Letters

Interrupting the sympathetic outflow in causalgia and reflex sympathetic dystrophy

BMJ 1998; 317 doi: http://dx.doi.org/10.1136/bmj.317.7160.752 (Published 12 September 1998) Cite this as: BMJ 1998;317:752

Terminology is outdated—1994 taxonomy should be used

  1. Laurie Allan, Director of chronic pain services
  1. Northwick Park and St Mark's NHS Trust, Harrow HA1 3UJ
  2. Pain Management Clinic, Queen Alexandra Hospital, Cosham, Portsmouth PO6 3LY
  3. Anaesthetic Department, Musgrove Park Hospital, Taunton, Somerset TA1 4NA

    EDITOR—Schott's editorial questions the value of interrupting the sympathetic outflow in causalgia and reflex sympathetic dystrophy when clinical studies and meta-analyses fail to prove benefit.1 Continued use of terms such as “reflex sympathetic dystrophy” merely serve to perpetuate the misconception that sympathetic block should always be therapeutic. A consensus workshop in 1993 recommended a new taxonomy—accepted by the International Association for the Study of Pain—in which “complex regional pain syndrome” types I and II replace the terms reflex sympathetic dystrophy and causalgia respectively.2 Reclassification has significant advantages in the establishment of clinical criteria for diagnosis, which should lead to reduced use of numerous synonyms and different treatments. Clinically, the triad of autonomic, motor, and sensory symptoms and signs are variable, and laboratory investigations (thermography, skin blood flow, sudomotor function, and galvanic skin and ice response) are beyond the capability of many hospitals.3 The three phase bone scan is helpful in only 50% of cases.

    Most authorities agree that the longer the pain remains untreated (with the concomitant disuse of the limbs), the greater the disability.4 Currently, referrals to pain clinics occur as a “last resort strategy,” so the result is a more difficult, complex treatment programme and a less successful outcome. The primary pain becomes complicated by secondary pain; gain phenomena; inability to perform daily, occupational, or recreational activities; inappropriate drug use; and even suicide.2 This is probably why single treatments, such as sympathetic blockade, do not provide complete pain relief in patients with long term symptoms.4 The clinical impression that smokers are refractory to sympathetic block therapy3 may also account for poor results. When diagnosis is definitive, with early referral …

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