A LOW-FREQUENCY, HIGH AMPLITUDE RHYTHMIC FLUCTUATION OF LASER-DOPPLERSKIN BLOOD-FLOW AFTER SUBARACHNOID PHENOL BLOCK

A 51-year-old male with a huge chondrosarcoma received subarachnoid do rsal root blocks with 10% phenol in glycerine to treat severe pain alo ng the left leg. The dermatomes below the Th9 lost all somatic sensati on on the left side after the nerve blocks, but the patient was not co mpletely relieved from the pain. Laser-Doppler flowmetry on the toe of the left foot disclosed an increased blood flow and an abnormal fluct uation of the cutaneous capillary blood flow, i.e. a high amplitude rh ythmic (HAR) wave with 2.5 to 3 cycles . min-1. The low frequency HAR wave persisted for the subsequent 3 months until a tingling sensation returned to the left leg. It would seem that some travelling roots of the sympathetic nerve were preserved from the chemical neurolysis and the remaining efferent and afferent nerve fibers were responsible for the persisting low frequency HAR wave and pain in the left leg.