Proprioceptive reflexes in patients with reflex sympathetic dystrophy
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Reflex sympathetic dystrophy (RSD) is a syndrome that frequently follows an injury and is characterized by sensory, autonomic and motor features of the affected extremities. One of the more common motor features of RSD is tonic dystonia, which is caused by impairment of inhibitory interneuronal spinal circuits. In this study the circuits that modulate the gain of proprioceptive reflexes of the shoulder musculature are quantitatively assessed in 19 RSD patients, 9 of whom presented with dystonia. The proprioceptive reflexes are quantified by applying two types of force disturbances: (1) disturbances with a fixed low frequency and a variable bandwidth and (2) disturbances with a small bandwidth around a prescribed centre frequency. Compared to controls, patients have lower reflex gains for velocity feedback in response to the disturbances around a prescribed centre frequency. Additionally, patients with dystonia lack the ability to generate negative reflex gains for position feedback, for these same disturbances. Proprioceptive reflexes to the disturbances with a fixed low frequency and variable bandwidth present no difference between patients and controls. Although dystonia in the RSD patients was limited to the distal musculature, the results suggest involvement of interneuronal circuits that mediate postsynaptic inhibition of the motoneurons of the proximal musculature.
KeywordsReflex sympathetic dystrophy Dystonia Propriocepsis Reflexes Shoulder
This research was supported financially by the Netherlands Organization for Scientific Research (NWO).
- Illert M, Kummel H, Scott JJ (1996) Beta innervation and recurrent inhibition: a hypothesis for manipulatory and postural control. Pflugers Arch 432:R61–R67Google Scholar
- Jenkins GM, Watts DG (1968) Spectral analysis and its applications. Holden-Day, San FranciscoGoogle Scholar
- Van Hilten BJ, Van de Beek WJT, Hoff JI, Voormolen JH, Delhaas EM (2000) Intrathecal baclofen for the treatment of dystonia in patients with reflex sympathetic dystrophy. N Engl J Med 343:625–630Google Scholar