Nerve root pricking and intra-vascular injection during Kambin's triangle and subpedicular approaches of Lumbar Transforaminal Epidural Injection, are common (1). Furthermore, artery spasm, is known to be related to needle-artery contact or intra-vascular injections. 
The aim of the study was to assess whether an iodine contrast injection of local anaesthetics and dexamethasone at the level of the mid L4-L5 or L5-S1 inter-transverse ligament (fig 1), allows its diffusion to peri-radicular areas. 
This would minimize the chances of the described complications.
In two patients with L4-5 and L5-S1 bilateral symptomatic spinal stenosis respectively, needles were placed in three different positions under CT scan: 1) at the posterior mid-level of the L4 transverse process and both 2) superficially and 3) deep into the inter-transverse ligament (ITL) of L4-5 and L5-S1. A 3cc iodine contrast solution was administered along with 7 cc of 0.125% bupivacaine with 2 mg of dexamethasone at each site. 

CT-3D contrast segmentation was performed to analyse injectate diffusion.

In both needle positions (L4-5 and L5-S1) deep into the inter-transverse ligament, the solution reached both peri-radicular L4 and L5 areas (fig 2). 
Injectable solution spread mainly to posterior areas, including medial and lateral branches, when needle was placed posterior to the inter-transverse ligament or superficial to the transverse process (fig 3).

FEASIBILITY OF LUMBAR PERI-RADICULAR AND MEDIAL BRANCH BLOCK THROUGH MID LATERAL INTER-TRANSVERSE LIGAMENT NEEDLE PLACEMENT