSD patients exhibited lower reflex gains for velocity feedback compared to controls, especially with prescribed center frequency disturbances.
- Patients with dystonia could not generate negative reflex gains for position feedback under the same conditions.
- No significant differences in proprioceptive reflexes were observed for fixed low frequency/variable bandwidth disturbances.
Conclusions:
- Impaired inhibitory interneuronal spinal circuits contribute to motor deficits in Reflex Sympathetic Dystrophy.
- Altered proprioceptive reflex gains, particularly in patients with dystonia, suggest dysfunction in postsynaptic inhibition of motoneurons.
- Findings indicate involvement of proximal muscle motoneuron circuits despite distal dystonia presentation in RSD.