Analgesic Territory Assessment of the Spinal Erector Block Using Pupillometry

Few works have studied the area of analgesia covered by the spinal erector block in an objective manner, especially on the cephalo-caudal spread. The available data are dissection works or subjective data such as thermoalgesic or epicritic sensitivity.This information would however be relevant in order to propose a better analgesia. Indeed, it could explain certain failures by insufficient diffusion of the block. The use of a multistage block could be relevant, especially in the case of osteosynthesis on several vertebral levels.

Inclusion Criteria:Patients receiving erector spinae block for pain management of spinal osteosynthesisExclusion Criteria:Patient refusalKnown allergy to local anestheticsContraindication to locoregional anesthesia (haemostasis disorder, infection, peripheral neuropathy)Technical impossibility to perform a spinal erector blockPathology with dysautonomia altering the pupillary reflex: diabetes mellitus with diabetic retinopathy, multiple sclerosis, systemic amyloidosis, uncontrolled hypertension, glaucomaCurrent treatment likely to alter pupillary dilation reflex to pain : antiemetic (droperidol, metoclopramide), alpha-2 agonist (clonidine)Serious psychiatric historyDrug abusePregnancy