SPINAL-ANESTHESIA INHIBITS CENTRAL TEMPORAL SUMMATION

in a previous investigation we found that extradural anaesthesia did n ot adequately inhibit temporal summation of repeated electrical stimul i: pain to repeated stimuli was blocked in only one of 10 patients, an d pain thresholds to repeated stimuli were significantly lower than pa in thresholds to a single stimulus. In this study we have investigated in 10 patients the effect of spinal anaesthesia on temporal summation , assessed by repeated electrical stimulation of the sural nerve. Plai n 0.5% bupivacaine 18 mg was injected at L2-3. The pain threshold to a single electrical stimulus, summation threshold (increase in percepti on during repeated electrical stimuli with five impulses of the same i ntensity at 2 Hz), pinprick and cold sensation were assessed. After sp inal anaesthesia, pain to both single and repeated stimulation, and pi nprick and cold sensation, disappeared in ail patients. We conclude th at spinal anaesthesia inhibits temporal summation elicited by repeated electrical stimulation.