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The existence of a differential block is still part of the theory of regional anaesthesia. In 1980 it was described in detail by Cousins and Bridenbough in their standard work Neural Blockade. The theory of differential sensitivity of fibres in the peripheral nervous system essentially goes back to Gasser and Erlanger, who in 1929 established that when isolated peripheral nerves are electri cally stimulated in the presence of increasing concentrations of co caine, the compound action potentials of slow-conducting fibres are blocked before those of fast-conducting fibres show any measur able changes. In man, regional anaesthesia begins subjectively with a feeling of warmth, objectively with a corresponding increase in skin tem perature. There is then, in order of occurence, loss of sensation of cold, heat and pain, and pressure and touch, and fmally loss of voluntary motoricity. In recovery from anaesthesia, these return in the reverse order. The theory of differential block is by no means undisputed. In 1981, de Jong, commenting in Anesthesiology on the work pub lished in that journal by Gissen et al. which showed a new sequence of differential sensitivity in the rabbit, wrote, "There remains plen ty to be done yet before the book on differential nerve block can be closed".
List of contents
Physiology and Pharmacology of Regional Anaesthesia.- Mode of Action of Local Anaesthetics.- Classification of Nerve Fibres by Conduction Velocity and Function.- Latency and Regression Times of Regional Anaesthesia.- Methods for Measuring Effectiveness of Local Anaesthesia on Groups of Fibres in Nervous System.- Animal Experiments.- Clinical Experiments.- Theory of Differential Block.- Experimental and Clinical Foundations.- Contradictory Findings.- Statement of Problem.- Methods.- Subjects and Parameters.- Techniques of Anaesthesia.- Blockade of Median Nerve.- Blockade of Brachial Plexus.- Blockade of Tibial Nerve and Common Peroneal Nerve.- Dosage and Choice of Local Anaesthetics.- Measurement of Voluntary Motoricity.- Measurement of Sympathetic Activity.- Cold Stimulation of Sympathetic Activity.- Measurement of Vasomotor Tone by Telethermography.- Technical Details of Measuring Apparatus.- Skin Areas Investigated.- Quantitative Evaluation of Thermograms.- Graphic Presentation of Measured Values.- Definition of Latency and Regression Times.- Evaluation of Results.- Results.- Documentation.- Individual Investigations.- Summary.- Discussion.- Criticism of Methods.- Discussion of Results.- A Notable Incidental Finding: Influence of Further Injections on Dynamics of Blockade.- Summary.- References.
