Efficacy of Soluble Dexamethasone in Refractory Sciatica

Inclusion Criteria: * Patients with sciatica of disc origin (radio-clinical concordance on MRI or CT) postero-lateral * Duration of evolution greater than 3 weeks despite analgesic / AINS treatment, and less than 3 months * EVA sciatica pain \> 4/10 * Oswestry 30 at inclusion * Patient aged 18 years and older * Patient affiliated to a social security scheme * Patient able to understand the protocol and having signed an informed consent * Patient with an indication for corticosteroid infiltration in the context of their pathology Criteria for non-inclusion * Signs or risks of infection, in particular signs of virosis * Poor local skin condition * Anticoagulation with VKA or anti-Xa, or haemorrhagic disease * Neurological deficit \< 3/5 or signs of cauda equina irritation * Tarlov's cyst or low dural sac below week 4 * Hypersensitivity to Lidocaine, Dexamethasone, or any of its excipients * Infiltration of the spine within the previous 3 months * Patient with bilateral sciatica * Patient with sciatica of osteoarthritic origin * Patients with chronic respiratory insufficiency * Pregnant or breastfeeding women or women refusing effective contraception until M3 * Patient deprived of liberty or under legal protection (guardianship or curatorship) * Patient under court protection * Patients participating in another clinical research protocol involving a drug or medical device * Patients unable to follow the protocol, as judged by the investigator * Patient refusing to participate in the study * Patient with clinically narrowed lumbar canal * Patient with polyneuropathy or myelopathy * Patient with sequelae of neuropathic pain