The use of hydromorphone and clonidine, delivered intrathecally by an implanted infusion pump, is described in a patient with intractable cancer pain. The patient was a 48-year-old woman with uterine cervical cancer-related pain that was poorly responsive to conventional oral narcotics. Hydromorphone was used because of the patient's history of morphine intolerance. When progressive intrathecal hydromorphone dosages were required, intrathecal clonidine (an alpha 2 adrenergic agonist) was infused concomitantly. Intrathecal hydromorphone and clonidine successfully controlled this patient's pain without the necessity to resort to destructive neurosurgery.

Cryoanalgesia, the technique of freezing peripheral nerves, is used clinically for the treatment of postoperative and chronic pain. Paradoxically, this same technique produces characteristics in a rat model suggestive of neuropathic pain. We have developed a peripheral neuropathy model by freezing the proximal sciatic nerve (sciatic cryoneurolysis, SCN) using a cryoprobe cooled to -60 degrees C in a 30/5/30 sec freeze-thaw-freeze sequence. Each freeze cycle produced a transient ice ball on the surface of the nerve. These studies provide behavioral evidence that SCN is a valid mononeuropathy animal model. All animals demonstrate some degree of autotomy following SCN. The average onset of autotomy occurs 4 days postoperatively and peaks in severity and incidence at 14 days. By examining the latency of responses to a noxious heat stimulus, we have shown there is no direct relationship between an hypoesthetic paw and autotomy, i.e., autotomy did not occur immediately after the freeze lesion when the limb was dysfunctional. Rather, autotomy peaked when sensation was returning to the affected limb. The transient time course of certain behaviors including hypoesthesia and possible return of limb sensation, autotomy, touch-evoked allodynia, foot edema and the presence of spontaneous nociceptive behaviors demonstrate a multiple phase nociceptive process. The temporary nature of these nociceptive behaviors is in sharp contrast to the prolonged bilateral mechanical allodynia evident when these behaviors subside. The surgical anesthetics used during the SCN procedure are shown to variably alter or suppress autotomy following SCN.(ABSTRACT TRUNCATED AT 250 WORDS)

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Preliminary reports of continuous intraspinal morphine analgesia have been enthusiastic regarding the resultant cancer pain control. Reports of continuous intraspinal infusion have not documented the duration of useful analgesia, need for concomitant analgesic therapies, or complication rates. Thus, the overall outcomes and complications of six chronic intrathecal and eight epidural morphine infusions were analyzed in the first 14 cancer pain patients implanted with continuous intraspinal morphine infusion reservoirs at this clinic. A five-point scale was used to assess the analgesic therapy required to maintain pain control during three consecutive intervals of intraspinal morphine infusion (zero to two months, two to six months, after six months). Comparison with pre-implant narcotic requirements revealed equal or reduced narcotic use for up to six months of therapy, with a definite trend toward escalation of intraspinal narcotics, systemic analgesia, and adjunctive procedures after two months. This occurred most likely due to narcotic tolerance and disease progression. Failure of pain control was the rule with continuous intraspinal morphine after six months. Three patients ultimately required neurolytic blocks. No clear difference was found in pain control requirements between epidural and intrathecal morphine infusion. No infection or respiratory depression occurred as a direct result of the intraspinal morphine implanted system.

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