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Normal sympathetic nerve activity in a reflex sympathetic dystrophy with marked skin vasoconstriction
1Service of Clinical Neurophysiology, Foundation Clinica del Lavoro IRCCS-Pavia, Montescano, Italy.
Journal of the Autonomic Nervous System
|December 1, 1992
Summary
This study found that even with severe pain and vasoconstriction after finger amputation, sympathetic nerve activity was low. This suggests that increased sympathetic discharge does not always maintain neuropathic pain.
Area of Science:
- Neurology
- Pain Medicine
- Autonomic Nervous System Research
Background:
- Reflex sympathetic dystrophy (RSD) is a complex pain condition.
- It often involves sensory and autonomic disturbances like allodynia and vasoconstriction.
- The role of sympathetic nervous system overactivity in maintaining RSD pain is debated.
Observation:
- Intraneural recordings were made in a patient with RSD following Vth finger amputation.
- The patient experienced allodynia and marked vasoconstriction in the left hand.
- Skin sympathetic activity was monitored at rest and during various stimuli.
Findings:
- Resting sympathetic discharge was weak, with normal characteristics.
- Sympathetic bursts were evoked by sympatho-excitatory stimuli.
- Few sympathetic bursts were induced by painful stimuli or inspiratory gasps.
- Marked vasoconstriction was observed despite low sympathetic discharge.
Implications:
- Sympathetic effector organ hyperactivity (vasoconstriction, hyperhidrosis) does not equate to increased sympathetic neural discharge.
- The patient's neuropathic pain syndrome was not maintained by increased sympathetic neural discharge to the affected limb.
- This challenges the direct link between sympathetic overactivity and pain maintenance in certain neuropathic pain conditions.