Reference Work Entry

Encyclopedia of Pain

pp 2382-2383

Sympathetically Maintained Pain, Clinical Pharmacological Tests

  • Peter D. DrummondAffiliated withSchool of Psychology, Murdoch University
  • , Jörn SchattschneiderAffiliated withDepartment of Neurology, University Hospital Schleswig-Holstein


SMP; sympathetically maintained pain; CRPS; complex regional pain syndrome


Neuropathic pain patients can be divided into groups based on their response to selective sympathetic blockade or antagonism of α-adrenoreceptor mechanisms (Price et al. 1998). The component of spontaneous and evoked pain (hyperalgesia) which is relieved by specific sympatholytic procedures is termed sympathetically maintained pain (SMP). Hyperalgesia can be defined as a leftward shift of the stimulus response function that relates the magnitude of pain to the intensity of a noxious stimulus. An increased sensitivity to painful heat is termed thermal hyperalgesia. Hyperalgesia can also be evoked by application of different mechanical stimuli; for instance, punctate stimuli (e.g. firm von Frey hairs) can evoke punctate hyperalgesia, whereas gently stroking sensitized skin with a cotton swab can provoke dynamic hyperalgesia (also termed mechanical allodynia).

Intradermal injection or iontophoresis ...

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