Are sympathetic blocks useful for diagnostic purposes?
Elena K Krumova1, Christoph Gussone, Sabrina Regeniter
1Department of Pain Management, Clinic of Anaesthesiology, Intensive Care, Palliative and Pain Medicine, BG University Hospital Bergmannsheil Bochum, Ruhr-University of Bochum, Germany. Elena.Krumova@rub.de
Regional Anesthesia and Pain Medicine
|September 24, 2011
Summary
Sympathetic blocks aid in diagnosing sympathetically maintained pain (SMP). However, careful monitoring is crucial to avoid false positives or negatives, ensuring accurate diagnosis of neuropathic pain.
Area of Science:
- Anesthesiology
- Pain Management
- Neurology
Background:
- Sympathetically maintained pain (SMP) is a type of neuropathic pain.
- Clinical diagnosis of SMP often involves sympathetic blocks (SBs).
- The accuracy of SBs depends on effective sympathetic blockade and avoiding sensory nerve block.
Purpose of the Study:
- To evaluate the diagnostic utility of sympathetic blocks for sympathetically maintained pain.
- To assess the rate of diagnostically valuable SBs performed by anesthesiologists.
- To determine the necessary monitoring duration for accurate SMP diagnosis.
Main Methods:
- Pilot study involving 19 patients undergoing stellate/thoracic or lumbar blocks.
- Pain ratings, bilateral skin temperature, and sensory detection thresholds (cold, warmth, tactile, vibration) were monitored before and after SBs.
- Monitoring extended up to 6 hours post-block, with specific attention to skin temperature and sensory thresholds for 120 minutes.
Main Results:
- 43% of SBs were ineligible for SMP diagnosis due to insufficient temperature change or altered sensory thresholds.
- In a subset of blocks with no significant sensory changes, 3 patients (25%) were diagnosed with SMP.
- Adequate sympathetic blockade without sensory compromise was achieved in some cases, enabling diagnosis.
Conclusions:
- Sympathetic blocks are valuable tools for diagnosing sympathetically maintained pain.
- Diagnostic accuracy is limited by potential false positives (unintentional sensory block) and false negatives (insufficient sympathetic blockade).
- Continuous monitoring of sympathetic and somatosensory function for at least 90 minutes post-intervention is essential for reliable SMP diagnosis.
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