Small doses of morphine given intrathecally and extradurally produce long-lasting relief of chronic and postoperative pain in man (Behar et al., 1979; Wang, Nauss and Thomas, 1979). In addition to morphine, the efficacy of pethidine (Cousins et al., 1979), fentanyl (Bailey and Smith, 1980), methadone and hydromorphone (Bromage, Camporesi and Chestnut, 1980) has been studied. Using the extradural route, all the opiates, including pethidine, were able to interrupt pain at a spinal level without affecting motor and autonomic control (Cousins et al., 1979). Recent studies (Mircea et al., 1982; Sandu et al., 1983) showed that pethidine, unlike morphine, when given intrathecally did not produce a selective segmental analgesia, but exhibited all the effects of the subarachnoid administration of local anaesthetics-including motor, sensory and sympathetic blockades. Thus spinal anaesthesia was obtained which was adequate for surgical interventions, particularly in the perineal area. The purpose of this study was to assess the effectiveness of the intrathecal administration of pethidine in obtaining blockade, suitable for surgery on the perineum. PATIENTS AND METHODS Studies were carried out on 111 patients undergoing perineal surgery between March 1983 and December 1984 (table I). The group included 77 men and 34 women, aged between 20 and 72 yr (mean age of 37 yr). Institutional approval and informed patient consent were obtained.

Saddle blockade with pethidine hydrochloride was performed in 111 patients undergoing short surgical operations on the perineum. A dose of 5% pethidine 0.5 mg kg-1 was injected to the subarachnoid space at L4-5 or L5-S1 with the patient in the sitting position. Sensory blockade was achieved in 5.28 +/- 1.43 min. This extended to the sacrococcygeal area, perineum, buttocks and posterior surface of thighs, and was followed 1-2 min later by motor blockade. During the operation the patients were stable haemodynamically and no respiratory depression was recorded. Sensory blockade lasted for 141 +/- 26.06 min and was followed by postoperative analgesia, the mean duration of which was 301 +/- 98.38 min. Postoperative neurological complications were recorded in three patients (2.7%): headache alone in one, headache associated with backache in one, and leg weakness, backache, nuchal rigidity and photophobia in another. Seven patients (6.3%) complained of itching, five patients (4.5%) of nausea and vomiting and two (1.8%) developed urinary retention.