[High-dose intrathecal clonidine in the treatment of neuropathic tumor pain. Two case reports.].

Two cases with perineal pain caused by recurrent carcinoma of the rectum are reported. Initially both patients suffered from predominantly nociceptive pain, which was treated adequately with spinal opioids. Tumor growth with epidural spread and infiltration of the plexus lumbosacralis caused severe neuropathic pain. Both patients were free of pain with a combination of spinal clonidine and opioids. Clonidine doses had to be increased up to 1.31 and 1.46 mg daily in order to provide adequate analgesia. Outpatient treatment was possible for several weeks with stable dosage. Bradycardia and hypotension occurred with initial dose titration and after dose increases and were treated with parasympathicolytic drugs and vasopressor agents. Both patients were given spinal clonidine until their death 4 1/2 and 4 months later. In the final stages, adjuvant systemic administration of morphine was necessary to control dyspnea.