Thermal grill illusion and complex regional pain syndrome type I (reflex sympathetic dystrophy).

BACKGROUND AND OBJECTIVES

In normal humans, placing a hand on a thermal grill containing warm elements separated by cool ones produces a burning sensation. In this case report, responses to a thermal grill in a patient with neuropathic pain were examined.

METHODS

The responses of a 31-year-old woman with complex regional pain syndrome type I (reflex sympathetic dystrophy) to a thermal grill were evaluated before and after stellate ganglion block.

RESULTS

The patient experienced a burning sensation when the unaffected hand was placed on the grill and could distinguish which element was warm and which was cool. An intolerable burning sensation caused the patient to quickly (within 4 seconds) withdraw the affected hand when it was placed on the grill. Touching cool elements with the affected hand produced an intense burning sensation (cold allodynia), whereas touching warm elements produced a pleasant warm sensation. Stellate ganglion block with phenol, local anesthetic, and steroid resulted in long-lasting absence of cold allodynia.

CONCLUSION

The thermal grill may be a useful a tool to help understand the pathophysiology of complex regional pain syndrome type I.