Effects of local anesthetic infiltration on brain potentials evoked by painful dental stimulation

an image intensifier and 2 ml of air was injected through each to confirm that the tip lay in the correct fascial plain; 4 ml 7.5% aqueous phenol were injected through each needle. It is often necessary to repeat it before a fully successful result is obtained. The possible reasons for this success are discussed. Firstly, the original pain could have been a neuralgia caused by trauma or infection and subsequent surgery was the result of misdiagnosis. Secondly, damage to nervous tissue could have occurred during initial or subsequent necessary surgery. Thirdly, sympathetic lysis could also successfully relieve the pain in these circumstances. And also the utilities of diagnosis block are discussed.

ANESTHESIOLOGY Failure of transcutaneous electrical stimulation to alleviate experimental tourniquet pain. - R.M. Rosenblatt and A. Hetherington, Anesth. Analg. Curr. Res., 60 (1981) 720-722 The authors evaluated the effectiveness of transcutaneous electrical nerve stimulation (TENS) in alleviating ischemic pain produced experimentally during a submaximal-effort tourniquet test. Ten subjects were studied on 3 separate occasions. Cutaneous electrodes were placed proximal to the tourniquet and TENS was begun before ‘exsanguination’ of the arm by temporary tight application of an elastic bandage. The subjects then exercised the ischemic arm by repetitively squeezing a hand-held dynamometer. The time from inflation of the tourniquet to the onset of intolerable pain was noted; the subjects were also asked to indicate the pain intensity on a visual analog scale. TENS did not prolong the tolerated duration of ischemia or cause any reduction in the subjective intensity of pain. Effects of local anesthetic infiltration on brain potentials evoked by painful dental stimulation. - J.D. Gehrig, Y.H. Colpitts and C.R. Chapman, Anesth. Analg. Curr. Res., 60 (1981) 7799782 Painful electrical stimulation was applied to the pulp of healthy unfilled lateral incisor teeth. In 10 volunteers both the cerebral evoked potential wave form and the subjective pain were eliminated by infiltrating lidocaine 2% over the apex of the tooth. Saline infiltration under identical conditions in 10 other volunteers had no effect. The results support the claim that cerebral evoked potentials recorded during painful dental stimulation are a reliable physiologic correlate of human pain.

NEUROLOGY Reversible inactivation of raphe magnus neurons: effects on nociceptive threshold and morphine-induced analgesia. - H.K. Proudfit, Brain Res., 201 (1980) 459-464 Electrolytic lesions made in raphe magnus of the rat caused a decrease in nociceptive threshold on the tail-flick test but no alteration in the capacity of morphine to produce analgesia. The same result was obtained with injecting tetra-