DORSAL ROOT GANGLION BLOCKADE DURING THRESHOLD SEGMENTAL SPINAL ANESTHESIA IN MAN

¹ Department of Anesthesiology, College of Physicians and Surgeons, Columbia University; The Anesthesiology Service, The Presbyterian Hospital; The Research Service, Third New York University Medical Division, Goldwater Memorial Hospital, New York, N. Y.; and The Laboratory of Chemical Pharmacology, National Heart Institute, National Institutes of Health, Public Health Service, Department of Health, Education and Welfare, Bethesda, Maryland

Segmental spinal anesthesia of the lower thoracic and upper lumbar dermatomes was produced in ten adult human subjects by the intrathecal deposition of 0.5 ml. of 5 per cent procaine HC1 (25 mgm.) at the 12th thoracic vertebral level. The pattern of segmental sensory block and the concentrations of procaine in the spinal fluid at both the point of deposition and at more caudal levels support the concept that the dorsal root ganglion is more sensitive to the local anesthetic agent than either the cord or the dorsal roots when a minimal threshold block is produced.